connection.c File Reference

#include "postgres.h"
#include <poll.h>
#include "access/xact.h"
#include "catalog/pg_user_mapping.h"
#include "commands/defrem.h"
#include "common/base64.h"
#include "funcapi.h"
#include "libpq/libpq-be.h"
#include "libpq/libpq-be-fe-helpers.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postgres_fdw.h"
#include "storage/latch.h"
#include "utils/builtins.h"
#include "utils/hsearch.h"
#include "utils/inval.h"
#include "utils/syscache.h"

Include dependency graph for connection.c:

Go to the source code of this file.

Data Structures
struct	ConnCacheEntry

Macros
#define	CONNECTION_CLEANUP_TIMEOUT   30000
#define	RETRY_CANCEL_TIMEOUT   1000
#define	CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel)
#define	POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1   2
#define	POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2   6
#define	POSTGRES_FDW_GET_CONNECTIONS_COLS   6 /* maximum of above */

Typedefs
typedef Oid	ConnCacheKey
typedef struct ConnCacheEntry	ConnCacheEntry

Enumerations
enum	pgfdwVersion { PGFDW_V1_1 = 0 , PGFDW_V1_2 }

Functions
	PG_FUNCTION_INFO_V1 (postgres_fdw_get_connections)
	PG_FUNCTION_INFO_V1 (postgres_fdw_get_connections_1_2)
	PG_FUNCTION_INFO_V1 (postgres_fdw_disconnect)
	PG_FUNCTION_INFO_V1 (postgres_fdw_disconnect_all)
static void	make_new_connection (ConnCacheEntry *entry, UserMapping *user)
static PGconn *	connect_pg_server (ForeignServer *server, UserMapping *user)
static void	disconnect_pg_server (ConnCacheEntry *entry)
static void	check_conn_params (const char **keywords, const char **values, UserMapping *user)
static void	configure_remote_session (PGconn *conn)
static void	do_sql_command_begin (PGconn *conn, const char *sql)
static void	do_sql_command_end (PGconn *conn, const char *sql, bool consume_input)
static void	begin_remote_xact (ConnCacheEntry *entry)
static void	pgfdw_xact_callback (XactEvent event, void *arg)
static void	pgfdw_subxact_callback (SubXactEvent event, SubTransactionId mySubid, SubTransactionId parentSubid, void *arg)
static void	pgfdw_inval_callback (Datum arg, int cacheid, uint32 hashvalue)
static void	pgfdw_reject_incomplete_xact_state_change (ConnCacheEntry *entry)
static void	pgfdw_reset_xact_state (ConnCacheEntry *entry, bool toplevel)
static bool	pgfdw_cancel_query (PGconn *conn)
static bool	pgfdw_cancel_query_begin (PGconn *conn, TimestampTz endtime)
static bool	pgfdw_cancel_query_end (PGconn *conn, TimestampTz endtime, TimestampTz retrycanceltime, bool consume_input)
static bool	pgfdw_exec_cleanup_query (PGconn *conn, const char *query, bool ignore_errors)
static bool	pgfdw_exec_cleanup_query_begin (PGconn *conn, const char *query)
static bool	pgfdw_exec_cleanup_query_end (PGconn *conn, const char *query, TimestampTz endtime, bool consume_input, bool ignore_errors)
static bool	pgfdw_get_cleanup_result (PGconn *conn, TimestampTz endtime, TimestampTz retrycanceltime, PGresult **result, bool *timed_out)
static void	pgfdw_abort_cleanup (ConnCacheEntry *entry, bool toplevel)
static bool	pgfdw_abort_cleanup_begin (ConnCacheEntry *entry, bool toplevel, List **pending_entries, List **cancel_requested)
static void	pgfdw_finish_pre_commit_cleanup (List *pending_entries)
static void	pgfdw_finish_pre_subcommit_cleanup (List *pending_entries, int curlevel)
static void	pgfdw_finish_abort_cleanup (List *pending_entries, List *cancel_requested, bool toplevel)
static void	pgfdw_security_check (const char **keywords, const char **values, UserMapping *user, PGconn *conn)
static bool	UserMappingPasswordRequired (UserMapping *user)
static bool	UseScramPassthrough (ForeignServer *server, UserMapping *user)
static bool	disconnect_cached_connections (Oid serverid)
static void	postgres_fdw_get_connections_internal (FunctionCallInfo fcinfo, enum pgfdwVersion api_version)
static int	pgfdw_conn_check (PGconn *conn)
static bool	pgfdw_conn_checkable (void)
static bool	pgfdw_has_required_scram_options (const char **keywords, const char **values)
PGconn *	GetConnection (UserMapping *user, bool will_prep_stmt, PgFdwConnState **state)
void	do_sql_command (PGconn *conn, const char *sql)
void	ReleaseConnection (PGconn *conn)
unsigned int	GetCursorNumber (PGconn *conn)
unsigned int	GetPrepStmtNumber (PGconn *conn)
PGresult *	pgfdw_exec_query (PGconn *conn, const char *query, PgFdwConnState *state)
PGresult *	pgfdw_get_result (PGconn *conn)
void	pgfdw_report_error (int elevel, PGresult *res, PGconn *conn, bool clear, const char *sql)
Datum	postgres_fdw_get_connections_1_2 (PG_FUNCTION_ARGS)
Datum	postgres_fdw_get_connections (PG_FUNCTION_ARGS)
Datum	postgres_fdw_disconnect (PG_FUNCTION_ARGS)
Datum	postgres_fdw_disconnect_all (PG_FUNCTION_ARGS)

Variables
static HTAB *	ConnectionHash = NULL
static unsigned int	cursor_number = 0
static unsigned int	prep_stmt_number = 0
static bool	xact_got_connection = false
static uint32	pgfdw_we_cleanup_result = 0
static uint32	pgfdw_we_connect = 0
static uint32	pgfdw_we_get_result = 0

Macro Definition Documentation

CONNECTION_CLEANUP_TIMEOUT

#define CONNECTION_CLEANUP_TIMEOUT   30000

Definition at line 97 of file connection.c.

CONSTRUCT_ABORT_COMMAND

#define CONSTRUCT_ABORT_COMMAND	(		sql,
			entry,
			toplevel
	)

Value:

    do { \
        if (toplevel) \
            snprintf((sql), sizeof(sql), \
                     "ABORT TRANSACTION"); \
		else \
			snprintf((sql), sizeof(sql), \
                     "ROLLBACK TO SAVEPOINT s%d; RELEASE SAVEPOINT s%d", \
                     (entry)->xact_depth, (entry)->xact_depth); \
    } while(0)

Definition at line 107 of file connection.c.

POSTGRES_FDW_GET_CONNECTIONS_COLS

#define POSTGRES_FDW_GET_CONNECTIONS_COLS   6 /* maximum of above */

Definition at line 2136 of file connection.c.

POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1

#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1   2

Definition at line 2134 of file connection.c.

POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2

#define POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2   6

Definition at line 2135 of file connection.c.

RETRY_CANCEL_TIMEOUT

#define RETRY_CANCEL_TIMEOUT   1000

Definition at line 104 of file connection.c.

Typedef Documentation

ConnCacheEntry

typedef struct ConnCacheEntry ConnCacheEntry

ConnCacheKey

typedef Oid ConnCacheKey

Definition at line 52 of file connection.c.

Enumeration Type Documentation

pgfdwVersion

enum pgfdwVersion

Enumerator
PGFDW_V1_1
PGFDW_V1_2

Definition at line 121 of file connection.c.

{
    PGFDW_V1_1 = 0,
    PGFDW_V1_2,
};

Function Documentation

begin_remote_xact()

static void begin_remote_xact ( ConnCacheEntry *  entry )

static

Definition at line 848 of file connection.c.

{
    int         curlevel = GetCurrentTransactionNestLevel();
 
    /* Start main transaction if we haven't yet */
    if (entry->xact_depth <= 0)
    {
        const char *sql;
 
        elog(DEBUG3, "starting remote transaction on connection %p",
             entry->conn);
 
        if (IsolationIsSerializable())
            sql = "START TRANSACTION ISOLATION LEVEL SERIALIZABLE";
        else
            sql = "START TRANSACTION ISOLATION LEVEL REPEATABLE READ";
        entry->changing_xact_state = true;
        do_sql_command(entry->conn, sql);
        entry->xact_depth = 1;
        entry->changing_xact_state = false;
    }
 
    /*
     * If we're in a subtransaction, stack up savepoints to match our level.
     * This ensures we can rollback just the desired effects when a
     * subtransaction aborts.
     */
    while (entry->xact_depth < curlevel)
    {
        char        sql[64];
 
        snprintf(sql, sizeof(sql), "SAVEPOINT s%d", entry->xact_depth + 1);
        entry->changing_xact_state = true;
        do_sql_command(entry->conn, sql);
        entry->xact_depth++;
        entry->changing_xact_state = false;
    }
}

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, DEBUG3, do_sql_command(), elog, GetCurrentTransactionNestLevel(), IsolationIsSerializable, snprintf, and ConnCacheEntry::xact_depth.

Referenced by GetConnection().

check_conn_params()

static void check_conn_params ( const char **  keywords, const char **  values, UserMapping *  user  )

static

Definition at line 715 of file connection.c.

{
    int         i;
 
    /* no check required if superuser */
    if (superuser_arg(user->userid))
        return;
 
#ifdef ENABLE_GSS
    /* ok if the user provided their own delegated credentials */
    if (be_gssapi_get_delegation(MyProcPort))
        return;
#endif
 
    /* ok if params contain a non-empty password */
    for (i = 0; keywords[i] != NULL; i++)
    {
        if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
            return;
    }
 
    /* ok if the superuser explicitly said so at user mapping creation time */
    if (!UserMappingPasswordRequired(user))
        return;
 
    /*
     * Ok if SCRAM pass-through is being used and all required scram options
     * are set correctly. If pgfdw_has_required_scram_options returns true we
     * assume that UseScramPassthrough is also true since SCRAM options are
     * only set when UseScramPassthrough is enabled.
     */
    if (MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
        return;
 
    ereport(ERROR,
            (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
             errmsg("password or GSSAPI delegated credentials required"),
             errdetail("Non-superusers must delegate GSSAPI credentials, provide a password, or enable SCRAM pass-through in user mapping.")));
}

References be_gssapi_get_delegation(), ereport, errcode(), errdetail(), errmsg(), ERROR, Port::has_scram_keys, i, keywords, MyProcPort, pgfdw_has_required_scram_options(), superuser_arg(), user, UserMappingPasswordRequired(), and values.

Referenced by connect_pg_server().

configure_remote_session()

static void configure_remote_session ( PGconn *  conn )

static

Definition at line 767 of file connection.c.

{
    int         remoteversion = PQserverVersion(conn);
 
    /* Force the search path to contain only pg_catalog (see deparse.c) */
    do_sql_command(conn, "SET search_path = pg_catalog");
 
    /*
     * Set remote timezone; this is basically just cosmetic, since all
     * transmitted and returned timestamptzs should specify a zone explicitly
     * anyway.  However it makes the regression test outputs more predictable.
     *
     * We don't risk setting remote zone equal to ours, since the remote
     * server might use a different timezone database.  Instead, use GMT
     * (quoted, because very old servers are picky about case).  That's
     * guaranteed to work regardless of the remote's timezone database,
     * because pg_tzset() hard-wires it (at least in PG 9.2 and later).
     */
    do_sql_command(conn, "SET timezone = 'GMT'");
 
    /*
     * Set values needed to ensure unambiguous data output from remote.  (This
     * logic should match what pg_dump does.  See also set_transmission_modes
     * in postgres_fdw.c.)
     */
    do_sql_command(conn, "SET datestyle = ISO");
    if (remoteversion >= 80400)
        do_sql_command(conn, "SET intervalstyle = postgres");
    if (remoteversion >= 90000)
        do_sql_command(conn, "SET extra_float_digits = 3");
    else
        do_sql_command(conn, "SET extra_float_digits = 2");
}

References conn, do_sql_command(), and PQserverVersion().

Referenced by connect_pg_server().

connect_pg_server()

static PGconn * connect_pg_server ( ForeignServer *  server, UserMapping *  user  )

static

Definition at line 479 of file connection.c.

{
    PGconn     *volatile conn = NULL;
 
    /*
     * Use PG_TRY block to ensure closing connection on error.
     */
    PG_TRY();
    {
        const char **keywords;
        const char **values;
        char       *appname = NULL;
        int         n;
 
        /*
         * Construct connection params from generic options of ForeignServer
         * and UserMapping.  (Some of them might not be libpq options, in
         * which case we'll just waste a few array slots.)  Add 4 extra slots
         * for application_name, fallback_application_name, client_encoding,
         * end marker, and 3 extra slots for scram keys and required scram
         * pass-through options.
         */
        n = list_length(server->options) + list_length(user->options) + 4 + 3;
        keywords = (const char **) palloc(n * sizeof(char *));
        values = (const char **) palloc(n * sizeof(char *));
 
        n = 0;
        n += ExtractConnectionOptions(server->options,
                                      keywords + n, values + n);
        n += ExtractConnectionOptions(user->options,
                                      keywords + n, values + n);
 
        /*
         * Use pgfdw_application_name as application_name if set.
         *
         * PQconnectdbParams() processes the parameter arrays from start to
         * end. If any key word is repeated, the last value is used. Therefore
         * note that pgfdw_application_name must be added to the arrays after
         * options of ForeignServer are, so that it can override
         * application_name set in ForeignServer.
         */
        if (pgfdw_application_name && *pgfdw_application_name != '\0')
        {
            keywords[n] = "application_name";
            values[n] = pgfdw_application_name;
            n++;
        }
 
        /*
         * Search the parameter arrays to find application_name setting, and
         * replace escape sequences in it with status information if found.
         * The arrays are searched backwards because the last value is used if
         * application_name is repeatedly set.
         */
        for (int i = n - 1; i >= 0; i--)
        {
            if (strcmp(keywords[i], "application_name") == 0 &&
                *(values[i]) != '\0')
            {
                /*
                 * Use this application_name setting if it's not empty string
                 * even after any escape sequences in it are replaced.
                 */
                appname = process_pgfdw_appname(values[i]);
                if (appname[0] != '\0')
                {
                    values[i] = appname;
                    break;
                }
 
                /*
                 * This empty application_name is not used, so we set
                 * values[i] to NULL and keep searching the array to find the
                 * next one.
                 */
                values[i] = NULL;
                pfree(appname);
                appname = NULL;
            }
        }
 
        /* Use "postgres_fdw" as fallback_application_name */
        keywords[n] = "fallback_application_name";
        values[n] = "postgres_fdw";
        n++;
 
        /* Set client_encoding so that libpq can convert encoding properly. */
        keywords[n] = "client_encoding";
        values[n] = GetDatabaseEncodingName();
        n++;
 
        /* Add required SCRAM pass-through connection options if it's enabled. */
        if (MyProcPort->has_scram_keys && UseScramPassthrough(server, user))
        {
            int         len;
            int         encoded_len;
 
            keywords[n] = "scram_client_key";
            len = pg_b64_enc_len(sizeof(MyProcPort->scram_ClientKey));
            /* don't forget the zero-terminator */
            values[n] = palloc0(len + 1);
            encoded_len = pg_b64_encode((const char *) MyProcPort->scram_ClientKey,
                                        sizeof(MyProcPort->scram_ClientKey),
                                        (char *) values[n], len);
            if (encoded_len < 0)
                elog(ERROR, "could not encode SCRAM client key");
            n++;
 
            keywords[n] = "scram_server_key";
            len = pg_b64_enc_len(sizeof(MyProcPort->scram_ServerKey));
            /* don't forget the zero-terminator */
            values[n] = palloc0(len + 1);
            encoded_len = pg_b64_encode((const char *) MyProcPort->scram_ServerKey,
                                        sizeof(MyProcPort->scram_ServerKey),
                                        (char *) values[n], len);
            if (encoded_len < 0)
                elog(ERROR, "could not encode SCRAM server key");
            n++;
 
            /*
             * Require scram-sha-256 to ensure that no other auth method is
             * used when connecting with foreign server.
             */
            keywords[n] = "require_auth";
            values[n] = "scram-sha-256";
            n++;
        }
 
        keywords[n] = values[n] = NULL;
 
        /* Verify the set of connection parameters. */
        check_conn_params(keywords, values, user);
 
        /* first time, allocate or get the custom wait event */
        if (pgfdw_we_connect == 0)
            pgfdw_we_connect = WaitEventExtensionNew("PostgresFdwConnect");
 
        /* OK to make connection */
        conn = libpqsrv_connect_params(keywords, values,
                                       false,   /* expand_dbname */
                                       pgfdw_we_connect);
 
        if (!conn || PQstatus(conn) != CONNECTION_OK)
            ereport(ERROR,
                    (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
                     errmsg("could not connect to server \"%s\"",
                            server->servername),
                     errdetail_internal("%s", pchomp(PQerrorMessage(conn)))));
 
        /* Perform post-connection security checks. */
        pgfdw_security_check(keywords, values, user, conn);
 
        /* Prepare new session for use */
        configure_remote_session(conn);
 
        if (appname != NULL)
            pfree(appname);
        pfree(keywords);
        pfree(values);
    }
    PG_CATCH();
    {
        libpqsrv_disconnect(conn);
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    return conn;
}

References check_conn_params(), configure_remote_session(), conn, CONNECTION_OK, elog, ereport, errcode(), errdetail_internal(), errmsg(), ERROR, ExtractConnectionOptions(), GetDatabaseEncodingName(), Port::has_scram_keys, i, keywords, len, libpqsrv_connect_params(), libpqsrv_disconnect(), list_length(), MyProcPort, ForeignServer::options, palloc(), palloc0(), pchomp(), pfree(), pg_b64_enc_len(), pg_b64_encode(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, pgfdw_application_name, pgfdw_security_check(), pgfdw_we_connect, PQerrorMessage(), PQstatus(), process_pgfdw_appname(), Port::scram_ClientKey, Port::scram_ServerKey, ForeignServer::servername, user, UseScramPassthrough(), values, and WaitEventExtensionNew().

Referenced by make_new_connection().

disconnect_cached_connections()

static bool disconnect_cached_connections ( Oid  serverid )

static

Definition at line 2394 of file connection.c.

{
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
    bool        all = !OidIsValid(serverid);
    bool        result = false;
 
    /*
     * Connection cache hashtable has not been initialized yet in this
     * session, so return false.
     */
    if (!ConnectionHash)
        return false;
 
    hash_seq_init(&scan, ConnectionHash);
    while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
    {
        /* Ignore cache entry if no open connection right now. */
        if (!entry->conn)
            continue;
 
        if (all || entry->serverid == serverid)
        {
            /*
             * Emit a warning because the connection to close is used in the
             * current transaction and cannot be disconnected right now.
             */
            if (entry->xact_depth > 0)
            {
                ForeignServer *server;
 
                server = GetForeignServerExtended(entry->serverid,
                                                  FSV_MISSING_OK);
 
                if (!server)
                {
                    /*
                     * If the foreign server was dropped while its connection
                     * was used in the current transaction, the connection
                     * must have been marked as invalid by
                     * pgfdw_inval_callback at the end of DROP SERVER command.
                     */
                    Assert(entry->invalidated);
 
                    ereport(WARNING,
                            (errmsg("cannot close dropped server connection because it is still in use")));
                }
                else
                    ereport(WARNING,
                            (errmsg("cannot close connection for server \"%s\" because it is still in use",
                                    server->servername)));
            }
            else
            {
                elog(DEBUG3, "discarding connection %p", entry->conn);
                disconnect_pg_server(entry);
                result = true;
            }
        }
    }
 
    return result;
}

References Assert(), ConnCacheEntry::conn, ConnectionHash, DEBUG3, disconnect_pg_server(), elog, ereport, errmsg(), FSV_MISSING_OK, GetForeignServerExtended(), hash_seq_init(), hash_seq_search(), ConnCacheEntry::invalidated, OidIsValid, ConnCacheEntry::serverid, ForeignServer::servername, WARNING, and ConnCacheEntry::xact_depth.

Referenced by postgres_fdw_disconnect(), and postgres_fdw_disconnect_all().

disconnect_pg_server()

static void disconnect_pg_server ( ConnCacheEntry *  entry )

static

Definition at line 653 of file connection.c.

{
    if (entry->conn != NULL)
    {
        libpqsrv_disconnect(entry->conn);
        entry->conn = NULL;
    }
}

References ConnCacheEntry::conn, and libpqsrv_disconnect().

Referenced by disconnect_cached_connections(), GetConnection(), pgfdw_inval_callback(), pgfdw_reject_incomplete_xact_state_change(), and pgfdw_reset_xact_state().

do_sql_command()

void do_sql_command	(	PGconn *	conn,
		const char *	sql
	)

Definition at line 805 of file connection.c.

{
    do_sql_command_begin(conn, sql);
    do_sql_command_end(conn, sql, false);
}

References conn, do_sql_command_begin(), and do_sql_command_end().

Referenced by begin_remote_xact(), configure_remote_session(), pgfdw_subxact_callback(), pgfdw_xact_callback(), and postgresExecForeignTruncate().

do_sql_command_begin()

static void do_sql_command_begin ( PGconn *  conn, const char *  sql  )

static

Definition at line 812 of file connection.c.

{
    if (!PQsendQuery(conn, sql))
        pgfdw_report_error(ERROR, NULL, conn, false, sql);
}

References conn, ERROR, pgfdw_report_error(), and PQsendQuery().

Referenced by do_sql_command(), pgfdw_subxact_callback(), and pgfdw_xact_callback().

do_sql_command_end()

static void do_sql_command_end ( PGconn *  conn, const char *  sql, bool  consume_input  )

static

Definition at line 819 of file connection.c.

{
    PGresult   *res;
 
    /*
     * If requested, consume whatever data is available from the socket. (Note
     * that if all data is available, this allows pgfdw_get_result to call
     * PQgetResult without forcing the overhead of WaitLatchOrSocket, which
     * would be large compared to the overhead of PQconsumeInput.)
     */
    if (consume_input && !PQconsumeInput(conn))
        pgfdw_report_error(ERROR, NULL, conn, false, sql);
    res = pgfdw_get_result(conn);
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
        pgfdw_report_error(ERROR, res, conn, true, sql);
    PQclear(res);
}

References conn, ERROR, pgfdw_get_result(), pgfdw_report_error(), PGRES_COMMAND_OK, PQclear(), PQconsumeInput(), and PQresultStatus().

Referenced by do_sql_command(), pgfdw_finish_pre_commit_cleanup(), and pgfdw_finish_pre_subcommit_cleanup().

GetConnection()

PGconn * GetConnection	(	UserMapping *	user,
		bool	will_prep_stmt,
		PgFdwConnState **	state
	)

Definition at line 203 of file connection.c.

{
    bool        found;
    bool        retry = false;
    ConnCacheEntry *entry;
    ConnCacheKey key;
    MemoryContext ccxt = CurrentMemoryContext;
 
    /* First time through, initialize connection cache hashtable */
    if (ConnectionHash == NULL)
    {
        HASHCTL     ctl;
 
        if (pgfdw_we_get_result == 0)
            pgfdw_we_get_result =
                WaitEventExtensionNew("PostgresFdwGetResult");
 
        ctl.keysize = sizeof(ConnCacheKey);
        ctl.entrysize = sizeof(ConnCacheEntry);
        ConnectionHash = hash_create("postgres_fdw connections", 8,
                                     &ctl,
                                     HASH_ELEM | HASH_BLOBS);
 
        /*
         * Register some callback functions that manage connection cleanup.
         * This should be done just once in each backend.
         */
        RegisterXactCallback(pgfdw_xact_callback, NULL);
        RegisterSubXactCallback(pgfdw_subxact_callback, NULL);
        CacheRegisterSyscacheCallback(FOREIGNSERVEROID,
                                      pgfdw_inval_callback, (Datum) 0);
        CacheRegisterSyscacheCallback(USERMAPPINGOID,
                                      pgfdw_inval_callback, (Datum) 0);
    }
 
    /* Set flag that we did GetConnection during the current transaction */
    xact_got_connection = true;
 
    /* Create hash key for the entry.  Assume no pad bytes in key struct */
    key = user->umid;
 
    /*
     * Find or create cached entry for requested connection.
     */
    entry = hash_search(ConnectionHash, &key, HASH_ENTER, &found);
    if (!found)
    {
        /*
         * We need only clear "conn" here; remaining fields will be filled
         * later when "conn" is set.
         */
        entry->conn = NULL;
    }
 
    /* Reject further use of connections which failed abort cleanup. */
    pgfdw_reject_incomplete_xact_state_change(entry);
 
    /*
     * If the connection needs to be remade due to invalidation, disconnect as
     * soon as we're out of all transactions.
     */
    if (entry->conn != NULL && entry->invalidated && entry->xact_depth == 0)
    {
        elog(DEBUG3, "closing connection %p for option changes to take effect",
             entry->conn);
        disconnect_pg_server(entry);
    }
 
    /*
     * If cache entry doesn't have a connection, we have to establish a new
     * connection.  (If connect_pg_server throws an error, the cache entry
     * will remain in a valid empty state, ie conn == NULL.)
     */
    if (entry->conn == NULL)
        make_new_connection(entry, user);
 
    /*
     * We check the health of the cached connection here when using it.  In
     * cases where we're out of all transactions, if a broken connection is
     * detected, we try to reestablish a new connection later.
     */
    PG_TRY();
    {
        /* Process a pending asynchronous request if any. */
        if (entry->state.pendingAreq)
            process_pending_request(entry->state.pendingAreq);
        /* Start a new transaction or subtransaction if needed. */
        begin_remote_xact(entry);
    }
    PG_CATCH();
    {
        MemoryContext ecxt = MemoryContextSwitchTo(ccxt);
        ErrorData  *errdata = CopyErrorData();
 
        /*
         * Determine whether to try to reestablish the connection.
         *
         * After a broken connection is detected in libpq, any error other
         * than connection failure (e.g., out-of-memory) can be thrown
         * somewhere between return from libpq and the expected ereport() call
         * in pgfdw_report_error(). In this case, since PQstatus() indicates
         * CONNECTION_BAD, checking only PQstatus() causes the false detection
         * of connection failure. To avoid this, we also verify that the
         * error's sqlstate is ERRCODE_CONNECTION_FAILURE. Note that also
         * checking only the sqlstate can cause another false detection
         * because pgfdw_report_error() may report ERRCODE_CONNECTION_FAILURE
         * for any libpq-originated error condition.
         */
        if (errdata->sqlerrcode != ERRCODE_CONNECTION_FAILURE ||
            PQstatus(entry->conn) != CONNECTION_BAD ||
            entry->xact_depth > 0)
        {
            MemoryContextSwitchTo(ecxt);
            PG_RE_THROW();
        }
 
        /* Clean up the error state */
        FlushErrorState();
        FreeErrorData(errdata);
        errdata = NULL;
 
        retry = true;
    }
    PG_END_TRY();
 
    /*
     * If a broken connection is detected, disconnect it, reestablish a new
     * connection and retry a new remote transaction. If connection failure is
     * reported again, we give up getting a connection.
     */
    if (retry)
    {
        Assert(entry->xact_depth == 0);
 
        ereport(DEBUG3,
                (errmsg_internal("could not start remote transaction on connection %p",
                                 entry->conn)),
                errdetail_internal("%s", pchomp(PQerrorMessage(entry->conn))));
 
        elog(DEBUG3, "closing connection %p to reestablish a new one",
             entry->conn);
        disconnect_pg_server(entry);
 
        make_new_connection(entry, user);
 
        begin_remote_xact(entry);
    }
 
    /* Remember if caller will prepare statements */
    entry->have_prep_stmt |= will_prep_stmt;
 
    /* If caller needs access to the per-connection state, return it. */
    if (state)
        *state = &entry->state;
 
    return entry->conn;
}

References Assert(), begin_remote_xact(), CacheRegisterSyscacheCallback(), ConnCacheEntry::conn, CONNECTION_BAD, ConnectionHash, CopyErrorData(), ctl, CurrentMemoryContext, DEBUG3, disconnect_pg_server(), elog, ereport, errdetail_internal(), errmsg_internal(), FlushErrorState(), FreeErrorData(), HASH_BLOBS, hash_create(), HASH_ELEM, HASH_ENTER, hash_search(), ConnCacheEntry::have_prep_stmt, ConnCacheEntry::invalidated, sort-test::key, make_new_connection(), MemoryContextSwitchTo(), pchomp(), PgFdwConnState::pendingAreq, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, pgfdw_inval_callback(), pgfdw_reject_incomplete_xact_state_change(), pgfdw_subxact_callback(), pgfdw_we_get_result, pgfdw_xact_callback(), PQerrorMessage(), PQstatus(), process_pending_request(), RegisterSubXactCallback(), RegisterXactCallback(), ErrorData::sqlerrcode, ConnCacheEntry::state, user, WaitEventExtensionNew(), ConnCacheEntry::xact_depth, and xact_got_connection.

Referenced by create_foreign_modify(), dumpDatabase(), dumpDatabaseConfig(), dumpLOs(), dumpTableData_copy(), estimate_path_cost_size(), expand_extension_name_patterns(), expand_foreign_server_name_patterns(), expand_schema_name_patterns(), expand_table_name_patterns(), getTables(), main(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresBeginDirectModify(), postgresBeginForeignScan(), postgresExecForeignTruncate(), postgresGetAnalyzeInfoForForeignTable(), postgresImportForeignSchema(), setup_connection(), StartLogStreamer(), StreamLog(), and StreamLogicalLog().

GetCursorNumber()

unsigned int GetCursorNumber

(

PGconn *

conn

)

Definition at line 912 of file connection.c.

{
    return ++cursor_number;
}

References cursor_number.

Referenced by postgresAcquireSampleRowsFunc(), and postgresBeginForeignScan().

GetPrepStmtNumber()

unsigned int GetPrepStmtNumber

(

PGconn *

conn

)

Definition at line 926 of file connection.c.

{
    return ++prep_stmt_number;
}

References prep_stmt_number.

Referenced by prepare_foreign_modify().

make_new_connection()

static void make_new_connection ( ConnCacheEntry *  entry, UserMapping *  user  )

static

Definition at line 366 of file connection.c.

{
    ForeignServer *server = GetForeignServer(user->serverid);
    ListCell   *lc;
 
    Assert(entry->conn == NULL);
 
    /* Reset all transient state fields, to be sure all are clean */
    entry->xact_depth = 0;
    entry->have_prep_stmt = false;
    entry->have_error = false;
    entry->changing_xact_state = false;
    entry->invalidated = false;
    entry->serverid = server->serverid;
    entry->server_hashvalue =
        GetSysCacheHashValue1(FOREIGNSERVEROID,
                              ObjectIdGetDatum(server->serverid));
    entry->mapping_hashvalue =
        GetSysCacheHashValue1(USERMAPPINGOID,
                              ObjectIdGetDatum(user->umid));
    memset(&entry->state, 0, sizeof(entry->state));
 
    /*
     * Determine whether to keep the connection that we're about to make here
     * open even after the transaction using it ends, so that the subsequent
     * transactions can re-use it.
     *
     * By default, all the connections to any foreign servers are kept open.
     *
     * Also determine whether to commit/abort (sub)transactions opened on the
     * remote server in parallel at (sub)transaction end, which is disabled by
     * default.
     *
     * Note: it's enough to determine these only when making a new connection
     * because if these settings for it are changed, it will be closed and
     * re-made later.
     */
    entry->keep_connections = true;
    entry->parallel_commit = false;
    entry->parallel_abort = false;
    foreach(lc, server->options)
    {
        DefElem    *def = (DefElem *) lfirst(lc);
 
        if (strcmp(def->defname, "keep_connections") == 0)
            entry->keep_connections = defGetBoolean(def);
        else if (strcmp(def->defname, "parallel_commit") == 0)
            entry->parallel_commit = defGetBoolean(def);
        else if (strcmp(def->defname, "parallel_abort") == 0)
            entry->parallel_abort = defGetBoolean(def);
    }
 
    /* Now try to make the connection */
    entry->conn = connect_pg_server(server, user);
 
    elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\" (user mapping oid %u, userid %u)",
         entry->conn, server->servername, user->umid, user->userid);
}

References Assert(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, connect_pg_server(), DEBUG3, defGetBoolean(), DefElem::defname, elog, GetForeignServer(), GetSysCacheHashValue1, ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, ConnCacheEntry::invalidated, ConnCacheEntry::keep_connections, lfirst, ConnCacheEntry::mapping_hashvalue, ObjectIdGetDatum(), ForeignServer::options, ConnCacheEntry::parallel_abort, ConnCacheEntry::parallel_commit, ConnCacheEntry::server_hashvalue, ConnCacheEntry::serverid, ForeignServer::serverid, ForeignServer::servername, ConnCacheEntry::state, user, and ConnCacheEntry::xact_depth.

Referenced by GetConnection().

PG_FUNCTION_INFO_V1() [1/4]

PG_FUNCTION_INFO_V1

(

postgres_fdw_disconnect

)

PG_FUNCTION_INFO_V1() [2/4]

PG_FUNCTION_INFO_V1

(

postgres_fdw_disconnect_all

)

PG_FUNCTION_INFO_V1() [3/4]

PG_FUNCTION_INFO_V1

(

postgres_fdw_get_connections

)

PG_FUNCTION_INFO_V1() [4/4]

PG_FUNCTION_INFO_V1

(

postgres_fdw_get_connections_1_2

)

pgfdw_abort_cleanup()

static void pgfdw_abort_cleanup ( ConnCacheEntry *  entry, bool  toplevel  )

static

Definition at line 1731 of file connection.c.

{
    char        sql[100];
 
    /*
     * Don't try to clean up the connection if we're already in error
     * recursion trouble.
     */
    if (in_error_recursion_trouble())
        entry->changing_xact_state = true;
 
    /*
     * If connection is already unsalvageable, don't touch it further.
     */
    if (entry->changing_xact_state)
        return;
 
    /*
     * Mark this connection as in the process of changing transaction state.
     */
    entry->changing_xact_state = true;
 
    /* Assume we might have lost track of prepared statements */
    entry->have_error = true;
 
    /*
     * If a command has been submitted to the remote server by using an
     * asynchronous execution function, the command might not have yet
     * completed.  Check to see if a command is still being processed by the
     * remote server, and if so, request cancellation of the command.
     */
    if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE &&
        !pgfdw_cancel_query(entry->conn))
        return;                 /* Unable to cancel running query */
 
    CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
    if (!pgfdw_exec_cleanup_query(entry->conn, sql, false))
        return;                 /* Unable to abort remote (sub)transaction */
 
    if (toplevel)
    {
        if (entry->have_prep_stmt && entry->have_error &&
            !pgfdw_exec_cleanup_query(entry->conn,
                                      "DEALLOCATE ALL",
                                      true))
            return;             /* Trouble clearing prepared statements */
 
        entry->have_prep_stmt = false;
        entry->have_error = false;
    }
 
    /*
     * If pendingAreq of the per-connection state is not NULL, it means that
     * an asynchronous fetch begun by fetch_more_data_begin() was not done
     * successfully and thus the per-connection state was not reset in
     * fetch_more_data(); in that case reset the per-connection state here.
     */
    if (entry->state.pendingAreq)
        memset(&entry->state, 0, sizeof(entry->state));
 
    /* Disarm changing_xact_state if it all worked */
    entry->changing_xact_state = false;
}

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, CONSTRUCT_ABORT_COMMAND, ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, in_error_recursion_trouble(), PgFdwConnState::pendingAreq, pgfdw_cancel_query(), pgfdw_exec_cleanup_query(), PQTRANS_ACTIVE, PQtransactionStatus(), and ConnCacheEntry::state.

Referenced by pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_abort_cleanup_begin()

static bool pgfdw_abort_cleanup_begin ( ConnCacheEntry *  entry, bool  toplevel, List **  pending_entries, List **  cancel_requested  )

static

Definition at line 1805 of file connection.c.

{
    /*
     * Don't try to clean up the connection if we're already in error
     * recursion trouble.
     */
    if (in_error_recursion_trouble())
        entry->changing_xact_state = true;
 
    /*
     * If connection is already unsalvageable, don't touch it further.
     */
    if (entry->changing_xact_state)
        return false;
 
    /*
     * Mark this connection as in the process of changing transaction state.
     */
    entry->changing_xact_state = true;
 
    /* Assume we might have lost track of prepared statements */
    entry->have_error = true;
 
    /*
     * If a command has been submitted to the remote server by using an
     * asynchronous execution function, the command might not have yet
     * completed.  Check to see if a command is still being processed by the
     * remote server, and if so, request cancellation of the command.
     */
    if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE)
    {
        TimestampTz endtime;
 
        endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
                                              CONNECTION_CLEANUP_TIMEOUT);
        if (!pgfdw_cancel_query_begin(entry->conn, endtime))
            return false;       /* Unable to cancel running query */
        *cancel_requested = lappend(*cancel_requested, entry);
    }
    else
    {
        char        sql[100];
 
        CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
        if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
            return false;       /* Unable to abort remote transaction */
        *pending_entries = lappend(*pending_entries, entry);
    }
 
    return true;
}

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, CONNECTION_CLEANUP_TIMEOUT, CONSTRUCT_ABORT_COMMAND, GetCurrentTimestamp(), ConnCacheEntry::have_error, in_error_recursion_trouble(), lappend(), pgfdw_cancel_query_begin(), pgfdw_exec_cleanup_query_begin(), PQTRANS_ACTIVE, PQtransactionStatus(), and TimestampTzPlusMilliseconds.

Referenced by pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_cancel_query()

static bool pgfdw_cancel_query ( PGconn *  conn )

static

Definition at line 1415 of file connection.c.

{
    TimestampTz now = GetCurrentTimestamp();
    TimestampTz endtime;
    TimestampTz retrycanceltime;
 
    /*
     * If it takes too long to cancel the query and discard the result, assume
     * the connection is dead.
     */
    endtime = TimestampTzPlusMilliseconds(now, CONNECTION_CLEANUP_TIMEOUT);
 
    /*
     * Also, lose patience and re-issue the cancel request after a little bit.
     * (This serves to close some race conditions.)
     */
    retrycanceltime = TimestampTzPlusMilliseconds(now, RETRY_CANCEL_TIMEOUT);
 
    if (!pgfdw_cancel_query_begin(conn, endtime))
        return false;
    return pgfdw_cancel_query_end(conn, endtime, retrycanceltime, false);
}

References conn, CONNECTION_CLEANUP_TIMEOUT, GetCurrentTimestamp(), now(), pgfdw_cancel_query_begin(), pgfdw_cancel_query_end(), RETRY_CANCEL_TIMEOUT, and TimestampTzPlusMilliseconds.

Referenced by pgfdw_abort_cleanup().

pgfdw_cancel_query_begin()

static bool pgfdw_cancel_query_begin ( PGconn *  conn, TimestampTz  endtime  )

static

Definition at line 1448 of file connection.c.

{
    const char *errormsg = libpqsrv_cancel(conn, endtime);
 
    if (errormsg != NULL)
        ereport(WARNING,
                errcode(ERRCODE_CONNECTION_FAILURE),
                errmsg("could not send cancel request: %s", errormsg));
 
    return errormsg == NULL;
}

References conn, ereport, errcode(), errmsg(), libpqsrv_cancel(), and WARNING.

Referenced by pgfdw_abort_cleanup_begin(), and pgfdw_cancel_query().

pgfdw_cancel_query_end()

static bool pgfdw_cancel_query_end ( PGconn *  conn, TimestampTz  endtime, TimestampTz  retrycanceltime, bool  consume_input  )

static

Definition at line 1461 of file connection.c.

{
    PGresult   *result;
    bool        timed_out;
 
    /*
     * If requested, consume whatever data is available from the socket. (Note
     * that if all data is available, this allows pgfdw_get_cleanup_result to
     * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
     * which would be large compared to the overhead of PQconsumeInput.)
     */
    if (consume_input && !PQconsumeInput(conn))
    {
        ereport(WARNING,
                (errcode(ERRCODE_CONNECTION_FAILURE),
                 errmsg("could not get result of cancel request: %s",
                        pchomp(PQerrorMessage(conn)))));
        return false;
    }
 
    /* Get and discard the result of the query. */
    if (pgfdw_get_cleanup_result(conn, endtime, retrycanceltime,
                                 &result, &timed_out))
    {
        if (timed_out)
            ereport(WARNING,
                    (errmsg("could not get result of cancel request due to timeout")));
        else
            ereport(WARNING,
                    (errcode(ERRCODE_CONNECTION_FAILURE),
                     errmsg("could not get result of cancel request: %s",
                            pchomp(PQerrorMessage(conn)))));
 
        return false;
    }
    PQclear(result);
 
    return true;
}

References conn, ereport, errcode(), errmsg(), pchomp(), pgfdw_get_cleanup_result(), PQclear(), PQconsumeInput(), PQerrorMessage(), and WARNING.

Referenced by pgfdw_cancel_query(), and pgfdw_finish_abort_cleanup().

pgfdw_conn_check()

static int pgfdw_conn_check ( PGconn *  conn )

static

Definition at line 2466 of file connection.c.

{
    int         sock = PQsocket(conn);
 
    if (PQstatus(conn) != CONNECTION_OK || sock == -1)
        return -1;
 
#if (defined(HAVE_POLL) && defined(POLLRDHUP))
    {
        struct pollfd input_fd;
        int         result;
 
        input_fd.fd = sock;
        input_fd.events = POLLRDHUP;
        input_fd.revents = 0;
 
        do
            result = poll(&input_fd, 1, 0);
        while (result < 0 && errno == EINTR);
 
        if (result < 0)
            return -1;
 
        return (input_fd.revents &
                (POLLRDHUP | POLLHUP | POLLERR | POLLNVAL)) ? 1 : 0;
    }
#else
    return 0;
#endif
}

References conn, CONNECTION_OK, EINTR, PQsocket(), and PQstatus().

Referenced by postgres_fdw_get_connections_internal().

pgfdw_conn_checkable()

static bool pgfdw_conn_checkable ( void  )

static

Definition at line 2503 of file connection.c.

{
#if (defined(HAVE_POLL) && defined(POLLRDHUP))
    return true;
#else
    return false;
#endif
}

Referenced by postgres_fdw_get_connections_internal().

pgfdw_exec_cleanup_query()

static bool pgfdw_exec_cleanup_query ( PGconn *  conn, const char *  query, bool  ignore_errors  )

static

Definition at line 1515 of file connection.c.

{
    TimestampTz endtime;
 
    /*
     * If it takes too long to execute a cleanup query, assume the connection
     * is dead.  It's fairly likely that this is why we aborted in the first
     * place (e.g. statement timeout, user cancel), so the timeout shouldn't
     * be too long.
     */
    endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
                                          CONNECTION_CLEANUP_TIMEOUT);
 
    if (!pgfdw_exec_cleanup_query_begin(conn, query))
        return false;
    return pgfdw_exec_cleanup_query_end(conn, query, endtime,
                                        false, ignore_errors);
}

References conn, CONNECTION_CLEANUP_TIMEOUT, GetCurrentTimestamp(), pgfdw_exec_cleanup_query_begin(), pgfdw_exec_cleanup_query_end(), and TimestampTzPlusMilliseconds.

Referenced by pgfdw_abort_cleanup().

pgfdw_exec_cleanup_query_begin()

static bool pgfdw_exec_cleanup_query_begin ( PGconn *  conn, const char *  query  )

static

Definition at line 1535 of file connection.c.

{
    Assert(query != NULL);
 
    /*
     * Submit a query.  Since we don't use non-blocking mode, this also can
     * block.  But its risk is relatively small, so we ignore that for now.
     */
    if (!PQsendQuery(conn, query))
    {
        pgfdw_report_error(WARNING, NULL, conn, false, query);
        return false;
    }
 
    return true;
}

References Assert(), conn, pgfdw_report_error(), PQsendQuery(), and WARNING.

Referenced by pgfdw_abort_cleanup_begin(), pgfdw_exec_cleanup_query(), and pgfdw_finish_abort_cleanup().

pgfdw_exec_cleanup_query_end()

static bool pgfdw_exec_cleanup_query_end ( PGconn *  conn, const char *  query, TimestampTz  endtime, bool  consume_input, bool  ignore_errors  )

static

Definition at line 1553 of file connection.c.

{
    PGresult   *result;
    bool        timed_out;
 
    Assert(query != NULL);
 
    /*
     * If requested, consume whatever data is available from the socket. (Note
     * that if all data is available, this allows pgfdw_get_cleanup_result to
     * call PQgetResult without forcing the overhead of WaitLatchOrSocket,
     * which would be large compared to the overhead of PQconsumeInput.)
     */
    if (consume_input && !PQconsumeInput(conn))
    {
        pgfdw_report_error(WARNING, NULL, conn, false, query);
        return false;
    }
 
    /* Get the result of the query. */
    if (pgfdw_get_cleanup_result(conn, endtime, endtime, &result, &timed_out))
    {
        if (timed_out)
            ereport(WARNING,
                    (errmsg("could not get query result due to timeout"),
                     errcontext("remote SQL command: %s", query)));
        else
            pgfdw_report_error(WARNING, NULL, conn, false, query);
 
        return false;
    }
 
    /* Issue a warning if not successful. */
    if (PQresultStatus(result) != PGRES_COMMAND_OK)
    {
        pgfdw_report_error(WARNING, result, conn, true, query);
        return ignore_errors;
    }
    PQclear(result);
 
    return true;
}

References Assert(), conn, ereport, errcontext, errmsg(), pgfdw_get_cleanup_result(), pgfdw_report_error(), PGRES_COMMAND_OK, PQclear(), PQconsumeInput(), PQresultStatus(), and WARNING.

Referenced by pgfdw_exec_cleanup_query(), and pgfdw_finish_abort_cleanup().

pgfdw_exec_query()

PGresult * pgfdw_exec_query	(	PGconn *	conn,
		const char *	query,
		PgFdwConnState *	state
	)

Definition at line 941 of file connection.c.

{
    /* First, process a pending asynchronous request, if any. */
    if (state && state->pendingAreq)
        process_pending_request(state->pendingAreq);
 
    if (!PQsendQuery(conn, query))
        return NULL;
    return pgfdw_get_result(conn);
}

References conn, pgfdw_get_result(), PQsendQuery(), and process_pending_request().

Referenced by close_cursor(), deallocate_query(), fetch_more_data(), get_remote_estimate(), pgfdw_xact_callback(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresGetAnalyzeInfoForForeignTable(), postgresImportForeignSchema(), and postgresReScanForeignScan().

pgfdw_finish_abort_cleanup()

static void pgfdw_finish_abort_cleanup ( List *  pending_entries, List *  cancel_requested, bool  toplevel  )

static

Definition at line 1971 of file connection.c.

{
    List       *pending_deallocs = NIL;
    ListCell   *lc;
 
    /*
     * For each of the pending cancel requests (if any), get and discard the
     * result of the query, and submit an abort command to the remote server.
     */
    if (cancel_requested)
    {
        foreach(lc, cancel_requested)
        {
            ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
            TimestampTz now = GetCurrentTimestamp();
            TimestampTz endtime;
            TimestampTz retrycanceltime;
            char        sql[100];
 
            Assert(entry->changing_xact_state);
 
            /*
             * Set end time.  You might think we should do this before issuing
             * cancel request like in normal mode, but that is problematic,
             * because if, for example, it took longer than 30 seconds to
             * process the first few entries in the cancel_requested list, it
             * would cause a timeout error when processing each of the
             * remaining entries in the list, leading to slamming that entry's
             * connection shut.
             */
            endtime = TimestampTzPlusMilliseconds(now,
                                                  CONNECTION_CLEANUP_TIMEOUT);
            retrycanceltime = TimestampTzPlusMilliseconds(now,
                                                          RETRY_CANCEL_TIMEOUT);
 
            if (!pgfdw_cancel_query_end(entry->conn, endtime,
                                        retrycanceltime, true))
            {
                /* Unable to cancel running query */
                pgfdw_reset_xact_state(entry, toplevel);
                continue;
            }
 
            /* Send an abort command in parallel if needed */
            CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
            if (!pgfdw_exec_cleanup_query_begin(entry->conn, sql))
            {
                /* Unable to abort remote (sub)transaction */
                pgfdw_reset_xact_state(entry, toplevel);
            }
            else
                pending_entries = lappend(pending_entries, entry);
        }
    }
 
    /* No further work if no pending entries */
    if (!pending_entries)
        return;
 
    /*
     * Get the result of the abort command for each of the pending entries
     */
    foreach(lc, pending_entries)
    {
        ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
        TimestampTz endtime;
        char        sql[100];
 
        Assert(entry->changing_xact_state);
 
        /*
         * Set end time.  We do this now, not before issuing the command like
         * in normal mode, for the same reason as for the cancel_requested
         * entries.
         */
        endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
                                              CONNECTION_CLEANUP_TIMEOUT);
 
        CONSTRUCT_ABORT_COMMAND(sql, entry, toplevel);
        if (!pgfdw_exec_cleanup_query_end(entry->conn, sql, endtime,
                                          true, false))
        {
            /* Unable to abort remote (sub)transaction */
            pgfdw_reset_xact_state(entry, toplevel);
            continue;
        }
 
        if (toplevel)
        {
            /* Do a DEALLOCATE ALL in parallel if needed */
            if (entry->have_prep_stmt && entry->have_error)
            {
                if (!pgfdw_exec_cleanup_query_begin(entry->conn,
                                                    "DEALLOCATE ALL"))
                {
                    /* Trouble clearing prepared statements */
                    pgfdw_reset_xact_state(entry, toplevel);
                }
                else
                    pending_deallocs = lappend(pending_deallocs, entry);
                continue;
            }
            entry->have_prep_stmt = false;
            entry->have_error = false;
        }
 
        /* Reset the per-connection state if needed */
        if (entry->state.pendingAreq)
            memset(&entry->state, 0, sizeof(entry->state));
 
        /* We're done with this entry; unset the changing_xact_state flag */
        entry->changing_xact_state = false;
        pgfdw_reset_xact_state(entry, toplevel);
    }
 
    /* No further work if no pending entries */
    if (!pending_deallocs)
        return;
    Assert(toplevel);
 
    /*
     * Get the result of the DEALLOCATE command for each of the pending
     * entries
     */
    foreach(lc, pending_deallocs)
    {
        ConnCacheEntry *entry = (ConnCacheEntry *) lfirst(lc);
        TimestampTz endtime;
 
        Assert(entry->changing_xact_state);
        Assert(entry->have_prep_stmt);
        Assert(entry->have_error);
 
        /*
         * Set end time.  We do this now, not before issuing the command like
         * in normal mode, for the same reason as for the cancel_requested
         * entries.
         */
        endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(),
                                              CONNECTION_CLEANUP_TIMEOUT);
 
        if (!pgfdw_exec_cleanup_query_end(entry->conn, "DEALLOCATE ALL",
                                          endtime, true, true))
        {
            /* Trouble clearing prepared statements */
            pgfdw_reset_xact_state(entry, toplevel);
            continue;
        }
        entry->have_prep_stmt = false;
        entry->have_error = false;
 
        /* Reset the per-connection state if needed */
        if (entry->state.pendingAreq)
            memset(&entry->state, 0, sizeof(entry->state));
 
        /* We're done with this entry; unset the changing_xact_state flag */
        entry->changing_xact_state = false;
        pgfdw_reset_xact_state(entry, toplevel);
    }
}

References Assert(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, CONNECTION_CLEANUP_TIMEOUT, CONSTRUCT_ABORT_COMMAND, GetCurrentTimestamp(), ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, lappend(), lfirst, NIL, now(), PgFdwConnState::pendingAreq, pgfdw_cancel_query_end(), pgfdw_exec_cleanup_query_begin(), pgfdw_exec_cleanup_query_end(), pgfdw_reset_xact_state(), RETRY_CANCEL_TIMEOUT, ConnCacheEntry::state, and TimestampTzPlusMilliseconds.

Referenced by pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_finish_pre_commit_cleanup()

static void pgfdw_finish_pre_commit_cleanup ( List *  pending_entries )

static

Definition at line 1863 of file connection.c.

{
    ConnCacheEntry *entry;
    List       *pending_deallocs = NIL;
    ListCell   *lc;
 
    Assert(pending_entries);
 
    /*
     * Get the result of the COMMIT command for each of the pending entries
     */
    foreach(lc, pending_entries)
    {
        entry = (ConnCacheEntry *) lfirst(lc);
 
        Assert(entry->changing_xact_state);
 
        /*
         * We might already have received the result on the socket, so pass
         * consume_input=true to try to consume it first
         */
        do_sql_command_end(entry->conn, "COMMIT TRANSACTION", true);
        entry->changing_xact_state = false;
 
        /* Do a DEALLOCATE ALL in parallel if needed */
        if (entry->have_prep_stmt && entry->have_error)
        {
            /* Ignore errors (see notes in pgfdw_xact_callback) */
            if (PQsendQuery(entry->conn, "DEALLOCATE ALL"))
            {
                pending_deallocs = lappend(pending_deallocs, entry);
                continue;
            }
        }
        entry->have_prep_stmt = false;
        entry->have_error = false;
 
        pgfdw_reset_xact_state(entry, true);
    }
 
    /* No further work if no pending entries */
    if (!pending_deallocs)
        return;
 
    /*
     * Get the result of the DEALLOCATE command for each of the pending
     * entries
     */
    foreach(lc, pending_deallocs)
    {
        PGresult   *res;
 
        entry = (ConnCacheEntry *) lfirst(lc);
 
        /* Ignore errors (see notes in pgfdw_xact_callback) */
        while ((res = PQgetResult(entry->conn)) != NULL)
        {
            PQclear(res);
            /* Stop if the connection is lost (else we'll loop infinitely) */
            if (PQstatus(entry->conn) == CONNECTION_BAD)
                break;
        }
        entry->have_prep_stmt = false;
        entry->have_error = false;
 
        pgfdw_reset_xact_state(entry, true);
    }
}

References Assert(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, CONNECTION_BAD, do_sql_command_end(), ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, lappend(), lfirst, NIL, pgfdw_reset_xact_state(), PQclear(), PQgetResult(), PQsendQuery(), and PQstatus().

Referenced by pgfdw_xact_callback().

pgfdw_finish_pre_subcommit_cleanup()

static void pgfdw_finish_pre_subcommit_cleanup ( List *  pending_entries, int  curlevel  )

static

Definition at line 1937 of file connection.c.

{
    ConnCacheEntry *entry;
    char        sql[100];
    ListCell   *lc;
 
    Assert(pending_entries);
 
    /*
     * Get the result of the RELEASE command for each of the pending entries
     */
    snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
    foreach(lc, pending_entries)
    {
        entry = (ConnCacheEntry *) lfirst(lc);
 
        Assert(entry->changing_xact_state);
 
        /*
         * We might already have received the result on the socket, so pass
         * consume_input=true to try to consume it first
         */
        do_sql_command_end(entry->conn, sql, true);
        entry->changing_xact_state = false;
 
        pgfdw_reset_xact_state(entry, false);
    }
}

References Assert(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, do_sql_command_end(), lfirst, pgfdw_reset_xact_state(), and snprintf.

Referenced by pgfdw_subxact_callback().

pgfdw_get_cleanup_result()

static bool pgfdw_get_cleanup_result ( PGconn *  conn, TimestampTz  endtime, TimestampTz  retrycanceltime, PGresult **  result, bool *  timed_out  )

static

Definition at line 1613 of file connection.c.

{
    volatile bool failed = false;
    PGresult   *volatile last_res = NULL;
 
    *result = NULL;
    *timed_out = false;
 
    /* In what follows, do not leak any PGresults on an error. */
    PG_TRY();
    {
        int         canceldelta = RETRY_CANCEL_TIMEOUT * 2;
 
        for (;;)
        {
            PGresult   *res;
 
            while (PQisBusy(conn))
            {
                int         wc;
                TimestampTz now = GetCurrentTimestamp();
                long        cur_timeout;
 
                /* If timeout has expired, give up. */
                if (now >= endtime)
                {
                    *timed_out = true;
                    failed = true;
                    goto exit;
                }
 
                /* If we need to re-issue the cancel request, do that. */
                if (now >= retrycanceltime)
                {
                    /* We ignore failure to issue the repeated request. */
                    (void) libpqsrv_cancel(conn, endtime);
 
                    /* Recompute "now" in case that took measurable time. */
                    now = GetCurrentTimestamp();
 
                    /* Adjust re-cancel timeout in increasing steps. */
                    retrycanceltime = TimestampTzPlusMilliseconds(now,
                                                                  canceldelta);
                    canceldelta += canceldelta;
                }
 
                /* If timeout has expired, give up, else get sleep time. */
                cur_timeout = TimestampDifferenceMilliseconds(now,
                                                              Min(endtime,
                                                                  retrycanceltime));
                if (cur_timeout <= 0)
                {
                    *timed_out = true;
                    failed = true;
                    goto exit;
                }
 
                /* first time, allocate or get the custom wait event */
                if (pgfdw_we_cleanup_result == 0)
                    pgfdw_we_cleanup_result = WaitEventExtensionNew("PostgresFdwCleanupResult");
 
                /* Sleep until there's something to do */
                wc = WaitLatchOrSocket(MyLatch,
                                       WL_LATCH_SET | WL_SOCKET_READABLE |
                                       WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
                                       PQsocket(conn),
                                       cur_timeout, pgfdw_we_cleanup_result);
                ResetLatch(MyLatch);
 
                CHECK_FOR_INTERRUPTS();
 
                /* Data available in socket? */
                if (wc & WL_SOCKET_READABLE)
                {
                    if (!PQconsumeInput(conn))
                    {
                        /* connection trouble */
                        failed = true;
                        goto exit;
                    }
                }
            }
 
            res = PQgetResult(conn);
            if (res == NULL)
                break;          /* query is complete */
 
            PQclear(last_res);
            last_res = res;
        }
exit:   ;
    }
    PG_CATCH();
    {
        PQclear(last_res);
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    if (failed)
        PQclear(last_res);
    else
        *result = last_res;
    return failed;
}

References CHECK_FOR_INTERRUPTS, conn, GetCurrentTimestamp(), libpqsrv_cancel(), Min, MyLatch, now(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, pgfdw_we_cleanup_result, PQclear(), PQconsumeInput(), PQgetResult(), PQisBusy(), PQsocket(), ResetLatch(), RETRY_CANCEL_TIMEOUT, TimestampDifferenceMilliseconds(), TimestampTzPlusMilliseconds, WaitEventExtensionNew(), WaitLatchOrSocket(), WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, WL_SOCKET_READABLE, and WL_TIMEOUT.

Referenced by pgfdw_cancel_query_end(), and pgfdw_exec_cleanup_query_end().

pgfdw_get_result()

PGresult * pgfdw_get_result

(

PGconn *

conn

)

Definition at line 958 of file connection.c.

{
    return libpqsrv_get_result_last(conn, pgfdw_we_get_result);
}

References conn, libpqsrv_get_result_last(), and pgfdw_we_get_result.

Referenced by create_cursor(), do_sql_command_end(), execute_dml_stmt(), execute_foreign_modify(), fetch_more_data(), pgfdw_exec_query(), and prepare_foreign_modify().

pgfdw_has_required_scram_options()

static bool pgfdw_has_required_scram_options ( const char **  keywords, const char **  values  )

static

Definition at line 2521 of file connection.c.

{
    bool        has_scram_server_key = false;
    bool        has_scram_client_key = false;
    bool        has_require_auth = false;
    bool        has_scram_keys = false;
 
    /*
     * Continue iterating even if we found the keys that we need to validate
     * to make sure that there is no other declaration of these keys that can
     * overwrite the first.
     */
    for (int i = 0; keywords[i] != NULL; i++)
    {
        if (strcmp(keywords[i], "scram_client_key") == 0)
        {
            if (values[i] != NULL && values[i][0] != '\0')
                has_scram_client_key = true;
            else
                has_scram_client_key = false;
        }
 
        if (strcmp(keywords[i], "scram_server_key") == 0)
        {
            if (values[i] != NULL && values[i][0] != '\0')
                has_scram_server_key = true;
            else
                has_scram_server_key = false;
        }
 
        if (strcmp(keywords[i], "require_auth") == 0)
        {
            if (values[i] != NULL && strcmp(values[i], "scram-sha-256") == 0)
                has_require_auth = true;
            else
                has_require_auth = false;
        }
    }
 
    has_scram_keys = has_scram_client_key && has_scram_server_key && MyProcPort->has_scram_keys;
 
    return (has_scram_keys && has_require_auth);
}

References Port::has_scram_keys, i, keywords, MyProcPort, and values.

Referenced by check_conn_params(), and pgfdw_security_check().

pgfdw_inval_callback()

static void pgfdw_inval_callback ( Datum  arg, int  cacheid, uint32  hashvalue  )

static

Definition at line 1296 of file connection.c.

{
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
 
    Assert(cacheid == FOREIGNSERVEROID || cacheid == USERMAPPINGOID);
 
    /* ConnectionHash must exist already, if we're registered */
    hash_seq_init(&scan, ConnectionHash);
    while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
    {
        /* Ignore invalid entries */
        if (entry->conn == NULL)
            continue;
 
        /* hashvalue == 0 means a cache reset, must clear all state */
        if (hashvalue == 0 ||
            (cacheid == FOREIGNSERVEROID &&
             entry->server_hashvalue == hashvalue) ||
            (cacheid == USERMAPPINGOID &&
             entry->mapping_hashvalue == hashvalue))
        {
            /*
             * Close the connection immediately if it's not used yet in this
             * transaction. Otherwise mark it as invalid so that
             * pgfdw_xact_callback() can close it at the end of this
             * transaction.
             */
            if (entry->xact_depth == 0)
            {
                elog(DEBUG3, "discarding connection %p", entry->conn);
                disconnect_pg_server(entry);
            }
            else
                entry->invalidated = true;
        }
    }
}

References Assert(), ConnCacheEntry::conn, ConnectionHash, DEBUG3, disconnect_pg_server(), elog, hash_seq_init(), hash_seq_search(), ConnCacheEntry::invalidated, ConnCacheEntry::mapping_hashvalue, ConnCacheEntry::server_hashvalue, and ConnCacheEntry::xact_depth.

Referenced by GetConnection().

pgfdw_reject_incomplete_xact_state_change()

static void pgfdw_reject_incomplete_xact_state_change ( ConnCacheEntry *  entry )

static

Definition at line 1346 of file connection.c.

{
    ForeignServer *server;
 
    /* nothing to do for inactive entries and entries of sane state */
    if (entry->conn == NULL || !entry->changing_xact_state)
        return;
 
    /* make sure this entry is inactive */
    disconnect_pg_server(entry);
 
    /* find server name to be shown in the message below */
    server = GetForeignServer(entry->serverid);
 
    ereport(ERROR,
            (errcode(ERRCODE_CONNECTION_EXCEPTION),
             errmsg("connection to server \"%s\" was lost",
                    server->servername)));
}

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, disconnect_pg_server(), ereport, errcode(), errmsg(), ERROR, GetForeignServer(), ConnCacheEntry::serverid, and ForeignServer::servername.

Referenced by GetConnection(), pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_report_error()

void pgfdw_report_error	(	int	elevel,
		PGresult *	res,
		PGconn *	conn,
		bool	clear,
		const char *	sql
	)

Definition at line 977 of file connection.c.

{
    /* If requested, PGresult must be released before leaving this function. */
    PG_TRY();
    {
        char       *diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
        char       *message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
        char       *message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
        char       *message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
        char       *message_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
        int         sqlstate;
 
        if (diag_sqlstate)
            sqlstate = MAKE_SQLSTATE(diag_sqlstate[0],
                                     diag_sqlstate[1],
                                     diag_sqlstate[2],
                                     diag_sqlstate[3],
                                     diag_sqlstate[4]);
        else
            sqlstate = ERRCODE_CONNECTION_FAILURE;
 
        /*
         * If we don't get a message from the PGresult, try the PGconn.  This
         * is needed because for connection-level failures, PQgetResult may
         * just return NULL, not a PGresult at all.
         */
        if (message_primary == NULL)
            message_primary = pchomp(PQerrorMessage(conn));
 
        ereport(elevel,
                (errcode(sqlstate),
                 (message_primary != NULL && message_primary[0] != '\0') ?
                 errmsg_internal("%s", message_primary) :
                 errmsg("could not obtain message string for remote error"),
                 message_detail ? errdetail_internal("%s", message_detail) : 0,
                 message_hint ? errhint("%s", message_hint) : 0,
                 message_context ? errcontext("%s", message_context) : 0,
                 sql ? errcontext("remote SQL command: %s", sql) : 0));
    }
    PG_FINALLY();
    {
        if (clear)
            PQclear(res);
    }
    PG_END_TRY();
}

References conn, ereport, errcode(), errcontext, errdetail_internal(), errhint(), errmsg(), errmsg_internal(), MAKE_SQLSTATE, pchomp(), PG_DIAG_CONTEXT, PG_DIAG_MESSAGE_DETAIL, PG_DIAG_MESSAGE_HINT, PG_DIAG_MESSAGE_PRIMARY, PG_DIAG_SQLSTATE, PG_END_TRY, PG_FINALLY, PG_TRY, PQclear(), PQerrorMessage(), and PQresultErrorField().

Referenced by close_cursor(), create_cursor(), deallocate_query(), do_sql_command_begin(), do_sql_command_end(), execute_dml_stmt(), execute_foreign_modify(), fetch_more_data(), fetch_more_data_begin(), get_remote_estimate(), pgfdw_exec_cleanup_query_begin(), pgfdw_exec_cleanup_query_end(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresForeignAsyncNotify(), postgresGetAnalyzeInfoForForeignTable(), postgresImportForeignSchema(), postgresReScanForeignScan(), and prepare_foreign_modify().

pgfdw_reset_xact_state()

static void pgfdw_reset_xact_state ( ConnCacheEntry *  entry, bool  toplevel  )

static

Definition at line 1370 of file connection.c.

{
    if (toplevel)
    {
        /* Reset state to show we're out of a transaction */
        entry->xact_depth = 0;
 
        /*
         * If the connection isn't in a good idle state, it is marked as
         * invalid or keep_connections option of its server is disabled, then
         * discard it to recover. Next GetConnection will open a new
         * connection.
         */
        if (PQstatus(entry->conn) != CONNECTION_OK ||
            PQtransactionStatus(entry->conn) != PQTRANS_IDLE ||
            entry->changing_xact_state ||
            entry->invalidated ||
            !entry->keep_connections)
        {
            elog(DEBUG3, "discarding connection %p", entry->conn);
            disconnect_pg_server(entry);
        }
    }
    else
    {
        /* Reset state to show we're out of a subtransaction */
        entry->xact_depth--;
    }
}

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, CONNECTION_OK, DEBUG3, disconnect_pg_server(), elog, ConnCacheEntry::invalidated, ConnCacheEntry::keep_connections, PQstatus(), PQTRANS_IDLE, PQtransactionStatus(), and ConnCacheEntry::xact_depth.

Referenced by pgfdw_finish_abort_cleanup(), pgfdw_finish_pre_commit_cleanup(), pgfdw_finish_pre_subcommit_cleanup(), pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_security_check()

static void pgfdw_security_check ( const char **  keywords, const char **  values, UserMapping *  user, PGconn *  conn  )

static

Definition at line 432 of file connection.c.

{
    /* Superusers bypass the check */
    if (superuser_arg(user->userid))
        return;
 
#ifdef ENABLE_GSS
    /* Connected via GSSAPI with delegated credentials- all good. */
    if (PQconnectionUsedGSSAPI(conn) && be_gssapi_get_delegation(MyProcPort))
        return;
#endif
 
    /* Ok if superuser set PW required false. */
    if (!UserMappingPasswordRequired(user))
        return;
 
    /* Connected via PW, with PW required true, and provided non-empty PW. */
    if (PQconnectionUsedPassword(conn))
    {
        /* ok if params contain a non-empty password */
        for (int i = 0; keywords[i] != NULL; i++)
        {
            if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
                return;
        }
    }
 
    /*
     * Ok if SCRAM pass-through is being used and all required SCRAM options
     * are set correctly. If pgfdw_has_required_scram_options returns true we
     * assume that UseScramPassthrough is also true since SCRAM options are
     * only set when UseScramPassthrough is enabled.
     */
    if (MyProcPort->has_scram_keys && pgfdw_has_required_scram_options(keywords, values))
        return;
 
    ereport(ERROR,
            (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
             errmsg("password or GSSAPI delegated credentials required"),
             errdetail("Non-superuser cannot connect if the server does not request a password or use GSSAPI with delegated credentials."),
             errhint("Target server's authentication method must be changed or password_required=false set in the user mapping attributes.")));
}

References be_gssapi_get_delegation(), conn, ereport, errcode(), errdetail(), errhint(), errmsg(), ERROR, Port::has_scram_keys, i, keywords, MyProcPort, pgfdw_has_required_scram_options(), PQconnectionUsedGSSAPI(), PQconnectionUsedPassword(), superuser_arg(), user, UserMappingPasswordRequired(), and values.

Referenced by connect_pg_server().

pgfdw_subxact_callback()

static void pgfdw_subxact_callback ( SubXactEvent  event, SubTransactionId  mySubid, SubTransactionId  parentSubid, void *  arg  )

static

Definition at line 1183 of file connection.c.

{
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
    int         curlevel;
    List       *pending_entries = NIL;
    List       *cancel_requested = NIL;
 
    /* Nothing to do at subxact start, nor after commit. */
    if (!(event == SUBXACT_EVENT_PRE_COMMIT_SUB ||
          event == SUBXACT_EVENT_ABORT_SUB))
        return;
 
    /* Quick exit if no connections were touched in this transaction. */
    if (!xact_got_connection)
        return;
 
    /*
     * Scan all connection cache entries to find open remote subtransactions
     * of the current level, and close them.
     */
    curlevel = GetCurrentTransactionNestLevel();
    hash_seq_init(&scan, ConnectionHash);
    while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
    {
        char        sql[100];
 
        /*
         * We only care about connections with open remote subtransactions of
         * the current level.
         */
        if (entry->conn == NULL || entry->xact_depth < curlevel)
            continue;
 
        if (entry->xact_depth > curlevel)
            elog(ERROR, "missed cleaning up remote subtransaction at level %d",
                 entry->xact_depth);
 
        if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
        {
            /*
             * If abort cleanup previously failed for this connection, we
             * can't issue any more commands against it.
             */
            pgfdw_reject_incomplete_xact_state_change(entry);
 
            /* Commit all remote subtransactions during pre-commit */
            snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
            entry->changing_xact_state = true;
            if (entry->parallel_commit)
            {
                do_sql_command_begin(entry->conn, sql);
                pending_entries = lappend(pending_entries, entry);
                continue;
            }
            do_sql_command(entry->conn, sql);
            entry->changing_xact_state = false;
        }
        else
        {
            /* Rollback all remote subtransactions during abort */
            if (entry->parallel_abort)
            {
                if (pgfdw_abort_cleanup_begin(entry, false,
                                              &pending_entries,
                                              &cancel_requested))
                    continue;
            }
            else
                pgfdw_abort_cleanup(entry, false);
        }
 
        /* OK, we're outta that level of subtransaction */
        pgfdw_reset_xact_state(entry, false);
    }
 
    /* If there are any pending connections, finish cleaning them up */
    if (pending_entries || cancel_requested)
    {
        if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
        {
            Assert(cancel_requested == NIL);
            pgfdw_finish_pre_subcommit_cleanup(pending_entries, curlevel);
        }
        else
        {
            Assert(event == SUBXACT_EVENT_ABORT_SUB);
            pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
                                       false);
        }
    }
}

References Assert(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, ConnectionHash, do_sql_command(), do_sql_command_begin(), elog, ERROR, GetCurrentTransactionNestLevel(), hash_seq_init(), hash_seq_search(), lappend(), NIL, ConnCacheEntry::parallel_abort, ConnCacheEntry::parallel_commit, pgfdw_abort_cleanup(), pgfdw_abort_cleanup_begin(), pgfdw_finish_abort_cleanup(), pgfdw_finish_pre_subcommit_cleanup(), pgfdw_reject_incomplete_xact_state_change(), pgfdw_reset_xact_state(), snprintf, SUBXACT_EVENT_ABORT_SUB, SUBXACT_EVENT_PRE_COMMIT_SUB, ConnCacheEntry::xact_depth, and xact_got_connection.

Referenced by GetConnection().

pgfdw_xact_callback()

static void pgfdw_xact_callback ( XactEvent  event, void *  arg  )

static

Definition at line 1033 of file connection.c.

{
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
    List       *pending_entries = NIL;
    List       *cancel_requested = NIL;
 
    /* Quick exit if no connections were touched in this transaction. */
    if (!xact_got_connection)
        return;
 
    /*
     * Scan all connection cache entries to find open remote transactions, and
     * close them.
     */
    hash_seq_init(&scan, ConnectionHash);
    while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
    {
        PGresult   *res;
 
        /* Ignore cache entry if no open connection right now */
        if (entry->conn == NULL)
            continue;
 
        /* If it has an open remote transaction, try to close it */
        if (entry->xact_depth > 0)
        {
            elog(DEBUG3, "closing remote transaction on connection %p",
                 entry->conn);
 
            switch (event)
            {
                case XACT_EVENT_PARALLEL_PRE_COMMIT:
                case XACT_EVENT_PRE_COMMIT:
 
                    /*
                     * If abort cleanup previously failed for this connection,
                     * we can't issue any more commands against it.
                     */
                    pgfdw_reject_incomplete_xact_state_change(entry);
 
                    /* Commit all remote transactions during pre-commit */
                    entry->changing_xact_state = true;
                    if (entry->parallel_commit)
                    {
                        do_sql_command_begin(entry->conn, "COMMIT TRANSACTION");
                        pending_entries = lappend(pending_entries, entry);
                        continue;
                    }
                    do_sql_command(entry->conn, "COMMIT TRANSACTION");
                    entry->changing_xact_state = false;
 
                    /*
                     * If there were any errors in subtransactions, and we
                     * made prepared statements, do a DEALLOCATE ALL to make
                     * sure we get rid of all prepared statements. This is
                     * annoying and not terribly bulletproof, but it's
                     * probably not worth trying harder.
                     *
                     * DEALLOCATE ALL only exists in 8.3 and later, so this
                     * constrains how old a server postgres_fdw can
                     * communicate with.  We intentionally ignore errors in
                     * the DEALLOCATE, so that we can hobble along to some
                     * extent with older servers (leaking prepared statements
                     * as we go; but we don't really support update operations
                     * pre-8.3 anyway).
                     */
                    if (entry->have_prep_stmt && entry->have_error)
                    {
                        res = pgfdw_exec_query(entry->conn, "DEALLOCATE ALL",
                                               NULL);
                        PQclear(res);
                    }
                    entry->have_prep_stmt = false;
                    entry->have_error = false;
                    break;
                case XACT_EVENT_PRE_PREPARE:
 
                    /*
                     * We disallow any remote transactions, since it's not
                     * very reasonable to hold them open until the prepared
                     * transaction is committed.  For the moment, throw error
                     * unconditionally; later we might allow read-only cases.
                     * Note that the error will cause us to come right back
                     * here with event == XACT_EVENT_ABORT, so we'll clean up
                     * the connection state at that point.
                     */
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot PREPARE a transaction that has operated on postgres_fdw foreign tables")));
                    break;
                case XACT_EVENT_PARALLEL_COMMIT:
                case XACT_EVENT_COMMIT:
                case XACT_EVENT_PREPARE:
                    /* Pre-commit should have closed the open transaction */
                    elog(ERROR, "missed cleaning up connection during pre-commit");
                    break;
                case XACT_EVENT_PARALLEL_ABORT:
                case XACT_EVENT_ABORT:
                    /* Rollback all remote transactions during abort */
                    if (entry->parallel_abort)
                    {
                        if (pgfdw_abort_cleanup_begin(entry, true,
                                                      &pending_entries,
                                                      &cancel_requested))
                            continue;
                    }
                    else
                        pgfdw_abort_cleanup(entry, true);
                    break;
            }
        }
 
        /* Reset state to show we're out of a transaction */
        pgfdw_reset_xact_state(entry, true);
    }
 
    /* If there are any pending connections, finish cleaning them up */
    if (pending_entries || cancel_requested)
    {
        if (event == XACT_EVENT_PARALLEL_PRE_COMMIT ||
            event == XACT_EVENT_PRE_COMMIT)
        {
            Assert(cancel_requested == NIL);
            pgfdw_finish_pre_commit_cleanup(pending_entries);
        }
        else
        {
            Assert(event == XACT_EVENT_PARALLEL_ABORT ||
                   event == XACT_EVENT_ABORT);
            pgfdw_finish_abort_cleanup(pending_entries, cancel_requested,
                                       true);
        }
    }
 
    /*
     * Regardless of the event type, we can now mark ourselves as out of the
     * transaction.  (Note: if we are here during PRE_COMMIT or PRE_PREPARE,
     * this saves a useless scan of the hashtable during COMMIT or PREPARE.)
     */
    xact_got_connection = false;
 
    /* Also reset cursor numbering for next transaction */
    cursor_number = 0;
}

References Assert(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, ConnectionHash, cursor_number, DEBUG3, do_sql_command(), do_sql_command_begin(), elog, ereport, errcode(), errmsg(), ERROR, hash_seq_init(), hash_seq_search(), ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, lappend(), NIL, ConnCacheEntry::parallel_abort, ConnCacheEntry::parallel_commit, pgfdw_abort_cleanup(), pgfdw_abort_cleanup_begin(), pgfdw_exec_query(), pgfdw_finish_abort_cleanup(), pgfdw_finish_pre_commit_cleanup(), pgfdw_reject_incomplete_xact_state_change(), pgfdw_reset_xact_state(), PQclear(), ConnCacheEntry::xact_depth, XACT_EVENT_ABORT, XACT_EVENT_COMMIT, XACT_EVENT_PARALLEL_ABORT, XACT_EVENT_PARALLEL_COMMIT, XACT_EVENT_PARALLEL_PRE_COMMIT, XACT_EVENT_PRE_COMMIT, XACT_EVENT_PRE_PREPARE, XACT_EVENT_PREPARE, and xact_got_connection.

Referenced by GetConnection().

postgres_fdw_disconnect()

Datum postgres_fdw_disconnect

(

PG_FUNCTION_ARGS

)

Definition at line 2345 of file connection.c.

{
    ForeignServer *server;
    char       *servername;
 
    servername = text_to_cstring(PG_GETARG_TEXT_PP(0));
    server = GetForeignServerByName(servername, false);
 
    PG_RETURN_BOOL(disconnect_cached_connections(server->serverid));
}

References disconnect_cached_connections(), GetForeignServerByName(), PG_GETARG_TEXT_PP, PG_RETURN_BOOL, ForeignServer::serverid, and text_to_cstring().

postgres_fdw_disconnect_all()

Datum postgres_fdw_disconnect_all

(

PG_FUNCTION_ARGS

)

Definition at line 2366 of file connection.c.

{
    PG_RETURN_BOOL(disconnect_cached_connections(InvalidOid));
}

References disconnect_cached_connections(), InvalidOid, and PG_RETURN_BOOL.

postgres_fdw_get_connections()

Datum postgres_fdw_get_connections

(

PG_FUNCTION_ARGS

)

Definition at line 2325 of file connection.c.

{
    postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_1);
 
    PG_RETURN_VOID();
}

References PG_RETURN_VOID, PGFDW_V1_1, and postgres_fdw_get_connections_internal().

postgres_fdw_get_connections_1_2()

Datum postgres_fdw_get_connections_1_2

(

PG_FUNCTION_ARGS

)

Definition at line 2317 of file connection.c.

{
    postgres_fdw_get_connections_internal(fcinfo, PGFDW_V1_2);
 
    PG_RETURN_VOID();
}

References PG_RETURN_VOID, PGFDW_V1_2, and postgres_fdw_get_connections_internal().

postgres_fdw_get_connections_internal()

static void postgres_fdw_get_connections_internal ( FunctionCallInfo  fcinfo, enum pgfdwVersion  api_version  )

static

Definition at line 2165 of file connection.c.

{
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
 
    InitMaterializedSRF(fcinfo, 0);
 
    /* If cache doesn't exist, we return no records */
    if (!ConnectionHash)
        return;
 
    /* Check we have the expected number of output arguments */
    switch (rsinfo->setDesc->natts)
    {
        case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1:
            if (api_version != PGFDW_V1_1)
                elog(ERROR, "incorrect number of output arguments");
            break;
        case POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2:
            if (api_version != PGFDW_V1_2)
                elog(ERROR, "incorrect number of output arguments");
            break;
        default:
            elog(ERROR, "incorrect number of output arguments");
    }
 
    hash_seq_init(&scan, ConnectionHash);
    while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
    {
        ForeignServer *server;
        Datum       values[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
        bool        nulls[POSTGRES_FDW_GET_CONNECTIONS_COLS] = {0};
        int         i = 0;
 
        /* We only look for open remote connections */
        if (!entry->conn)
            continue;
 
        server = GetForeignServerExtended(entry->serverid, FSV_MISSING_OK);
 
        /*
         * The foreign server may have been dropped in current explicit
         * transaction. It is not possible to drop the server from another
         * session when the connection associated with it is in use in the
         * current transaction, if tried so, the drop query in another session
         * blocks until the current transaction finishes.
         *
         * Even though the server is dropped in the current transaction, the
         * cache can still have associated active connection entry, say we
         * call such connections dangling. Since we can not fetch the server
         * name from system catalogs for dangling connections, instead we show
         * NULL value for server name in output.
         *
         * We could have done better by storing the server name in the cache
         * entry instead of server oid so that it could be used in the output.
         * But the server name in each cache entry requires 64 bytes of
         * memory, which is huge, when there are many cached connections and
         * the use case i.e. dropping the foreign server within the explicit
         * current transaction seems rare. So, we chose to show NULL value for
         * server name in output.
         *
         * Such dangling connections get closed either in next use or at the
         * end of current explicit transaction in pgfdw_xact_callback.
         */
        if (!server)
        {
            /*
             * If the server has been dropped in the current explicit
             * transaction, then this entry would have been invalidated in
             * pgfdw_inval_callback at the end of drop server command. Note
             * that this connection would not have been closed in
             * pgfdw_inval_callback because it is still being used in the
             * current explicit transaction. So, assert that here.
             */
            Assert(entry->conn && entry->xact_depth > 0 && entry->invalidated);
 
            /* Show null, if no server name was found */
            nulls[i++] = true;
        }
        else
            values[i++] = CStringGetTextDatum(server->servername);
 
        if (api_version >= PGFDW_V1_2)
        {
            HeapTuple   tp;
 
            /* Use the system cache to obtain the user mapping */
            tp = SearchSysCache1(USERMAPPINGOID, ObjectIdGetDatum(entry->key));
 
            /*
             * Just like in the foreign server case, user mappings can also be
             * dropped in the current explicit transaction. Therefore, the
             * similar check as in the server case is required.
             */
            if (!HeapTupleIsValid(tp))
            {
                /*
                 * If we reach here, this entry must have been invalidated in
                 * pgfdw_inval_callback, same as in the server case.
                 */
                Assert(entry->conn && entry->xact_depth > 0 &&
                       entry->invalidated);
 
                nulls[i++] = true;
            }
            else
            {
                Oid         userid;
 
                userid = ((Form_pg_user_mapping) GETSTRUCT(tp))->umuser;
                values[i++] = CStringGetTextDatum(MappingUserName(userid));
                ReleaseSysCache(tp);
            }
        }
 
        values[i++] = BoolGetDatum(!entry->invalidated);
 
        if (api_version >= PGFDW_V1_2)
        {
            bool        check_conn = PG_GETARG_BOOL(0);
 
            /* Is this connection used in the current transaction? */
            values[i++] = BoolGetDatum(entry->xact_depth > 0);
 
            /*
             * If a connection status check is requested and supported, return
             * whether the connection is closed. Otherwise, return NULL.
             */
            if (check_conn && pgfdw_conn_checkable())
                values[i++] = BoolGetDatum(pgfdw_conn_check(entry->conn) != 0);
            else
                nulls[i++] = true;
 
            /* Return process ID of remote backend */
            values[i++] = Int32GetDatum(PQbackendPID(entry->conn));
        }
 
        tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
    }
}

References Assert(), BoolGetDatum(), ConnectionHash, CStringGetTextDatum, elog, ERROR, FSV_MISSING_OK, GetForeignServerExtended(), GETSTRUCT(), hash_seq_init(), hash_seq_search(), HeapTupleIsValid, i, InitMaterializedSRF(), Int32GetDatum(), MappingUserName, TupleDescData::natts, ObjectIdGetDatum(), PG_GETARG_BOOL, pgfdw_conn_check(), pgfdw_conn_checkable(), PGFDW_V1_1, PGFDW_V1_2, POSTGRES_FDW_GET_CONNECTIONS_COLS, POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_1, POSTGRES_FDW_GET_CONNECTIONS_COLS_V1_2, PQbackendPID(), ReleaseSysCache(), FunctionCallInfoBaseData::resultinfo, SearchSysCache1(), ForeignServer::servername, ReturnSetInfo::setDesc, ReturnSetInfo::setResult, tuplestore_putvalues(), and values.

Referenced by postgres_fdw_get_connections(), and postgres_fdw_get_connections_1_2().

ReleaseConnection()

void ReleaseConnection

(

PGconn *

conn

)

Definition at line 891 of file connection.c.

{
    /*
     * Currently, we don't actually track connection references because all
     * cleanup is managed on a transaction or subtransaction basis instead. So
     * there's nothing to do here.
     */
}

Referenced by estimate_path_cost_size(), finish_foreign_modify(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresEndDirectModify(), postgresEndForeignScan(), postgresGetAnalyzeInfoForForeignTable(), and postgresImportForeignSchema().

UserMappingPasswordRequired()

static bool UserMappingPasswordRequired ( UserMapping *  user )

static

Definition at line 667 of file connection.c.

{
    ListCell   *cell;
 
    foreach(cell, user->options)
    {
        DefElem    *def = (DefElem *) lfirst(cell);
 
        if (strcmp(def->defname, "password_required") == 0)
            return defGetBoolean(def);
    }
 
    return true;
}

References defGetBoolean(), DefElem::defname, lfirst, and user.

Referenced by check_conn_params(), and pgfdw_security_check().

UseScramPassthrough()

static bool UseScramPassthrough ( ForeignServer *  server, UserMapping *  user  )

static

Definition at line 683 of file connection.c.

{
    ListCell   *cell;
 
    foreach(cell, server->options)
    {
        DefElem    *def = (DefElem *) lfirst(cell);
 
        if (strcmp(def->defname, "use_scram_passthrough") == 0)
            return defGetBoolean(def);
    }
 
    foreach(cell, user->options)
    {
        DefElem    *def = (DefElem *) lfirst(cell);
 
        if (strcmp(def->defname, "use_scram_passthrough") == 0)
            return defGetBoolean(def);
    }
 
    return false;
}

References defGetBoolean(), DefElem::defname, lfirst, ForeignServer::options, and user.

Referenced by connect_pg_server().

Variable Documentation

ConnectionHash

HTAB* ConnectionHash = NULL

static

Definition at line 78 of file connection.c.

Referenced by disconnect_cached_connections(), GetConnection(), pgfdw_inval_callback(), pgfdw_subxact_callback(), pgfdw_xact_callback(), and postgres_fdw_get_connections_internal().

cursor_number

unsigned int cursor_number = 0

static

Definition at line 81 of file connection.c.

Referenced by close_cursor(), GetCursorNumber(), pgfdw_xact_callback(), and postgresAcquireSampleRowsFunc().

pgfdw_we_cleanup_result

uint32 pgfdw_we_cleanup_result = 0

static

Definition at line 88 of file connection.c.

Referenced by pgfdw_get_cleanup_result().

pgfdw_we_connect

uint32 pgfdw_we_connect = 0

static

Definition at line 89 of file connection.c.

Referenced by connect_pg_server().

pgfdw_we_get_result

uint32 pgfdw_we_get_result = 0

static

Definition at line 90 of file connection.c.

Referenced by GetConnection(), and pgfdw_get_result().

prep_stmt_number

unsigned int prep_stmt_number = 0

static

Definition at line 82 of file connection.c.

Referenced by GetPrepStmtNumber().

xact_got_connection

bool xact_got_connection = false

static

Definition at line 85 of file connection.c.

Referenced by GetConnection(), pgfdw_subxact_callback(), and pgfdw_xact_callback().