connection.c File Reference

#include "postgres.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/pg_user_mapping.h"
#include "commands/defrem.h"
#include "funcapi.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postgres_fdw.h"
#include "storage/fd.h"
#include "storage/latch.h"
#include "utils/builtins.h"
#include "utils/datetime.h"
#include "utils/hsearch.h"
#include "utils/inval.h"
#include "utils/memutils.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	POSTGRES_FDW_GET_CONNECTIONS_COLS   2

Typedefs
typedef Oid	ConnCacheKey
typedef struct ConnCacheEntry	ConnCacheEntry

Functions
	PG_FUNCTION_INFO_V1 (postgres_fdw_get_connections)
	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_exec_cleanup_query (PGconn *conn, const char *query, bool ignore_errors)
static bool	pgfdw_get_cleanup_result (PGconn *conn, TimestampTz endtime, PGresult **result, bool *timed_out)
static void	pgfdw_abort_cleanup (ConnCacheEntry *entry, bool toplevel)
static void	pgfdw_finish_pre_commit_cleanup (List *pending_entries)
static void	pgfdw_finish_pre_subcommit_cleanup (List *pending_entries, int curlevel)
static bool	UserMappingPasswordRequired (UserMapping *user)
static bool	disconnect_cached_connections (Oid serverid)
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, const char *query)
void	pgfdw_report_error (int elevel, PGresult *res, PGconn *conn, bool clear, const char *sql)
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

Macro Definition Documentation

POSTGRES_FDW_GET_CONNECTIONS_COLS

#define POSTGRES_FDW_GET_CONNECTIONS_COLS   2

Typedef Documentation

ConnCacheEntry

typedef struct ConnCacheEntry ConnCacheEntry

ConnCacheKey

typedef Oid ConnCacheKey

Definition at line 49 of file connection.c.

Function Documentation

begin_remote_xact()

static void begin_remote_xact ( ConnCacheEntry *  entry )

static

Definition at line 681 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 565 of file connection.c.

{
    int         i;
 
    /* no check required if superuser */
    if (superuser_arg(user->userid))
        return;
 
    /* 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;
 
    ereport(ERROR,
            (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
             errmsg("password is required"),
             errdetail("Non-superusers must provide a password in the user mapping.")));
}

References ereport, errcode(), errdetail(), errmsg(), ERROR, i, 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 602 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 UTC
     * (quoted, because very old servers are picky about case).
     */
    do_sql_command(conn, "SET timezone = 'UTC'");
 
    /*
     * 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 354 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.
         */
        n = list_length(server->options) + list_length(user->options) + 4;
        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++;
 
        keywords[n] = values[n] = NULL;
 
        /* verify the set of connection parameters */
        check_conn_params(keywords, values, user);
 
        /*
         * We must obey fd.c's limit on non-virtual file descriptors.  Assume
         * that a PGconn represents one long-lived FD.  (Doing this here also
         * ensures that VFDs are closed if needed to make room.)
         */
        if (!AcquireExternalFD())
        {
#ifndef WIN32                   /* can't write #if within ereport() macro */
            ereport(ERROR,
                    (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
                     errmsg("could not connect to server \"%s\"",
                            server->servername),
                     errdetail("There are too many open files on the local server."),
                     errhint("Raise the server's max_files_per_process and/or \"ulimit -n\" limits.")));
#else
            ereport(ERROR,
                    (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
                     errmsg("could not connect to server \"%s\"",
                            server->servername),
                     errdetail("There are too many open files on the local server."),
                     errhint("Raise the server's max_files_per_process setting.")));
#endif
        }
 
        /* OK to make connection */
        conn = PQconnectdbParams(keywords, values, false);
 
        if (!conn)
            ReleaseExternalFD();    /* because the PG_CATCH block won't */
 
        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)))));
 
        /*
         * Check that non-superuser has used password to establish connection;
         * otherwise, he's piggybacking on the postgres server's user
         * identity. See also dblink_security_check() in contrib/dblink and
         * check_conn_params.
         */
        if (!superuser_arg(user->userid) && UserMappingPasswordRequired(user) &&
            !PQconnectionUsedPassword(conn))
            ereport(ERROR,
                    (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
                     errmsg("password is required"),
                     errdetail("Non-superuser cannot connect if the server does not request a password."),
                     errhint("Target server's authentication method must be changed or password_required=false set in the user mapping attributes.")));
 
        /* Prepare new session for use */
        configure_remote_session(conn);
 
        if (appname != NULL)
            pfree(appname);
        pfree(keywords);
        pfree(values);
    }
    PG_CATCH();
    {
        /* Release PGconn data structure if we managed to create one */
        if (conn)
        {
            PQfinish(conn);
            ReleaseExternalFD();
        }
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    return conn;
}

References AcquireExternalFD(), check_conn_params(), configure_remote_session(), conn, CONNECTION_OK, ereport, errcode(), errdetail(), errdetail_internal(), errhint(), errmsg(), ERROR, ExtractConnectionOptions(), GetDatabaseEncodingName(), i, list_length(), ForeignServer::options, palloc(), pchomp(), pfree(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, pgfdw_application_name, PQconnectdbParams(), PQconnectionUsedPassword(), PQerrorMessage(), PQfinish(), PQstatus(), process_pgfdw_appname(), ReleaseExternalFD(), ForeignServer::servername, superuser_arg(), user, UserMappingPasswordRequired(), and values.

Referenced by make_new_connection().

disconnect_cached_connections()

static bool disconnect_cached_connections ( Oid  serverid )

static

Definition at line 1802 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 527 of file connection.c.

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

References ConnCacheEntry::conn, PQfinish(), and ReleaseExternalFD().

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 638 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 645 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 652 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, sql);
    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(), PQresultStatus(), and res.

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 134 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;
 
        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);
 
        if (entry->conn == NULL)
            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(), CurrentMemoryContext, DEBUG3, disconnect_pg_server(), elog(), HASHCTL::entrysize, ereport, errdetail_internal(), errmsg_internal(), FlushErrorState(), FOREIGNSERVEROID, FreeErrorData(), HASH_BLOBS, hash_create(), HASH_ELEM, HASH_ENTER, hash_search(), ConnCacheEntry::have_prep_stmt, ConnCacheEntry::invalidated, sort-test::key, HASHCTL::keysize, 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_xact_callback(), PQerrorMessage(), PQstatus(), process_pending_request(), RegisterSubXactCallback(), RegisterXactCallback(), ErrorData::sqlerrcode, ConnCacheEntry::state, user, USERMAPPINGOID, ConnCacheEntry::xact_depth, and xact_got_connection.

Referenced by create_foreign_modify(), dumpBlobs(), dumpDatabase(), dumpDatabaseConfig(), 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(), postgresImportForeignSchema(), setup_connection(), StartLogStreamer(), StreamLog(), and StreamLogicalLog().

GetCursorNumber()

unsigned int GetCursorNumber

(

PGconn *

conn

)

Definition at line 745 of file connection.c.

{
    return ++cursor_number;
}

References cursor_number.

Referenced by postgresAcquireSampleRowsFunc(), and postgresBeginForeignScan().

GetPrepStmtNumber()

unsigned int GetPrepStmtNumber

(

PGconn *

conn

)

Definition at line 759 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 294 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 (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;
    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);
    }
 
    /* 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(), FOREIGNSERVEROID, GetForeignServer(), GetSysCacheHashValue1, ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, ConnCacheEntry::invalidated, ConnCacheEntry::keep_connections, lfirst, ConnCacheEntry::mapping_hashvalue, ObjectIdGetDatum(), ForeignServer::options, ConnCacheEntry::parallel_commit, ConnCacheEntry::server_hashvalue, ConnCacheEntry::serverid, ForeignServer::serverid, ForeignServer::servername, ConnCacheEntry::state, user, USERMAPPINGOID, and ConnCacheEntry::xact_depth.

Referenced by GetConnection().

PG_FUNCTION_INFO_V1() [1/3]

PG_FUNCTION_INFO_V1

(

postgres_fdw_disconnect

)

PG_FUNCTION_INFO_V1() [2/3]

PG_FUNCTION_INFO_V1

(

postgres_fdw_disconnect_all

)

PG_FUNCTION_INFO_V1() [3/3]

PG_FUNCTION_INFO_V1

(

postgres_fdw_get_connections

)

pgfdw_abort_cleanup()

static void pgfdw_abort_cleanup ( ConnCacheEntry *  entry, bool  toplevel  )

static

Definition at line 1473 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 */
 
    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);
    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, ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, in_error_recursion_trouble(), PgFdwConnState::pendingAreq, pgfdw_cancel_query(), pgfdw_exec_cleanup_query(), PQTRANS_ACTIVE, PQtransactionStatus(), snprintf, ConnCacheEntry::state, and ConnCacheEntry::xact_depth.

Referenced by pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_cancel_query()

static bool pgfdw_cancel_query ( PGconn *  conn )

static

Definition at line 1265 of file connection.c.

{
    PGcancel   *cancel;
    char        errbuf[256];
    PGresult   *result = NULL;
    TimestampTz endtime;
    bool        timed_out;
 
    /*
     * If it takes too long to cancel the query and discard the result, assume
     * the connection is dead.
     */
    endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(), 30000);
 
    /*
     * Issue cancel request.  Unfortunately, there's no good way to limit the
     * amount of time that we might block inside PQgetCancel().
     */
    if ((cancel = PQgetCancel(conn)))
    {
        if (!PQcancel(cancel, errbuf, sizeof(errbuf)))
        {
            ereport(WARNING,
                    (errcode(ERRCODE_CONNECTION_FAILURE),
                     errmsg("could not send cancel request: %s",
                            errbuf)));
            PQfreeCancel(cancel);
            return false;
        }
        PQfreeCancel(cancel);
    }
 
    /* Get and discard the result of the query. */
    if (pgfdw_get_cleanup_result(conn, endtime, &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(), GetCurrentTimestamp(), pchomp(), pgfdw_get_cleanup_result(), PQcancel(), PQclear(), PQerrorMessage(), PQfreeCancel(), PQgetCancel(), TimestampTzPlusMilliseconds, and WARNING.

Referenced by pgfdw_abort_cleanup().

pgfdw_exec_cleanup_query()

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

static

Definition at line 1329 of file connection.c.

{
    PGresult   *result = NULL;
    TimestampTz endtime;
    bool        timed_out;
 
    /*
     * 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(), 30000);
 
    /*
     * 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;
    }
 
    /* Get the result of the query. */
    if (pgfdw_get_cleanup_result(conn, endtime, &result, &timed_out))
    {
        if (timed_out)
            ereport(WARNING,
                    (errmsg("could not get query result due to timeout"),
                     query ? errcontext("remote SQL command: %s", query) : 0));
        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 conn, ereport, errcontext, errmsg(), GetCurrentTimestamp(), pgfdw_get_cleanup_result(), pgfdw_report_error(), PGRES_COMMAND_OK, PQclear(), PQresultStatus(), PQsendQuery(), TimestampTzPlusMilliseconds, and WARNING.

Referenced by pgfdw_abort_cleanup().

pgfdw_exec_query()

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

Definition at line 772 of file connection.c.

{
    /* First, process a pending asynchronous request, if any. */
    if (state && state->pendingAreq)
        process_pending_request(state->pendingAreq);
 
    /*
     * 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(ERROR, NULL, conn, false, query);
 
    /* Wait for the result. */
    return pgfdw_get_result(conn, query);
}

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

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

pgfdw_finish_pre_commit_cleanup()

static void pgfdw_finish_pre_commit_cleanup ( List *  pending_entries )

static

Definition at line 1547 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(), PQstatus(), and res.

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 1621 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, PGresult **  result, bool *  timed_out  )

static

Definition at line 1389 of file connection.c.

{
    volatile bool failed = false;
    PGresult   *volatile last_res = NULL;
 
    *timed_out = false;
 
    /* In what follows, do not leak any PGresults on an error. */
    PG_TRY();
    {
        for (;;)
        {
            PGresult   *res;
 
            while (PQisBusy(conn))
            {
                int         wc;
                TimestampTz now = GetCurrentTimestamp();
                long        cur_timeout;
 
                /* If timeout has expired, give up, else get sleep time. */
                cur_timeout = TimestampDifferenceMilliseconds(now, endtime);
                if (cur_timeout <= 0)
                {
                    *timed_out = true;
                    failed = true;
                    goto exit;
                }
 
                /* 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, PG_WAIT_EXTENSION);
                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, exit(), GetCurrentTimestamp(), MyLatch, now(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PG_WAIT_EXTENSION, PQclear(), PQconsumeInput(), PQgetResult(), PQisBusy(), PQsocket(), res, ResetLatch(), TimestampDifferenceMilliseconds(), WaitLatchOrSocket(), WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, WL_SOCKET_READABLE, and WL_TIMEOUT.

Referenced by pgfdw_cancel_query(), and pgfdw_exec_cleanup_query().

pgfdw_get_result()

PGresult* pgfdw_get_result	(	PGconn *	conn,
		const char *	query
	)

Definition at line 800 of file connection.c.

{
    PGresult   *volatile last_res = NULL;
 
    /* In what follows, do not leak any PGresults on an error. */
    PG_TRY();
    {
        for (;;)
        {
            PGresult   *res;
 
            while (PQisBusy(conn))
            {
                int         wc;
 
                /* Sleep until there's something to do */
                wc = WaitLatchOrSocket(MyLatch,
                                       WL_LATCH_SET | WL_SOCKET_READABLE |
                                       WL_EXIT_ON_PM_DEATH,
                                       PQsocket(conn),
                                       -1L, PG_WAIT_EXTENSION);
                ResetLatch(MyLatch);
 
                CHECK_FOR_INTERRUPTS();
 
                /* Data available in socket? */
                if (wc & WL_SOCKET_READABLE)
                {
                    if (!PQconsumeInput(conn))
                        pgfdw_report_error(ERROR, NULL, conn, false, query);
                }
            }
 
            res = PQgetResult(conn);
            if (res == NULL)
                break;          /* query is complete */
 
            PQclear(last_res);
            last_res = res;
        }
    }
    PG_CATCH();
    {
        PQclear(last_res);
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    return last_res;
}

References CHECK_FOR_INTERRUPTS, conn, ERROR, MyLatch, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PG_WAIT_EXTENSION, pgfdw_report_error(), PQclear(), PQconsumeInput(), PQgetResult(), PQisBusy(), PQsocket(), res, ResetLatch(), WaitLatchOrSocket(), WL_EXIT_ON_PM_DEATH, WL_LATCH_SET, and WL_SOCKET_READABLE.

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_inval_callback()

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

static

Definition at line 1146 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(), FOREIGNSERVEROID, hash_seq_init(), hash_seq_search(), ConnCacheEntry::invalidated, ConnCacheEntry::mapping_hashvalue, ConnCacheEntry::server_hashvalue, USERMAPPINGOID, 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 1196 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 865 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, PQexec 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(), PQresultErrorField(), and res.

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(), pgfdw_exec_query(), pgfdw_get_result(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresForeignAsyncNotify(), postgresImportForeignSchema(), postgresReScanForeignScan(), and prepare_foreign_modify().

pgfdw_reset_xact_state()

static void pgfdw_reset_xact_state ( ConnCacheEntry *  entry, bool  toplevel  )

static

Definition at line 1220 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_pre_commit_cleanup(), pgfdw_finish_pre_subcommit_cleanup(), pgfdw_subxact_callback(), and pgfdw_xact_callback().

pgfdw_subxact_callback()

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

static

Definition at line 1051 of file connection.c.

{
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
    int         curlevel;
    List       *pending_entries = 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 */
            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)
    {
        Assert(event == SUBXACT_EVENT_PRE_COMMIT_SUB);
        pgfdw_finish_pre_subcommit_cleanup(pending_entries, curlevel);
    }
}

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_commit, pgfdw_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 921 of file connection.c.

{
    HASH_SEQ_STATUS scan;
    ConnCacheEntry *entry;
    List       *pending_entries = 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 = PQexec(entry->conn, "DEALLOCATE ALL");
                        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 */
                    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)
    {
        Assert(event == XACT_EVENT_PARALLEL_PRE_COMMIT ||
               event == XACT_EVENT_PRE_COMMIT);
        pgfdw_finish_pre_commit_cleanup(pending_entries);
    }
 
    /*
     * 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_commit, pgfdw_abort_cleanup(), pgfdw_finish_pre_commit_cleanup(), pgfdw_reject_incomplete_xact_state_change(), pgfdw_reset_xact_state(), PQclear(), PQexec(), res, 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 1753 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 1774 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 1664 of file connection.c.

{
#define POSTGRES_FDW_GET_CONNECTIONS_COLS   2
    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)
        PG_RETURN_VOID();
 
    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};
 
        /* 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[0] = true;
        }
        else
            values[0] = CStringGetTextDatum(server->servername);
 
        values[1] = BoolGetDatum(!entry->invalidated);
 
        tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
    }
 
    PG_RETURN_VOID();
}

References Assert(), BoolGetDatum(), ConnectionHash, CStringGetTextDatum, FSV_MISSING_OK, GetForeignServerExtended(), hash_seq_init(), hash_seq_search(), InitMaterializedSRF(), PG_RETURN_VOID, POSTGRES_FDW_GET_CONNECTIONS_COLS, ForeignServer::servername, ReturnSetInfo::setDesc, ReturnSetInfo::setResult, tuplestore_putvalues(), and values.

ReleaseConnection()

void ReleaseConnection

(

PGconn *

conn

)

Definition at line 724 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(), and postgresImportForeignSchema().

UserMappingPasswordRequired()

static bool UserMappingPasswordRequired ( UserMapping *  user )

static

Definition at line 542 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 connect_pg_server().

Variable Documentation

ConnectionHash

HTAB* ConnectionHash = NULL

static

Definition at line 74 of file connection.c.

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

cursor_number

unsigned int cursor_number = 0

static

Definition at line 77 of file connection.c.

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

prep_stmt_number

unsigned int prep_stmt_number = 0

static

Definition at line 78 of file connection.c.

Referenced by GetPrepStmtNumber().

xact_got_connection

bool xact_got_connection = false

static

Definition at line 81 of file connection.c.

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