#include "postgres.h"
#include "postgres_fdw.h"
#include "access/htup_details.h"
#include "catalog/pg_user_mapping.h"
#include "access/xact.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/latch.h"
#include "utils/hsearch.h"
#include "utils/inval.h"
#include "utils/memutils.h"
#include "utils/syscache.h"

Include dependency graph for connection.c:

Data Structures
struct	ConnCacheEntry

Typedefs
typedef Oid	ConnCacheKey

typedef struct ConnCacheEntry	ConnCacheEntry

Functions
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)

static void	configure_remote_session (PGconn *conn)

static void	do_sql_command (PGconn conn, const char sql)

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 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)

PGconn *	GetConnection (UserMapping *user, bool will_prep_stmt)

void	ReleaseConnection (PGconn *conn)

unsigned int	GetCursorNumber (PGconn *conn)

unsigned int	GetPrepStmtNumber (PGconn *conn)

PGresult *	pgfdw_exec_query (PGconn conn, const char query)

PGresult *	pgfdw_get_result (PGconn conn, const char query)

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

Variables
static HTAB *	ConnectionHash = NULL

static unsigned int	cursor_number = 0

static unsigned int	prep_stmt_number = 0

static bool	xact_got_connection = false

Typedef Documentation

typedef struct ConnCacheEntry ConnCacheEntry

typedef Oid ConnCacheKey

Definition at line 46 of file connection.c.

Function Documentation

static void begin_remote_xact ( ConnCacheEntry * entry )

static

Definition at line 417 of file connection.c.

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

Referenced by GetConnection().

 {
     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;
     }
 }

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

static

Definition at line 325 of file connection.c.

References ereport, errcode(), errdetail(), errmsg(), ERROR, i, NULL, and superuser().

Referenced by connect_pg_server().

 {
     int         i;
 
     /* no check required if superuser */
     if (superuser())
         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;
     }
 
     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.")));
 }

static void configure_remote_session ( PGconn * conn )

static

Definition at line 358 of file connection.c.

References do_sql_command(), and PQserverVersion().

Referenced by connect_pg_server().

 {
     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");
 }

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

static

Definition at line 222 of file connection.c.

References check_conn_params(), configure_remote_session(), conn, CONNECTION_OK, ereport, errcode(), errdetail(), errdetail_internal(), errhint(), errmsg(), ERROR, ExtractConnectionOptions(), GetDatabaseEncodingName(), list_length(), NULL, ForeignServer::options, UserMapping::options, palloc(), pchomp(), pfree(), PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PQconnectdbParams(), PQconnectionUsedPassword(), PQerrorMessage(), PQfinish(), PQstatus(), ForeignServer::servername, superuser(), and values.

Referenced by GetConnection().

 {
     PGconn     *volatile conn = NULL;
 
     /*
      * Use PG_TRY block to ensure closing connection on error.
      */
     PG_TRY();
     {
         const char **keywords;
         const char **values;
         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 3 extra slots
          * for fallback_application_name, client_encoding, end marker.
          */
         n = list_length(server->options) + list_length(user->options) + 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 "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 connection parameters and make connection */
         check_conn_params(keywords, values);
 
         conn = PQconnectdbParams(keywords, values, false);
         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.
          */
         if (!superuser() && !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.")));
 
         /* Prepare new session for use */
         configure_remote_session(conn);
 
         pfree(keywords);
         pfree(values);
     }
     PG_CATCH();
     {
         /* Release PGconn data structure if we managed to create one */
         if (conn)
             PQfinish(conn);
         PG_RE_THROW();
     }
     PG_END_TRY();
 
     return conn;
 }

static void disconnect_pg_server ( ConnCacheEntry * entry )

static

Definition at line 308 of file connection.c.

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

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

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

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

static

Definition at line 394 of file connection.c.

References ERROR, NULL, pgfdw_get_result(), pgfdw_report_error(), PGRES_COMMAND_OK, PQclear(), PQresultStatus(), and PQsendQuery().

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

 {
     PGresult   *res;
 
     if (!PQsendQuery(conn, sql))
         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);
 }

PGconn* GetConnection	(	UserMapping *	user,
		bool	will_prep_stmt
	)

Definition at line 107 of file connection.c.

References begin_remote_xact(), CacheMemoryContext, CacheRegisterSyscacheCallback(), ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, connect_pg_server(), DEBUG3, disconnect_pg_server(), elog, HASHCTL::entrysize, FOREIGNSERVEROID, GetForeignServer(), GetSysCacheHashValue1, HASH_BLOBS, HASH_CONTEXT, hash_create(), HASH_ELEM, HASH_ENTER, hash_search(), ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, HASHCTL::hcxt, ConnCacheEntry::invalidated, HASHCTL::keysize, ConnCacheEntry::mapping_hashvalue, MemSet, NULL, ObjectIdGetDatum, pgfdw_inval_callback(), pgfdw_reject_incomplete_xact_state_change(), pgfdw_subxact_callback(), pgfdw_xact_callback(), RegisterSubXactCallback(), RegisterXactCallback(), ConnCacheEntry::server_hashvalue, ForeignServer::serverid, UserMapping::serverid, ForeignServer::servername, UserMapping::umid, UserMapping::userid, USERMAPPINGOID, ConnCacheEntry::xact_depth, and xact_got_connection.

Referenced by dumpBlobs(), dumpDatabase(), dumpTableData_copy(), estimate_path_cost_size(), expand_schema_name_patterns(), expand_table_name_patterns(), getTables(), main(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresBeginDirectModify(), postgresBeginForeignModify(), postgresBeginForeignScan(), postgresImportForeignSchema(), setup_connection(), StartLogStreamer(), StreamLog(), and StreamLogicalLog().

 {
     bool        found;
     ConnCacheEntry *entry;
     ConnCacheKey key;
 
     /* First time through, initialize connection cache hashtable */
     if (ConnectionHash == NULL)
     {
         HASHCTL     ctl;
 
         MemSet(&ctl, 0, sizeof(ctl));
         ctl.keysize = sizeof(ConnCacheKey);
         ctl.entrysize = sizeof(ConnCacheEntry);
         /* allocate ConnectionHash in the cache context */
         ctl.hcxt = CacheMemoryContext;
         ConnectionHash = hash_create("postgres_fdw connections", 8,
                                      &ctl,
                                      HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
 
         /*
          * 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);
     }
 
     /*
      * We don't check the health of cached connection here, because it would
      * require some overhead.  Broken connection will be detected when the
      * connection is actually used.
      */
 
     /*
      * 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)
     {
         ForeignServer *server = GetForeignServer(user->serverid);
 
         /* 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->server_hashvalue =
             GetSysCacheHashValue1(FOREIGNSERVEROID,
                                   ObjectIdGetDatum(server->serverid));
         entry->mapping_hashvalue =
             GetSysCacheHashValue1(USERMAPPINGOID,
                                   ObjectIdGetDatum(user->umid));
 
         /* 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);
     }
 
     /*
      * Start a new transaction or subtransaction if needed.
      */
     begin_remote_xact(entry);
 
     /* Remember if caller will prepare statements */
     entry->have_prep_stmt |= will_prep_stmt;
 
     return entry->conn;
 }

unsigned int GetCursorNumber ( PGconn * conn )

Definition at line 481 of file connection.c.

References cursor_number.

Referenced by postgresAcquireSampleRowsFunc(), and postgresBeginForeignScan().

 {
     return ++cursor_number;
 }

unsigned int GetPrepStmtNumber ( PGconn * conn )

Definition at line 495 of file connection.c.

References prep_stmt_number.

Referenced by prepare_foreign_modify().

 {
     return ++prep_stmt_number;
 }

static bool pgfdw_cancel_query ( PGconn * conn )

static

Definition at line 1021 of file connection.c.

References ereport, errcode(), errmsg(), GetCurrentTimestamp(), NULL, pgfdw_get_cleanup_result(), PQcancel(), PQclear(), PQfreeCancel(), PQgetCancel(), result, TimestampTzPlusMilliseconds, and WARNING.

Referenced by pgfdw_subxact_callback(), and pgfdw_xact_callback().

 {
     PGcancel   *cancel;
     char        errbuf[256];
     PGresult   *result = NULL;
     TimestampTz endtime;
 
     /*
      * 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))
         return false;
     PQclear(result);
 
     return true;
 }

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

static

Definition at line 1068 of file connection.c.

References GetCurrentTimestamp(), NULL, pgfdw_get_cleanup_result(), pgfdw_report_error(), PGRES_COMMAND_OK, PQclear(), PQresultStatus(), PQsendQuery(), result, TimestampTzPlusMilliseconds, and WARNING.

Referenced by pgfdw_subxact_callback(), and pgfdw_xact_callback().

 {
     PGresult   *result = NULL;
     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(), 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))
         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;
 }

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

Definition at line 508 of file connection.c.

References ERROR, NULL, pgfdw_get_result(), pgfdw_report_error(), and PQsendQuery().

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

 {
     /*
      * 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);
 }

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

static

Definition at line 1122 of file connection.c.

References CHECK_FOR_INTERRUPTS, GetCurrentTimestamp(), Min, MyLatch, now(), NULL, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, PG_WAIT_EXTENSION, PQclear(), PQconsumeInput(), PQgetResult(), PQisBusy(), PQsocket(), ResetLatch(), TimestampDifference(), USECS_PER_SEC, WaitLatchOrSocket(), WL_LATCH_SET, WL_SOCKET_READABLE, and WL_TIMEOUT.

Referenced by pgfdw_cancel_query(), and pgfdw_exec_cleanup_query().

 {
     volatile bool timed_out = false;
     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;
                 TimestampTz now = GetCurrentTimestamp();
                 long        secs;
                 int         microsecs;
                 long        cur_timeout;
 
                 /* If timeout has expired, give up, else get sleep time. */
                 if (now >= endtime)
                 {
                     timed_out = true;
                     goto exit;
                 }
                 TimestampDifference(now, endtime, &secs, &microsecs);
 
                 /* To protect against clock skew, limit sleep to one minute. */
                 cur_timeout = Min(60000, secs * USECS_PER_SEC + microsecs);
 
                 /* Sleep until there's something to do */
                 wc = WaitLatchOrSocket(MyLatch,
                                        WL_LATCH_SET | WL_SOCKET_READABLE | WL_TIMEOUT,
                                        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; treat the same as a timeout */
                         timed_out = 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 (timed_out)
         PQclear(last_res);
     else
         *result = last_res;
     return timed_out;
 }

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

Definition at line 532 of file connection.c.

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

Referenced by create_cursor(), do_sql_command(), execute_dml_stmt(), pgfdw_exec_query(), postgresExecForeignDelete(), postgresExecForeignInsert(), postgresExecForeignUpdate(), and prepare_foreign_modify().

 {
     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,
                                        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;
 }

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

static

Definition at line 951 of file connection.c.

References Assert, ConnCacheEntry::conn, FOREIGNSERVEROID, hash_seq_init(), hash_seq_search(), ConnCacheEntry::invalidated, ConnCacheEntry::mapping_hashvalue, NULL, ConnCacheEntry::server_hashvalue, and USERMAPPINGOID.

Referenced by GetConnection().

 {
     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))
             entry->invalidated = true;
     }
 }

static void pgfdw_reject_incomplete_xact_state_change ( ConnCacheEntry * entry )

static

Definition at line 987 of file connection.c.

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, disconnect_pg_server(), elog, ereport, errcode(), errmsg(), ERROR, GetForeignServer(), GETSTRUCT, HeapTupleIsValid, ConnCacheEntry::key, NULL, ObjectIdGetDatum, ReleaseSysCache(), SearchSysCache1, ForeignServer::servername, and USERMAPPINGOID.

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

 {
     HeapTuple   tup;
     Form_pg_user_mapping umform;
     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 */
     tup = SearchSysCache1(USERMAPPINGOID,
                           ObjectIdGetDatum(entry->key));
     if (!HeapTupleIsValid(tup))
         elog(ERROR, "cache lookup failed for user mapping %u", entry->key);
     umform = (Form_pg_user_mapping) GETSTRUCT(tup);
     server = GetForeignServer(umform->umserver);
     ReleaseSysCache(tup);
 
     ereport(ERROR,
             (errcode(ERRCODE_CONNECTION_EXCEPTION),
              errmsg("connection to server \"%s\" was lost",
                     server->servername)));
 }

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

Definition at line 596 of file connection.c.

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

Referenced by close_cursor(), create_cursor(), do_sql_command(), execute_dml_stmt(), fetch_more_data(), get_remote_estimate(), pgfdw_exec_cleanup_query(), pgfdw_exec_query(), pgfdw_get_result(), postgresAcquireSampleRowsFunc(), postgresAnalyzeForeignTable(), postgresEndForeignModify(), postgresExecForeignDelete(), postgresExecForeignInsert(), postgresExecForeignUpdate(), postgresImportForeignSchema(), postgresReScanForeignScan(), and prepare_foreign_modify().

 {
     /* 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 ? 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_CATCH();
     {
         if (clear)
             PQclear(res);
         PG_RE_THROW();
     }
     PG_END_TRY();
     if (clear)
         PQclear(res);
 }

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

static

Definition at line 837 of file connection.c.

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, do_sql_command(), elog, ERROR, GetCurrentTransactionNestLevel(), hash_seq_init(), hash_seq_search(), ConnCacheEntry::have_error, in_error_recursion_trouble(), NULL, pgfdw_cancel_query(), pgfdw_exec_cleanup_query(), pgfdw_reject_incomplete_xact_state_change(), PQTRANS_ACTIVE, PQtransactionStatus(), snprintf(), SUBXACT_EVENT_ABORT_SUB, SUBXACT_EVENT_PRE_COMMIT_SUB, ConnCacheEntry::xact_depth, and xact_got_connection.

Referenced by GetConnection().

 {
     HASH_SEQ_STATUS scan;
     ConnCacheEntry *entry;
     int         curlevel;
 
     /* 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;
             do_sql_command(entry->conn, sql);
             entry->changing_xact_state = false;
         }
         else if (in_error_recursion_trouble())
         {
             /*
              * Don't try to clean up the connection if we're already in error
              * recursion trouble.
              */
             entry->changing_xact_state = true;
         }
         else if (!entry->changing_xact_state)
         {
             bool        abort_cleanup_failure = false;
 
             /* Remember that abort cleanup is in progress. */
             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))
                 abort_cleanup_failure = true;
             else
             {
                 /* Rollback all remote subtransactions during abort */
                 snprintf(sql, sizeof(sql),
                          "ROLLBACK TO SAVEPOINT s%d; RELEASE SAVEPOINT s%d",
                          curlevel, curlevel);
                 if (!pgfdw_exec_cleanup_query(entry->conn, sql, false))
                     abort_cleanup_failure = true;
             }
 
             /* Disarm changing_xact_state if it all worked. */
             entry->changing_xact_state = abort_cleanup_failure;
         }
 
         /* OK, we're outta that level of subtransaction */
         entry->xact_depth--;
     }
 }

static void pgfdw_xact_callback	(	XactEvent	event,
		void *	arg
	)

static

Definition at line 650 of file connection.c.

References ConnCacheEntry::changing_xact_state, ConnCacheEntry::conn, CONNECTION_OK, cursor_number, DEBUG3, disconnect_pg_server(), do_sql_command(), elog, ereport, errcode(), errmsg(), ERROR, hash_seq_init(), hash_seq_search(), ConnCacheEntry::have_error, ConnCacheEntry::have_prep_stmt, in_error_recursion_trouble(), NULL, pgfdw_cancel_query(), pgfdw_exec_cleanup_query(), pgfdw_reject_incomplete_xact_state_change(), PQclear(), PQexec(), PQstatus(), PQTRANS_ACTIVE, PQTRANS_IDLE, PQtransactionStatus(), 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().

 {
     HASH_SEQ_STATUS scan;
     ConnCacheEntry *entry;
 
     /* 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)
         {
             bool        abort_cleanup_failure = false;
 
             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;
                     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 remote transactions that modified anything,
                      * 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 modified remote 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:
 
                     /*
                      * 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)
                         break;
 
                     /*
                      * 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))
                     {
                         /* Unable to cancel running query. */
                         abort_cleanup_failure = true;
                     }
                     else if (!pgfdw_exec_cleanup_query(entry->conn,
                                                        "ABORT TRANSACTION",
                                                        false))
                     {
                         /* Unable to abort remote transaction. */
                         abort_cleanup_failure = true;
                     }
                     else if (entry->have_prep_stmt && entry->have_error &&
                              !pgfdw_exec_cleanup_query(entry->conn,
                                                        "DEALLOCATE ALL",
                                                        true))
                     {
                         /* Trouble clearing prepared statements. */
                         abort_cleanup_failure = true;
                     }
                     else
                     {
                         entry->have_prep_stmt = false;
                         entry->have_error = false;
                     }
 
                     /* Disarm changing_xact_state if it all worked. */
                     entry->changing_xact_state = abort_cleanup_failure;
                     break;
             }
         }
 
         /* Reset state to show we're out of a transaction */
         entry->xact_depth = 0;
 
         /*
          * If the connection isn't in a good idle state, 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)
         {
             elog(DEBUG3, "discarding connection %p", entry->conn);
             disconnect_pg_server(entry);
         }
     }
 
     /*
      * 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;
 }

void ReleaseConnection ( PGconn * conn )

Definition at line 460 of file connection.c.

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

 {
     /*
      * 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.
      */
 }

Variable Documentation

HTAB* ConnectionHash = NULL

static

Definition at line 66 of file connection.c.

unsigned int cursor_number = 0

static

Definition at line 69 of file connection.c.

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

unsigned int prep_stmt_number = 0

static

Definition at line 70 of file connection.c.

Referenced by GetPrepStmtNumber().

bool xact_got_connection = false

static

Definition at line 73 of file connection.c.

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

Data Structures

Typedefs

Functions

Variables

Typedef Documentation

Function Documentation

Variable Documentation