diff options
Diffstat (limited to 'contrib/postgres_fdw/connection.c')
| -rw-r--r-- | contrib/postgres_fdw/connection.c | 135 |
1 files changed, 132 insertions, 3 deletions
diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c index a1404cb6bb1..ee0b4acf0ba 100644 --- a/contrib/postgres_fdw/connection.c +++ b/contrib/postgres_fdw/connection.c @@ -80,6 +80,8 @@ static bool xact_got_connection = false; * SQL functions */ PG_FUNCTION_INFO_V1(postgres_fdw_get_connections); +PG_FUNCTION_INFO_V1(postgres_fdw_disconnect); +PG_FUNCTION_INFO_V1(postgres_fdw_disconnect_all); /* prototypes of private functions */ static void make_new_connection(ConnCacheEntry *entry, UserMapping *user); @@ -102,6 +104,7 @@ static bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query, static bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime, PGresult **result); static bool UserMappingPasswordRequired(UserMapping *user); +static bool disconnect_cached_connections(Oid serverid); /* * Get a PGconn which can be used to execute queries on the remote PostgreSQL @@ -1428,8 +1431,8 @@ postgres_fdw_get_connections(PG_FUNCTION_ARGS) * 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. + * 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. @@ -1447,7 +1450,7 @@ postgres_fdw_get_connections(PG_FUNCTION_ARGS) /* * 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 sever command. Note + * 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. @@ -1470,3 +1473,129 @@ postgres_fdw_get_connections(PG_FUNCTION_ARGS) PG_RETURN_VOID(); } + +/* + * Disconnect the specified cached connections. + * + * This function discards the open connections that are established by + * postgres_fdw from the local session to the foreign server with + * the given name. Note that there can be multiple connections to + * the given server using different user mappings. If the connections + * are used in the current local transaction, they are not disconnected + * and warning messages are reported. This function returns true + * if it disconnects at least one connection, otherwise false. If no + * foreign server with the given name is found, an error is reported. + */ +Datum +postgres_fdw_disconnect(PG_FUNCTION_ARGS) +{ + 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)); +} + +/* + * Disconnect all the cached connections. + * + * This function discards all the open connections that are established by + * postgres_fdw from the local session to the foreign servers. + * If the connections are used in the current local transaction, they are + * not disconnected and warning messages are reported. This function + * returns true if it disconnects at least one connection, otherwise false. + */ +Datum +postgres_fdw_disconnect_all(PG_FUNCTION_ARGS) +{ + PG_RETURN_BOOL(disconnect_cached_connections(InvalidOid)); +} + +/* + * Workhorse to disconnect cached connections. + * + * This function scans all the connection cache entries and disconnects + * the open connections whose foreign server OID matches with + * the specified one. If InvalidOid is specified, it disconnects all + * the cached connections. + * + * This function emits a warning for each connection that's used in + * the current transaction and doesn't close it. It returns true if + * it disconnects at least one connection, otherwise false. + * + * Note that this function disconnects even the connections that are + * established by other users in the same local session using different + * user mappings. This leads even non-superuser to be able to close + * the connections established by superusers in the same local session. + * + * XXX As of now we don't see any security risk doing this. But we should + * set some restrictions on that, for example, prevent non-superuser + * from closing the connections established by superusers even + * in the same session? + */ +static bool +disconnect_cached_connections(Oid serverid) +{ + 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; +} |