pg_dump: Remove global connection pointer.

Parallel pg_dump wants to have multiple ArchiveHandle objects, and
therefore multiple PGconns, in play at the same time.  This should
be just about the end of the refactoring that we need in order to
make that workable.

Author: robertmhaas

src/bin/pg_dump/pg_backup.h

@@ -159,13 +159,14 @@ typedef struct _restoreOptions
  * Main archiver interface.
  */
 
-extern PGconn *ConnectDatabase(Archive *AH,
+extern void ConnectDatabase(Archive *AH,
 				const char *dbname,
 				const char *pghost,
 				const char *pgport,
 				const char *username,
 				enum trivalue prompt_password);
 extern void DisconnectDatabase(Archive *AHX);
+extern PGconn *GetConnection(Archive *AHX);
 
 /* Called to add a TOC entry */
 extern void ArchiveEntry(Archive *AHX,

src/bin/pg_dump/pg_backup_db.c

@@ -225,7 +225,7 @@ _connectDB(ArchiveHandle *AH, const char *reqdb, const char *requser)
  * cache if the username keeps changing.  In current usage, however, the
  * username never does change, so one savedPassword is sufficient.
  */
-PGconn *
+void
 ConnectDatabase(Archive *AHX,
 				const char *dbname,
 				const char *pghost,
@@ -306,8 +306,6 @@ ConnectDatabase(Archive *AHX,
 	_check_database_version(AH);
 
 	PQsetNoticeProcessor(AH->connection, notice_processor, NULL);
-
-	return AH->connection;
 }
 
 void
@@ -319,6 +317,13 @@ DisconnectDatabase(Archive *AHX)
 	AH->connection = NULL;
 }
 
+PGconn *
+GetConnection(Archive *AHX)
+{
+	ArchiveHandle *AH = (ArchiveHandle *) AHX;
+
+	return AH->connection;
+}
 
 static void
 notice_processor(void *arg, const char *message)

src/bin/pg_dump/pg_dump.c

@@ -86,7 +86,6 @@ typedef struct
 /* global decls */
 bool		g_verbose;			/* User wants verbose narration of our
 								 * activities. */
-PGconn	   *g_conn;				/* the database connection */
 
 /* various user-settable parameters */
 bool		schemaOnly;
@@ -614,9 +613,7 @@ main(int argc, char **argv)
 	 * Open the database using the Archiver, so it knows about it. Errors mean
 	 * death.
 	 */
-	g_conn = ConnectDatabase(fout, dbname, pghost, pgport,
-							 username, prompt_password);
-
+	ConnectDatabase(fout, dbname, pghost, pgport, username, prompt_password);
 	setup_connection(fout, dumpencoding, use_role);
 
 	/*
@@ -657,7 +654,8 @@ main(int argc, char **argv)
 	if (fout->remoteVersion < 70300)
 	{
 		if (fout->remoteVersion >= 70100)
-			g_last_builtin_oid = findLastBuiltinOid_V71(fout, PQdb(g_conn));
+			g_last_builtin_oid = findLastBuiltinOid_V71(fout,
+				PQdb(GetConnection(fout)));
 		else
 			g_last_builtin_oid = findLastBuiltinOid_V70(fout);
 		if (g_verbose)
@@ -870,12 +868,13 @@ pgdump_cleanup_at_exit(int code, void *arg)
 static void
 setup_connection(Archive *AH, const char *dumpencoding, char *use_role)
 {
+	PGconn	   *conn = GetConnection(AH);
 	const char *std_strings;
 
 	/* Set the client encoding if requested */
 	if (dumpencoding)
 	{
-		if (PQsetClientEncoding(g_conn, dumpencoding) < 0)
+		if (PQsetClientEncoding(conn, dumpencoding) < 0)
 		{
 			write_msg(NULL, "invalid client encoding \"%s\" specified\n",
 					  dumpencoding);
@@ -887,9 +886,9 @@ setup_connection(Archive *AH, const char *dumpencoding, char *use_role)
 	 * Get the active encoding and the standard_conforming_strings setting, so
 	 * we know how to escape strings.
 	 */
-	AH->encoding = PQclientEncoding(g_conn);
+	AH->encoding = PQclientEncoding(conn);
 
-	std_strings = PQparameterStatus(g_conn, "standard_conforming_strings");
+	std_strings = PQparameterStatus(conn, "standard_conforming_strings");
 	AH->std_strings = (std_strings && strcmp(std_strings, "on") == 0);
 
 	/* Set the role if requested */
@@ -1018,9 +1017,8 @@ expand_schema_name_patterns(Archive *fout,
 			appendPQExpBuffer(query, "UNION ALL\n");
 		appendPQExpBuffer(query,
 						  "SELECT oid FROM pg_catalog.pg_namespace n\n");
-		processSQLNamePattern(g_conn, query, cell->val, false, false,
-							  NULL, "n.nspname", NULL,
-							  NULL);
+		processSQLNamePattern(GetConnection(fout), query, cell->val, false,
+							  false, NULL, "n.nspname", NULL, NULL);
 	}
 
 	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
@@ -1068,8 +1066,8 @@ expand_table_name_patterns(Archive *fout,
 						  "\nWHERE c.relkind in ('%c', '%c', '%c', '%c')\n",
 						  RELKIND_RELATION, RELKIND_SEQUENCE, RELKIND_VIEW,
 						  RELKIND_FOREIGN_TABLE);
-		processSQLNamePattern(g_conn, query, cell->val, true, false,
-							  "n.nspname", "c.relname", NULL,
+		processSQLNamePattern(GetConnection(fout), query, cell->val, true,
+							  false, "n.nspname", "c.relname", NULL,
 							  "pg_catalog.pg_table_is_visible(c.oid)");
 	}
 
@@ -1266,6 +1264,7 @@ dumpTableData_copy(Archive *fout, void *dcontext)
 	const bool	hasoids = tbinfo->hasoids;
 	const bool	oids = tdinfo->oids;
 	PQExpBuffer q = createPQExpBuffer();
+	PGconn	   *conn = GetConnection(fout);
 	PGresult   *res;
 	int			ret;
 	char	   *copybuf;
@@ -1332,7 +1331,7 @@ dumpTableData_copy(Archive *fout, void *dcontext)
 
 	for (;;)
 	{
-		ret = PQgetCopyData(g_conn, &copybuf, 0);
+		ret = PQgetCopyData(conn, &copybuf, 0);
 
 		if (ret < 0)
 			break;				/* done or error */
@@ -1395,17 +1394,17 @@ dumpTableData_copy(Archive *fout, void *dcontext)
 	{
 		/* copy data transfer failed */
 		write_msg(NULL, "Dumping the contents of table \"%s\" failed: PQgetCopyData() failed.\n", classname);
-		write_msg(NULL, "Error message from server: %s", PQerrorMessage(g_conn));
+		write_msg(NULL, "Error message from server: %s", PQerrorMessage(conn));
 		write_msg(NULL, "The command was: %s\n", q->data);
 		exit_nicely(1);
 	}
 
 	/* Check command status and return to normal libpq state */
-	res = PQgetResult(g_conn);
+	res = PQgetResult(conn);
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
 	{
 		write_msg(NULL, "Dumping the contents of table \"%s\" failed: PQgetResult() failed.\n", classname);
-		write_msg(NULL, "Error message from server: %s", PQerrorMessage(g_conn));
+		write_msg(NULL, "Error message from server: %s", PQerrorMessage(conn));
 		write_msg(NULL, "The command was: %s\n", q->data);
 		exit_nicely(1);
 	}
@@ -1830,6 +1829,7 @@ dumpDatabase(Archive *fout)
 	PQExpBuffer dbQry = createPQExpBuffer();
 	PQExpBuffer delQry = createPQExpBuffer();
 	PQExpBuffer creaQry = createPQExpBuffer();
+	PGconn	   *conn = GetConnection(fout);
 	PGresult   *res;
 	int			ntups;
 	int			i_tableoid,
@@ -1850,7 +1850,7 @@ dumpDatabase(Archive *fout)
 			   *tablespace;
 	uint32		frozenxid;
 
-	datname = PQdb(g_conn);
+	datname = PQdb(conn);
 
 	if (g_verbose)
 		write_msg(NULL, "saving database definition\n");
@@ -2150,10 +2150,10 @@ dumpDatabase(Archive *fout)
 	{
 		PQExpBuffer seclabelQry = createPQExpBuffer();
 
-		buildShSecLabelQuery(g_conn, "pg_database", dbCatId.oid, seclabelQry);
+		buildShSecLabelQuery(conn, "pg_database", dbCatId.oid, seclabelQry);
 		res = ExecuteSqlQuery(fout, seclabelQry->data, PGRES_TUPLES_OK);
 		resetPQExpBuffer(seclabelQry);
-		emitShSecLabels(g_conn, res, seclabelQry, "DATABASE", datname);
+		emitShSecLabels(conn, res, seclabelQry, "DATABASE", datname);
 		if (strlen(seclabelQry->data))
 			ArchiveEntry(fout, dbCatId, createDumpId(), datname, NULL, NULL,
 						 dba, false, "SECURITY LABEL", SECTION_NONE,
@@ -2362,6 +2362,7 @@ dumpBlobs(Archive *fout, void *arg)
 {
 	const char *blobQry;
 	const char *blobFetchQry;
+	PGconn	   *conn = GetConnection(fout);
 	PGresult   *res;
 	char		buf[LOBBUFSIZE];
 	int			ntups;
@@ -2404,11 +2405,11 @@ dumpBlobs(Archive *fout, void *arg)
 
 			blobOid = atooid(PQgetvalue(res, i, 0));
 			/* Open the BLOB */
-			loFd = lo_open(g_conn, blobOid, INV_READ);
+			loFd = lo_open(conn, blobOid, INV_READ);
 			if (loFd == -1)
 			{
 				write_msg(NULL, "could not open large object %u: %s",
-						  blobOid, PQerrorMessage(g_conn));
+						  blobOid, PQerrorMessage(conn));
 				exit_nicely(1);
 			}
 
@@ -2417,18 +2418,18 @@ dumpBlobs(Archive *fout, void *arg)
 			/* Now read it in chunks, sending data to archive */
 			do
 			{
-				cnt = lo_read(g_conn, loFd, buf, LOBBUFSIZE);
+				cnt = lo_read(conn, loFd, buf, LOBBUFSIZE);
 				if (cnt < 0)
 				{
 					write_msg(NULL, "error reading large object %u: %s",
-							  blobOid, PQerrorMessage(g_conn));
+							  blobOid, PQerrorMessage(conn));
 					exit_nicely(1);
 				}
 
 				WriteData(fout, buf, cnt);
 			} while (cnt > 0);
 
-			lo_close(g_conn, loFd);
+			lo_close(conn, loFd);
 
 			EndBlob(fout, blobOid);
 		}
@@ -4298,7 +4299,7 @@ getTables(Archive *fout, int *numTables)
 		 */
 		resetPQExpBuffer(query);
 		appendPQExpBuffer(query, "SET statement_timeout = ");
-		appendStringLiteralConn(query, lockWaitTimeout, g_conn);
+		appendStringLiteralConn(query, lockWaitTimeout, GetConnection(fout));
 		ExecuteSqlStatement(fout, query->data);
 	}