Rename the logical replication global "wrconn"

The worker.c global wrconn is only meant to be used by logical apply/
tablesync workers, but there are other variables with the same name. To
reduce future confusion rename the global from "wrconn" to
"LogRepWorkerWalRcvConn".

While this is just cosmetic, it seems better to backpatch it all the way
back to 10 where this code appeared, to avoid future backpatching
issues.

Author: Peter Smith <smithpb2250@gmail.com>
Discussion: https://postgr.es/m/CAHut+Pu7Jv9L2BOEx_Z0UtJxfDevQSAUW2mJqWU+CtmDrEZVAg@mail.gmail.com

Author: alvherre

src/backend/replication/logical/launcher.c

@@ -716,8 +716,8 @@ static void
 logicalrep_worker_onexit(int code, Datum arg)
 {
 	/* Disconnect gracefully from the remote side. */
-	if (wrconn)
-		walrcv_disconnect(wrconn);
+	if (LogRepWorkerWalRcvConn)
+		walrcv_disconnect(LogRepWorkerWalRcvConn);
 
 	logicalrep_worker_detach();
 

src/backend/replication/logical/tablesync.c

@@ -295,7 +295,7 @@ process_syncing_tables_for_sync(XLogRecPtr current_lsn)
 								   MyLogicalRepWorker->relstate,
 								   MyLogicalRepWorker->relstate_lsn);
 
-		walrcv_endstreaming(wrconn, &tli);
+		walrcv_endstreaming(LogRepWorkerWalRcvConn, &tli);
 		finish_sync_worker();
 	}
 	else
@@ -591,7 +591,7 @@ copy_read_data(void *outbuf, int minread, int maxread)
 		for (;;)
 		{
 			/* Try read the data. */
-			len = walrcv_receive(wrconn, &buf, &fd);
+			len = walrcv_receive(LogRepWorkerWalRcvConn, &buf, &fd);
 
 			CHECK_FOR_INTERRUPTS();
 
@@ -665,7 +665,8 @@ fetch_remote_table_info(char *nspname, char *relname,
 					 "   AND c.relkind = 'r'",
 					 quote_literal_cstr(nspname),
 					 quote_literal_cstr(relname));
-	res = walrcv_exec(wrconn, cmd.data, 2, tableRow);
+	res = walrcv_exec(LogRepWorkerWalRcvConn, cmd.data,
+					  lengthof(tableRow), tableRow);
 
 	if (res->status != WALRCV_OK_TUPLES)
 		ereport(ERROR,
@@ -701,9 +702,11 @@ fetch_remote_table_info(char *nspname, char *relname,
 					 "   AND a.attrelid = %u"
 					 " ORDER BY a.attnum",
 					 lrel->remoteid,
-					 (walrcv_server_version(wrconn) >= 120000 ? "AND a.attgenerated = ''" : ""),
+					 (walrcv_server_version(LogRepWorkerWalRcvConn) >= 120000 ?
+					  "AND a.attgenerated = ''" : ""),
 					 lrel->remoteid);
-	res = walrcv_exec(wrconn, cmd.data, 4, attrRow);
+	res = walrcv_exec(LogRepWorkerWalRcvConn, cmd.data,
+					  lengthof(attrRow), attrRow);
 
 	if (res->status != WALRCV_OK_TUPLES)
 		ereport(ERROR,
@@ -773,7 +776,7 @@ copy_table(Relation rel)
 	initStringInfo(&cmd);
 	appendStringInfo(&cmd, "COPY %s TO STDOUT",
 					 quote_qualified_identifier(lrel.nspname, lrel.relname));
-	res = walrcv_exec(wrconn, cmd.data, 0, NULL);
+	res = walrcv_exec(LogRepWorkerWalRcvConn, cmd.data, 0, NULL);
 	pfree(cmd.data);
 	if (res->status != WALRCV_OK_COPY_OUT)
 		ereport(ERROR,
@@ -840,8 +843,9 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 	 * application_name, so that it is different from the main apply worker,
 	 * so that synchronous replication can distinguish them.
 	 */
-	wrconn = walrcv_connect(MySubscription->conninfo, true, slotname, &err);
-	if (wrconn == NULL)
+	LogRepWorkerWalRcvConn = walrcv_connect(MySubscription->conninfo, true,
+											slotname, &err);
+	if (LogRepWorkerWalRcvConn == NULL)
 		ereport(ERROR,
 				(errmsg("could not connect to the publisher: %s", err)));
 
@@ -886,7 +890,7 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 				 * inside the transaction so that we can use the snapshot made
 				 * by the slot to get existing data.
 				 */
-				res = walrcv_exec(wrconn,
+				res = walrcv_exec(LogRepWorkerWalRcvConn,
 								  "BEGIN READ ONLY ISOLATION LEVEL "
 								  "REPEATABLE READ", 0, NULL);
 				if (res->status != WALRCV_OK_COMMAND)
@@ -903,14 +907,14 @@ LogicalRepSyncTableStart(XLogRecPtr *origin_startpos)
 				 * that is consistent with the lsn used by the slot to start
 				 * decoding.
 				 */
-				walrcv_create_slot(wrconn, slotname, true,
+				walrcv_create_slot(LogRepWorkerWalRcvConn, slotname, true,
 								   CRS_USE_SNAPSHOT, origin_startpos);
 
 				PushActiveSnapshot(GetTransactionSnapshot());
 				copy_table(rel);
 				PopActiveSnapshot();
 
-				res = walrcv_exec(wrconn, "COMMIT", 0, NULL);
+				res = walrcv_exec(LogRepWorkerWalRcvConn, "COMMIT", 0, NULL);
 				if (res->status != WALRCV_OK_COMMAND)
 					ereport(ERROR,
 							(errmsg("table copy could not finish transaction on publisher"),

src/backend/replication/logical/worker.c

@@ -96,7 +96,7 @@ typedef struct SlotErrCallbackArg
 static MemoryContext ApplyMessageContext = NULL;
 MemoryContext ApplyContext = NULL;
 
-WalReceiverConn *wrconn = NULL;
+WalReceiverConn *LogRepWorkerWalRcvConn = NULL;
 
 Subscription *MySubscription = NULL;
 bool		MySubscriptionValid = false;
@@ -1158,7 +1158,7 @@ LogicalRepApplyLoop(XLogRecPtr last_received)
 
 		MemoryContextSwitchTo(ApplyMessageContext);
 
-		len = walrcv_receive(wrconn, &buf, &fd);
+		len = walrcv_receive(LogRepWorkerWalRcvConn, &buf, &fd);
 
 		if (len != 0)
 		{
@@ -1238,7 +1238,7 @@ LogicalRepApplyLoop(XLogRecPtr last_received)
 					MemoryContextReset(ApplyMessageContext);
 				}
 
-				len = walrcv_receive(wrconn, &buf, &fd);
+				len = walrcv_receive(LogRepWorkerWalRcvConn, &buf, &fd);
 			}
 		}
 
@@ -1268,7 +1268,7 @@ LogicalRepApplyLoop(XLogRecPtr last_received)
 		{
 			TimeLineID	tli;
 
-			walrcv_endstreaming(wrconn, &tli);
+			walrcv_endstreaming(LogRepWorkerWalRcvConn, &tli);
 			break;
 		}
 
@@ -1431,7 +1431,8 @@ send_feedback(XLogRecPtr recvpos, bool force, bool requestReply)
 		 (uint32) (flushpos >> 32), (uint32) flushpos
 		);
 
-	walrcv_send(wrconn, reply_message->data, reply_message->len);
+	walrcv_send(LogRepWorkerWalRcvConn,
+				reply_message->data, reply_message->len);
 
 	if (recvpos > last_recvpos)
 		last_recvpos = recvpos;
@@ -1743,18 +1744,17 @@ ApplyWorkerMain(Datum main_arg)
 		origin_startpos = replorigin_session_get_progress(false);
 		CommitTransactionCommand();
 
-		wrconn = walrcv_connect(MySubscription->conninfo, true, MySubscription->name,
-								&err);
-		if (wrconn == NULL)
+		LogRepWorkerWalRcvConn = walrcv_connect(MySubscription->conninfo, true,
+												MySubscription->name, &err);
+		if (LogRepWorkerWalRcvConn == NULL)
 			ereport(ERROR,
 					(errmsg("could not connect to the publisher: %s", err)));
 
 		/*
 		 * We don't really use the output identify_system for anything but it
 		 * does some initializations on the upstream so let's still call it.
 		 */
-		(void) walrcv_identify_system(wrconn, &startpointTLI);
-
+		(void) walrcv_identify_system(LogRepWorkerWalRcvConn, &startpointTLI);
 	}
 
 	/*
@@ -1773,7 +1773,7 @@ ApplyWorkerMain(Datum main_arg)
 	options.proto.logical.publication_names = MySubscription->publications;
 
 	/* Start normal logical streaming replication. */
-	walrcv_startstreaming(wrconn, &options);
+	walrcv_startstreaming(LogRepWorkerWalRcvConn, &options);
 
 	/* Run the main loop. */
 	LogicalRepApplyLoop(origin_startpos);

src/include/replication/worker_internal.h

@@ -60,7 +60,7 @@ typedef struct LogicalRepWorker
 extern MemoryContext ApplyContext;
 
 /* libpqreceiver connection */
-extern struct WalReceiverConn *wrconn;
+extern struct WalReceiverConn *LogRepWorkerWalRcvConn;
 
 /* Worker and subscription objects. */
 extern Subscription *MySubscription;