From ec97a0b68de76126508507fcb4305e6cad09a20a Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Fri, 8 Dec 2023 10:30:37 +0200
Subject: [PATCH v5 2/8] Remove ConnCreate and ConnFree, and allocate Port in
 stack

By allocating Port in stack, we don't need to deal with out-of-memory
errors, which makes the code a little less verbose.

XXX: This should perhaps be squashed with the next commit. It changes
how the Port structure is allocated again. But maybe it's easier to
review separately.

Reviewed-by: Tristan Partin, Andres Freund
Discussion: https://www.postgresql.org/message-id/7a59b073-5b5b-151e-7ed3-8b01ff7ce9ef@iki.fi
---
 src/backend/postmaster/postmaster.c | 68 +++++------------------------
 src/backend/tcop/postgres.c         |  6 +--
 2 files changed, 13 insertions(+), 61 deletions(-)

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index e53057e83a7..8a12ca696de 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -397,8 +397,6 @@ static void CloseServerPorts(int status, Datum arg);
 static void unlink_external_pid_file(int status, Datum arg);
 static void getInstallationPaths(const char *argv0);
 static void checkControlFile(void);
-static Port *ConnCreate(int serverFd);
-static void ConnFree(Port *port);
 static void handle_pm_pmsignal_signal(SIGNAL_ARGS);
 static void handle_pm_child_exit_signal(SIGNAL_ARGS);
 static void handle_pm_reload_request_signal(SIGNAL_ARGS);
@@ -1772,20 +1770,18 @@ ServerLoop(void)
 
 			if (events[i].events & WL_SOCKET_ACCEPT)
 			{
-				Port	   *port;
+				Port		port;
 
-				port = ConnCreate(events[i].fd);
-				if (port)
-				{
-					BackendStartup(port);
+				memset(&port, 0, sizeof(port));
+				if (StreamConnection(events[i].fd, &port) == STATUS_OK)
+					BackendStartup(&port);
 
-					/*
-					 * We no longer need the open socket or port structure in
-					 * this process
-					 */
-					StreamClose(port->sock);
-					ConnFree(port);
-				}
+				/*
+				 * We no longer need the open socket or port structure in this
+				 * process
+				 */
+				if (port.sock != PGINVALID_SOCKET)
+					StreamClose(port.sock);
 			}
 		}
 
@@ -2447,50 +2443,6 @@ canAcceptConnections(int backend_type)
 	return result;
 }
 
-
-/*
- * ConnCreate -- create a local connection data structure
- *
- * Returns NULL on failure, other than out-of-memory which is fatal.
- */
-static Port *
-ConnCreate(int serverFd)
-{
-	Port	   *port;
-
-	if (!(port = (Port *) calloc(1, sizeof(Port))))
-	{
-		ereport(LOG,
-				(errcode(ERRCODE_OUT_OF_MEMORY),
-				 errmsg("out of memory")));
-		ExitPostmaster(1);
-	}
-
-	if (StreamConnection(serverFd, port) != STATUS_OK)
-	{
-		if (port->sock != PGINVALID_SOCKET)
-			StreamClose(port->sock);
-		ConnFree(port);
-		return NULL;
-	}
-
-	return port;
-}
-
-
-/*
- * ConnFree -- free a local connection data structure
- *
- * Caller has already closed the socket if any, so there's not much
- * to do here.
- */
-static void
-ConnFree(Port *port)
-{
-	free(port);
-}
-
-
 /*
  * ClosePostmasterPorts -- close all the postmaster's open sockets
  *
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 7298a187d18..0dc2132dac5 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -4214,9 +4214,9 @@ PostgresMain(const char *dbname, const char *username)
 	/*
 	 * If the PostmasterContext is still around, recycle the space; we don't
 	 * need it anymore after InitPostgres completes.  Note this does not trash
-	 * *MyProcPort, because ConnCreate() allocated that space with malloc()
-	 * ... else we'd need to copy the Port data first.  Also, subsidiary data
-	 * such as the username isn't lost either; see ProcessStartupPacket().
+	 * *MyProcPort, because that space is allocated in stack ... else we'd
+	 * need to copy the Port data first.  Also, subsidiary data such as the
+	 * username isn't lost either; see ProcessStartupPacket().
 	 */
 	if (PostmasterContext)
 	{
-- 
2.39.2