From 8edd8c77c88e75822334ccb8376d2c151d6e5615 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Fri, 24 Jan 2025 17:00:10 -0500
Subject: [PATCH] postmaster: Move code to switch into FatalError state into
 function

There are two places switching to FatalError mode, behaving somewhat
differently. An upcoming commit will introduce a third. That doesn't seem seem
like a good idea.

This commit just moves the FatalError related code from HandleChildCrash()
into its own function, a subsequent commit will evolve the state machine
change to be suitable for other callers.

Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/kgng5nrvnlv335evmsuvpnh354rw7qyazl73kdysev2cr2v5zu@m3cfzxicm5kp
---
 src/backend/postmaster/postmaster.c | 76 ++++++++++++++++++++---------
 1 file changed, 52 insertions(+), 24 deletions(-)

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index a24c0385fe6..a92fe4240b2 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -2673,6 +2673,55 @@ CleanupBackend(PMChild *bp,
 		LogChildExit(DEBUG2, procname, bp_pid, exitstatus);
 }
 
+/*
+ * Transition into FatalError state, in response to something bad having
+ * happened. Commonly the caller will have logged the reason for entering
+ * FatalError state.
+ *
+ * This should only be called when not already in FatalError or
+ * ImmediateShutdown state.
+ */
+static void
+HandleFatalError(QuitSignalReason reason, bool consider_sigabrt)
+{
+	int			sigtosend;
+
+	Assert(!FatalError);
+	Assert(Shutdown != ImmediateShutdown);
+
+	SetQuitSignalReason(reason);
+
+	if (consider_sigabrt && send_abort_for_crash)
+		sigtosend = SIGABRT;
+	else
+		sigtosend = SIGQUIT;
+
+	/*
+	 * Signal all other child processes to exit.
+	 *
+	 * We could exclude dead-end children here, but at least when sending
+	 * SIGABRT it seems better to include them.
+	 */
+	TerminateChildren(sigtosend);
+
+	FatalError = true;
+
+	/* We now transit into a state of waiting for children to die */
+	if (pmState == PM_RECOVERY ||
+		pmState == PM_HOT_STANDBY ||
+		pmState == PM_RUN ||
+		pmState == PM_STOP_BACKENDS ||
+		pmState == PM_WAIT_XLOG_SHUTDOWN)
+		UpdatePMState(PM_WAIT_BACKENDS);
+
+	/*
+	 * .. and if this doesn't happen quickly enough, now the clock is ticking
+	 * for us to kill them without mercy.
+	 */
+	if (AbortStartTime == 0)
+		AbortStartTime = time(NULL);
+}
+
 /*
  * HandleChildCrash -- cleanup after failed backend, bgwriter, checkpointer,
  * walwriter, autovacuum, archiver, slot sync worker, or background worker.
@@ -2698,33 +2747,12 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
 	LogChildExit(LOG, procname, pid, exitstatus);
 	ereport(LOG,
 			(errmsg("terminating any other active server processes")));
-	SetQuitSignalReason(PMQUIT_FOR_CRASH);
 
 	/*
-	 * Signal all other child processes to exit.  The crashed process has
-	 * already been removed from ActiveChildList.
-	 *
-	 * We could exclude dead-end children here, but at least when sending
-	 * SIGABRT it seems better to include them.
+	 * Switch into error state. The crashed process has already been removed
+	 * from ActiveChildList.
 	 */
-	TerminateChildren(send_abort_for_crash ? SIGABRT : SIGQUIT);
-
-	FatalError = true;
-
-	/* We now transit into a state of waiting for children to die */
-	if (pmState == PM_RECOVERY ||
-		pmState == PM_HOT_STANDBY ||
-		pmState == PM_RUN ||
-		pmState == PM_STOP_BACKENDS ||
-		pmState == PM_WAIT_XLOG_SHUTDOWN)
-		UpdatePMState(PM_WAIT_BACKENDS);
-
-	/*
-	 * .. and if this doesn't happen quickly enough, now the clock is ticking
-	 * for us to kill them without mercy.
-	 */
-	if (AbortStartTime == 0)
-		AbortStartTime = time(NULL);
+	HandleFatalError(PMQUIT_FOR_CRASH, true);
 }
 
 /*