Refactor xlog.c to create src/backend/postmaster/startup.c

Startup process now has its own dedicated file, just like all other
special/background processes. Reduces role and size of xlog.c

src/backend/postmaster/startup.c

@@ -0,0 +1,259 @@
+/*-------------------------------------------------------------------------
+ *
+ * startup.c
+ *
+ * The Startup process initialises the server and performs any recovery
+ * actions that have been specified. Notice that there is no "main loop"
+ * since the Startup process ends as soon as initialisation is complete.
+ *
+ *
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/postmaster/startup.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <signal.h>
+#include <unistd.h>
+
+#include "access/xlog.h"
+#include "libpq/pqsignal.h"
+#include "miscadmin.h"
+#include "postmaster/startup.h"
+#include "storage/ipc.h"
+#include "storage/latch.h"
+#include "storage/pmsignal.h"
+#include "storage/proc.h"
+#include "utils/guc.h"
+
+
+/*
+ * Flags set by interrupt handlers for later service in the redo loop.
+ */
+static volatile sig_atomic_t got_SIGHUP = false;
+static volatile sig_atomic_t shutdown_requested = false;
+static volatile sig_atomic_t promote_triggered = false;
+
+/*
+ * Flag set when executing a restore command, to tell SIGTERM signal handler
+ * that it's safe to just proc_exit.
+ */
+static volatile sig_atomic_t in_restore_command = false;
+
+/* Signal handlers */
+static void startupproc_quickdie(SIGNAL_ARGS);
+static void StartupProcSigUsr1Handler(SIGNAL_ARGS);
+static void StartupProcTriggerHandler(SIGNAL_ARGS);
+static void StartupProcSigHupHandler(SIGNAL_ARGS);
+
+
+/* --------------------------------
+ *		signal handler routines
+ * --------------------------------
+ */
+
+/*
+ * startupproc_quickdie() occurs when signalled SIGQUIT by the postmaster.
+ *
+ * Some backend has bought the farm,
+ * so we need to stop what we're doing and exit.
+ */
+static void
+startupproc_quickdie(SIGNAL_ARGS)
+{
+	PG_SETMASK(&BlockSig);
+
+	/*
+	 * We DO NOT want to run proc_exit() callbacks -- we're here because
+	 * shared memory may be corrupted, so we don't want to try to clean up our
+	 * transaction.  Just nail the windows shut and get out of town.  Now that
+	 * there's an atexit callback to prevent third-party code from breaking
+	 * things by calling exit() directly, we have to reset the callbacks
+	 * explicitly to make this work as intended.
+	 */
+	on_exit_reset();
+
+	/*
+	 * Note we do exit(2) not exit(0).	This is to force the postmaster into a
+	 * system reset cycle if some idiot DBA sends a manual SIGQUIT to a random
+	 * backend.  This is necessary precisely because we don't clean up our
+	 * shared memory state.  (The "dead man switch" mechanism in pmsignal.c
+	 * should ensure the postmaster sees this as a crash, too, but no harm in
+	 * being doubly sure.)
+	 */
+	exit(2);
+}
+
+
+/* SIGUSR1: let latch facility handle the signal */
+static void
+StartupProcSigUsr1Handler(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	latch_sigusr1_handler();
+
+	errno = save_errno;
+}
+
+/* SIGUSR2: set flag to finish recovery */
+static void
+StartupProcTriggerHandler(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	promote_triggered = true;
+	WakeupRecovery();
+
+	errno = save_errno;
+}
+
+/* SIGHUP: set flag to re-read config file at next convenient time */
+static void
+StartupProcSigHupHandler(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	got_SIGHUP = true;
+	WakeupRecovery();
+
+	errno = save_errno;
+}
+
+/* SIGTERM: set flag to abort redo and exit */
+static void
+StartupProcShutdownHandler(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	if (in_restore_command)
+		proc_exit(1);
+	else
+		shutdown_requested = true;
+	WakeupRecovery();
+
+	errno = save_errno;
+}
+
+/* Handle SIGHUP and SIGTERM signals of startup process */
+void
+HandleStartupProcInterrupts(void)
+{
+	/*
+	 * Check if we were requested to re-read config file.
+	 */
+	if (got_SIGHUP)
+	{
+		got_SIGHUP = false;
+		ProcessConfigFile(PGC_SIGHUP);
+	}
+
+	/*
+	 * Check if we were requested to exit without finishing recovery.
+	 */
+	if (shutdown_requested)
+		proc_exit(1);
+
+	/*
+	 * Emergency bailout if postmaster has died.  This is to avoid the
+	 * necessity for manual cleanup of all postmaster children.
+	 */
+	if (IsUnderPostmaster && !PostmasterIsAlive())
+		exit(1);
+}
+
+
+/* ----------------------------------
+ *	Startup Process main entry point
+ * ----------------------------------
+ */
+void
+StartupProcessMain(void)
+{
+	/*
+	 * If possible, make this process a group leader, so that the postmaster
+	 * can signal any child processes too.
+	 */
+#ifdef HAVE_SETSID
+	if (setsid() < 0)
+		elog(FATAL, "setsid() failed: %m");
+#endif
+
+	/*
+	 * Properly accept or ignore signals the postmaster might send us.
+	 *
+	 * Note: ideally we'd not enable handle_standby_sig_alarm unless actually
+	 * doing hot standby, but we don't know that yet.  Rely on it to not do
+	 * anything if it shouldn't.
+	 */
+	pqsignal(SIGHUP, StartupProcSigHupHandler); /* reload config file */
+	pqsignal(SIGINT, SIG_IGN);	/* ignore query cancel */
+	pqsignal(SIGTERM, StartupProcShutdownHandler);		/* request shutdown */
+	pqsignal(SIGQUIT, startupproc_quickdie);	/* hard crash time */
+	if (EnableHotStandby)
+		pqsignal(SIGALRM, handle_standby_sig_alarm);	/* ignored unless
+														 * InHotStandby */
+	else
+		pqsignal(SIGALRM, SIG_IGN);
+	pqsignal(SIGPIPE, SIG_IGN);
+	pqsignal(SIGUSR1, StartupProcSigUsr1Handler);
+	pqsignal(SIGUSR2, StartupProcTriggerHandler);
+
+	/*
+	 * Reset some signals that are accepted by postmaster but not here
+	 */
+	pqsignal(SIGCHLD, SIG_DFL);
+	pqsignal(SIGTTIN, SIG_DFL);
+	pqsignal(SIGTTOU, SIG_DFL);
+	pqsignal(SIGCONT, SIG_DFL);
+	pqsignal(SIGWINCH, SIG_DFL);
+
+	/*
+	 * Unblock signals (they were blocked when the postmaster forked us)
+	 */
+	PG_SETMASK(&UnBlockSig);
+
+	StartupXLOG();
+
+	/*
+	 * Exit normally. Exit code 0 tells postmaster that we completed recovery
+	 * successfully.
+	 */
+	proc_exit(0);
+}
+
+void
+PreRestoreCommand(void)
+{
+	/*
+	 * Set in_restore_command to tell the signal handler that we should exit
+	 * right away on SIGTERM. We know that we're at a safe point to do that.
+	 * Check if we had already received the signal, so that we don't miss a
+	 * shutdown request received just before this.
+	 */
+	in_restore_command = true;
+	if (shutdown_requested)
+		proc_exit(1);
+}
+
+void
+PostRestoreCommand(void)
+{
+	in_restore_command = false;
+}
+
+bool
+IsPromoteTriggered(void)
+{
+	return promote_triggered;
+}
+
+void
+ResetPromoteTriggered(void)
+{
+	promote_triggered = false;
+}