Code review for EXEC_BACKEND changes. Reduce the number of #ifdefs by

about a third, make it work on non-Windows platforms again.  (But perhaps
I broke the WIN32 code, since I have no way to test that.)  Fold all the
paths that fork postmaster child processes to go through the single
routine SubPostmasterMain, which takes care of resurrecting the state that
would normally be inherited from the postmaster (including GUC variables).
Clean up some places where there's no particularly good reason for the
EXEC and non-EXEC cases to work differently.  Take care of one or two
FIXMEs that remained in the code.

Author: tglsfdc

src/backend/access/transam/slru.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/slru.c,v 1.13 2004/02/23 23:03:10 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/slru.c,v 1.14 2004/05/28 05:12:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -164,10 +164,9 @@ static bool SlruScanDirectory(SlruCtl ctl, int cutoffPage, bool doDeletions);
 int
 SimpleLruShmemSize(void)
 {
-	return MAXALIGN(sizeof(SlruSharedData)) + BLCKSZ * NUM_CLOG_BUFFERS
-#ifdef EXEC_BACKEND
+	return MAXALIGN(sizeof(SlruSharedData))
+		+ BLCKSZ * NUM_CLOG_BUFFERS
 		+ MAXALIGN(sizeof(SlruLockData))
-#endif
 		;
 }
 
@@ -181,21 +180,8 @@ SimpleLruInit(SlruCtl ctl, const char *name, const char *subdir)
 
 	ptr = ShmemInitStruct(name, SimpleLruShmemSize(), &found);
 	shared = (SlruShared) ptr;
-
-#ifdef EXEC_BACKEND
-	/*
-	 * Locks are in shared memory
-	 */
 	locks = (SlruLock) (ptr + MAXALIGN(sizeof(SlruSharedData)) +
 						BLCKSZ * NUM_CLOG_BUFFERS);
-#else
-	/*
-	 * Locks are in private memory
-	 */
-	Assert(!IsUnderPostmaster);
-	locks = malloc(sizeof(SlruLockData));
-	Assert(locks);
-#endif
 
 	if (!IsUnderPostmaster)
 	{
@@ -225,6 +211,7 @@ SimpleLruInit(SlruCtl ctl, const char *name, const char *subdir)
 	else
 		Assert(found);
 
+	/* Initialize the unshared control struct */
 	ctl->locks = locks;
 	ctl->shared = shared;
 

src/backend/access/transam/xlog.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.143 2004/05/27 17:12:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.144 2004/05/28 05:12:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -397,7 +397,7 @@ static char ControlFilePath[MAXPGPATH];
  * Private, possibly out-of-date copy of shared LogwrtResult.
  * See discussion above.
  */
-NON_EXEC_STATIC XLogwrtResult LogwrtResult = {{0, 0}, {0, 0}};
+static XLogwrtResult LogwrtResult = {{0, 0}, {0, 0}};
 
 /*
  * openLogFile is -1 or a kernel FD for an open log file segment.

src/backend/bootstrap/bootstrap.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.180 2004/05/27 17:12:49 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.181 2004/05/28 05:12:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,17 +43,12 @@
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
 #include "utils/lsyscache.h"
+#include "utils/ps_status.h"
 #include "utils/relcache.h"
 
 
 #define ALLOC(t, c)		((t *) calloc((unsigned)(c), sizeof(t)))
 
-#ifdef EXEC_BACKEND
-typedef struct Port Port;
-extern void SSDataBaseInit(int);
-extern void read_backend_variables(unsigned long, Port*);
-#endif
-
 extern int	Int_yyparse(void);
 static hashnode *AddStr(char *str, int strlength, int mderef);
 static Form_pg_attribute AllocateAttribute(void);
@@ -233,42 +228,37 @@ usage(void)
 }
 
 
-
-int
-BootstrapMain(int argc, char *argv[])
-/* ----------------------------------------------------------------
- *	 The main loop for handling the backend in bootstrap mode
- *	 the bootstrap mode is used to initialize the template database
- *	 the bootstrap backend doesn't speak SQL, but instead expects
+/*
+ *	 The main loop for running the backend in bootstrap mode
+ *
+ *	 The bootstrap mode is used to initialize the template database.
+ *	 The bootstrap backend doesn't speak SQL, but instead expects
  *	 commands in a special bootstrap language.
  *
- *	 The arguments passed in to BootstrapMain are the run-time arguments
- *	 without the argument '-boot', the caller is required to have
- *	 removed -boot from the run-time args
- * ----------------------------------------------------------------
+ *	 For historical reasons, BootstrapMain is also used as the control
+ *	 routine for non-backend subprocesses launched by the postmaster,
+ *	 such as startup and shutdown.
  */
+int
+BootstrapMain(int argc, char *argv[])
 {
 	int			i;
 	char	   *dbname;
 	int			flag;
 	int			xlogop = BS_XLOG_NOP;
 	char	   *potential_DataDir = NULL;
-#ifdef EXEC_BACKEND
-	unsigned long	backendID = 0;
-#endif
 
 	/*
 	 * initialize globals
 	 */
-
 	MyProcPid = getpid();
 
 	/*
 	 * Fire up essential subsystems: error and memory management
 	 *
 	 * If we are running under the postmaster, this is done already.
 	 */
-	if (!IsUnderPostmaster || ExecBackend)
+	if (!IsUnderPostmaster)
 		MemoryContextInit();
 
 	/*
@@ -284,6 +274,13 @@ BootstrapMain(int argc, char *argv[])
 												 * variable */
 	}
 
+	/* Ignore the initial -boot argument, if present */
+	if (argc > 1 && strcmp(argv[1], "-boot") == 0)
+	{
+		argv++;
+		argc--;
+	}
+
 	while ((flag = getopt(argc, argv, "B:c:d:D:Fo:p:x:-:")) != -1)
 	{
 		switch (flag)
@@ -315,14 +312,6 @@ BootstrapMain(int argc, char *argv[])
 				xlogop = atoi(optarg);
 				break;
 			case 'p':
-#ifdef EXEC_BACKEND
-				{
-					char buf[MAXPGPATH];
-					IsUnderPostmaster = true;
-					sscanf(optarg,"%lu,%s",&backendID,buf);
-					dbname = strdup(buf);
-				}
-#endif
 				dbname = strdup(optarg);
 				break;
 			case 'B':
@@ -369,7 +358,7 @@ BootstrapMain(int argc, char *argv[])
 	if (!dbname || argc != optind)
 		usage();
 
-	if (!IsUnderPostmaster || ExecBackend)
+	if (!IsUnderPostmaster)
 	{
 		if (!potential_DataDir)
 		{
@@ -388,21 +377,43 @@ BootstrapMain(int argc, char *argv[])
 	Assert(DataDir);
 	ValidatePgVersion(DataDir);
 
-	/* Acquire configuration parameters */
+	/*
+	 * Identify myself via ps
+	 */
 	if (IsUnderPostmaster)
 	{
-#ifdef EXEC_BACKEND
-		read_backend_variables(backendID,NULL);
-		read_nondefault_variables();
+		const char *statmsg;
 
-		SSDataBaseInit(xlogop);
-#endif
+		switch (xlogop)
+		{
+			case BS_XLOG_STARTUP:
+				statmsg = "startup subprocess";
+				break;
+			case BS_XLOG_CHECKPOINT:
+				statmsg = "checkpoint subprocess";
+				break;
+			case BS_XLOG_BGWRITER:
+				statmsg = "bgwriter subprocess";
+				break;
+			case BS_XLOG_SHUTDOWN:
+				statmsg = "shutdown subprocess";
+				break;
+			default:
+				statmsg = "??? subprocess";
+				break;
+		}
+		init_ps_display(statmsg, "", "");
+		set_ps_display("");
 	}
-	else
+
+	/* Acquire configuration parameters, unless inherited from postmaster */
+	if (!IsUnderPostmaster)
+	{
 		ProcessConfigFile(PGC_POSTMASTER);
 
-	/* If timezone is not set, determine what the OS uses */
-	pg_timezone_initialize();
+		/* If timezone is not set, determine what the OS uses */
+		pg_timezone_initialize();
+	}
 
 	if (IsUnderPostmaster)
 	{
@@ -450,10 +461,6 @@ BootstrapMain(int argc, char *argv[])
 	SetProcessingMode(BootstrapProcessing);
 	IgnoreSystemIndexes(true);
 
-#ifdef EXEC_BACKEND
-	if (IsUnderPostmaster)
-		CreateSharedMemoryAndSemaphores(false, MaxBackends, 0);
-#endif
 	XLOGPathInit();
 
 	BaseInit();

src/backend/main/main.c

@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/main/main.c,v 1.83 2004/05/27 15:07:40 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/main/main.c,v 1.84 2004/05/28 05:12:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -242,9 +242,9 @@ main(int argc, char *argv[])
 
 	/*
 	 * Now dispatch to one of PostmasterMain, PostgresMain, GucInfoMain,
-	 * SubPostmasterMain, pgstat_main, pgstat_mainChild or BootstrapMain
-	 * depending on the program name (and possibly first argument) we were
-	 * called with. The lack of consistency here is historical.
+	 * SubPostmasterMain, or BootstrapMain depending on the program name
+	 * (and possibly first argument) we were called with. The lack of
+	 * consistency here is historical.
 	 */
 	len = strlen(argv[0]);
 
@@ -259,43 +259,21 @@ main(int argc, char *argv[])
 	}
 
 	/*
-	 * If the first argument is "-boot", then invoke bootstrap mode. Note
-	 * we remove "-boot" from the arguments passed on to BootstrapMain.
+	 * If the first argument begins with "-fork", then invoke
+	 * SubPostmasterMain.  This is used for forking postmaster child
+	 * processes on systems where we can't simply fork.
 	 */
-	if (argc > 1 && strcmp(argv[1], "-boot") == 0)
-		exit(BootstrapMain(argc - 1, argv + 1));
-
 #ifdef EXEC_BACKEND
+	if (argc > 1 && strncmp(argv[1], "-fork", 5) == 0)
+		exit(SubPostmasterMain(argc, argv));
+#endif
 
 	/*
-	 * If the first argument is "-forkexec", then invoke
-	 * SubPostmasterMain. Note we remove "-forkexec" from the arguments
-	 * passed on to SubPostmasterMain.
-	 */
-	if (argc > 1 && strcmp(argv[1], "-forkexec") == 0)
-	{
-		SubPostmasterMain(argc - 2, argv + 2);
-		exit(0);
-	}
-
-	/*
-	 * If the first argument is "-statBuf", then invoke pgstat_main.
-	 */
-	if (argc > 1 && strcmp(argv[1], "-statBuf") == 0)
-	{
-		pgstat_main(argc, argv);
-		exit(0);
-	}
-
-	/*
-	 * If the first argument is "-statCol", then invoke pgstat_mainChild.
+	 * If the first argument is "-boot", then invoke bootstrap mode.
+	 * (This path is taken only for a standalone bootstrap process.)
 	 */
-	if (argc > 1 && strcmp(argv[1], "-statCol") == 0)
-	{
-		pgstat_mainChild(argc, argv);
-		exit(0);
-	}
-#endif
+	if (argc > 1 && strcmp(argv[1], "-boot") == 0)
+		exit(BootstrapMain(argc, argv));
 
 	/*
 	 * If the first argument is "--describe-config", then invoke runtime
@@ -331,7 +309,7 @@ main(int argc, char *argv[])
 			exit(1);
 		}
 	}
-#endif
+#endif /* WIN32 */
 
 	exit(PostgresMain(argc, argv, pw_name_persist));
 }

src/backend/port/ipc_test.c

@@ -21,7 +21,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/port/ipc_test.c,v 1.12 2003/12/12 18:45:09 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/port/ipc_test.c,v 1.13 2004/05/28 05:12:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -46,8 +46,6 @@ volatile bool ImmediateInterruptOK = false;
 volatile uint32 InterruptHoldoffCount = 0;
 volatile uint32 CritSectionCount = 0;
 
-const bool	ExecBackend = false;
-
 bool		IsUnderPostmaster = false;
 
 int			MaxBackends = 32;