v6-0002-Remove-MyAuxProcType-use-MyBackendType-instead.patch

From 68b8c662af229f93244b45282f3112d9a5d809b9 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Wed, 10 Jan 2024 14:00:09 +0200
Subject: [PATCH v6 2/3] Remove MyAuxProcType, use MyBackendType instead

MyAuxProcType was redundant with MyBackendType.

Reviewed-by: XXX
Discussion: XXX
---
 src/backend/postmaster/auxprocess.c         | 68 +++++---------------
 src/backend/postmaster/postmaster.c         | 36 +++++------
 src/backend/utils/activity/backend_status.c | 11 ++--
 src/include/miscadmin.h                     | 71 ++++++++++-----------
 src/include/postmaster/auxprocess.h         |  2 +-
 src/tools/pgindent/typedefs.list            |  1 -
 6 files changed, 74 insertions(+), 115 deletions(-)

diff --git a/src/backend/postmaster/auxprocess.c b/src/backend/postmaster/auxprocess.c
index ab86e802f21..bd3815b63d0 100644
--- a/src/backend/postmaster/auxprocess.c
+++ b/src/backend/postmaster/auxprocess.c
@@ -38,14 +38,6 @@
 static void ShutdownAuxiliaryProcess(int code, Datum arg);
 
 
-/* ----------------
- *		global variables
- * ----------------
- */
-
-AuxProcType MyAuxProcType = NotAnAuxProcess;	/* declared in miscadmin.h */
-
-
 /*
  *	 AuxiliaryProcessMain
  *
@@ -55,39 +47,13 @@ AuxProcType MyAuxProcType = NotAnAuxProcess;	/* declared in miscadmin.h */
  *	 This code is here just because of historical reasons.
  */
 void
-AuxiliaryProcessMain(AuxProcType auxtype)
+AuxiliaryProcessMain(BackendType auxtype)
 {
 	Assert(IsUnderPostmaster);
 
-	MyAuxProcType = auxtype;
-
-	switch (MyAuxProcType)
-	{
-		case StartupProcess:
-			MyBackendType = B_STARTUP;
-			break;
-		case ArchiverProcess:
-			MyBackendType = B_ARCHIVER;
-			break;
-		case BgWriterProcess:
-			MyBackendType = B_BG_WRITER;
-			break;
-		case CheckpointerProcess:
-			MyBackendType = B_CHECKPOINTER;
-			break;
-		case WalWriterProcess:
-			MyBackendType = B_WAL_WRITER;
-			break;
-		case WalReceiverProcess:
-			MyBackendType = B_WAL_RECEIVER;
-			break;
-		case WalSummarizerProcess:
-			MyBackendType = B_WAL_SUMMARIZER;
-			break;
-		default:
-			elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
-			MyBackendType = B_INVALID;
-	}
+	MyBackendType = auxtype;
+	if (!IsAuxProcess(MyBackendType))
+		elog(PANIC, "unrecognized process type: %d", (int) MyBackendType);
 
 	init_ps_display(NULL);
 
@@ -110,14 +76,14 @@ AuxiliaryProcessMain(AuxProcType auxtype)
 	/*
 	 * Assign the ProcSignalSlot for an auxiliary process.  Since it doesn't
 	 * have a BackendId, the slot is statically allocated based on the
-	 * auxiliary process type (MyAuxProcType).  Backends use slots indexed in
-	 * the range from 1 to MaxBackends (inclusive), so we use MaxBackends +
-	 * AuxProcType + 1 as the index of the slot for an auxiliary process.
+	 * auxiliary process type.  Backends use slots indexed in the range from 1
+	 * to MaxBackends (inclusive), and aux processes use the slots after that,
+	 * one reserved slot for each different kind of aux process.
 	 *
 	 * This will need rethinking if we ever want more than one of a particular
 	 * auxiliary process type.
 	 */
-	ProcSignalInit(MaxBackends + MyAuxProcType + 1);
+	ProcSignalInit(MaxBackends + MyBackendType - FIRST_AUX_PROC + 1);
 
 	/*
 	 * Auxiliary processes don't run transactions, but they may need a
@@ -136,38 +102,38 @@ AuxiliaryProcessMain(AuxProcType auxtype)
 
 	SetProcessingMode(NormalProcessing);
 
-	switch (MyAuxProcType)
+	switch (MyBackendType)
 	{
-		case StartupProcess:
+		case B_STARTUP:
 			StartupProcessMain();
 			proc_exit(1);
 
-		case ArchiverProcess:
+		case B_ARCHIVER:
 			PgArchiverMain();
 			proc_exit(1);
 
-		case BgWriterProcess:
+		case B_BG_WRITER:
 			BackgroundWriterMain();
 			proc_exit(1);
 
-		case CheckpointerProcess:
+		case B_CHECKPOINTER:
 			CheckpointerMain();
 			proc_exit(1);
 
-		case WalWriterProcess:
+		case B_WAL_WRITER:
 			WalWriterMain();
 			proc_exit(1);
 
-		case WalReceiverProcess:
+		case B_WAL_RECEIVER:
 			WalReceiverMain();
 			proc_exit(1);
 
-		case WalSummarizerProcess:
+		case B_WAL_SUMMARIZER:
 			WalSummarizerMain();
 			proc_exit(1);
 
 		default:
-			elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+			elog(PANIC, "unrecognized process type: %d", (int) MyBackendType);
 			proc_exit(1);
 	}
 }
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index feb471dd1df..c51b6a1376a 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -440,7 +440,7 @@ static int	CountChildren(int target);
 static bool assign_backendlist_entry(RegisteredBgWorker *rw);
 static void maybe_start_bgworkers(void);
 static bool CreateOptsFile(int argc, char *argv[], char *fullprogname);
-static pid_t StartChildProcess(AuxProcType type);
+static pid_t StartChildProcess(BackendType type);
 static void StartAutovacuumWorker(void);
 static void MaybeStartWalReceiver(void);
 static void MaybeStartWalSummarizer(void);
@@ -561,13 +561,13 @@ static void ShmemBackendArrayAdd(Backend *bn);
 static void ShmemBackendArrayRemove(Backend *bn);
 #endif							/* EXEC_BACKEND */
 
-#define StartupDataBase()		StartChildProcess(StartupProcess)
-#define StartArchiver()			StartChildProcess(ArchiverProcess)
-#define StartBackgroundWriter() StartChildProcess(BgWriterProcess)
-#define StartCheckpointer()		StartChildProcess(CheckpointerProcess)
-#define StartWalWriter()		StartChildProcess(WalWriterProcess)
-#define StartWalReceiver()		StartChildProcess(WalReceiverProcess)
-#define StartWalSummarizer()	StartChildProcess(WalSummarizerProcess)
+#define StartupDataBase()		StartChildProcess(B_STARTUP)
+#define StartArchiver()			StartChildProcess(B_ARCHIVER)
+#define StartBackgroundWriter() StartChildProcess(B_BG_WRITER)
+#define StartCheckpointer()		StartChildProcess(B_CHECKPOINTER)
+#define StartWalWriter()		StartChildProcess(B_WAL_WRITER)
+#define StartWalReceiver()		StartChildProcess(B_WAL_RECEIVER)
+#define StartWalSummarizer()	StartChildProcess(B_WAL_SUMMARIZER)
 
 /* Macros to check exit status of a child process */
 #define EXIT_STATUS_0(st)  ((st) == 0)
@@ -4953,7 +4953,7 @@ SubPostmasterMain(int argc, char *argv[])
 	}
 	if (strcmp(argv[1], "--forkaux") == 0)
 	{
-		AuxProcType auxtype;
+		BackendType auxtype;
 
 		Assert(argc == 4);
 
@@ -5292,7 +5292,7 @@ CountChildren(int target)
  * to start subprocess.
  */
 static pid_t
-StartChildProcess(AuxProcType type)
+StartChildProcess(BackendType type)
 {
 	pid_t		pid;
 
@@ -5344,31 +5344,31 @@ StartChildProcess(AuxProcType type)
 		errno = save_errno;
 		switch (type)
 		{
-			case StartupProcess:
+			case B_STARTUP:
 				ereport(LOG,
 						(errmsg("could not fork startup process: %m")));
 				break;
-			case ArchiverProcess:
+			case B_ARCHIVER:
 				ereport(LOG,
 						(errmsg("could not fork archiver process: %m")));
 				break;
-			case BgWriterProcess:
+			case B_BG_WRITER:
 				ereport(LOG,
 						(errmsg("could not fork background writer process: %m")));
 				break;
-			case CheckpointerProcess:
+			case B_CHECKPOINTER:
 				ereport(LOG,
 						(errmsg("could not fork checkpointer process: %m")));
 				break;
-			case WalWriterProcess:
+			case B_WAL_WRITER:
 				ereport(LOG,
 						(errmsg("could not fork WAL writer process: %m")));
 				break;
-			case WalReceiverProcess:
+			case B_WAL_RECEIVER:
 				ereport(LOG,
 						(errmsg("could not fork WAL receiver process: %m")));
 				break;
-			case WalSummarizerProcess:
+			case B_WAL_SUMMARIZER:
 				ereport(LOG,
 						(errmsg("could not fork WAL summarizer process: %m")));
 				break;
@@ -5382,7 +5382,7 @@ StartChildProcess(AuxProcType type)
 		 * fork failure is fatal during startup, but there's no need to choke
 		 * immediately if starting other child types fails.
 		 */
-		if (type == StartupProcess)
+		if (type == B_STARTUP)
 			ExitPostmaster(1);
 		return 0;
 	}
diff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.c
index 1a1050c8da1..92f24db4e18 100644
--- a/src/backend/utils/activity/backend_status.c
+++ b/src/backend/utils/activity/backend_status.c
@@ -257,17 +257,16 @@ pgstat_beinit(void)
 	else
 	{
 		/* Must be an auxiliary process */
-		Assert(MyAuxProcType != NotAnAuxProcess);
+		Assert(IsAuxProcess(MyBackendType));
 
 		/*
 		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
 		 * have a BackendId, the slot is statically allocated based on the
-		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
-		 * in the range from 0 to MaxBackends (exclusive), so we use
-		 * MaxBackends + AuxProcType as the index of the slot for an auxiliary
-		 * process.
+		 * auxiliary process type.  Backends use slots indexed in the range
+		 * from 0 to MaxBackends (exclusive), and aux processes use the slots
+		 * after that.
 		 */
-		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyBackendType - FIRST_AUX_PROC];
 	}
 
 	/* Set up a process-exit hook to clean up */
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 0b01c1f0935..70da52a7876 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -321,21 +321,36 @@ extern void InitProcessLocalLatch(void);
 extern void SwitchToSharedLatch(void);
 extern void SwitchBackToLocalLatch(void);
 
+/*
+ * MyBackendType indicates what kind of a backend this is.
+ */
 typedef enum BackendType
 {
 	B_INVALID = 0,
-	B_ARCHIVER,
+
+	/* Backends and other backend-like processes */
+	B_BACKEND,
 	B_AUTOVAC_LAUNCHER,
 	B_AUTOVAC_WORKER,
-	B_BACKEND,
 	B_BG_WORKER,
+	B_WAL_SENDER,
+
+	B_STANDALONE_BACKEND,
+	B_LOGGER,
+
+	/*
+	 * Auxiliary processes. These have PGPROC entries, but they are not
+	 * attached to any particular database. There can be only one of each of
+	 * these running at a time.
+	 *
+	 * If you modify these, make sure to update NUM_AUXILIARY_PROCS and the
+	 * glossary in the docs.
+	 */
+	B_ARCHIVER,
 	B_BG_WRITER,
 	B_CHECKPOINTER,
-	B_LOGGER,
-	B_STANDALONE_BACKEND,
 	B_STARTUP,
 	B_WAL_RECEIVER,
-	B_WAL_SENDER,
 	B_WAL_SUMMARIZER,
 	B_WAL_WRITER,
 } BackendType;
@@ -344,6 +359,19 @@ typedef enum BackendType
 
 extern PGDLLIMPORT BackendType MyBackendType;
 
+#define FIRST_AUX_PROC B_ARCHIVER
+#define NUM_AUXPROCTYPES (BACKEND_NUM_TYPES - FIRST_AUX_PROC)
+
+#define AmStartupProcess()			(MyBackendType == B_STARTUP)
+#define AmBackgroundWriterProcess() (MyBackendType == B_BG_WRITER)
+#define AmArchiverProcess()			(MyBackendType == B_ARCHIVER)
+#define AmCheckpointerProcess()		(MyBackendType == B_CHECKPOINTER)
+#define AmWalWriterProcess()		(MyBackendType == B_WAL_WRITER)
+#define AmWalReceiverProcess()		(MyBackendType == B_WAL_RECEIVER)
+#define AmWalSummarizerProcess()	(MyBackendType == B_WAL_SUMMARIZER)
+
+#define IsAuxProcess(type)			(MyBackendType >= FIRST_AUX_PROC)
+
 extern const char *GetBackendTypeDesc(BackendType backendType);
 
 extern void SetDatabasePath(const char *path);
@@ -426,39 +454,6 @@ extern PGDLLIMPORT ProcessingMode Mode;
 	} while(0)
 
 
-/*
- * Auxiliary-process type identifiers.  These used to be in bootstrap.h
- * but it seems saner to have them here, with the ProcessingMode stuff.
- * The MyAuxProcType global is defined and set in auxprocess.c.
- *
- * Make sure to list in the glossary any items you add here.
- */
-
-typedef enum
-{
-	NotAnAuxProcess = -1,
-	StartupProcess = 0,
-	BgWriterProcess,
-	ArchiverProcess,
-	CheckpointerProcess,
-	WalWriterProcess,
-	WalReceiverProcess,
-	WalSummarizerProcess,
-
-	NUM_AUXPROCTYPES			/* Must be last! */
-} AuxProcType;
-
-extern PGDLLIMPORT AuxProcType MyAuxProcType;
-
-#define AmStartupProcess()			(MyAuxProcType == StartupProcess)
-#define AmBackgroundWriterProcess() (MyAuxProcType == BgWriterProcess)
-#define AmArchiverProcess()			(MyAuxProcType == ArchiverProcess)
-#define AmCheckpointerProcess()		(MyAuxProcType == CheckpointerProcess)
-#define AmWalWriterProcess()		(MyAuxProcType == WalWriterProcess)
-#define AmWalReceiverProcess()		(MyAuxProcType == WalReceiverProcess)
-#define AmWalSummarizerProcess()	(MyAuxProcType == WalSummarizerProcess)
-
-
 /*****************************************************************************
  *	  pinit.h --															 *
  *			POSTGRES initialization and cleanup definitions.                 *
diff --git a/src/include/postmaster/auxprocess.h b/src/include/postmaster/auxprocess.h
index 1fdde3bb77b..3e443edde70 100644
--- a/src/include/postmaster/auxprocess.h
+++ b/src/include/postmaster/auxprocess.h
@@ -15,6 +15,6 @@
 
 #include "miscadmin.h"
 
-extern void AuxiliaryProcessMain(AuxProcType auxtype) pg_attribute_noreturn();
+extern void AuxiliaryProcessMain(BackendType auxtype) pg_attribute_noreturn();
 
 #endif							/* AUXPROCESS_H */
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 5fd46b7bd1f..2abe43c57f6 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -172,7 +172,6 @@ AutoVacOpts
 AutoVacuumShmemStruct
 AutoVacuumWorkItem
 AutoVacuumWorkItemType
-AuxProcType
 BF_ctx
 BF_key
 BF_word
-- 
2.39.2