v2-0002-Unify-several-ways-to-tracking-backend-type.patch

From 6a7f92c36119b345d8ec5b389e35af638cedf934 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 20 Feb 2020 18:14:33 +0100
Subject: [PATCH v2 2/4] Unify several ways to tracking backend type

Add a new global variable MyBackendType that uses the same BackendType
enum that was previously only used by the stats collector.  That way
several duplicate ways of checking what type a particular process is
can be simplified.
---
 src/backend/bootstrap/bootstrap.c   | 48 ++++++++----------
 src/backend/postmaster/autovacuum.c |  8 +--
 src/backend/postmaster/bgworker.c   |  2 +-
 src/backend/postmaster/pgarch.c     |  6 +--
 src/backend/postmaster/pgstat.c     | 75 ++++++-----------------------
 src/backend/postmaster/postmaster.c |  5 ++
 src/backend/postmaster/syslogger.c  |  3 +-
 src/backend/utils/init/globals.c    |  2 +
 src/backend/utils/misc/ps_status.c  | 11 ++++-
 src/include/miscadmin.h             | 20 ++++++++
 src/include/pgstat.h                | 20 +-------
 11 files changed, 81 insertions(+), 119 deletions(-)

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 4212333737..d090e68607 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -314,36 +314,28 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		proc_exit(1);
 	}
 
-	/*
-	 * Identify myself via ps
-	 */
-	if (IsUnderPostmaster)
+	switch (MyAuxProcType)
 	{
-		const char *statmsg;
-
-		switch (MyAuxProcType)
-		{
-			case StartupProcess:
-				statmsg = pgstat_get_backend_desc(B_STARTUP);
-				break;
-			case BgWriterProcess:
-				statmsg = pgstat_get_backend_desc(B_BG_WRITER);
-				break;
-			case CheckpointerProcess:
-				statmsg = pgstat_get_backend_desc(B_CHECKPOINTER);
-				break;
-			case WalWriterProcess:
-				statmsg = pgstat_get_backend_desc(B_WAL_WRITER);
-				break;
-			case WalReceiverProcess:
-				statmsg = pgstat_get_backend_desc(B_WAL_RECEIVER);
-				break;
-			default:
-				statmsg = "??? process";
-				break;
-		}
-		init_ps_display(statmsg);
+		case StartupProcess:
+			MyBackendType = B_STARTUP;
+			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;
+		default:
+			MyBackendType = B_INVALID;
 	}
+	if (IsUnderPostmaster)
+		init_ps_display(NULL);
 
 	/* Acquire configuration parameters, unless inherited from postmaster */
 	if (!IsUnderPostmaster)
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index c461af11b2..c152b5b83a 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -433,8 +433,8 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 	am_autovacuum_launcher = true;
 
-	/* Identify myself via ps */
-	init_ps_display(pgstat_get_backend_desc(B_AUTOVAC_LAUNCHER));
+	MyBackendType = B_AUTOVAC_LAUNCHER;
+	init_ps_display(NULL);
 
 	ereport(DEBUG1,
 			(errmsg("autovacuum launcher started")));
@@ -1506,8 +1506,8 @@ AutoVacWorkerMain(int argc, char *argv[])
 
 	am_autovacuum_worker = true;
 
-	/* Identify myself via ps */
-	init_ps_display(pgstat_get_backend_desc(B_AUTOVAC_WORKER));
+	MyBackendType = B_AUTOVAC_WORKER;
+	init_ps_display(NULL);
 
 	SetProcessingMode(InitProcessing);
 
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 684250984d..6c684b5e12 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -688,7 +688,7 @@ StartBackgroundWorker(void)
 
 	IsBackgroundWorker = true;
 
-	/* Identify myself via ps */
+	MyBackendType = B_BG_WORKER;
 	init_ps_display(worker->bgw_name);
 
 	/*
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 58f54544f6..01ffd6513c 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -238,10 +238,8 @@ PgArchiverMain(int argc, char *argv[])
 	pqsignal(SIGCHLD, SIG_DFL);
 	PG_SETMASK(&UnBlockSig);
 
-	/*
-	 * Identify myself via ps
-	 */
-	init_ps_display("archiver");
+	MyBackendType = B_ARCHIVER;
+	init_ps_display(NULL);
 
 	pgarch_MainLoop();
 
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 3934d03396..94f0953fd8 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2889,62 +2889,7 @@ pgstat_bestart(void)
 	 * out-of-line data.  Those have to be handled separately, below.
 	 */
 	lbeentry.st_procpid = MyProcPid;
-
-	if (MyBackendId != InvalidBackendId)
-	{
-		if (IsAutoVacuumLauncherProcess())
-		{
-			/* Autovacuum Launcher */
-			lbeentry.st_backendType = B_AUTOVAC_LAUNCHER;
-		}
-		else if (IsAutoVacuumWorkerProcess())
-		{
-			/* Autovacuum Worker */
-			lbeentry.st_backendType = B_AUTOVAC_WORKER;
-		}
-		else if (am_walsender)
-		{
-			/* Wal sender */
-			lbeentry.st_backendType = B_WAL_SENDER;
-		}
-		else if (IsBackgroundWorker)
-		{
-			/* bgworker */
-			lbeentry.st_backendType = B_BG_WORKER;
-		}
-		else
-		{
-			/* client-backend */
-			lbeentry.st_backendType = B_BACKEND;
-		}
-	}
-	else
-	{
-		/* Must be an auxiliary process */
-		Assert(MyAuxProcType != NotAnAuxProcess);
-		switch (MyAuxProcType)
-		{
-			case StartupProcess:
-				lbeentry.st_backendType = B_STARTUP;
-				break;
-			case BgWriterProcess:
-				lbeentry.st_backendType = B_BG_WRITER;
-				break;
-			case CheckpointerProcess:
-				lbeentry.st_backendType = B_CHECKPOINTER;
-				break;
-			case WalWriterProcess:
-				lbeentry.st_backendType = B_WAL_WRITER;
-				break;
-			case WalReceiverProcess:
-				lbeentry.st_backendType = B_WAL_RECEIVER;
-				break;
-			default:
-				elog(FATAL, "unrecognized process type: %d",
-					 (int) MyAuxProcType);
-		}
-	}
-
+	lbeentry.st_backendType = MyBackendType;
 	lbeentry.st_proc_start_timestamp = MyStartTimestamp;
 	lbeentry.st_activity_start_timestamp = 0;
 	lbeentry.st_state_start_timestamp = 0;
@@ -4273,6 +4218,9 @@ pgstat_get_backend_desc(BackendType backendType)
 
 	switch (backendType)
 	{
+		case B_INVALID:
+			backendDesc = "not initialized";
+			break;
 		case B_AUTOVAC_LAUNCHER:
 			backendDesc = "autovacuum launcher";
 			break;
@@ -4303,6 +4251,15 @@ pgstat_get_backend_desc(BackendType backendType)
 		case B_WAL_WRITER:
 			backendDesc = "walwriter";
 			break;
+		case B_ARCHIVER:
+			backendDesc = "archiver";
+			break;
+		case B_STATS_COLLECTOR:
+			backendDesc = "stats collector";
+			break;
+		case B_LOGGER:
+			backendDesc = "logger";
+			break;
 	}
 
 	return backendDesc;
@@ -4444,10 +4401,8 @@ PgstatCollectorMain(int argc, char *argv[])
 	pqsignal(SIGCHLD, SIG_DFL);
 	PG_SETMASK(&UnBlockSig);
 
-	/*
-	 * Identify myself via ps
-	 */
-	init_ps_display("stats collector");
+	MyBackendType = B_STATS_COLLECTOR;
+	init_ps_display(NULL);
 
 	/*
 	 * Read in existing stats files or initialize the stats to zero.
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 386fc54e6f..ff51d33b74 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -2259,6 +2259,11 @@ ProcessStartupPacket(Port *port, bool secure_done)
 	if (strlen(port->user_name) >= NAMEDATALEN)
 		port->user_name[NAMEDATALEN - 1] = '\0';
 
+	if (am_walsender)
+		MyBackendType = B_WAL_SENDER;
+	else
+		MyBackendType = B_BACKEND;
+
 	/*
 	 * Normal walsender backends, e.g. for streaming replication, are not
 	 * connected to a particular database. But walsenders used for logical
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index b0ab5d3076..20c59e9b6a 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -179,7 +179,8 @@ SysLoggerMain(int argc, char *argv[])
 
 	am_syslogger = true;
 
-	init_ps_display("logger");
+	MyBackendType = B_LOGGER;
+	init_ps_display(NULL);
 
 	/*
 	 * If we restarted, our stderr is already redirected into our own input
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index eb19644419..e75a29def7 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -78,6 +78,8 @@ char		postgres_exec_path[MAXPGPATH];	/* full path to backend */
 /* note: currently this is not valid in backend processes */
 #endif
 
+BackendType	MyBackendType;
+
 BackendId	MyBackendId = InvalidBackendId;
 
 BackendId	ParallelMasterBackendId = InvalidBackendId;
diff --git a/src/backend/utils/misc/ps_status.c b/src/backend/utils/misc/ps_status.c
index 8b160c0b40..0685a02a31 100644
--- a/src/backend/utils/misc/ps_status.c
+++ b/src/backend/utils/misc/ps_status.c
@@ -28,6 +28,7 @@
 
 #include "libpq/libpq.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "utils/guc.h"
 #include "utils/ps_status.h"
 
@@ -247,14 +248,20 @@ save_ps_display_args(int argc, char **argv)
 
 /*
  * Call this once during subprocess startup to set the identification
- * values.  At this point, the original argv[] array may be overwritten.
+ * values.
+ *
+ * If fixed_part is NULL, a default will be obtained from BackendType.
+ *
+ * At this point, the original argv[] array may be overwritten.
  */
 void
 init_ps_display(const char *fixed_part)
 {
 	bool		save_update_process_title;
 
-	Assert(fixed_part);
+	Assert(fixed_part || MyBackendType);
+	if (!fixed_part)
+		fixed_part = pgstat_get_backend_desc(MyBackendType);
 
 #ifndef PS_USE_NONE
 	/* no ps display for stand-alone backend */
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index f985453ec3..a41b6331da 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -178,6 +178,26 @@ extern char pkglib_path[];
 extern char postgres_exec_path[];
 #endif
 
+typedef enum BackendType
+{
+	B_INVALID = 0,
+	B_AUTOVAC_LAUNCHER,
+	B_AUTOVAC_WORKER,
+	B_BACKEND,
+	B_BG_WORKER,
+	B_BG_WRITER,
+	B_CHECKPOINTER,
+	B_STARTUP,
+	B_WAL_RECEIVER,
+	B_WAL_SENDER,
+	B_WAL_WRITER,
+	B_ARCHIVER,
+	B_STATS_COLLECTOR,
+	B_LOGGER,
+} BackendType;
+
+extern BackendType MyBackendType;
+
 /*
  * done in storage/backendid.h for now.
  *
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 3a65a51696..0facf7251b 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -13,6 +13,7 @@
 
 #include "datatype/timestamp.h"
 #include "libpq/pqcomm.h"
+#include "miscadmin.h"
 #include "port/atomics.h"
 #include "portability/instr_time.h"
 #include "postmaster/pgarch.h"
@@ -712,25 +713,6 @@ typedef struct PgStat_GlobalStats
 } PgStat_GlobalStats;
 
 
-/* ----------
- * Backend types
- * ----------
- */
-typedef enum BackendType
-{
-	B_AUTOVAC_LAUNCHER,
-	B_AUTOVAC_WORKER,
-	B_BACKEND,
-	B_BG_WORKER,
-	B_BG_WRITER,
-	B_CHECKPOINTER,
-	B_STARTUP,
-	B_WAL_RECEIVER,
-	B_WAL_SENDER,
-	B_WAL_WRITER
-} BackendType;
-
-
 /* ----------
  * Backend states
  * ----------
-- 
2.25.0