From 0163480f31887ce6ce581b951ddc115885e7fc6c Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Tue, 29 Mar 2022 21:57:22 -0700
Subject: [PATCH v68 07/31] pgstat: move transactional code into pgstat_xact.c.

Author:
Reviewed-By:
Discussion: https://postgr.es/m/
Backpatch:
---
 src/include/utils/pgstat_internal.h      |   8 +-
 src/backend/postmaster/pgstat.c          | 184 ++++-------------------
 src/backend/utils/activity/Makefile      |   3 +-
 src/backend/utils/activity/pgstat_xact.c | 139 +++++++++++++++++
 4 files changed, 178 insertions(+), 156 deletions(-)
 create mode 100644 src/backend/utils/activity/pgstat_xact.c

diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index b95e1f56eab..7f4d79470f7 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -77,7 +77,6 @@ static const char *const slru_names[] = {
  * Functions in pgstat.c
  */
 
-extern PgStat_SubXactStatus *pgstat_xact_stack_level_get(int nest_level);
 extern void pgstat_setheader(PgStat_MsgHdr *hdr, StatMsgType mtype);
 extern void pgstat_send(void *msg, int len);
 #ifdef USE_ASSERT_CHECKING
@@ -129,6 +128,13 @@ extern void pgstat_wal_initialize(void);
 extern bool pgstat_wal_pending(void);
 
 
+
+/*
+ * Functions in pgstat_xact.c
+ */
+
+extern PgStat_SubXactStatus *pgstat_xact_stack_level_get(int nest_level);
+
 /*
  * Variables in pgstat.c
  */
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index de981a89a5b..8cbed1d1bc3 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -198,8 +198,6 @@ static time_t last_pgstat_start_time;
 
 static bool pgStatRunningInCollector = false;
 
-static PgStat_SubXactStatus *pgStatXactStack = NULL;
-
 /*
  * Info about current "snapshot" of stats file
  */
@@ -740,158 +738,6 @@ pgstat_initialize(void)
 }
 
 
-/* ------------------------------------------------------------
- * Transaction integration
- * ------------------------------------------------------------
- */
-
-/*
- * Called from access/transam/xact.c at top-level transaction commit/abort.
- */
-void
-AtEOXact_PgStat(bool isCommit, bool parallel)
-{
-	PgStat_SubXactStatus *xact_state;
-
-	AtEOXact_PgStat_Database(isCommit, parallel);
-
-	/* handle transactional stats information */
-	xact_state = pgStatXactStack;
-	if (xact_state != NULL)
-	{
-		Assert(xact_state->nest_level == 1);
-		Assert(xact_state->prev == NULL);
-
-		AtEOXact_PgStat_Relations(xact_state, isCommit);
-	}
-	pgStatXactStack = NULL;
-
-	/* Make sure any stats snapshot is thrown away */
-	pgstat_clear_snapshot();
-}
-
-/*
- * Called from access/transam/xact.c at subtransaction commit/abort.
- */
-void
-AtEOSubXact_PgStat(bool isCommit, int nestDepth)
-{
-	PgStat_SubXactStatus *xact_state;
-
-	/* merge the sub-transaction's transactional stats into the parent */
-	xact_state = pgStatXactStack;
-	if (xact_state != NULL &&
-		xact_state->nest_level >= nestDepth)
-	{
-		/* delink xact_state from stack immediately to simplify reuse case */
-		pgStatXactStack = xact_state->prev;
-
-		AtEOSubXact_PgStat_Relations(xact_state, isCommit, nestDepth);
-
-		pfree(xact_state);
-	}
-}
-
-/*
- * Save the transactional stats state at 2PC transaction prepare.
- */
-void
-AtPrepare_PgStat(void)
-{
-	PgStat_SubXactStatus *xact_state;
-
-	xact_state = pgStatXactStack;
-	if (xact_state != NULL)
-	{
-		Assert(xact_state->nest_level == 1);
-		Assert(xact_state->prev == NULL);
-
-		AtPrepare_PgStat_Relations(xact_state);
-	}
-}
-
-/*
- * Clean up after successful PREPARE.
- *
- * Note: AtEOXact_PgStat is not called during PREPARE.
- */
-void
-PostPrepare_PgStat(void)
-{
-	PgStat_SubXactStatus *xact_state;
-
-	/*
-	 * We don't bother to free any of the transactional state, since it's all
-	 * in TopTransactionContext and will go away anyway.
-	 */
-	xact_state = pgStatXactStack;
-	if (xact_state != NULL)
-	{
-		Assert(xact_state->nest_level == 1);
-		Assert(xact_state->prev == NULL);
-
-		PostPrepare_PgStat_Relations(xact_state);
-	}
-	pgStatXactStack = NULL;
-
-	/* Make sure any stats snapshot is thrown away */
-	pgstat_clear_snapshot();
-}
-
-/*
- * Discard any data collected in the current transaction.  Any subsequent
- * request will cause new snapshots to be read.
- *
- * This is also invoked during transaction commit or abort to discard
- * the no-longer-wanted snapshot.
- */
-void
-pgstat_clear_snapshot(void)
-{
-	pgstat_assert_is_up();
-
-	/* Release memory, if any was allocated */
-	if (pgStatLocalContext)
-		MemoryContextDelete(pgStatLocalContext);
-
-	/* Reset variables */
-	pgStatLocalContext = NULL;
-	pgStatDBHash = NULL;
-	replSlotStatHash = NULL;
-	subscriptionStatHash = NULL;
-
-	/*
-	 * Historically the backend_status.c facilities lived in this file, and
-	 * were reset with the same function. For now keep it that way, and
-	 * forward the reset request.
-	 */
-	pgstat_clear_backend_activity_snapshot();
-}
-
-/*
- * Ensure (sub)transaction stack entry for the given nest_level exists, adding
- * it if needed.
- */
-PgStat_SubXactStatus *
-pgstat_xact_stack_level_get(int nest_level)
-{
-	PgStat_SubXactStatus *xact_state;
-
-	xact_state = pgStatXactStack;
-	if (xact_state == NULL || xact_state->nest_level != nest_level)
-	{
-		xact_state = (PgStat_SubXactStatus *)
-			MemoryContextAlloc(TopTransactionContext,
-							   sizeof(PgStat_SubXactStatus));
-		xact_state->nest_level = nest_level;
-		xact_state->prev = pgStatXactStack;
-		xact_state->first = NULL;
-		pgStatXactStack = xact_state;
-	}
-	return xact_state;
-}
-
-
 /* ------------------------------------------------------------
  * Public functions used by backends follow
  * ------------------------------------------------------------
@@ -1319,6 +1165,36 @@ pgstat_send_inquiry(TimestampTz clock_time, TimestampTz cutoff_time, Oid databas
 	pgstat_send(&msg, sizeof(msg));
 }
 
+/*
+ * Discard any data collected in the current transaction.  Any subsequent
+ * request will cause new snapshots to be read.
+ *
+ * This is also invoked during transaction commit or abort to discard
+ * the no-longer-wanted snapshot.
+ */
+void
+pgstat_clear_snapshot(void)
+{
+	pgstat_assert_is_up();
+
+	/* Release memory, if any was allocated */
+	if (pgStatLocalContext)
+		MemoryContextDelete(pgStatLocalContext);
+
+	/* Reset variables */
+	pgStatLocalContext = NULL;
+	pgStatDBHash = NULL;
+	replSlotStatHash = NULL;
+	subscriptionStatHash = NULL;
+
+	/*
+	 * Historically the backend_status.c facilities lived in this file, and
+	 * were reset with the same function. For now keep it that way, and
+	 * forward the reset request.
+	 */
+	pgstat_clear_backend_activity_snapshot();
+}
+
 /*
  * Support function for the SQL-callable pgstat* functions. Returns
  * the collected statistics for one database or NULL. NULL doesn't mean
diff --git a/src/backend/utils/activity/Makefile b/src/backend/utils/activity/Makefile
index 25a967ab7d7..791ba68e7e3 100644
--- a/src/backend/utils/activity/Makefile
+++ b/src/backend/utils/activity/Makefile
@@ -23,9 +23,10 @@ OBJS = \
 	pgstat_function.o \
 	pgstat_relation.o \
 	pgstat_replslot.o \
+	pgstat_slru.o \
 	pgstat_subscription.o \
 	pgstat_wal.o \
-	pgstat_slru.o \
+	pgstat_xact.o \
 	wait_event.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
new file mode 100644
index 00000000000..17907e32789
--- /dev/null
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -0,0 +1,139 @@
+/* -------------------------------------------------------------------------
+ *
+ * pgstat_xact.c
+ *	  Transactional integration for the cumulative statistics system.
+ *
+ * Copyright (c) 2001-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/activity/pgstat_xact.c
+ * -------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/transam.h"
+#include "access/xact.h"
+#include "pgstat.h"
+#include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
+
+
+static PgStat_SubXactStatus *pgStatXactStack = NULL;
+
+
+/*
+ * Called from access/transam/xact.c at top-level transaction commit/abort.
+ */
+void
+AtEOXact_PgStat(bool isCommit, bool parallel)
+{
+	PgStat_SubXactStatus *xact_state;
+
+	AtEOXact_PgStat_Database(isCommit, parallel);
+
+	/* handle transactional stats information */
+	xact_state = pgStatXactStack;
+	if (xact_state != NULL)
+	{
+		Assert(xact_state->nest_level == 1);
+		Assert(xact_state->prev == NULL);
+
+		AtEOXact_PgStat_Relations(xact_state, isCommit);
+	}
+	pgStatXactStack = NULL;
+
+	/* Make sure any stats snapshot is thrown away */
+	pgstat_clear_snapshot();
+}
+
+/*
+ * Called from access/transam/xact.c at subtransaction commit/abort.
+ */
+void
+AtEOSubXact_PgStat(bool isCommit, int nestDepth)
+{
+	PgStat_SubXactStatus *xact_state;
+
+	/* merge the sub-transaction's transactional stats into the parent */
+	xact_state = pgStatXactStack;
+	if (xact_state != NULL &&
+		xact_state->nest_level >= nestDepth)
+	{
+		/* delink xact_state from stack immediately to simplify reuse case */
+		pgStatXactStack = xact_state->prev;
+
+		AtEOSubXact_PgStat_Relations(xact_state, isCommit, nestDepth);
+
+		pfree(xact_state);
+	}
+}
+
+/*
+ * Save the transactional stats state at 2PC transaction prepare.
+ */
+void
+AtPrepare_PgStat(void)
+{
+	PgStat_SubXactStatus *xact_state;
+
+	xact_state = pgStatXactStack;
+	if (xact_state != NULL)
+	{
+		Assert(xact_state->nest_level == 1);
+		Assert(xact_state->prev == NULL);
+
+		AtPrepare_PgStat_Relations(xact_state);
+	}
+}
+
+/*
+ * Clean up after successful PREPARE.
+ *
+ * Note: AtEOXact_PgStat is not called during PREPARE.
+ */
+void
+PostPrepare_PgStat(void)
+{
+	PgStat_SubXactStatus *xact_state;
+
+	/*
+	 * We don't bother to free any of the transactional state, since it's all
+	 * in TopTransactionContext and will go away anyway.
+	 */
+	xact_state = pgStatXactStack;
+	if (xact_state != NULL)
+	{
+		Assert(xact_state->nest_level == 1);
+		Assert(xact_state->prev == NULL);
+
+		PostPrepare_PgStat_Relations(xact_state);
+	}
+	pgStatXactStack = NULL;
+
+	/* Make sure any stats snapshot is thrown away */
+	pgstat_clear_snapshot();
+}
+
+/*
+ * Ensure (sub)transaction stack entry for the given nest_level exists, adding
+ * it if needed.
+ */
+PgStat_SubXactStatus *
+pgstat_xact_stack_level_get(int nest_level)
+{
+	PgStat_SubXactStatus *xact_state;
+
+	xact_state = pgStatXactStack;
+	if (xact_state == NULL || xact_state->nest_level != nest_level)
+	{
+		xact_state = (PgStat_SubXactStatus *)
+			MemoryContextAlloc(TopTransactionContext,
+							   sizeof(PgStat_SubXactStatus));
+		xact_state->nest_level = nest_level;
+		xact_state->prev = pgStatXactStack;
+		xact_state->first = NULL;
+		pgStatXactStack = xact_state;
+	}
+	return xact_state;
+}
-- 
2.35.1.677.gabf474a5dd

