Move codes for pg_backend_memory_contexts from mmgr/mcxt.c to adt/mcxtfuncs.c.

Previously the codes for pg_backend_memory_contexts were in
src/backend/utils/mmgr/mcxt.c. This commit moves them to
src/backend/utils/adt/mcxtfuncs.c so that mcxt.c basically includes
only the low-level interface for memory contexts.

Author: Atsushi Torikoshi
Reviewed-by: Michael Paquier, Fujii Masao
Discussion: https://postgr.es/m/20200819135545.GC19121@paquier.xyz

3 files changed, 158 insertions, 137 deletions

diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile
index 5d2aca8cfe6..54d5c379472 100644
--- a/src/backend/utils/adt/Makefile
+++ b/src/backend/utils/adt/Makefile
@@ -57,6 +57,7 @@ OBJS = \
 	lockfuncs.o \
 	mac.o \
 	mac8.o \
+	mcxtfuncs.o \
 	misc.o \
 	name.o \
 	network.o \
diff --git a/src/backend/utils/adt/mcxtfuncs.c b/src/backend/utils/adt/mcxtfuncs.c
new file mode 100644
index 00000000000..50e1b07ff02
--- /dev/null
+++ b/src/backend/utils/adt/mcxtfuncs.c
@@ -0,0 +1,157 @@
+/*-------------------------------------------------------------------------
+ *
+ * mcxtfuncs.c
+ *	  Functions to show backend memory context.
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/mcxtfuncs.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "mb/pg_wchar.h"
+#include "utils/builtins.h"
+
+/* ----------
+ * The max bytes for showing identifiers of MemoryContext.
+ * ----------
+ */
+#define MEMORY_CONTEXT_IDENT_DISPLAY_SIZE	1024
+
+/*
+ * PutMemoryContextsStatsTupleStore
+ *		One recursion level for pg_get_backend_memory_contexts.
+ */
+static void
+PutMemoryContextsStatsTupleStore(Tuplestorestate *tupstore,
+								TupleDesc tupdesc, MemoryContext context,
+								const char *parent, int level)
+{
+#define PG_GET_BACKEND_MEMORY_CONTEXTS_COLS	9
+
+	Datum		values[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
+	bool		nulls[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
+	MemoryContextCounters stat;
+	MemoryContext child;
+	const char *name;
+	const char *ident;
+
+	AssertArg(MemoryContextIsValid(context));
+
+	name = context->name;
+	ident = context->ident;
+
+	/*
+	 * To be consistent with logging output, we label dynahash contexts
+	 * with just the hash table name as with MemoryContextStatsPrint().
+	 */
+	if (ident && strcmp(name, "dynahash") == 0)
+	{
+		name = ident;
+		ident = NULL;
+	}
+
+	/* Examine the context itself */
+	memset(&stat, 0, sizeof(stat));
+	(*context->methods->stats) (context, NULL, (void *) &level, &stat);
+
+	memset(values, 0, sizeof(values));
+	memset(nulls, 0, sizeof(nulls));
+
+	if (name)
+		values[0] = CStringGetTextDatum(name);
+	else
+		nulls[0] = true;
+
+	if (ident)
+	{
+		int		idlen = strlen(ident);
+		char		clipped_ident[MEMORY_CONTEXT_IDENT_DISPLAY_SIZE];
+
+		/*
+		 * Some identifiers such as SQL query string can be very long,
+		 * truncate oversize identifiers.
+		 */
+		if (idlen >= MEMORY_CONTEXT_IDENT_DISPLAY_SIZE)
+			idlen = pg_mbcliplen(ident, idlen, MEMORY_CONTEXT_IDENT_DISPLAY_SIZE - 1);
+
+		memcpy(clipped_ident, ident, idlen);
+		clipped_ident[idlen] = '\0';
+		values[1] = CStringGetTextDatum(clipped_ident);
+	}
+	else
+		nulls[1] = true;
+
+	if (parent)
+		values[2] = CStringGetTextDatum(parent);
+	else
+		nulls[2] = true;
+
+	values[3] = Int32GetDatum(level);
+	values[4] = Int64GetDatum(stat.totalspace);
+	values[5] = Int64GetDatum(stat.nblocks);
+	values[6] = Int64GetDatum(stat.freespace);
+	values[7] = Int64GetDatum(stat.freechunks);
+	values[8] = Int64GetDatum(stat.totalspace - stat.freespace);
+	tuplestore_putvalues(tupstore, tupdesc, values, nulls);
+
+	for (child = context->firstchild; child != NULL; child = child->nextchild)
+	{
+		PutMemoryContextsStatsTupleStore(tupstore, tupdesc,
+								  child, name, level + 1);
+	}
+}
+
+/*
+ * pg_get_backend_memory_contexts
+ *		SQL SRF showing backend memory context.
+ */
+Datum
+pg_get_backend_memory_contexts(PG_FUNCTION_ARGS)
+{
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	TupleDesc	tupdesc;
+	Tuplestorestate *tupstore;
+	MemoryContext per_query_ctx;
+	MemoryContext oldcontext;
+
+	/* check to see if caller supports us returning a tuplestore */
+	if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("set-valued function called in context that cannot accept a set")));
+	if (!(rsinfo->allowedModes & SFRM_Materialize))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("materialize mode required, but it is not allowed in this context")));
+
+	/* Build a tuple descriptor for our result type */
+	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+		elog(ERROR, "return type must be a row type");
+
+	per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
+	oldcontext = MemoryContextSwitchTo(per_query_ctx);
+
+	tupstore = tuplestore_begin_heap(true, false, work_mem);
+	rsinfo->returnMode = SFRM_Materialize;
+	rsinfo->setResult = tupstore;
+	rsinfo->setDesc = tupdesc;
+
+	MemoryContextSwitchTo(oldcontext);
+
+	PutMemoryContextsStatsTupleStore(tupstore, tupdesc,
+								TopMemoryContext, NULL, 0);
+
+	/* clean up and return the tuplestore */
+	tuplestore_donestoring(tupstore);
+
+	return (Datum) 0;
+}
diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c
index d9bb2499db7..88c76f290ce 100644
--- a/src/backend/utils/mmgr/mcxt.c
+++ b/src/backend/utils/mmgr/mcxt.c
@@ -21,10 +21,8 @@
 
 #include "postgres.h"
 
-#include "funcapi.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
-#include "utils/builtins.h"
 #include "utils/memdebug.h"
 #include "utils/memutils.h"
 
@@ -69,11 +67,6 @@ static void MemoryContextStatsPrint(MemoryContext context, void *passthru,
 #define AssertNotInCriticalSection(context) \
 	Assert(CritSectionCount == 0 || (context)->allowInCritSection)
 
-/* ----------
- * The max bytes for showing identifiers of MemoryContext.
- * ----------
- */
-#define MEMORY_CONTEXT_IDENT_DISPLAY_SIZE	1024
 
 /*****************************************************************************
  *	  EXPORTED ROUTINES														 *
@@ -1228,133 +1221,3 @@ pchomp(const char *in)
 		n--;
 	return pnstrdup(in, n);
 }
-
-/*
- * PutMemoryContextsStatsTupleStore
- *		One recursion level for pg_get_backend_memory_contexts.
- */
-static void
-PutMemoryContextsStatsTupleStore(Tuplestorestate *tupstore,
-								TupleDesc tupdesc, MemoryContext context,
-								const char *parent, int level)
-{
-#define PG_GET_BACKEND_MEMORY_CONTEXTS_COLS	9
-
-	Datum		values[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
-	bool		nulls[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
-	MemoryContextCounters stat;
-	MemoryContext child;
-	const char *name;
-	const char *ident;
-
-	AssertArg(MemoryContextIsValid(context));
-
-	name = context->name;
-	ident = context->ident;
-
-	/*
-	 * To be consistent with logging output, we label dynahash contexts
-	 * with just the hash table name as with MemoryContextStatsPrint().
-	 */
-	if (ident && strcmp(name, "dynahash") == 0)
-	{
-		name = ident;
-		ident = NULL;
-	}
-
-	/* Examine the context itself */
-	memset(&stat, 0, sizeof(stat));
-	(*context->methods->stats) (context, NULL, (void *) &level, &stat);
-
-	memset(values, 0, sizeof(values));
-	memset(nulls, 0, sizeof(nulls));
-
-	if (name)
-		values[0] = CStringGetTextDatum(name);
-	else
-		nulls[0] = true;
-
-	if (ident)
-	{
-		int		idlen = strlen(ident);
-		char		clipped_ident[MEMORY_CONTEXT_IDENT_DISPLAY_SIZE];
-
-		/*
-		 * Some identifiers such as SQL query string can be very long,
-		 * truncate oversize identifiers.
-		 */
-		if (idlen >= MEMORY_CONTEXT_IDENT_DISPLAY_SIZE)
-			idlen = pg_mbcliplen(ident, idlen, MEMORY_CONTEXT_IDENT_DISPLAY_SIZE - 1);
-
-		memcpy(clipped_ident, ident, idlen);
-		clipped_ident[idlen] = '\0';
-		values[1] = CStringGetTextDatum(clipped_ident);
-	}
-	else
-		nulls[1] = true;
-
-	if (parent)
-		values[2] = CStringGetTextDatum(parent);
-	else
-		nulls[2] = true;
-
-	values[3] = Int32GetDatum(level);
-	values[4] = Int64GetDatum(stat.totalspace);
-	values[5] = Int64GetDatum(stat.nblocks);
-	values[6] = Int64GetDatum(stat.freespace);
-	values[7] = Int64GetDatum(stat.freechunks);
-	values[8] = Int64GetDatum(stat.totalspace - stat.freespace);
-	tuplestore_putvalues(tupstore, tupdesc, values, nulls);
-
-	for (child = context->firstchild; child != NULL; child = child->nextchild)
-	{
-		PutMemoryContextsStatsTupleStore(tupstore, tupdesc,
-								  child, name, level + 1);
-	}
-}
-
-/*
- * pg_get_backend_memory_contexts
- *		SQL SRF showing backend memory context.
- */
-Datum
-pg_get_backend_memory_contexts(PG_FUNCTION_ARGS)
-{
-	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
-	TupleDesc	tupdesc;
-	Tuplestorestate *tupstore;
-	MemoryContext per_query_ctx;
-	MemoryContext oldcontext;
-
-	/* check to see if caller supports us returning a tuplestore */
-	if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("set-valued function called in context that cannot accept a set")));
-	if (!(rsinfo->allowedModes & SFRM_Materialize))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("materialize mode required, but it is not allowed in this context")));
-
-	/* Build a tuple descriptor for our result type */
-	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
-		elog(ERROR, "return type must be a row type");
-
-	per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
-	oldcontext = MemoryContextSwitchTo(per_query_ctx);
-
-	tupstore = tuplestore_begin_heap(true, false, work_mem);
-	rsinfo->returnMode = SFRM_Materialize;
-	rsinfo->setResult = tupstore;
-	rsinfo->setDesc = tupdesc;
-
-	MemoryContextSwitchTo(oldcontext);
-
-	PutMemoryContextsStatsTupleStore(tupstore, tupdesc,
-								TopMemoryContext, NULL, 0);
-
-	/* clean up and return the tuplestore */
-	tuplestore_donestoring(tupstore);
-
-	return (Datum) 0;
-}