0001-Add-shared_memory_type-GUC.patch

>From e090326d8b5933a162e8e503ccec714bde3a49b7 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Tue, 22 Apr 2014 14:17:34 +0200
Subject: [PATCH] Add shared_memory_type GUC.

---
 src/backend/port/sysv_shmem.c                 | 18 ++++++++++++------
 src/backend/storage/ipc/ipci.c                |  2 ++
 src/backend/utils/misc/guc.c                  | 23 +++++++++++++++++++++++
 src/backend/utils/misc/postgresql.conf.sample |  7 ++++++-
 src/include/storage/pg_shmem.h                | 21 +++++++++++++++++++--
 5 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
index 5e3850b..f6343d3 100644
--- a/src/backend/port/sysv_shmem.c
+++ b/src/backend/port/sysv_shmem.c
@@ -465,14 +465,20 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port,
 	 * developer use, this shouldn't be a big problem.
 	 */
 #ifndef EXEC_BACKEND
-	AnonymousShmem = CreateAnonymousSegment(&size);
-	AnonymousShmemSize = size;
+	if (shared_memory_type == SHMEM_TYPE_MMAP)
+	{
+		AnonymousShmem = CreateAnonymousSegment(&size);
+		AnonymousShmemSize = size;
 
-	/* Now we need only allocate a minimal-sized SysV shmem block. */
-	sysvsize = sizeof(PGShmemHeader);
-#else
-	sysvsize = size;
+		/* Now we need only allocate a minimal-sized SysV shmem block. */
+		sysvsize = sizeof(PGShmemHeader);
+	}
+	else
 #endif
+	{
+		Assert(shared_memory_type == SHMEM_TYPE_SYSV);
+		sysvsize = size;
+	}
 
 	/* Make sure PGSharedMemoryAttach doesn't fail without need */
 	UsedShmemSegAddr = NULL;
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 4290d2d..c58f171 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -42,6 +42,8 @@
 #include "storage/sinvaladt.h"
 #include "storage/spin.h"
 
+/* GUCs */
+int			shared_memory_type = DEFAULT_SHARED_MEMORY_TYPE;
 
 shmem_startup_hook_type shmem_startup_hook = NULL;
 
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ea54d16..f6d9dc4 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -403,6 +403,19 @@ static const struct config_enum_entry huge_pages_options[] = {
 	{NULL, 0, false}
 };
 
+static struct config_enum_entry shared_memory_options[] = {
+#ifndef WIN32
+	{ "sysv", SHMEM_TYPE_SYSV, false},
+#endif
+#ifndef EXEC_BACKEND
+	{ "mmap", SHMEM_TYPE_MMAP, false},
+#endif
+#ifdef WIN32
+	{ "windows", SHMEM_TYPE_WINDOWS, false},
+#endif
+	{NULL, 0, false}
+};
+
 /*
  * Options for enum values stored in other modules
  */
@@ -3453,6 +3466,16 @@ static struct config_enum ConfigureNamesEnum[] =
 	},
 
 	{
+		{"shared_memory_type", PGC_POSTMASTER, RESOURCES_MEM,
+			gettext_noop("Selects the shared memory implementation used."),
+			NULL
+		},
+		&shared_memory_type,
+		DEFAULT_SHARED_MEMORY_TYPE, shared_memory_options,
+		NULL, NULL, NULL
+	},
+
+	{
 		{"wal_sync_method", PGC_SIGHUP, WAL_SETTINGS,
 			gettext_noop("Selects the method used for forcing WAL updates to disk."),
 			NULL
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 70e5a51..1c5f02a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -127,7 +127,12 @@
 #maintenance_work_mem = 64MB		# min 1MB
 #autovacuum_work_mem = -1		# min 1MB, or -1 to use maintenance_work_mem
 #max_stack_depth = 2MB			# min 100kB
-#dynamic_shared_memory_type = posix # the default is the first option
+#shared_memory_type = mmap		# the default is the first option
+					# supported by the operating system:
+					#   mmap
+					#   sysv
+					#   windows
+#dynamic_shared_memory_type = posix	# the default is the first option
 					# supported by the operating system:
 					#   posix
 					#   sysv
diff --git a/src/include/storage/pg_shmem.h b/src/include/storage/pg_shmem.h
index ab28ebe..53ea43a 100644
--- a/src/include/storage/pg_shmem.h
+++ b/src/include/storage/pg_shmem.h
@@ -41,8 +41,13 @@ typedef struct PGShmemHeader	/* standard header for all Postgres shmem */
 #endif
 } PGShmemHeader;
 
-/* GUC variable */
-extern int huge_pages;
+/* Possible values for shared_memory_type */
+typedef enum
+{
+	SHMEM_TYPE_WINDOWS,
+	SHMEM_TYPE_SYSV,
+	SHMEM_TYPE_MMAP
+} PGShmemType;
 
 /* Possible values for huge_pages */
 typedef enum
@@ -52,6 +57,10 @@ typedef enum
 	HUGE_PAGES_TRY
 } HugePagesType;
 
+/* GUC variables */
+extern int shared_memory_type;
+extern int huge_pages;
+
 #ifndef WIN32
 extern unsigned long UsedShmemSegID;
 #else
@@ -59,6 +68,14 @@ extern HANDLE UsedShmemSegID;
 #endif
 extern void *UsedShmemSegAddr;
 
+#if !defined(WIN32) && !defined(EXEC_BACKEND)
+#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_MMAP
+#elif !defined(WIN32)
+#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_SYSV
+#else
+#define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_WINDOWS
+#endif
+
 #ifdef EXEC_BACKEND
 extern void PGSharedMemoryReAttach(void);
 #endif
-- 
1.8.5.rc2.dirty