[refer #PGPRO-3213] Add shared_memory_type=posix

Author: knizhnik

src/backend/port/sysv_shmem.c

@@ -98,6 +98,7 @@ unsigned long UsedShmemSegID = 0;
 void	   *UsedShmemSegAddr = NULL;
 
 void *AnonymousShmem = NULL;
+int   AnonymousShmemFile = -1;
 static Size AnonymousShmemSize;
 
 static void *InternalIpcMemoryCreate(IpcMemoryKey memKey, Size size);
@@ -540,26 +541,31 @@ CreateAnonymousSegment(Size *size)
 	void       *hint = NULL;
 	int         mmap_flags = PG_MMAP_FLAGS;
 
-	if (OnlineUpgradePath)
+	if (shared_memory_type == SHMEM_TYPE_POSIX)
 	{
-		int shm_flags = O_RDWR;
-		char path[64];
 		mmap_flags &= ~MAP_ANONYMOUS;
-		sprintf(path, "/%d", MyProcPid);
-
 		if (IsOnlineUpgrade)
 		{
+			Assert(AnonymousShmemFile >= 0);
+			fd = AnonymousShmemFile;
 			mmap_flags |= MAP_FIXED;
 			hint = AnonymousShmem;
 		}
 		else
 		{
-			shm_flags |= O_CREAT|O_TRUNC;
+			int flags;
+			char path[64];
+			sprintf(path, "/%d", MyProcPid);
+			fd = shm_open(path, O_CREAT|O_TRUNC|O_RDWR, pg_file_create_mode);
+			if (fd < 0)
+				ereport(FATAL,
+						(errmsg("could not create shared memory object: %m"), 0));
+			AnonymousShmemFile = fd;
+			shm_unlink(path);
+			flags = fcntl(fd, F_GETFD);
+			flags &= ~FD_CLOEXEC;
+			fcntl(fd, F_SETFD, flags);
 		}
-		fd = shm_open(path, shm_flags, pg_file_create_mode);
-		if (fd < 0)
-			ereport(FATAL,
-					(errmsg("could not create shared memory object: %m"), 0));
 	}
 
 #ifndef MAP_HUGETLB
@@ -692,7 +698,7 @@ PGSharedMemoryCreate(Size size,
 	/* Room for a header? */
 	Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
 
-	if (shared_memory_type == SHMEM_TYPE_MMAP)
+	if (shared_memory_type != SHMEM_TYPE_SYSV)
 	{
 		AnonymousShmem = CreateAnonymousSegment(&size);
 		AnonymousShmemSize = size;

src/backend/postmaster/postmaster.c

@@ -575,6 +575,7 @@ typedef struct
 #endif
 	void	   *UsedShmemSegAddr;
 	void       *AnonymousShmem;
+	int         AnonymousShmemFile;
 	slock_t    *ShmemLock;
 	VariableCache ShmemVariableCache;
 #ifndef HAVE_SPINLOCKS
@@ -624,6 +625,7 @@ static bool SavePostmasterParameters(void)
 	param.UsedShmemSegID = UsedShmemSegID;
 	param.UsedShmemSegAddr = UsedShmemSegAddr;
 	param.AnonymousShmem = AnonymousShmem;
+	param.AnonymousShmemFile = AnonymousShmemFile;
 	param.ShmemLock = ShmemLock;
 	param.ShmemVariableCache = ShmemVariableCache;
 
@@ -724,6 +726,7 @@ RestorePostmasterParameters(void)
 	UsedShmemSegID = param.UsedShmemSegID;
 	UsedShmemSegAddr = param.UsedShmemSegAddr;
 	AnonymousShmem = param.AnonymousShmem;
+	AnonymousShmemFile = param.AnonymousShmemFile;
 
 	ShmemLock = param.ShmemLock;
 	ShmemVariableCache = param.ShmemVariableCache;

src/backend/utils/misc/guc.c

@@ -160,6 +160,8 @@ static bool check_wal_consistency_checking(char **newval, void **extra,
 										   GucSource source);
 static void assign_wal_consistency_checking(const char *newval, void *extra);
 
+static bool check_online_update_support(char **newval, void **extra, GucSource source);
+
 #ifdef HAVE_SYSLOG
 static int	syslog_facility = LOG_LOCAL0;
 #else
@@ -460,6 +462,7 @@ const struct config_enum_entry ssl_protocol_versions_info[] = {
 static struct config_enum_entry shared_memory_options[] = {
 #ifndef WIN32
 	{"sysv", SHMEM_TYPE_SYSV, false},
+	{"posix", SHMEM_TYPE_POSIX, false},
 #endif
 #ifndef EXEC_BACKEND
 	{"mmap", SHMEM_TYPE_MMAP, false},
@@ -3675,8 +3678,8 @@ static struct config_string ConfigureNamesString[] =
 		 GUC_SUPERUSER_ONLY
 		},
 		&OnlineUpgradePath,
-		"",
-		NULL, NULL, NULL
+		NULL,
+		check_online_update_support, NULL, NULL
 	},
 
 	{
@@ -11726,4 +11729,19 @@ check_default_with_oids(bool *newval, void **extra, GucSource source)
 	return true;
 }
 
+static bool
+check_online_update_support(char **newval, void **extra, GucSource source)
+{
+	if (*newval && **newval != '\0')
+	{
+		if (shared_memory_type == SHMEM_TYPE_MMAP)
+		{
+			GUC_check_errcode(ERRCODE_FEATURE_NOT_SUPPORTED);
+			GUC_check_errmsg("Online upgrade is not possible with shared_memory_type=mmap, please use sysv or posix");
+			return false;
+		}
+	}
+	return true;
+}
+
 #include "guc-file.c"

src/include/storage/pg_shmem.h

@@ -58,7 +58,8 @@ typedef enum
 {
 	SHMEM_TYPE_WINDOWS,
 	SHMEM_TYPE_SYSV,
-	SHMEM_TYPE_MMAP
+	SHMEM_TYPE_MMAP,
+	SHMEM_TYPE_POSIX
 }			PGShmemType;
 
 #ifndef WIN32
@@ -69,6 +70,7 @@ extern void *ShmemProtectiveRegion;
 #endif
 extern void *UsedShmemSegAddr;
 extern void *AnonymousShmem;
+extern int   AnonymousShmemFile;
 
 #if !defined(WIN32) && !defined(EXEC_BACKEND)
 #define DEFAULT_SHARED_MEMORY_TYPE SHMEM_TYPE_MMAP