+++ /dev/null
-/*-------------------------------------------------------------------------
- *
- * shmem.c
- * Microsoft Windows Win32 Shared Memory Emulation
- *
- * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/port/win32/shmem.c,v 1.14 2007/01/05 22:19:35 momjian Exp $
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-static DWORD s_segsize = 0;
-
-/* Detach from a shared mem area based on its address */
-int
-shmdt(const void *shmaddr)
-{
- if (UnmapViewOfFile((LPCVOID *) shmaddr))
- return 0;
- else
- return -1;
-}
-
-/* Attach to an existing area */
-void *
-shmat(int memId, void *shmaddr, int flag)
-{
- /* TODO -- shmat needs to count # attached to shared mem */
- void *lpmem = MapViewOfFileEx((HANDLE) memId,
- FILE_MAP_WRITE | FILE_MAP_READ,
- 0, 0, /* (DWORD)pshmdsc->segsize */ 0 /* s_segsize */ , shmaddr);
-
- if (lpmem == NULL)
- {
- lpmem = (void *) -1;
- _dosmaperr(GetLastError());
- }
-
- return lpmem;
-}
-
-/* Control a shared mem area */
-int
-shmctl(int shmid, int flag, struct shmid_ds * dummy)
-{
- if (flag == IPC_RMID)
- {
- /* Delete the area */
- CloseHandle((HANDLE) shmid);
- return 0;
- }
- if (flag == IPC_STAT)
- {
- /* Can only test for if exists */
- int hmap = shmget(shmid, 0, 0);
-
- if (hmap < 0)
- {
- /* Shared memory does not exist */
- errno = EINVAL;
- return -1;
- }
- else
- {
- /* Shared memory does exist and must be in use */
- shmctl(hmap, IPC_RMID, NULL); /* Release our hold on it */
- errno = 0;
- return 0;
- }
- }
-
- errno = EINVAL;
- return -1;
-}
-
-/* Get an area based on the IPC key */
-int
-shmget(int memKey, int size, int flag)
-{
- HANDLE hmap;
- char szShareMem[32];
- DWORD dwRet;
-
- s_segsize = size;
- sprintf(szShareMem, "PostgreSQL.%d", memKey);
-
- if (flag & IPC_CREAT)
- {
- hmap = CreateFileMapping((HANDLE) 0xFFFFFFFF, /* Use the swap file */
- NULL,
- PAGE_READWRITE, /* Memory is Read/Write */
- 0L, /* Size Upper 32 Bits */
- (DWORD) s_segsize, /* Size Lower 32 bits */
- szShareMem);
- }
- else
- {
- hmap = OpenFileMapping(FILE_MAP_ALL_ACCESS,
- FALSE,
- szShareMem);
- if (!hmap)
- {
- errno = ENOENT;
- return -1;
- }
- }
-
- dwRet = GetLastError();
- if (dwRet == ERROR_ALREADY_EXISTS && hmap && (flag & (IPC_CREAT | IPC_EXCL)))
- {
- /* Caller wanted to create the segment -- error if already exists */
- CloseHandle(hmap);
- errno = EEXIST;
- return -1;
- }
- else if (!hmap)
- {
- /* Unable to get shared memory */
- _dosmaperr(GetLastError());
- return -1;
- }
-
- return (int) hmap;
-}
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * win32_shmem.c
+ * Implement shared memory using win32 facilities
+ *
+ * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * $PostgreSQL: pgsql/src/backend/port/win32_shmem.c,v 1.1 2007/03/21 14:39:23 mha Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "miscadmin.h"
+#include "storage/ipc.h"
+#include "storage/pg_shmem.h"
+
+unsigned long UsedShmemSegID = 0;
+void *UsedShmemSegAddr = NULL;
+
+static void pgwin32_SharedMemoryDelete(int status, Datum shmId);
+
+/*
+ * Generate shared memory segment name. Expand the data directory, to generate
+ * an identifier unique for this data directory. Then replace all backslashes
+ * with forward slashes, since backslashes aren't permitted in global object names.
+ *
+ * Store the shared memory segment in the Global\ namespace (requires NT2 TSE or
+ * 2000, but that's all we support for other reasons as well), to make sure you can't
+ * open two postmasters in different sessions against the same data directory.
+ *
+ * XXX: What happens with junctions? It's only someone breaking things on purpose,
+ * and this is still better than before, but we might want to do something about
+ * that sometime in the future.
+ */
+static char *
+GetSharedMemName(void)
+{
+ char *retptr;
+ DWORD bufsize;
+ DWORD r;
+ char *cp;
+
+ bufsize = GetFullPathName(DataDir, 0, NULL, NULL);
+ if (bufsize == 0)
+ elog(FATAL, "could not get size for full pathname of datadir %s: %lu",
+ DataDir, GetLastError());
+
+ retptr = malloc(bufsize + 1 + 18); /* 1 NULL and 18 for
+ * Global\PostgreSQL: */
+ if (retptr == NULL)
+ elog(FATAL, "could not allocate memory for shared memory name");
+
+ strcpy(retptr, "Global\\PostgreSQL:");
+ r = GetFullPathName(DataDir, bufsize, retptr + 11, NULL);
+ if (r == 0 || r > bufsize)
+ elog(FATAL, "could not generate full pathname for datadir %s: %lu",
+ DataDir, GetLastError());
+
+ for (cp = retptr; *cp; cp++)
+ if (*cp == '\\')
+ *cp = '/';
+
+ return retptr;
+}
+
+
+/*
+ * PGSharedMemoryIsInUse
+ *
+ * Is a previously-existing shmem segment still existing and in use?
+ *
+ * The point of this exercise is to detect the case where a prior postmaster
+ * crashed, but it left child backends that are still running. Therefore
+ * we only care about shmem segments that are associated with the intended
+ * DataDir. This is an important consideration since accidental matches of
+ * shmem segment IDs are reasonably common.
+ *
+ */
+bool
+PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
+{
+ char *szShareMem;
+ HANDLE hmap;
+
+ szShareMem = GetSharedMemName();
+
+ hmap = OpenFileMapping(FILE_MAP_READ, FALSE, szShareMem);
+
+ free(szShareMem);
+
+ if (hmap == NULL)
+ return false;
+
+ CloseHandle(hmap);
+ return true;
+}
+
+
+/*
+ * PGSharedMemoryCreate
+ *
+ * Create a shared memory segment of the given size and initialize its
+ * standard header.
+ *
+ * makePrivate means to always create a new segment, rather than attach to
+ * or recycle any existing segment. On win32, we always create a new segment,
+ * since there is no need for recycling (segments go away automatically
+ * when the last backend exits)
+ *
+ */
+PGShmemHeader *
+PGSharedMemoryCreate(Size size, bool makePrivate, int port)
+{
+ void *memAddress;
+ PGShmemHeader *hdr;
+ HANDLE hmap,
+ hmap2;
+ char *szShareMem;
+
+ /* Room for a header? */
+ Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
+
+ szShareMem = GetSharedMemName();
+
+ UsedShmemSegAddr = NULL;
+
+ hmap = CreateFileMapping((HANDLE) 0xFFFFFFFF, /* Use the pagefile */
+ NULL, /* Default security attrs */
+ PAGE_READWRITE, /* Memory is Read/Write */
+ 0L, /* Size Upper 32 Bits */
+ (DWORD) size, /* Size Lower 32 bits */
+ szShareMem);
+
+ if (!hmap)
+ ereport(FATAL,
+ (errmsg("could not create shared memory segment: %lu", GetLastError()),
+ errdetail("Failed system call was CreateFileMapping(size=%lu, name=%s)", size, szShareMem)));
+
+ /*
+ * If the segment already existed, CreateFileMapping() will return a
+ * handle to the existing one.
+ */
+ if (GetLastError() == ERROR_ALREADY_EXISTS)
+ {
+ /*
+ * When recycling a shared memory segment, it may take a short while
+ * before it gets dropped from the global namespace. So re-try after
+ * sleeping for a second.
+ */
+ CloseHandle(hmap); /* Close the old handle, since we got a valid
+ * one to the previous segment. */
+
+ Sleep(1000);
+
+ hmap = CreateFileMapping((HANDLE) 0xFFFFFFFF, NULL, PAGE_READWRITE, 0L, (DWORD) size, szShareMem);
+ if (!hmap)
+ ereport(FATAL,
+ (errmsg("could not create shared memory segment: %lu", GetLastError()),
+ errdetail("Failed system call was CreateFileMapping(size=%lu, name=%s)", size, szShareMem)));
+
+ if (GetLastError() == ERROR_ALREADY_EXISTS)
+ ereport(FATAL,
+ (errmsg("pre-existing shared memory block is still in use"),
+ errhint("Check if there are any old server processes still running, and terminate them.")));
+ }
+
+ free(szShareMem);
+
+ /*
+ * Make the handle inheritable
+ */
+ if (!DuplicateHandle(GetCurrentProcess(), hmap, GetCurrentProcess(), &hmap2, 0, TRUE, DUPLICATE_SAME_ACCESS))
+ ereport(FATAL,
+ (errmsg("could not create shared memory segment: %lu", GetLastError()),
+ errdetail("Failed system call was DuplicateHandle")));
+
+ /*
+ * Close the old, non-inheritable handle. If this fails we don't really
+ * care.
+ */
+ if (!CloseHandle(hmap))
+ elog(LOG, "could not close handle to shared memory: %lu", GetLastError());
+
+
+ /* Register on-exit routine to delete the new segment */
+ on_shmem_exit(pgwin32_SharedMemoryDelete, Int32GetDatum((unsigned long) hmap2));
+
+ /*
+ * Get a pointer to the new shared memory segment. Map the whole segment
+ * at once, and let the system decide on the initial address.
+ */
+ memAddress = MapViewOfFileEx(hmap2, FILE_MAP_WRITE | FILE_MAP_READ, 0, 0, 0, NULL);
+ if (!memAddress)
+ ereport(FATAL,
+ (errmsg("could not create shared memory segment: %lu", GetLastError()),
+ errdetail("Failed system call was MapViewOfFileEx")));
+
+
+
+ /*
+ * OK, we created a new segment. Mark it as created by this process. The
+ * order of assignments here is critical so that another Postgres process
+ * can't see the header as valid but belonging to an invalid PID!
+ */
+ hdr = (PGShmemHeader *) memAddress;
+ hdr->creatorPID = getpid();
+ hdr->magic = PGShmemMagic;
+
+ /*
+ * Initialize space allocation status for segment.
+ */
+ hdr->totalsize = size;
+ hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
+
+ /* Save info for possible future use */
+ UsedShmemSegAddr = memAddress;
+ UsedShmemSegID = (unsigned long) hmap2;
+
+ return hdr;
+}
+
+/*
+ * PGSharedMemoryReAttach
+ *
+ * Re-attach to an already existing shared memory segment. Use the
+ * handle inherited from the postmaster.
+ *
+ * UsedShmemSegID and UsedShmemSegAddr are implicit parameters to this
+ * routine. The caller must have already restored them to the postmaster's
+ * values.
+ */
+void
+PGSharedMemoryReAttach(void)
+{
+ PGShmemHeader *hdr;
+ void *origUsedShmemSegAddr = UsedShmemSegAddr;
+
+ Assert(UsedShmemSegAddr != NULL);
+ Assert(IsUnderPostmaster);
+
+ hdr = (PGShmemHeader *) MapViewOfFileEx((HANDLE) UsedShmemSegID, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0, UsedShmemSegAddr);
+ if (!hdr)
+ elog(FATAL, "could not reattach to shared memory (key=%d, addr=%p): %lu",
+ (int) UsedShmemSegID, UsedShmemSegAddr, GetLastError());
+ if (hdr != origUsedShmemSegAddr)
+ elog(FATAL, "reattaching to shared memory returned unexpected address (got %p, expected %p)",
+ hdr, origUsedShmemSegAddr);
+ if (hdr->magic != PGShmemMagic)
+ elog(FATAL, "reattaching to shared memory returned non-PostgreSQL memory");
+
+ UsedShmemSegAddr = hdr; /* probably redundant */
+}
+
+/*
+ * PGSharedMemoryDetach
+ *
+ * Detach from the shared memory segment, if still attached. This is not
+ * intended for use by the process that originally created the segment. Rather,
+ * this is for subprocesses that have inherited an attachment and want to
+ * get rid of it.
+ */
+void
+PGSharedMemoryDetach(void)
+{
+ if (UsedShmemSegAddr != NULL)
+ {
+ if (!UnmapViewOfFile(UsedShmemSegAddr))
+ elog(LOG, "could not unmap view of shared memory: %lu", GetLastError());
+
+ UsedShmemSegAddr = NULL;
+ }
+}
+
+
+/*
+ * pgwin32_SharedMemoryDelete(status, shmId) deletes a shared memory segment
+ * (called as an on_shmem_exit callback, hence funny argument list)
+ */
+static void
+pgwin32_SharedMemoryDelete(int status, Datum shmId)
+{
+ PGSharedMemoryDetach();
+ if (!CloseHandle((HANDLE) DatumGetInt32(shmId)))
+ elog(LOG, "could not close handle to shared memory: %lu", GetLastError());
+}
projects / postgresql / commitdiff