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Diffstat (limited to 'src/backend/storage/ipc/shmem.c')
-rw-r--r--src/backend/storage/ipc/shmem.c145
1 files changed, 84 insertions, 61 deletions
diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c
index dd86609875e..0ad168680a1 100644
--- a/src/backend/storage/ipc/shmem.c
+++ b/src/backend/storage/ipc/shmem.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.58 2001/09/07 00:27:29 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.59 2001/09/29 04:02:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -61,8 +61,10 @@
#include "postgres.h"
#include "access/transam.h"
+#include "storage/spin.h"
#include "utils/tqual.h"
+
/* shared memory global variables */
static PGShmemHeader *ShmemSegHdr; /* shared mem segment header */
@@ -71,9 +73,7 @@ SHMEM_OFFSET ShmemBase; /* start address of shared memory */
static SHMEM_OFFSET ShmemEnd; /* end+1 address of shared memory */
-SPINLOCK ShmemLock; /* lock for shared memory allocation */
-
-SPINLOCK ShmemIndexLock; /* lock for shmem index access */
+static slock_t *ShmemLock; /* spinlock for shared memory allocation */
static HTAB *ShmemIndex = NULL; /* primary index hashtable for shmem */
@@ -81,63 +81,33 @@ static bool ShmemBootstrap = false; /* bootstrapping shmem index? */
/*
- * InitShmemAllocation() --- set up shared-memory allocation and index table.
+ * InitShmemAllocation() --- set up shared-memory allocation.
+ *
+ * Note: the argument should be declared "PGShmemHeader *seghdr",
+ * but we use void to avoid having to include ipc.h in shmem.h.
*/
void
-InitShmemAllocation(PGShmemHeader *seghdr)
+InitShmemAllocation(void *seghdr)
{
- HASHCTL info;
- int hash_flags;
- ShmemIndexEnt *result,
- item;
- bool found;
+ PGShmemHeader *shmhdr = (PGShmemHeader *) seghdr;
/* Set up basic pointers to shared memory */
- ShmemSegHdr = seghdr;
- ShmemBase = (SHMEM_OFFSET) seghdr;
- ShmemEnd = ShmemBase + seghdr->totalsize;
-
- /*
- * Since ShmemInitHash calls ShmemInitStruct, which expects the
- * ShmemIndex hashtable to exist already, we have a bit of a
- * circularity problem in initializing the ShmemIndex itself. We set
- * ShmemBootstrap to tell ShmemInitStruct to fake it.
- */
- ShmemIndex = (HTAB *) NULL;
- ShmemBootstrap = true;
-
- /* create the shared memory shmem index */
- info.keysize = SHMEM_INDEX_KEYSIZE;
- info.datasize = SHMEM_INDEX_DATASIZE;
- hash_flags = HASH_ELEM;
-
- /* This will acquire the shmem index lock, but not release it. */
- ShmemIndex = ShmemInitHash("ShmemIndex",
- SHMEM_INDEX_SIZE, SHMEM_INDEX_SIZE,
- &info, hash_flags);
- if (!ShmemIndex)
- elog(FATAL, "InitShmemAllocation: couldn't initialize Shmem Index");
+ ShmemSegHdr = shmhdr;
+ ShmemBase = (SHMEM_OFFSET) shmhdr;
+ ShmemEnd = ShmemBase + shmhdr->totalsize;
/*
- * Now, create an entry in the hashtable for the index itself.
+ * Initialize the spinlock used by ShmemAlloc. We have to do the
+ * space allocation the hard way, since ShmemAlloc can't be called yet.
*/
- MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
- strncpy(item.key, "ShmemIndex", SHMEM_INDEX_KEYSIZE);
+ ShmemLock = (slock_t *) (((char *) shmhdr) + shmhdr->freeoffset);
+ shmhdr->freeoffset += MAXALIGN(sizeof(slock_t));
+ Assert(shmhdr->freeoffset <= shmhdr->totalsize);
- result = (ShmemIndexEnt *)
- hash_search(ShmemIndex, (char *) &item, HASH_ENTER, &found);
- if (!result)
- elog(FATAL, "InitShmemAllocation: corrupted shmem index");
+ SpinLockInit(ShmemLock);
- Assert(ShmemBootstrap && !found);
-
- result->location = MAKE_OFFSET(ShmemIndex->hctl);
- result->size = SHMEM_INDEX_SIZE;
-
- ShmemBootstrap = false;
-
- /* now release the lock acquired in ShmemInitStruct */
- SpinRelease(ShmemIndexLock);
+ /* ShmemIndex can't be set up yet (need LWLocks first) */
+ ShmemIndex = (HTAB *) NULL;
/*
* Initialize ShmemVariableCache for transaction manager.
@@ -167,9 +137,9 @@ ShmemAlloc(Size size)
*/
size = MAXALIGN(size);
- Assert(ShmemSegHdr);
+ Assert(ShmemSegHdr != NULL);
- SpinAcquire(ShmemLock);
+ SpinLockAcquire(ShmemLock);
newFree = ShmemSegHdr->freeoffset + size;
if (newFree <= ShmemSegHdr->totalsize)
@@ -180,7 +150,7 @@ ShmemAlloc(Size size)
else
newSpace = NULL;
- SpinRelease(ShmemLock);
+ SpinLockRelease(ShmemLock);
if (!newSpace)
elog(NOTICE, "ShmemAlloc: out of memory");
@@ -200,6 +170,60 @@ ShmemIsValid(unsigned long addr)
}
/*
+ * InitShmemIndex() --- set up shmem index table.
+ */
+void
+InitShmemIndex(void)
+{
+ HASHCTL info;
+ int hash_flags;
+ ShmemIndexEnt *result,
+ item;
+ bool found;
+
+ /*
+ * Since ShmemInitHash calls ShmemInitStruct, which expects the
+ * ShmemIndex hashtable to exist already, we have a bit of a
+ * circularity problem in initializing the ShmemIndex itself. We set
+ * ShmemBootstrap to tell ShmemInitStruct to fake it.
+ */
+ ShmemBootstrap = true;
+
+ /* create the shared memory shmem index */
+ info.keysize = SHMEM_INDEX_KEYSIZE;
+ info.datasize = SHMEM_INDEX_DATASIZE;
+ hash_flags = HASH_ELEM;
+
+ /* This will acquire the shmem index lock, but not release it. */
+ ShmemIndex = ShmemInitHash("ShmemIndex",
+ SHMEM_INDEX_SIZE, SHMEM_INDEX_SIZE,
+ &info, hash_flags);
+ if (!ShmemIndex)
+ elog(FATAL, "InitShmemIndex: couldn't initialize Shmem Index");
+
+ /*
+ * Now, create an entry in the hashtable for the index itself.
+ */
+ MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
+ strncpy(item.key, "ShmemIndex", SHMEM_INDEX_KEYSIZE);
+
+ result = (ShmemIndexEnt *)
+ hash_search(ShmemIndex, (char *) &item, HASH_ENTER, &found);
+ if (!result)
+ elog(FATAL, "InitShmemIndex: corrupted shmem index");
+
+ Assert(ShmemBootstrap && !found);
+
+ result->location = MAKE_OFFSET(ShmemIndex->hctl);
+ result->size = SHMEM_INDEX_SIZE;
+
+ ShmemBootstrap = false;
+
+ /* now release the lock acquired in ShmemInitStruct */
+ LWLockRelease(ShmemIndexLock);
+}
+
+/*
* ShmemInitHash -- Create/Attach to and initialize
* shared memory hash table.
*
@@ -207,8 +231,7 @@ ShmemIsValid(unsigned long addr)
*
* assume caller is doing some kind of synchronization
* so that two people dont try to create/initialize the
- * table at once. Use SpinAlloc() to create a spinlock
- * for the structure before creating the structure itself.
+ * table at once.
*/
HTAB *
ShmemInitHash(char *name, /* table string name for shmem index */
@@ -283,7 +306,7 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
strncpy(item.key, name, SHMEM_INDEX_KEYSIZE);
item.location = BAD_LOCATION;
- SpinAcquire(ShmemIndexLock);
+ LWLockAcquire(ShmemIndexLock, LW_EXCLUSIVE);
if (!ShmemIndex)
{
@@ -306,7 +329,7 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
if (!result)
{
- SpinRelease(ShmemIndexLock);
+ LWLockRelease(ShmemIndexLock);
elog(ERROR, "ShmemInitStruct: Shmem Index corrupted");
return NULL;
}
@@ -320,7 +343,7 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
*/
if (result->size != size)
{
- SpinRelease(ShmemIndexLock);
+ LWLockRelease(ShmemIndexLock);
elog(NOTICE, "ShmemInitStruct: ShmemIndex entry size is wrong");
/* let caller print its message too */
@@ -337,7 +360,7 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
/* out of memory */
Assert(ShmemIndex);
hash_search(ShmemIndex, (char *) &item, HASH_REMOVE, foundPtr);
- SpinRelease(ShmemIndexLock);
+ LWLockRelease(ShmemIndexLock);
*foundPtr = FALSE;
elog(NOTICE, "ShmemInitStruct: cannot allocate '%s'",
@@ -349,6 +372,6 @@ ShmemInitStruct(char *name, Size size, bool *foundPtr)
}
Assert(ShmemIsValid((unsigned long) structPtr));
- SpinRelease(ShmemIndexLock);
+ LWLockRelease(ShmemIndexLock);
return structPtr;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-06-05 09:55:56 +0000