*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.24 1998/06/27 14:06:41 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.25 1998/06/27 15:47:44 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/*
* POSTGRES processes share one or more regions of shared memory.
- * The shared memory is created by a postmaster and is "attached to"
- * by each of the backends. The routines in this file are used for
+ * The shared memory is created by a postmaster and is inherited
+ * by each backends via fork(). The routines in this file are used for
* allocating and binding to shared memory data structures.
*
* NOTES:
* it (assigned in the module that declares it).
*
* (b) During initialization, each module looks for its
- * shared data structures in a hash table called the "Binding Table".
+ * shared data structures in a hash table called the "Shmem Index".
* If the data structure is not present, the caller can allocate
* a new one and initialize it. If the data structure is present,
* the caller "attaches" to the structure by initializing a pointer
* in the local address space.
- * The binding table has two purposes: first, it gives us
+ * The shmem index has two purposes: first, it gives us
* a simple model of how the world looks when a backend process
- * initializes. If something is present in the binding table,
+ * initializes. If something is present in the shmem index,
* it is initialized. If it is not, it is uninitialized. Second,
- * the binding table allows us to allocate shared memory on demand
+ * the shmem index allows us to allocate shared memory on demand
* instead of trying to preallocate structures and hard-wire the
* sizes and locations in header files. If you are using a lot
* of shared memory in a lot of different places (and changing
* unnecessary.
*
* See InitSem() in sem.c for an example of how to use the
- * binding table.
+ * shmem index.
*
*/
#include <stdio.h>
SPINLOCK ShmemLock; /* lock for shared memory allocation */
-SPINLOCK BindingLock; /* lock for binding table access */
+SPINLOCK ShmemIndexLock; /* lock for shmem index access */
static unsigned long *ShmemFreeStart = NULL; /* pointer to the OFFSET
* of first free shared
* memory */
-static unsigned long *ShmemBindingTableOffset = NULL; /* start of the binding
+static unsigned long *ShmemIndexOffset = NULL; /* start of the shmem index
* table (for bootstrap) */
static int ShmemBootstrap = FALSE; /* flag becomes true when shared
* mem is created by POSTMASTER */
-static HTAB *BindingTable = NULL;
+static HTAB *ShmemIndex = NULL;
/* ---------------------
- * ShmemBindingTableReset() - Resets the binding table to NULL....
+ * ShmemIndexReset() - Resets the shmem index to NULL....
* useful when the postmaster destroys existing shared memory
* and creates all new segments after a backend crash.
* ----------------------
*/
void
-ShmemBindingTableReset(void)
+ShmemIndexReset(void)
{
- BindingTable = (HTAB *) NULL;
+ ShmemIndex = (HTAB *) NULL;
}
/*
HASHCTL info;
int hash_flags;
- BindingEnt *result,
+ ShmemIndexEnt *result,
item;
bool found;
IpcMemoryId shmid;
/* First long in shared memory is the count of available space */
ShmemFreeStart = (unsigned long *) ShmemBase;
- /* next is a shmem pointer to the binding table */
- ShmemBindingTableOffset = ShmemFreeStart + 1;
+ /* next is a shmem pointer to the shmem index */
+ ShmemIndexOffset = ShmemFreeStart + 1;
currFreeSpace +=
- sizeof(ShmemFreeStart) + sizeof(ShmemBindingTableOffset);
+ sizeof(ShmemFreeStart) + sizeof(ShmemIndexOffset);
/*
* bootstrap initialize spin locks so we can start to use the
- * allocator and binding table.
+ * allocator and shmem index.
*/
if (!InitSpinLocks(ShmemBootstrap, IPCKeyGetSpinLockSemaphoreKey(key)))
return (FALSE);
/* if ShmemFreeStart is NULL, then the allocator won't work */
Assert(*ShmemFreeStart);
- /* create OR attach to the shared memory binding table */
- info.keysize = BTABLE_KEYSIZE;
- info.datasize = BTABLE_DATASIZE;
+ /* create OR attach to the shared memory shmem index */
+ info.keysize = SHMEM_INDEX_KEYSIZE;
+ info.datasize = SHMEM_INDEX_DATASIZE;
hash_flags = (HASH_ELEM);
- /* This will acquire the binding table lock, but not release it. */
- BindingTable = ShmemInitHash("BindingTable",
- BTABLE_SIZE, BTABLE_SIZE,
+ /* This will acquire the shmem index lock, but not release it. */
+ ShmemIndex = ShmemInitHash("ShmemIndex",
+ SHMEM_INDEX_SIZE, SHMEM_INDEX_SIZE,
&info, hash_flags);
- if (!BindingTable)
+ if (!ShmemIndex)
{
- elog(FATAL, "InitShmem: couldn't initialize Binding Table");
+ elog(FATAL, "InitShmem: couldn't initialize Shmem Index");
return (FALSE);
}
/*
- * Now, check the binding table for an entry to the binding table. If
+ * Now, check the shmem index for an entry to the shmem index. If
* there is an entry there, someone else created the table. Otherwise,
* we did and we have to initialize it.
*/
- MemSet(item.key, 0, BTABLE_KEYSIZE);
- strncpy(item.key, "BindingTable", BTABLE_KEYSIZE);
+ MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
+ strncpy(item.key, "ShmemIndex", SHMEM_INDEX_KEYSIZE);
- result = (BindingEnt *)
- hash_search(BindingTable, (char *) &item, HASH_ENTER, &found);
+ result = (ShmemIndexEnt *)
+ hash_search(ShmemIndex, (char *) &item, HASH_ENTER, &found);
if (!result)
{
- elog(FATAL, "InitShmem: corrupted binding table");
+ elog(FATAL, "InitShmem: corrupted shmem index");
return (FALSE);
}
{
/*
- * bootstrapping shmem: we have to initialize the binding table
+ * bootstrapping shmem: we have to initialize the shmem index
* now.
*/
Assert(ShmemBootstrap);
- result->location = MAKE_OFFSET(BindingTable->hctl);
- *ShmemBindingTableOffset = result->location;
- result->size = BTABLE_SIZE;
+ result->location = MAKE_OFFSET(ShmemIndex->hctl);
+ *ShmemIndexOffset = result->location;
+ result->size = SHMEM_INDEX_SIZE;
ShmemBootstrap = FALSE;
else
Assert(!ShmemBootstrap);
/* now release the lock acquired in ShmemHashInit */
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
- Assert(result->location == MAKE_OFFSET(BindingTable->hctl));
+ Assert(result->location == MAKE_OFFSET(ShmemIndex->hctl));
return (TRUE);
}
* for the structure before creating the structure itself.
*/
HTAB *
-ShmemInitHash(char *name, /* table string name for binding */
+ShmemInitHash(char *name, /* table string name for shmem index */
long init_size, /* initial size */
long max_size, /* max size of the table */
HASHCTL *infoP, /* info about key and bucket size */
infoP->max_size = max_size;
hash_flags |= HASH_SHARED_MEM;
- /* look it up in the binding table */
+ /* look it up in the shmem index */
location =
ShmemInitStruct(name, my_log2(max_size) + sizeof(HHDR), &found);
/*
- * binding table is corrupted. Let someone else give the error
+ * shmem index is corrupted. Let someone else give the error
* message since they have more information
*/
if (location == NULL)
* ShmemPIDLookup -- lookup process data structure using process id
*
* Returns: TRUE if no error. locationPtr is initialized if PID is
- * found in the binding table.
+ * found in the shmem index.
*
* NOTES:
* only information about success or failure is the value of
bool
ShmemPIDLookup(int pid, SHMEM_OFFSET *locationPtr)
{
- BindingEnt *result,
+ ShmemIndexEnt *result,
item;
bool found;
- Assert(BindingTable);
- MemSet(item.key, 0, BTABLE_KEYSIZE);
+ Assert(ShmemIndex);
+ MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
sprintf(item.key, "PID %d", pid);
- SpinAcquire(BindingLock);
- result = (BindingEnt *)
- hash_search(BindingTable, (char *) &item, HASH_ENTER, &found);
+ SpinAcquire(ShmemIndexLock);
+ result = (ShmemIndexEnt *)
+ hash_search(ShmemIndex, (char *) &item, HASH_ENTER, &found);
if (!result)
{
- SpinRelease(BindingLock);
- elog(ERROR, "ShmemInitPID: BindingTable corrupted");
+ SpinRelease(ShmemIndexLock);
+ elog(ERROR, "ShmemInitPID: ShmemIndex corrupted");
return (FALSE);
}
else
result->location = *locationPtr;
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
return (TRUE);
}
/*
- * ShmemPIDDestroy -- destroy binding table entry for process
+ * ShmemPIDDestroy -- destroy shmem index entry for process
* using process id
*
* Returns: offset of the process struct in shared memory or
* INVALID_OFFSET if not found.
*
- * Side Effect: removes the entry from the binding table
+ * Side Effect: removes the entry from the shmem index
*/
SHMEM_OFFSET
ShmemPIDDestroy(int pid)
{
- BindingEnt *result,
+ ShmemIndexEnt *result,
item;
bool found;
SHMEM_OFFSET location = 0;
- Assert(BindingTable);
+ Assert(ShmemIndex);
- MemSet(item.key, 0, BTABLE_KEYSIZE);
+ MemSet(item.key, 0, SHMEM_INDEX_KEYSIZE);
sprintf(item.key, "PID %d", pid);
- SpinAcquire(BindingLock);
- result = (BindingEnt *)
- hash_search(BindingTable, (char *) &item, HASH_REMOVE, &found);
+ SpinAcquire(ShmemIndexLock);
+ result = (ShmemIndexEnt *)
+ hash_search(ShmemIndex, (char *) &item, HASH_REMOVE, &found);
if (found)
location = result->location;
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
if (!result)
{
* table is returned.
*
* Returns: real pointer to the object. FoundPtr is TRUE if
- * the object is already in the binding table (hence, already
+ * the object is already in the shmem index (hence, already
* initialized).
*/
long *
ShmemInitStruct(char *name, unsigned long size, bool *foundPtr)
{
- BindingEnt *result,
+ ShmemIndexEnt *result,
item;
long *structPtr;
- strncpy(item.key, name, BTABLE_KEYSIZE);
+ strncpy(item.key, name, SHMEM_INDEX_KEYSIZE);
item.location = BAD_LOCATION;
- SpinAcquire(BindingLock);
+ SpinAcquire(ShmemIndexLock);
- if (!BindingTable)
+ if (!ShmemIndex)
{
#ifdef USE_ASSERT_CHECKING
- char *strname = "BindingTable";
+ char *strname = "ShmemIndex";
#endif
/*
- * If the binding table doesnt exist, we fake it.
+ * If the shmem index doesnt exist, we fake it.
*
- * If we are creating the first binding table, then let shmemalloc()
+ * If we are creating the first shmem index, then let shmemalloc()
* allocate the space for a new HTAB. Otherwise, find the old one
- * and return that. Notice that the BindingLock is held until the
- * binding table has been completely initialized.
+ * and return that. Notice that the ShmemIndexLock is held until the
+ * shmem index has been completely initialized.
*/
Assert(!strcmp(name, strname));
if (ShmemBootstrap)
}
else
{
- Assert(ShmemBindingTableOffset);
+ Assert(ShmemIndexOffset);
*foundPtr = TRUE;
- return ((long *) MAKE_PTR(*ShmemBindingTableOffset));
+ return ((long *) MAKE_PTR(*ShmemIndexOffset));
}
}
else
{
- /* look it up in the binding table */
- result = (BindingEnt *)
- hash_search(BindingTable, (char *) &item, HASH_ENTER, foundPtr);
+ /* look it up in the shmem index */
+ result = (ShmemIndexEnt *)
+ hash_search(ShmemIndex, (char *) &item, HASH_ENTER, foundPtr);
}
if (!result)
{
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
- elog(ERROR, "ShmemInitStruct: Binding Table corrupted");
+ elog(ERROR, "ShmemInitStruct: Shmem Index corrupted");
return (NULL);
}
else if (*foundPtr)
{
/*
- * Structure is in the binding table so someone else has allocated
+ * Structure is in the shmem index so someone else has allocated
* it already. The size better be the same as the size we are
* trying to initialize to or there is a name conflict (or worse).
*/
if (result->size != size)
{
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
- elog(NOTICE, "ShmemInitStruct: BindingTable entry size is wrong");
+ elog(NOTICE, "ShmemInitStruct: ShmemIndex entry size is wrong");
/* let caller print its message too */
return (NULL);
}
if (!structPtr)
{
/* out of memory */
- Assert(BindingTable);
- hash_search(BindingTable, (char *) &item, HASH_REMOVE, foundPtr);
- SpinRelease(BindingLock);
+ Assert(ShmemIndex);
+ hash_search(ShmemIndex, (char *) &item, HASH_REMOVE, foundPtr);
+ SpinRelease(ShmemIndexLock);
*foundPtr = FALSE;
elog(NOTICE, "ShmemInitStruct: cannot allocate '%s'",
}
Assert(ShmemIsValid((unsigned long) structPtr));
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
return (structPtr);
}
bool
TransactionIdIsInProgress(TransactionId xid)
{
- BindingEnt *result;
+ ShmemIndexEnt *result;
PROC *proc;
- Assert(BindingTable);
+ Assert(ShmemIndex);
- SpinAcquire(BindingLock);
+ SpinAcquire(ShmemIndexLock);
hash_seq((HTAB *) NULL);
- while ((result = (BindingEnt *) hash_seq(BindingTable)) != NULL)
+ while ((result = (ShmemIndexEnt *) hash_seq(ShmemIndex)) != NULL)
{
- if (result == (BindingEnt *) TRUE)
+ if (result == (ShmemIndexEnt *) TRUE)
{
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
return (false);
}
if (result->location == INVALID_OFFSET ||
proc = (PROC *) MAKE_PTR(result->location);
if (proc->xid == xid)
{
- SpinRelease(BindingLock);
+ SpinRelease(ShmemIndexLock);
return (true);
}
}
- SpinRelease(BindingLock);
- elog(ERROR, "TransactionIdIsInProgress: BindingTable corrupted");
+ SpinRelease(ShmemIndexLock);
+ elog(ERROR, "TransactionIdIsInProgress: ShmemIndex corrupted");
return (false);
}
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