Remove BufferLocks[] array in favor of a single pointer to the buffer
(if any) currently waited for by LockBufferForCleanup(), which is all that we were using it for anymore. Saves some space and eliminates proportional-to-NBuffers slowdown in UnlockBuffers().
This commit is contained in:
Tom Lane
parent
72f9013741
commit
1c2de47746
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_init.c,v 1.68 2004/08/29 05:06:47 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/buf_init.c,v 1.69 2004/10/16 18:05:06 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -20,9 +20,7 @@
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BufferDesc *BufferDescriptors;
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Block *BufferBlockPointers;
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int32 *PrivateRefCount; /* also used in freelist.c */
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bits8 *BufferLocks; /* flag bits showing locks I have set */
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int32 *PrivateRefCount;
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/* statistics counters */
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long int ReadBufferCount;
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@ -177,7 +175,6 @@ InitBufferPoolAccess(void)
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sizeof(*BufferBlockPointers));
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PrivateRefCount = (int32 *) calloc(NBuffers,
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sizeof(*PrivateRefCount));
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BufferLocks = (bits8 *) calloc(NBuffers, sizeof(*BufferLocks));
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/*
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* Convert shmem offsets into addresses as seen by this process. This
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.178 2004/10/15 22:39:59 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.179 2004/10/16 18:05:06 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -66,6 +66,13 @@ long NDirectFileRead; /* some I/O's are direct file access.
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long NDirectFileWrite; /* e.g., I/O in psort and hashjoin. */
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/* local state for StartBufferIO and related functions */
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static BufferDesc *InProgressBuf = NULL;
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static bool IsForInput;
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/* local state for LockBufferForCleanup */
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static BufferDesc *PinCountWaitBuf = NULL;
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static void PinBuffer(BufferDesc *buf, bool fixOwner);
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static void UnpinBuffer(BufferDesc *buf, bool fixOwner);
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static void WaitIO(BufferDesc *buf);
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@ -1650,48 +1657,38 @@ SetBufferCommitInfoNeedsSave(Buffer buffer)
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* Release buffer context locks for shared buffers.
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*
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* Used to clean up after errors.
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*
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* Currently, we can expect that lwlock.c's LWLockReleaseAll() took care
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* of releasing buffer context locks per se; the only thing we need to deal
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* with here is clearing any PIN_COUNT request that was in progress.
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*/
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void
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UnlockBuffers(void)
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{
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BufferDesc *buf;
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int i;
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BufferDesc *buf = PinCountWaitBuf;
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for (i = 0; i < NBuffers; i++)
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if (buf)
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{
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bits8 buflocks = BufferLocks[i];
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if (buflocks == 0)
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continue;
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buf = &(BufferDescriptors[i]);
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HOLD_INTERRUPTS(); /* don't want to die() partway through... */
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LWLockAcquire(BufMgrLock, LW_EXCLUSIVE);
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/*
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* The buffer's cntx_lock has already been released by lwlock.c.
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* Don't complain if flag bit not set; it could have been
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* reset but we got a cancel/die interrupt before getting the
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* signal.
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*/
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if ((buf->flags & BM_PIN_COUNT_WAITER) != 0 &&
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buf->wait_backend_id == MyBackendId)
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buf->flags &= ~BM_PIN_COUNT_WAITER;
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LWLockRelease(BufMgrLock);
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if (buflocks & BL_PIN_COUNT_LOCK)
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{
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LWLockAcquire(BufMgrLock, LW_EXCLUSIVE);
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/*
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* Don't complain if flag bit not set; it could have been
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* reset but we got a cancel/die interrupt before getting the
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* signal.
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*/
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if ((buf->flags & BM_PIN_COUNT_WAITER) != 0 &&
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buf->wait_backend_id == MyBackendId)
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buf->flags &= ~BM_PIN_COUNT_WAITER;
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LWLockRelease(BufMgrLock);
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ProcCancelWaitForSignal();
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}
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BufferLocks[i] = 0;
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ProcCancelWaitForSignal();
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RESUME_INTERRUPTS();
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}
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PinCountWaitBuf = NULL;
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}
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/*
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@ -1779,9 +1776,9 @@ void
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LockBufferForCleanup(Buffer buffer)
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{
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BufferDesc *bufHdr;
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bits8 *buflock;
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Assert(BufferIsValid(buffer));
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Assert(PinCountWaitBuf == NULL);
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if (BufferIsLocal(buffer))
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{
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@ -1799,7 +1796,6 @@ LockBufferForCleanup(Buffer buffer)
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PrivateRefCount[buffer - 1]);
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bufHdr = &BufferDescriptors[buffer - 1];
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buflock = &(BufferLocks[buffer - 1]);
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for (;;)
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{
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@ -1822,12 +1818,12 @@ LockBufferForCleanup(Buffer buffer)
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}
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bufHdr->wait_backend_id = MyBackendId;
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bufHdr->flags |= BM_PIN_COUNT_WAITER;
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*buflock |= BL_PIN_COUNT_LOCK;
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PinCountWaitBuf = bufHdr;
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LWLockRelease(BufMgrLock);
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LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
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/* Wait to be signaled by UnpinBuffer() */
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ProcWaitForSignal();
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*buflock &= ~BL_PIN_COUNT_LOCK;
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PinCountWaitBuf = NULL;
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/* Loop back and try again */
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}
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}
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@ -1835,11 +1831,9 @@ LockBufferForCleanup(Buffer buffer)
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/*
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* Functions for IO error handling
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*
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* Note : We assume that nested buffer IO never occur.
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* Note: We assume that nested buffer IO never occurs.
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* i.e at most one io_in_progress lock is held per proc.
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*/
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static BufferDesc *InProgressBuf = NULL;
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static bool IsForInput;
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*/
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/*
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* Function:StartBufferIO
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.73 2004/08/29 05:06:58 momjian Exp $
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* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.74 2004/10/16 18:05:07 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -75,8 +75,7 @@ typedef struct buftag
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)
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/*
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* BufferDesc -- shared buffer cache metadata for a single
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* shared buffer descriptor.
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* BufferDesc -- shared descriptor/state data for a single shared buffer.
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*/
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typedef struct sbufdesc
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{
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@ -108,16 +107,6 @@ typedef struct sbufdesc
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#define BufferDescriptorGetBuffer(bdesc) ((bdesc)->buf_id + 1)
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/*
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* Each backend has its own BufferLocks[] array holding flag bits
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* showing what locks it has set on each buffer.
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*
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* We have to free these locks during ereport(ERROR)...
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*/
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#define BL_IO_IN_PROGRESS (1 << 0) /* unimplemented */
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#define BL_PIN_COUNT_LOCK (1 << 1)
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/* entry for buffer lookup hashtable */
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typedef struct
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{
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@ -206,7 +195,6 @@ extern void BufTableDelete(BufferTag *tagPtr);
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/* bufmgr.c */
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extern BufferDesc *BufferDescriptors;
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extern bits8 *BufferLocks;
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/* localbuf.c */
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extern BufferDesc *LocalBufferDescriptors;
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