99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
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/****************************************************************
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* *
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* Copyright 2008 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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/* gtm_relqueopi - C-callable relative queue interlocked routines
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*
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* These routines perform interlocked operations on doubly-linked
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* relative queues. They are designed to emulate the VAX machine
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* instructions (and corresponding VAX C library routines) after
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* which they are named.
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*
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* insqhi - insert entry into queue at head, interlocked
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* insqti - insert entry into queue at tail, interlocked
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* remqhi - remove entry from queue at head, interlocked
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* remqti - remove entry from queue at tail, interlocked
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*/
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#include "mdef.h"
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#include "relqueopi.h"
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#ifdef DEBUG
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/* An element that is not present in the queue should have its fl,bl fields zero.
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* An element that is present in the queue should have its fl,bl fields non-zero.
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* Ensure/Check this property for all queue operations.
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* This will help catch a case when an element that is already present in the queue is re-added into the same queue.
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* Such operations will cause queue corruption and since the queue is in shared memory (given that the interlocked
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* queue operations are being done), could cause shared memory corruption and database damage (D9H03-002644).
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*/
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int gtm_insqhi(que_ent_ptr_t new, que_head_ptr_t base)
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{
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int4 status;
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assert(0 == new->fl);
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assert(0 == new->bl);
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status = SYS_INSQHI(new, base);
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/* We cannot assert that new->fl and new->bl are non-zero at this point since they
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* could be concurrently removed from the queue right after we inserted it above.
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*/
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return status;
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}
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int gtm_insqti(que_ent_ptr_t new, que_head_ptr_t base)
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{
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int4 status;
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assert(0 == new->fl);
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assert(0 == new->bl);
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status = SYS_INSQTI(new, base);
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/* We cannot assert that new->fl and new->bl are non-zero at this point since they
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* could be concurrently removed from the queue right after we inserted it above.
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*/
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return status;
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}
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void_ptr_t gtm_remqhi(que_head_ptr_t base)
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{
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que_ent_ptr_t ret;
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ret = SYS_REMQHI(base);
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if (NULL != ret)
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{
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# ifndef UNIX /* in Unix, relqueopi.c already does the rest of fl,bl to 0 just before releasing the swap lock */
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ret->fl = 0;
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ret->bl = 0;
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# endif
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assert(0 == ret->fl);
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assert(0 == ret->bl);
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}
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return (void_ptr_t)ret;
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}
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void_ptr_t gtm_remqti(que_head_ptr_t base)
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{
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que_ent_ptr_t ret;
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ret = SYS_REMQTI(base);
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if (NULL != ret)
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{
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# ifndef UNIX /* in Unix, relqueopi.c already does the rest of fl,bl to 0 just before releasing the swap lock */
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ret->fl = 0;
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ret->bl = 0;
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# endif
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assert(0 == ret->fl);
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assert(0 == ret->bl);
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}
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return (void_ptr_t)ret;
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}
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#endif
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