42 lines
1.9 KiB
C
42 lines
1.9 KiB
C
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/****************************************************************
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* *
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* Copyright 2003, 2004 Sanchez Computer Associates, 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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#include "mdef.h"
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#include "memcoherency.h"
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#include "gdsroot.h"
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#include "gdsblk.h"
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#include "gtm_facility.h"
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#include "fileinfo.h"
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#include "gdsbt.h"
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#include "gdsfhead.h"
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#include "filestruct.h"
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#include "repl_msg.h"
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#ifdef VMS
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#include <descrip.h>
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#endif
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#include "gtmsource.h"
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boolean_t jnlpool_hasnt_overflowed(jnlpool_ctl_ptr_t jctl, uint4 jnlpool_size, qw_num read_addr)
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{ /* the advantage of passing the three arguments is they are likely (on most platforms) to be scratch registers that can also
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* be used for computation. Also, besides all callers would have already loaded jctl and jnlpool_size */
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/* For systems with UNORDERED memory access (example, ALPHA, POWER4, PA-RISC 2.0), on a multi processor system, it is
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* possible that the source server notices the change in jnlpool_ctl->write_addr before seeing the change to the content
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* to be read (including the jnl_data_header). To avoid such conditions, we should commit the order of shared memory
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* updates before and after the content is updated (see t_end.c, tp_tend.c). To ensure the source server reads content
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* that is correct, it should invalidate its cache before the read. After the read, to ensure that the content is correct
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* (not some that may have been overwritten), it has to invalidate its cache to fetch the latest value of early_write_addr.
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*
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*/
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SHM_READ_MEMORY_BARRIER; /* to fetch the latest early_write_addr */
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return (jnlpool_size >= (jctl->early_write_addr - read_addr));
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}
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