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/*-
* Copyright (c) 2014-2016 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __wt_block_map --
* Map a segment of the file in, if possible.
*/
int
__wt_block_map(
WT_SESSION_IMPL *session, WT_BLOCK *block, void *mapp, size_t *maplenp,
void **mappingcookie)
{
*(void **)mapp = NULL;
*maplenp = 0;
#ifdef WORDS_BIGENDIAN
/*
* The underlying objects are little-endian, mapping objects isn't
* currently supported on big-endian systems.
*/
WT_UNUSED(session);
WT_UNUSED(block);
WT_UNUSED(mappingcookie);
#else
/* Map support is configurable. */
if (!S2C(session)->mmap)
return (0);
/*
* Turn off mapping when verifying the file, because we can't perform
* checksum validation of mapped segments, and verify has to checksum
* pages.
*/
if (block->verify)
return (0);
/*
* Turn off mapping when direct I/O is configured for the file, the
* Linux open(2) documentation says applications should avoid mixing
* mmap(2) of files with direct I/O to the same files.
*/
if (block->fh->direct_io)
return (0);
/*
* Turn off mapping if the application configured a cache size maximum,
* we can't control how much of the cache size we use in that case.
*/
if (block->os_cache_max != 0)
return (0);
/*
* Map the file into memory.
* Ignore errors, we'll read the file through the cache if map fails.
*/
(void)__wt_mmap(session, block->fh, mapp, maplenp, mappingcookie);
#endif
return (0);
}
/*
* __wt_block_unmap --
* Unmap any mapped-in segment of the file.
*/
int
__wt_block_unmap(
WT_SESSION_IMPL *session, WT_BLOCK *block, void *map, size_t maplen,
void **mappingcookie)
{
/* Unmap the file from memory. */
return (__wt_munmap(session, block->fh, map, maplen, mappingcookie));
}
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