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/*-
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __wt_mmap --
* Map a file into memory.
*/
int
__wt_mmap(WT_SESSION_IMPL *session,
WT_FH *fh, void *mapp, size_t *lenp, void **mappingcookie)
{
void *map;
size_t orig_size;
WT_UNUSED(mappingcookie);
/*
* Record the current size and only map and set that as the length, it
* could change between the map call and when we set the return length.
* For the same reason we could actually map past the end of the file;
* we don't read bytes past the end of the file though, so as long as
* the map call succeeds, it's all OK.
*/
orig_size = (size_t)fh->size;
if ((map = mmap(NULL, orig_size,
PROT_READ,
#ifdef MAP_NOCORE
MAP_NOCORE |
#endif
MAP_PRIVATE,
fh->fd, (wt_off_t)0)) == MAP_FAILED) {
WT_RET_MSG(session, __wt_errno(),
"%s map error: failed to map %" WT_SIZET_FMT " bytes",
fh->name, orig_size);
}
(void)__wt_verbose(session, WT_VERB_FILEOPS,
"%s: map %p: %" WT_SIZET_FMT " bytes", fh->name, map, orig_size);
*(void **)mapp = map;
*lenp = orig_size;
return (0);
}
#define WT_VM_PAGESIZE 4096
/*
* __wt_mmap_preload --
* Cause a section of a memory map to be faulted in.
*/
int
__wt_mmap_preload(WT_SESSION_IMPL *session, const void *p, size_t size)
{
#ifdef HAVE_POSIX_MADVISE
/* Linux requires the address be aligned to a 4KB boundary. */
WT_BM *bm = S2BT(session)->bm;
WT_DECL_RET;
void *blk = (void *)((uintptr_t)p & ~(uintptr_t)(WT_VM_PAGESIZE - 1));
size += WT_PTRDIFF(p, blk);
/* XXX proxy for "am I doing a scan?" -- manual read-ahead */
if (F_ISSET(session, WT_SESSION_NO_CACHE)) {
/* Read in 2MB blocks every 1MB of data. */
if (((uintptr_t)((uint8_t *)blk + size) &
(uintptr_t)((1<<20) - 1)) < (uintptr_t)blk)
return (0);
size = WT_MIN(WT_MAX(20 * size, 2 << 20),
WT_PTRDIFF((uint8_t *)bm->map + bm->maplen, blk));
}
/*
* Manual pages aren't clear on whether alignment is required for the
* size, so we will be conservative.
*/
size &= ~(size_t)(WT_VM_PAGESIZE - 1);
if (size > WT_VM_PAGESIZE &&
(ret = posix_madvise(blk, size, POSIX_MADV_WILLNEED)) != 0)
WT_RET_MSG(session, ret, "posix_madvise will need");
#else
WT_UNUSED(session);
WT_UNUSED(p);
WT_UNUSED(size);
#endif
return (0);
}
/*
* __wt_mmap_discard --
* Discard a chunk of the memory map.
*/
int
__wt_mmap_discard(WT_SESSION_IMPL *session, void *p, size_t size)
{
#ifdef HAVE_POSIX_MADVISE
/* Linux requires the address be aligned to a 4KB boundary. */
WT_DECL_RET;
void *blk = (void *)((uintptr_t)p & ~(uintptr_t)(WT_VM_PAGESIZE - 1));
size += WT_PTRDIFF(p, blk);
if ((ret = posix_madvise(blk, size, POSIX_MADV_DONTNEED)) != 0)
WT_RET_MSG(session, ret, "posix_madvise don't need");
#else
WT_UNUSED(session);
WT_UNUSED(p);
WT_UNUSED(size);
#endif
return (0);
}
/*
* __wt_munmap --
* Remove a memory mapping.
*/
int
__wt_munmap(WT_SESSION_IMPL *session,
WT_FH *fh, void *map, size_t len, void **mappingcookie)
{
WT_UNUSED(mappingcookie);
WT_RET(__wt_verbose(session, WT_VERB_FILEOPS,
"%s: unmap %p: %" WT_SIZET_FMT " bytes", fh->name, map, len));
if (munmap(map, len) == 0)
return (0);
WT_RET_MSG(session, __wt_errno(),
"%s unmap error: failed to unmap %" WT_SIZET_FMT " bytes",
fh->name, len);
}
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