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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_posix_map --
* Map a file into memory.
*/
int
__wt_posix_map(WT_FILE_HANDLE *fh, WT_SESSION *wt_session,
void *mapped_regionp, size_t *lenp, void *mapped_cookiep)
{
WT_FILE_HANDLE_POSIX *pfh;
WT_SESSION_IMPL *session;
size_t len;
wt_off_t file_size;
void *map;
WT_UNUSED(mapped_cookiep);
session = (WT_SESSION_IMPL *)wt_session;
pfh = (WT_FILE_HANDLE_POSIX *)fh;
/*
* Mapping isn't possible if direct I/O 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 (pfh->direct_io)
return (ENOTSUP);
/*
* There's no locking here to prevent the underlying file from changing
* underneath us, our caller needs to ensure consistency of the mapped
* region vs. any other file activity.
*/
WT_RET(fh->fh_size(fh, wt_session, &file_size));
len = (size_t)file_size;
(void)__wt_verbose(session, WT_VERB_HANDLEOPS,
"%s: memory-map: %" WT_SIZET_FMT " bytes", fh->name, len);
if ((map = mmap(NULL, len,
PROT_READ,
#ifdef MAP_NOCORE
MAP_NOCORE |
#endif
MAP_PRIVATE,
pfh->fd, (wt_off_t)0)) == MAP_FAILED)
WT_RET_MSG(session,
__wt_errno(), "%s: memory-map: mmap", fh->name);
*(void **)mapped_regionp = map;
*lenp = len;
return (0);
}
#ifdef HAVE_POSIX_MADVISE
/*
* __wt_posix_map_preload --
* Cause a section of a memory map to be faulted in.
*/
int
__wt_posix_map_preload(WT_FILE_HANDLE *fh,
WT_SESSION *wt_session, const void *map, size_t length, void *mapped_cookie)
{
WT_BM *bm;
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_SESSION_IMPL *session;
void *blk;
WT_UNUSED(mapped_cookie);
session = (WT_SESSION_IMPL *)wt_session;
conn = S2C(session);
bm = S2BT(session)->bm;
/* Linux requires the address be aligned to a 4KB boundary. */
blk = (void *)((uintptr_t)map & ~(uintptr_t)(conn->page_size - 1));
length += WT_PTRDIFF(map, 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 + length) &
(uintptr_t)((1<<20) - 1)) < (uintptr_t)blk)
return (0);
length = WT_MIN(WT_MAX(20 * length, 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.
*/
length &= ~(size_t)(conn->page_size - 1);
if (length <= (size_t)conn->page_size)
return (0);
WT_SYSCALL(posix_madvise(blk, length, POSIX_MADV_WILLNEED), ret);
if (ret == 0)
return (0);
WT_RET_MSG(session, ret,
"%s: memory-map preload: posix_madvise: POSIX_MADV_WILLNEED",
fh->name);
}
#endif
#ifdef HAVE_POSIX_MADVISE
/*
* __wt_posix_map_discard --
* Discard a chunk of the memory map.
*/
int
__wt_posix_map_discard(WT_FILE_HANDLE *fh,
WT_SESSION *wt_session, void *map, size_t length, void *mapped_cookie)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_SESSION_IMPL *session;
void *blk;
WT_UNUSED(mapped_cookie);
session = (WT_SESSION_IMPL *)wt_session;
conn = S2C(session);
/* Linux requires the address be aligned to a 4KB boundary. */
blk = (void *)((uintptr_t)map & ~(uintptr_t)(conn->page_size - 1));
length += WT_PTRDIFF(map, blk);
WT_SYSCALL(posix_madvise(blk, length, POSIX_MADV_DONTNEED), ret);
if (ret == 0)
return (0);
WT_RET_MSG(session, ret,
"%s: memory-map discard: posix_madvise: POSIX_MADV_DONTNEED",
fh->name);
}
#endif
/*
* __wt_posix_unmap --
* Remove a memory mapping.
*/
int
__wt_posix_unmap(WT_FILE_HANDLE *fh, WT_SESSION *wt_session,
void *mapped_region, size_t len, void *mapped_cookie)
{
WT_SESSION_IMPL *session;
WT_UNUSED(mapped_cookie);
session = (WT_SESSION_IMPL *)wt_session;
(void)__wt_verbose(session, WT_VERB_HANDLEOPS,
"%s: memory-unmap: %" WT_SIZET_FMT " bytes", fh->name, len);
if (munmap(mapped_region, len) == 0)
return (0);
WT_RET_MSG(session, __wt_errno(), "%s: memory-unmap: munmap", fh->name);
}
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