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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_bm_preload --
* Pre-load a page.
*/
int
__wt_bm_preload(WT_BM *bm,
WT_SESSION_IMPL *session, const uint8_t *addr, size_t addr_size)
{
WT_BLOCK *block;
WT_DECL_RET;
off_t offset;
uint32_t cksum, size;
int mapped;
WT_UNUSED(addr_size);
block = bm->block;
ret = EINVAL; /* Play games due to conditional compilation */
/* Crack the cookie. */
WT_RET(__wt_block_buffer_to_addr(block, addr, &offset, &size, &cksum));
/* Check for a mapped block. */
mapped = bm->map != NULL && offset + size <= (off_t)bm->maplen;
if (mapped)
WT_RET(__wt_mmap_preload(
session, (uint8_t *)bm->map + offset, size));
else {
#ifdef HAVE_POSIX_FADVISE
ret = posix_fadvise(block->fh->fd,
(off_t)offset, (off_t)size, POSIX_FADV_WILLNEED);
#endif
if (ret != 0) {
WT_DECL_ITEM(tmp);
WT_RET(__wt_scr_alloc(session, size, &tmp));
ret = __wt_block_read_off(
session, block, tmp, offset, size, cksum);
__wt_scr_free(&tmp);
WT_RET(ret);
}
}
WT_STAT_FAST_CONN_INCR(session, block_preload);
return (0);
}
/*
* __wt_bm_read --
* Map or read address cookie referenced block into a buffer.
*/
int
__wt_bm_read(WT_BM *bm, WT_SESSION_IMPL *session,
WT_ITEM *buf, const uint8_t *addr, size_t addr_size)
{
WT_BLOCK *block;
int mapped;
off_t offset;
uint32_t cksum, size;
WT_UNUSED(addr_size);
block = bm->block;
/* Crack the cookie. */
WT_RET(__wt_block_buffer_to_addr(block, addr, &offset, &size, &cksum));
/*
* Map the block if it's possible.
*/
mapped = bm->map != NULL && offset + size <= (off_t)bm->maplen;
if (mapped) {
buf->data = (uint8_t *)bm->map + offset;
buf->size = size;
WT_RET(__wt_mmap_preload(session, buf->data, buf->size));
WT_STAT_FAST_CONN_INCR(session, block_map_read);
WT_STAT_FAST_CONN_INCRV(session, block_byte_map_read, size);
return (0);
}
#ifdef HAVE_DIAGNOSTIC
/*
* In diagnostic mode, verify the block we're about to read isn't on
* the available list, or for live systems, the discard list.
*
* Don't check during the salvage read phase, we might be reading an
* already freed overflow page.
*/
if (!F_ISSET(session, WT_SESSION_SALVAGE_CORRUPT_OK))
WT_RET(__wt_block_misplaced(
session, block, "read", offset, size, bm->is_live));
#endif
/* Read the block. */
WT_RET(__wt_block_read_off(session, block, buf, offset, size, cksum));
#ifdef HAVE_POSIX_FADVISE
/* Optionally discard blocks from the system's buffer cache. */
if (block->os_cache_max != 0 &&
(block->os_cache += size) > block->os_cache_max) {
WT_DECL_RET;
block->os_cache = 0;
/* Ignore EINVAL - some file systems don't support the flag. */
if ((ret = posix_fadvise(block->fh->fd,
(off_t)0, (off_t)0, POSIX_FADV_DONTNEED)) != 0 &&
ret != EINVAL)
WT_RET_MSG(
session, ret, "%s: posix_fadvise", block->name);
}
#endif
return (0);
}
#ifdef HAVE_DIAGNOSTIC
/*
* __wt_block_read_off_blind --
* Read the block at an offset, try to figure out what it looks like,
* debugging only.
*/
int
__wt_block_read_off_blind(
WT_SESSION_IMPL *session, WT_BLOCK *block, WT_ITEM *buf, off_t offset)
{
WT_BLOCK_HEADER *blk;
uint32_t cksum, size;
/*
* Make sure the buffer is large enough for the header and read the
* the first allocation-size block.
*/
WT_RET(__wt_buf_init(session, buf, block->allocsize));
WT_RET(__wt_read(
session, block->fh, offset, (size_t)block->allocsize, buf->mem));
blk = WT_BLOCK_HEADER_REF(buf->mem);
/*
* Copy out the size and checksum (we're about to re-use the buffer),
* and if the size isn't insane, read the rest of the block.
*/
size = blk->disk_size;
cksum = blk->cksum;
if (__wt_block_offset_invalid(block, offset, size))
WT_RET_MSG(session, EINVAL,
"block at offset %" PRIuMAX " cannot be a valid block, no "
"read attempted",
(uintmax_t)offset);
return (__wt_block_read_off(session, block, buf, offset, size, cksum));
}
#endif
/*
* __wt_block_read_off --
* Read an addr/size pair referenced block into a buffer.
*/
int
__wt_block_read_off(WT_SESSION_IMPL *session,
WT_BLOCK *block, WT_ITEM *buf, off_t offset, uint32_t size, uint32_t cksum)
{
WT_BLOCK_HEADER *blk;
size_t bufsize;
uint32_t page_cksum;
WT_VERBOSE_RET(session, read,
"off %" PRIuMAX ", size %" PRIu32 ", cksum %" PRIu32,
(uintmax_t)offset, size, cksum);
/*
* Grow the buffer as necessary and read the block. Buffers should be
* aligned for reading, but there are lots of buffers (for example, file
* cursors have two buffers each, key and value), and it's difficult to
* be sure we've found all of them. If the buffer isn't aligned, it's
* an easy fix: set the flag and guarantee we reallocate it. (Most of
* the time on reads, the buffer memory has not yet been allocated, so
* we're not adding any additional processing time.)
*/
if (F_ISSET(buf, WT_ITEM_ALIGNED))
bufsize = size;
else {
F_SET(buf, WT_ITEM_ALIGNED);
bufsize = WT_MAX(size, buf->memsize + 10);
}
WT_RET(__wt_buf_init(session, buf, bufsize));
WT_RET(__wt_read(session, block->fh, offset, size, buf->mem));
buf->size = size;
blk = WT_BLOCK_HEADER_REF(buf->mem);
blk->cksum = 0;
page_cksum = __wt_cksum(buf->mem,
F_ISSET(blk, WT_BLOCK_DATA_CKSUM) ? size : WT_BLOCK_COMPRESS_SKIP);
if (cksum != page_cksum) {
if (!F_ISSET(session, WT_SESSION_SALVAGE_CORRUPT_OK))
__wt_errx(session,
"read checksum error [%"
PRIu32 "B @ %" PRIuMAX ", %"
PRIu32 " != %" PRIu32 "]",
size, (uintmax_t)offset, cksum, page_cksum);
/* Panic if a checksum fails during an ordinary read. */
return (block->verify ||
F_ISSET(session, WT_SESSION_SALVAGE_CORRUPT_OK) ?
WT_ERROR :
__wt_illegal_value(session, block->name));
}
WT_STAT_FAST_CONN_INCR(session, block_read);
WT_STAT_FAST_CONN_INCRV(session, block_byte_read, size);
return (0);
}
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