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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"
/*
* Per session handle cached block manager information.
*/
typedef struct {
WT_EXT *ext_cache; /* List of WT_EXT handles */
u_int ext_cache_cnt; /* Count */
WT_SIZE *sz_cache; /* List of WT_SIZE handles */
u_int sz_cache_cnt; /* Count */
} WT_BLOCK_MGR_SESSION;
/*
* __block_ext_alloc --
* Allocate a new WT_EXT structure.
*/
static int
__block_ext_alloc(WT_SESSION_IMPL *session, WT_EXT **extp)
{
WT_EXT *ext;
u_int skipdepth;
skipdepth = __wt_skip_choose_depth(session);
WT_RET(__wt_calloc(session, 1,
sizeof(WT_EXT) + skipdepth * 2 * sizeof(WT_EXT *), &ext));
ext->depth = (uint8_t)skipdepth;
(*extp) = ext;
return (0);
}
/*
* __wt_block_ext_alloc --
* Return a WT_EXT structure for use.
*/
int
__wt_block_ext_alloc(WT_SESSION_IMPL *session, WT_EXT **extp)
{
WT_EXT *ext;
WT_BLOCK_MGR_SESSION *bms;
u_int i;
bms = session->block_manager;
/* Return a WT_EXT structure for use from a cached list. */
if (bms != NULL && bms->ext_cache != NULL) {
ext = bms->ext_cache;
bms->ext_cache = ext->next[0];
/* Clear any left-over references. */
for (i = 0; i < ext->depth; ++i)
ext->next[i] = ext->next[i + ext->depth] = NULL;
/*
* The count is advisory to minimize our exposure to bugs, but
* don't let it go negative.
*/
if (bms->ext_cache_cnt > 0)
--bms->ext_cache_cnt;
*extp = ext;
return (0);
}
return (__block_ext_alloc(session, extp));
}
/*
* __block_ext_prealloc --
* Pre-allocate WT_EXT structures.
*/
static int
__block_ext_prealloc(WT_SESSION_IMPL *session, u_int max)
{
WT_BLOCK_MGR_SESSION *bms;
WT_EXT *ext;
bms = session->block_manager;
for (; bms->ext_cache_cnt < max; ++bms->ext_cache_cnt) {
WT_RET(__block_ext_alloc(session, &ext));
ext->next[0] = bms->ext_cache;
bms->ext_cache = ext;
}
return (0);
}
/*
* __wt_block_ext_free --
* Add a WT_EXT structure to the cached list.
*/
void
__wt_block_ext_free(WT_SESSION_IMPL *session, WT_EXT *ext)
{
WT_BLOCK_MGR_SESSION *bms;
if ((bms = session->block_manager) == NULL)
__wt_free(session, ext);
else {
ext->next[0] = bms->ext_cache;
bms->ext_cache = ext;
++bms->ext_cache_cnt;
}
}
/*
* __block_ext_discard --
* Discard some or all of the WT_EXT structure cache.
*/
static int
__block_ext_discard(WT_SESSION_IMPL *session, u_int max)
{
WT_BLOCK_MGR_SESSION *bms;
WT_EXT *ext, *next;
bms = session->block_manager;
if (max != 0 && bms->ext_cache_cnt <= max)
return (0);
for (ext = bms->ext_cache; ext != NULL;) {
next = ext->next[0];
__wt_free(session, ext);
ext = next;
--bms->ext_cache_cnt;
if (max != 0 && bms->ext_cache_cnt <= max)
break;
}
bms->ext_cache = ext;
if (max == 0 && bms->ext_cache_cnt != 0)
WT_RET_MSG(session, WT_ERROR,
"incorrect count in session handle's block manager cache");
return (0);
}
/*
* __block_size_alloc --
* Allocate a new WT_SIZE structure.
*/
static int
__block_size_alloc(WT_SESSION_IMPL *session, WT_SIZE **szp)
{
return (__wt_calloc_one(session, szp));
}
/*
* __wt_block_size_alloc --
* Return a WT_SIZE structure for use.
*/
int
__wt_block_size_alloc(WT_SESSION_IMPL *session, WT_SIZE **szp)
{
WT_BLOCK_MGR_SESSION *bms;
bms = session->block_manager;
/* Return a WT_SIZE structure for use from a cached list. */
if (bms != NULL && bms->sz_cache != NULL) {
(*szp) = bms->sz_cache;
bms->sz_cache = bms->sz_cache->next[0];
/*
* The count is advisory to minimize our exposure to bugs, but
* don't let it go negative.
*/
if (bms->sz_cache_cnt > 0)
--bms->sz_cache_cnt;
return (0);
}
return (__block_size_alloc(session, szp));
}
/*
* __block_size_prealloc --
* Pre-allocate WT_SIZE structures.
*/
static int
__block_size_prealloc(WT_SESSION_IMPL *session, u_int max)
{
WT_BLOCK_MGR_SESSION *bms;
WT_SIZE *sz;
bms = session->block_manager;
for (; bms->sz_cache_cnt < max; ++bms->sz_cache_cnt) {
WT_RET(__block_size_alloc(session, &sz));
sz->next[0] = bms->sz_cache;
bms->sz_cache = sz;
}
return (0);
}
/*
* __wt_block_size_free --
* Add a WT_SIZE structure to the cached list.
*/
void
__wt_block_size_free(WT_SESSION_IMPL *session, WT_SIZE *sz)
{
WT_BLOCK_MGR_SESSION *bms;
if ((bms = session->block_manager) == NULL)
__wt_free(session, sz);
else {
sz->next[0] = bms->sz_cache;
bms->sz_cache = sz;
++bms->sz_cache_cnt;
}
}
/*
* __block_size_discard --
* Discard some or all of the WT_SIZE structure cache.
*/
static int
__block_size_discard(WT_SESSION_IMPL *session, u_int max)
{
WT_BLOCK_MGR_SESSION *bms;
WT_SIZE *sz, *nsz;
bms = session->block_manager;
if (max != 0 && bms->sz_cache_cnt <= max)
return (0);
for (sz = bms->sz_cache; sz != NULL;) {
nsz = sz->next[0];
__wt_free(session, sz);
sz = nsz;
--bms->sz_cache_cnt;
if (max != 0 && bms->sz_cache_cnt <= max)
break;
}
bms->sz_cache = sz;
if (max == 0 && bms->sz_cache_cnt != 0)
WT_RET_MSG(session, WT_ERROR,
"incorrect count in session handle's block manager cache");
return (0);
}
/*
* __block_manager_session_cleanup --
* Clean up the session handle's block manager information.
*/
static int
__block_manager_session_cleanup(WT_SESSION_IMPL *session)
{
WT_DECL_RET;
if (session->block_manager == NULL)
return (0);
WT_TRET(__block_ext_discard(session, 0));
WT_TRET(__block_size_discard(session, 0));
__wt_free(session, session->block_manager);
return (ret);
}
/*
* __wt_block_ext_prealloc --
* Pre-allocate WT_EXT and WT_SIZE structures.
*/
int
__wt_block_ext_prealloc(WT_SESSION_IMPL *session, u_int max)
{
if (session->block_manager == NULL) {
WT_RET(__wt_calloc(session, 1,
sizeof(WT_BLOCK_MGR_SESSION), &session->block_manager));
session->block_manager_cleanup =
__block_manager_session_cleanup;
}
WT_RET(__block_ext_prealloc(session, max));
WT_RET(__block_size_prealloc(session, max));
return (0);
}
/*
* __wt_block_ext_discard --
* Discard WT_EXT and WT_SIZE structures after checkpoint runs.
*/
int
__wt_block_ext_discard(WT_SESSION_IMPL *session, u_int max)
{
WT_RET(__block_ext_discard(session, max));
WT_RET(__block_size_discard(session, max));
return (0);
}
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