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|
/*-
* Copyright (c) 2014-2018 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __col_instantiate --
* Update a column-store page entry based on a lookaside table update list.
*/
static int
__col_instantiate(WT_SESSION_IMPL *session,
uint64_t recno, WT_REF *ref, WT_CURSOR_BTREE *cbt, WT_UPDATE *updlist)
{
WT_PAGE *page;
WT_UPDATE *upd;
page = ref->page;
/*
* Discard any of the updates we don't need.
*
* Just free the memory: it hasn't been accounted for on the page yet.
*/
if (updlist->next != NULL &&
(upd = __wt_update_obsolete_check(session, page, updlist)) != NULL)
__wt_free_update_list(session, upd);
/* Search the page and add updates. */
WT_RET(__wt_col_search(session, recno, ref, cbt, true));
WT_RET(__wt_col_modify(
session, cbt, recno, NULL, updlist, WT_UPDATE_INVALID, false));
return (0);
}
/*
* __row_instantiate --
* Update a row-store page entry based on a lookaside table update list.
*/
static int
__row_instantiate(WT_SESSION_IMPL *session,
WT_ITEM *key, WT_REF *ref, WT_CURSOR_BTREE *cbt, WT_UPDATE *updlist)
{
WT_PAGE *page;
WT_UPDATE *upd;
page = ref->page;
/*
* Discard any of the updates we don't need.
*
* Just free the memory: it hasn't been accounted for on the page yet.
*/
if (updlist->next != NULL &&
(upd = __wt_update_obsolete_check(session, page, updlist)) != NULL)
__wt_free_update_list(session, upd);
/* Search the page and add updates. */
WT_RET(__wt_row_search(session, key, ref, cbt, true, true));
WT_RET(__wt_row_modify(
session, cbt, key, NULL, updlist, WT_UPDATE_INVALID, false));
return (0);
}
/*
* __las_page_instantiate_verbose --
* Create a verbose message to display at most once per checkpoint when
* performing a lookaside table read.
*/
static void
__las_page_instantiate_verbose(WT_SESSION_IMPL *session, uint64_t las_pageid)
{
WT_CACHE *cache;
uint64_t ckpt_gen_current, ckpt_gen_last;
if (!WT_VERBOSE_ISSET(session,
WT_VERB_LOOKASIDE | WT_VERB_LOOKASIDE_ACTIVITY))
return;
cache = S2C(session)->cache;
ckpt_gen_current = __wt_gen(session, WT_GEN_CHECKPOINT);
ckpt_gen_last = cache->las_verb_gen_read;
/*
* This message is throttled to one per checkpoint. To do this we
* track the generation of the last checkpoint for which the message
* was printed and check against the current checkpoint generation.
*/
if (WT_VERBOSE_ISSET(session, WT_VERB_LOOKASIDE) ||
ckpt_gen_current > ckpt_gen_last) {
/*
* Attempt to atomically replace the last checkpoint generation
* for which this message was printed. If the atomic swap fails
* we have raced and the winning thread will print the message.
*/
if (__wt_atomic_casv64(&cache->las_verb_gen_read,
ckpt_gen_last, ckpt_gen_current)) {
__wt_verbose(session,
WT_VERB_LOOKASIDE | WT_VERB_LOOKASIDE_ACTIVITY,
"Read from lookaside file triggered for "
"file ID %" PRIu32 ", page ID %" PRIu64,
S2BT(session)->id, las_pageid);
}
}
}
/*
* __las_page_instantiate --
* Instantiate lookaside update records in a recently read page.
*/
static int
__las_page_instantiate(WT_SESSION_IMPL *session, WT_REF *ref, uint32_t btree_id)
{
WT_CACHE *cache;
WT_CURSOR *cursor;
WT_CURSOR_BTREE cbt;
WT_DECL_ITEM(current_key);
WT_DECL_RET;
WT_ITEM las_key, las_timestamp, las_value;
WT_PAGE *page;
WT_UPDATE *first_upd, *last_upd, *upd;
size_t incr, total_incr;
uint64_t current_recno, las_counter, las_pageid, las_txnid, recno;
uint32_t las_id, session_flags;
const uint8_t *p;
uint8_t upd_type;
bool locked;
cursor = NULL;
page = ref->page;
first_upd = last_upd = upd = NULL;
locked = false;
total_incr = 0;
current_recno = recno = WT_RECNO_OOB;
session_flags = 0; /* [-Werror=maybe-uninitialized] */
WT_CLEAR(las_key);
cache = S2C(session)->cache;
__las_page_instantiate_verbose(session, ref->page_las->las_pageid);
WT_STAT_CONN_INCR(session, cache_read_lookaside);
WT_STAT_DATA_INCR(session, cache_read_lookaside);
__wt_btcur_init(session, &cbt);
__wt_btcur_open(&cbt);
WT_ERR(__wt_scr_alloc(session, 0, ¤t_key));
/* Open a lookaside table cursor. */
__wt_las_cursor(session, &cursor, &session_flags);
/*
* The lookaside records are in key and update order, that is, there
* will be a set of in-order updates for a key, then another set of
* in-order updates for a subsequent key. We process all of the updates
* for a key and then insert those updates into the page, then all the
* updates for the next key, and so on.
*/
ret = __wt_las_cursor_position(
cursor, btree_id, ref->page_las->las_pageid);
__wt_readlock(session, &cache->las_sweepwalk_lock);
locked = true;
for (; ret == 0; ret = cursor->next(cursor)) {
WT_ERR(cursor->get_key(cursor,
&las_pageid, &las_id, &las_counter, &las_key));
/*
* Confirm the search using the unique prefix; if not a match,
* we're done searching for records for this page.
*/
if (las_id != btree_id ||
las_pageid != ref->page_las->las_pageid)
break;
/* Allocate the WT_UPDATE structure. */
WT_ERR(cursor->get_value(cursor,
&las_txnid, &las_timestamp, &upd_type, &las_value));
WT_ERR(__wt_update_alloc(
session, &las_value, &upd, &incr, upd_type));
total_incr += incr;
upd->txnid = las_txnid;
#ifdef HAVE_TIMESTAMPS
WT_ASSERT(session, las_timestamp.size == WT_TIMESTAMP_SIZE);
memcpy(&upd->timestamp, las_timestamp.data, las_timestamp.size);
#endif
switch (page->type) {
case WT_PAGE_COL_FIX:
case WT_PAGE_COL_VAR:
p = las_key.data;
WT_ERR(__wt_vunpack_uint(&p, 0, &recno));
if (current_recno == recno)
break;
WT_ASSERT(session, current_recno < recno);
if (first_upd != NULL) {
WT_ERR(__col_instantiate(session,
current_recno, ref, &cbt, first_upd));
first_upd = NULL;
}
current_recno = recno;
break;
case WT_PAGE_ROW_LEAF:
if (current_key->size == las_key.size &&
memcmp(current_key->data,
las_key.data, las_key.size) == 0)
break;
if (first_upd != NULL) {
WT_ERR(__row_instantiate(session,
current_key, ref, &cbt, first_upd));
first_upd = NULL;
}
WT_ERR(__wt_buf_set(session,
current_key, las_key.data, las_key.size));
break;
WT_ILLEGAL_VALUE_ERR(session);
}
/* Append the latest update to the list. */
if (first_upd == NULL)
first_upd = last_upd = upd;
else {
last_upd->next = upd;
last_upd = upd;
}
upd = NULL;
}
__wt_readunlock(session, &cache->las_sweepwalk_lock);
locked = false;
WT_ERR_NOTFOUND_OK(ret);
/* Insert the last set of updates, if any. */
if (first_upd != NULL)
switch (page->type) {
case WT_PAGE_COL_FIX:
case WT_PAGE_COL_VAR:
WT_ERR(__col_instantiate(session,
current_recno, ref, &cbt, first_upd));
first_upd = NULL;
break;
case WT_PAGE_ROW_LEAF:
WT_ERR(__row_instantiate(session,
current_key, ref, &cbt, first_upd));
first_upd = NULL;
break;
WT_ILLEGAL_VALUE_ERR(session);
}
/* Discard the cursor. */
WT_ERR(__wt_las_cursor_close(session, &cursor, session_flags));
if (total_incr != 0) {
__wt_cache_page_inmem_incr(session, page, total_incr);
/*
* If the updates in lookaside are newer than the versions on
* the page, it must be included in the next checkpoint.
*
* Otherwise, the page image contained the newest versions of
* data so the updates are all older and we could consider
* marking it clean (i.e., the next checkpoint can use the
* version already on disk).
*
* This needs care because (a) it creates pages with history
* that can't be evicted until they are marked dirty again, and
* (b) checkpoints may need to visit these pages to resolve
* changes evicted while a checkpoint is running.
*/
page->modify->first_dirty_txn = WT_TXN_FIRST;
if (ref->page_las->las_skew_newest &&
!S2C(session)->txn_global.has_stable_timestamp &&
__wt_txn_visible_all(session, ref->page_las->las_max_txn,
WT_TIMESTAMP_NULL(&ref->page_las->onpage_timestamp))) {
page->modify->rec_max_txn = ref->page_las->las_max_txn;
__wt_timestamp_set(&page->modify->rec_max_timestamp,
&ref->page_las->onpage_timestamp);
__wt_page_modify_clear(session, page);
}
}
err: if (locked)
__wt_readunlock(session, &cache->las_sweepwalk_lock);
WT_TRET(__wt_las_cursor_close(session, &cursor, session_flags));
WT_TRET(__wt_btcur_close(&cbt, true));
/*
* On error, upd points to a single unlinked WT_UPDATE structure,
* first_upd points to a list.
*/
__wt_free(session, upd);
__wt_free_update_list(session, first_upd);
__wt_scr_free(session, ¤t_key);
return (ret);
}
/*
* __evict_force_check --
* Check if a page matches the criteria for forced eviction.
*/
static bool
__evict_force_check(WT_SESSION_IMPL *session, WT_REF *ref)
{
WT_BTREE *btree;
WT_PAGE *page;
btree = S2BT(session);
page = ref->page;
/* Leaf pages only. */
if (WT_PAGE_IS_INTERNAL(page))
return (false);
/*
* It's hard to imagine a page with a huge memory footprint that has
* never been modified, but check to be sure.
*/
if (__wt_page_evict_clean(page))
return (false);
/* Pages are usually small enough, check that first. */
if (page->memory_footprint < btree->splitmempage)
return (false);
/*
* If this session has more than one hazard pointer, eviction will fail
* and there is no point trying.
*/
if (__wt_hazard_count(session, ref) > 1)
return (false);
/* If we can do an in-memory split, do it. */
if (__wt_leaf_page_can_split(session, page))
return (true);
if (page->memory_footprint < btree->maxmempage)
return (false);
/* Bump the oldest ID, we're about to do some visibility checks. */
WT_IGNORE_RET(__wt_txn_update_oldest(session, 0));
/*
* Allow some leeway if the transaction ID isn't moving forward since
* it is unlikely eviction will be able to evict the page. Don't keep
* skipping the page indefinitely or large records can lead to
* extremely large memory footprints.
*/
if (!__wt_page_evict_retry(session, page))
return (false);
/* Trigger eviction on the next page release. */
__wt_page_evict_soon(session, ref);
/* If eviction cannot succeed, don't try. */
return (__wt_page_can_evict(session, ref, NULL));
}
/*
* __page_read --
* Read a page from the file.
*/
static int
__page_read(WT_SESSION_IMPL *session, WT_REF *ref, uint32_t flags)
{
WT_BTREE *btree;
WT_DECL_RET;
WT_ITEM tmp;
WT_PAGE *notused;
size_t addr_size;
uint64_t time_start, time_stop;
uint32_t page_flags, final_state, new_state, previous_state;
const uint8_t *addr;
bool timer;
btree = S2BT(session);
time_start = time_stop = 0;
/*
* Don't pass an allocated buffer to the underlying block read function,
* force allocation of new memory of the appropriate size.
*/
WT_CLEAR(tmp);
/*
* Attempt to set the state to WT_REF_READING for normal reads, or
* WT_REF_LOCKED, for deleted pages or pages with lookaside entries.
* The difference is that checkpoints can skip over clean pages that
* are being read into cache, but need to wait for deletes or lookaside
* updates to be resolved (in order for checkpoint to write the correct
* version of the page).
*
* If successful, we've won the race, read the page.
*/
switch (previous_state = ref->state) {
case WT_REF_DISK:
new_state = WT_REF_READING;
break;
case WT_REF_DELETED:
case WT_REF_LIMBO:
case WT_REF_LOOKASIDE:
new_state = WT_REF_LOCKED;
break;
default:
return (0);
}
if (!__wt_atomic_casv32(&ref->state, previous_state, new_state))
return (0);
final_state = WT_REF_MEM;
/* If we already have the page image, just instantiate the history. */
if (previous_state == WT_REF_LIMBO)
goto skip_read;
/*
* Get the address: if there is no address, the page was deleted or had
* only lookaside entries, and a subsequent search or insert is forcing
* re-creation of the name space.
*/
__wt_ref_info(ref, &addr, &addr_size, NULL);
if (addr == NULL) {
WT_ASSERT(session, previous_state != WT_REF_DISK);
WT_ERR(__wt_btree_new_leaf_page(session, &ref->page));
goto skip_read;
}
/*
* There's an address, read or map the backing disk page and build an
* in-memory version of the page.
*/
timer = !F_ISSET(session, WT_SESSION_INTERNAL);
if (timer)
time_start = __wt_clock(session);
WT_ERR(__wt_bt_read(session, &tmp, addr, addr_size));
if (timer) {
time_stop = __wt_clock(session);
WT_STAT_CONN_INCR(session, cache_read_app_count);
WT_STAT_CONN_INCRV(session, cache_read_app_time,
WT_CLOCKDIFF_US(time_stop, time_start));
}
/*
* Build the in-memory version of the page. Clear our local reference to
* the allocated copy of the disk image on return, the in-memory object
* steals it.
*
* If a page is read with eviction disabled, we don't count evicting it
* as progress. Since disabling eviction allows pages to be read even
* when the cache is full, we want to avoid workloads repeatedly reading
* a page with eviction disabled (e.g., a metadata page), then evicting
* that page and deciding that is a sign that eviction is unstuck.
*/
page_flags =
WT_DATA_IN_ITEM(&tmp) ? WT_PAGE_DISK_ALLOC : WT_PAGE_DISK_MAPPED;
if (LF_ISSET(WT_READ_IGNORE_CACHE_SIZE))
FLD_SET(page_flags, WT_PAGE_EVICT_NO_PROGRESS);
WT_ERR(__wt_page_inmem(session, ref, tmp.data, page_flags, ¬used));
tmp.mem = NULL;
/*
* The WT_REF lookaside state should match the page-header state of
* any page we read.
*/
WT_ASSERT(session,
(previous_state != WT_REF_LIMBO &&
previous_state != WT_REF_LOOKASIDE) ||
ref->page->dsk == NULL ||
F_ISSET(ref->page->dsk, WT_PAGE_LAS_UPDATE));
skip_read:
switch (previous_state) {
case WT_REF_DELETED:
/*
* A truncated page may also have lookaside information. The
* delete happened after page eviction (writing the lookaside
* information), first update based on the lookaside table and
* then apply the delete.
*/
if (ref->page_las != NULL) {
WT_ERR(__las_page_instantiate(session, ref, btree->id));
ref->page_las->eviction_to_lookaside = false;
}
/* Move all records to a deleted state. */
WT_ERR(__wt_delete_page_instantiate(session, ref));
break;
case WT_REF_LOOKASIDE:
if (__wt_las_page_skip_locked(session, ref)) {
WT_STAT_CONN_INCR(
session, cache_read_lookaside_skipped);
ref->page_las->eviction_to_lookaside = true;
final_state = WT_REF_LIMBO;
break;
}
/* FALLTHROUGH */
case WT_REF_LIMBO:
/* Instantiate updates from the database's lookaside table. */
if (previous_state == WT_REF_LIMBO)
WT_STAT_CONN_INCR(session, cache_read_lookaside_delay);
WT_ERR(__las_page_instantiate(session, ref, btree->id));
ref->page_las->eviction_to_lookaside = false;
break;
}
/*
* We no longer need lookaside entries once the page is instantiated.
* There's no reason for the lookaside remove to fail, but ignore it
* if for some reason it fails, we've got a valid page.
*
* Don't free WT_REF.page_las, there may be concurrent readers.
*/
if (final_state == WT_REF_MEM && ref->page_las != NULL)
WT_IGNORE_RET(__wt_las_remove_block(
session, btree->id, ref->page_las->las_pageid));
WT_PUBLISH(ref->state, final_state);
return (ret);
err: /*
* If the function building an in-memory version of the page failed,
* it discarded the page, but not the disk image. Discard the page
* and separately discard the disk image in all cases.
*/
if (ref->page != NULL && previous_state != WT_REF_LIMBO)
__wt_ref_out(session, ref);
WT_PUBLISH(ref->state, previous_state);
__wt_buf_free(session, &tmp);
return (ret);
}
/*
* __wt_page_in_func --
* Acquire a hazard pointer to a page; if the page is not in-memory,
* read it from the disk and build an in-memory version.
*/
int
__wt_page_in_func(WT_SESSION_IMPL *session, WT_REF *ref, uint32_t flags
#ifdef HAVE_DIAGNOSTIC
, const char *file, int line
#endif
)
{
WT_BTREE *btree;
WT_DECL_RET;
WT_PAGE *page;
uint64_t sleep_cnt, wait_cnt;
uint32_t current_state;
int force_attempts;
bool busy, cache_work, did_read, stalled, wont_need;
btree = S2BT(session);
if (F_ISSET(session, WT_SESSION_IGNORE_CACHE_SIZE))
LF_SET(WT_READ_IGNORE_CACHE_SIZE);
/*
* Ignore reads of pages already known to be in cache, otherwise the
* eviction server can dominate these statistics.
*/
if (!LF_ISSET(WT_READ_CACHE)) {
WT_STAT_CONN_INCR(session, cache_pages_requested);
WT_STAT_DATA_INCR(session, cache_pages_requested);
}
for (did_read = wont_need = stalled = false,
force_attempts = 0, sleep_cnt = wait_cnt = 0;;) {
switch (current_state = ref->state) {
case WT_REF_DELETED:
if (LF_ISSET(WT_READ_NO_EMPTY) &&
__wt_delete_page_skip(session, ref, false))
return (WT_NOTFOUND);
goto read;
case WT_REF_LOOKASIDE:
if (LF_ISSET(WT_READ_CACHE)) {
if (!LF_ISSET(WT_READ_LOOKASIDE))
return (WT_NOTFOUND);
/*
* If we skip a lookaside page, the tree
* cannot be left clean: lookaside entries
* must be resolved before the tree can be
* discarded.
*/
if (__wt_las_page_skip(session, ref)) {
__wt_tree_modify_set(session);
return (WT_NOTFOUND);
}
}
goto read;
case WT_REF_DISK:
if (LF_ISSET(WT_READ_CACHE))
return (WT_NOTFOUND);
read: /*
* The page isn't in memory, read it. If this thread
* respects the cache size, check for space in the
* cache.
*/
if (!LF_ISSET(WT_READ_IGNORE_CACHE_SIZE))
WT_RET(__wt_cache_eviction_check(
session, true,
!F_ISSET(&session->txn, WT_TXN_HAS_ID),
NULL));
WT_RET(__page_read(session, ref, flags));
/*
* We just read a page, don't evict it before we have a
* chance to use it.
*/
did_read = true;
/*
* If configured to not trash the cache, leave the page
* generation unset, we'll set it before returning to
* the oldest read generation, so the page is forcibly
* evicted as soon as possible. We don't do that set
* here because we don't want to evict the page before
* we "acquire" it.
*/
wont_need = LF_ISSET(WT_READ_WONT_NEED) ||
F_ISSET(session, WT_SESSION_READ_WONT_NEED);
continue;
case WT_REF_READING:
if (LF_ISSET(WT_READ_CACHE))
return (WT_NOTFOUND);
if (LF_ISSET(WT_READ_NO_WAIT))
return (WT_NOTFOUND);
/* Waiting on another thread's read, stall. */
WT_STAT_CONN_INCR(session, page_read_blocked);
stalled = true;
break;
case WT_REF_LOCKED:
if (LF_ISSET(WT_READ_NO_WAIT))
return (WT_NOTFOUND);
/* Waiting on eviction, stall. */
WT_STAT_CONN_INCR(session, page_locked_blocked);
stalled = true;
break;
case WT_REF_SPLIT:
return (WT_RESTART);
case WT_REF_LIMBO:
case WT_REF_MEM:
/*
* The page is in memory.
*
* Get a hazard pointer if one is required. We cannot
* be evicting if no hazard pointer is required, we're
* done.
*/
if (F_ISSET(btree, WT_BTREE_IN_MEMORY))
goto skip_evict;
/*
* The expected reason we can't get a hazard pointer is
* because the page is being evicted, yield, try again.
*/
#ifdef HAVE_DIAGNOSTIC
WT_RET(
__wt_hazard_set(session, ref, &busy, file, line));
#else
WT_RET(__wt_hazard_set(session, ref, &busy));
#endif
if (busy) {
WT_STAT_CONN_INCR(session, page_busy_blocked);
break;
}
/*
* If we are a limbo page check whether we need to
* instantiate the history. By having a hazard pointer
* we can use the locked version.
*/
if (current_state == WT_REF_LIMBO &&
((!LF_ISSET(WT_READ_CACHE) ||
LF_ISSET(WT_READ_LOOKASIDE)) &&
!__wt_las_page_skip_locked(session, ref))) {
WT_RET(__wt_hazard_clear(session, ref));
goto read;
}
if (current_state == WT_REF_LIMBO &&
LF_ISSET(WT_READ_CACHE) &&
LF_ISSET(WT_READ_LOOKASIDE))
__wt_tree_modify_set(session);
/*
* Check if the page requires forced eviction.
*/
if (did_read || LF_ISSET(WT_READ_NO_SPLIT) ||
btree->evict_disabled > 0 || btree->lsm_primary)
goto skip_evict;
/*
* If reconciliation is disabled (e.g., when inserting
* into the lookaside table), skip forced eviction if
* the page can't split.
*/
if (F_ISSET(session, WT_SESSION_NO_RECONCILE) &&
!__wt_leaf_page_can_split(session, ref->page))
goto skip_evict;
/*
* Forcibly evict pages that are too big.
*/
if (force_attempts < 10 &&
__evict_force_check(session, ref)) {
++force_attempts;
ret = __wt_page_release_evict(session, ref);
/* If forced eviction fails, stall. */
if (ret == EBUSY) {
WT_NOT_READ(ret, 0);
WT_STAT_CONN_INCR(session,
page_forcible_evict_blocked);
stalled = true;
break;
}
WT_RET(ret);
/*
* The result of a successful forced eviction
* is a page-state transition (potentially to
* an in-memory page we can use, or a restart
* return for our caller), continue the outer
* page-acquisition loop.
*/
continue;
}
skip_evict: /*
* If we read the page and are configured to not trash
* the cache, and no other thread has already used the
* page, set the read generation so the page is evicted
* soon.
*
* Otherwise, if we read the page, or, if configured to
* update the page's read generation and the page isn't
* already flagged for forced eviction, update the page
* read generation.
*/
page = ref->page;
if (page->read_gen == WT_READGEN_NOTSET) {
if (wont_need)
page->read_gen = WT_READGEN_WONT_NEED;
else
__wt_cache_read_gen_new(session, page);
} else if (!LF_ISSET(WT_READ_NO_GEN))
__wt_cache_read_gen_bump(session, page);
/*
* Check if we need an autocommit transaction.
* Starting a transaction can trigger eviction, so skip
* it if eviction isn't permitted.
*
* The logic here is a little weird: some code paths do
* a blanket ban on checking the cache size in
* sessions, but still require a transaction (e.g.,
* when updating metadata or lookaside). If
* WT_READ_IGNORE_CACHE_SIZE was passed in explicitly,
* we're done. If we set WT_READ_IGNORE_CACHE_SIZE
* because it was set in the session then make sure we
* start a transaction.
*/
return (LF_ISSET(WT_READ_IGNORE_CACHE_SIZE) &&
!F_ISSET(session, WT_SESSION_IGNORE_CACHE_SIZE) ?
0 : __wt_txn_autocommit_check(session));
WT_ILLEGAL_VALUE(session);
}
/*
* We failed to get the page -- yield before retrying, and if
* we've yielded enough times, start sleeping so we don't burn
* CPU to no purpose.
*/
if (stalled)
wait_cnt += WT_THOUSAND;
else if (++wait_cnt < WT_THOUSAND) {
__wt_yield();
continue;
}
/*
* If stalling and this thread is allowed to do eviction work,
* check if the cache needs help. If we do work for the cache,
* substitute that for a sleep.
*/
if (!LF_ISSET(WT_READ_IGNORE_CACHE_SIZE)) {
WT_RET(__wt_cache_eviction_check(
session, true,
!F_ISSET(&session->txn, WT_TXN_HAS_ID),
&cache_work));
if (cache_work)
continue;
}
__wt_ref_state_yield_sleep(&wait_cnt, &sleep_cnt);
WT_STAT_CONN_INCRV(session, page_sleep, sleep_cnt);
}
}
|