/*
* __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_DECL_RET;
WT_PAGE *page;
int busy, force_attempts, oldgen;
for (force_attempts = oldgen = 0;;) {
switch (ref->state) {
case WT_REF_DISK:
case WT_REF_DELETED:
if (LF_ISSET(WT_READ_CACHE))
return (WT_NOTFOUND);
/*
* The page isn't in memory, attempt to read it.
* Make sure there is space in the cache.
*/
WT_RET(__wt_cache_full_check(session));
WT_RET(__wt_cache_read(session, ref));
oldgen = LF_ISSET(WT_READ_WONT_NEED) ||
F_ISSET(session, WT_SESSION_NO_CACHE);
continue;
case WT_REF_READING:
if (LF_ISSET(WT_READ_CACHE))
return (WT_NOTFOUND);
/* FALLTHROUGH */
case WT_REF_LOCKED:
if (LF_ISSET(WT_READ_NO_WAIT))
return (WT_NOTFOUND);
/* The page is busy -- wait. */
break;
case WT_REF_SPLIT:
return (WT_RESTART);
case WT_REF_MEM:
/*
* The page is in memory: get a hazard pointer, update
* the page's LRU and return. The expected reason we
* can't get a hazard pointer is because the page is
* being evicted; yield and 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)
break;
page = ref->page;
WT_ASSERT(session, page != NULL);
/* Forcibly evict pages that are too big. */
if (!LF_ISSET(WT_READ_NO_EVICT) &&
force_attempts < 10 &&
__evict_force_check(session, page)) {
++force_attempts;
WT_RET(__wt_page_release(session, ref, flags));
break;
}
/* Check if we need an autocommit transaction. */
if ((ret = __wt_txn_autocommit_check(session)) != 0) {
WT_TRET(__wt_hazard_clear(session, page));
return (ret);
}
/*
* If we read the page and we are configured to not
* trash the cache, set the oldest read generation so
* the page is forcibly evicted as soon as possible.
*
* Otherwise, update the page's read generation.
*/
if (oldgen && page->read_gen == WT_READGEN_NOTSET)
__wt_page_evict_soon(page);
else if (!LF_ISSET(WT_READ_NO_GEN) &&
page->read_gen < __wt_cache_read_gen(session))
page->read_gen =
__wt_cache_read_gen_set(session);
return (0);
WT_ILLEGAL_VALUE(session);
}
/* We failed to get the page -- yield before retrying. */
__wt_yield();
}
}
/*
* __wt_page_in --
* 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_PAGE *parent, WT_REF *ref
#ifdef HAVE_DIAGNOSTIC
, const char *file, int line
#endif
)
{
WT_DECL_RET;
WT_PAGE *page;
int busy;
for (;;) {
switch (ref->state) {
case WT_REF_DISK:
case WT_REF_DELETED:
/*
* The page isn't in memory, attempt to read it.
*
* First make sure there is space in the cache.
*/
WT_RET(__wt_cache_full_check(session));
WT_RET(__wt_cache_read(session, parent, ref));
continue;
case WT_REF_EVICT_FORCE:
case WT_REF_LOCKED:
case WT_REF_READING:
/*
* The page is being read or considered for eviction --
* wait for that to be resolved.
*/
break;
case WT_REF_EVICT_WALK:
case WT_REF_MEM:
/*
* The page is in memory: get a hazard pointer, update
* the page's LRU and return. The expected reason we
* can't get a hazard pointer is because the page is
* being evicted; yield and 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)
break;
page = ref->page;
WT_ASSERT(session,
page != NULL && !WT_PAGE_IS_ROOT(page));
/*
* Ensure the page doesn't have ancient updates on it.
* If it did, reading the page could ignore committed
* updates. This should be extremely unlikely in real
* applications, wait for eviction of the page to avoid
* the issue.
*/
if (page->modify != NULL &&
__wt_txn_ancient(session, page->modify->first_id)) {
page->read_gen = WT_READ_GEN_OLDEST;
WT_RET(__wt_hazard_clear(session, page));
WT_RET(__wt_evict_server_wake(session));
break;
}
/* Check if we need an autocommit transaction. */
if ((ret = __wt_txn_autocommit_check(session)) != 0) {
WT_TRET(__wt_hazard_clear(session, page));
return (ret);
}
/*
* If this page has ever been considered for eviction,
* and its generation is aging, update it.
*/
if (page->read_gen != WT_READ_GEN_NOTSET &&
page->read_gen < __wt_cache_read_gen(session))
page->read_gen =
__wt_cache_read_gen_set(session);
return (0);
WT_ILLEGAL_VALUE(session);
}
/* We failed to get the page -- yield before retrying. */
__wt_yield();
}
}
/*
* __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_DECL_RET;
WT_PAGE *page;
u_int sleep_cnt, wait_cnt;
int busy, force_attempts, oldgen;
for (force_attempts = oldgen = 0, wait_cnt = 0;;) {
switch (ref->state) {
case WT_REF_DISK:
case WT_REF_DELETED:
if (LF_ISSET(WT_READ_CACHE))
return (WT_NOTFOUND);
/*
* The page isn't in memory, attempt to read it.
* Make sure there is space in the cache.
*/
WT_RET(__wt_cache_full_check(session));
WT_RET(__wt_cache_read(session, ref));
oldgen = LF_ISSET(WT_READ_WONT_NEED) ||
F_ISSET(session, WT_SESSION_NO_CACHE);
continue;
case WT_REF_READING:
if (LF_ISSET(WT_READ_CACHE))
return (WT_NOTFOUND);
if (LF_ISSET(WT_READ_NO_WAIT))
return (WT_NOTFOUND);
WT_STAT_FAST_CONN_INCR(session, page_read_blocked);
break;
case WT_REF_LOCKED:
if (LF_ISSET(WT_READ_NO_WAIT))
return (WT_NOTFOUND);
WT_STAT_FAST_CONN_INCR(session, page_locked_blocked);
break;
case WT_REF_SPLIT:
return (WT_RESTART);
case WT_REF_MEM:
/*
* The page is in memory: get a hazard pointer, update
* the page's LRU and return. The expected reason we
* can't get a hazard pointer is because the page is
* being evicted; yield and 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_FAST_CONN_INCR(
session, page_busy_blocked);
break;
}
page = ref->page;
WT_ASSERT(session, page != NULL);
/*
* Forcibly evict pages that are too big.
*/
if (force_attempts < 10 &&
__evict_force_check(session, page, flags)) {
++force_attempts;
ret = __wt_page_release_evict(session, ref);
/* If forced eviction fails, stall. */
if (ret == EBUSY) {
ret = 0;
wait_cnt += 1000;
WT_STAT_FAST_CONN_INCR(session,
page_forcible_evict_blocked);
break;
} else
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;
}
/* Check if we need an autocommit transaction. */
if ((ret = __wt_txn_autocommit_check(session)) != 0) {
WT_TRET(__wt_hazard_clear(session, page));
return (ret);
}
/*
* If we read the page and we are configured to not
* trash the cache, set the oldest read generation so
* the page is forcibly evicted as soon as possible.
*
* Otherwise, update the page's read generation.
*/
if (oldgen && page->read_gen == WT_READGEN_NOTSET)
__wt_page_evict_soon(page);
else if (!LF_ISSET(WT_READ_NO_GEN) &&
page->read_gen != WT_READGEN_OLDEST &&
page->read_gen < __wt_cache_read_gen(session))
page->read_gen =
__wt_cache_read_gen_set(session);
return (0);
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 (++wait_cnt < 1000)
__wt_yield();
else {
sleep_cnt = WT_MIN(wait_cnt, 10000);
wait_cnt *= 2;
WT_STAT_FAST_CONN_INCRV(session, page_sleep, sleep_cnt);
__wt_sleep(0, sleep_cnt);
}
}
}
/*
* __wt_page_in --
* 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_PAGE *parent, WT_REF *ref
#ifdef HAVE_DIAGNOSTIC
, const char *file, int line
#endif
)
{
WT_DECL_RET;
WT_PAGE *page;
WT_TXN *txn;
int busy, oldgen;
txn = &session->txn;
for (oldgen = 0;;) {
switch (ref->state) {
case WT_REF_DISK:
case WT_REF_DELETED:
/*
* The page isn't in memory, attempt to read it.
*
* First make sure there is space in the cache.
*/
WT_RET(__wt_cache_full_check(session, 0));
WT_RET(__wt_cache_read(session, parent, ref));
oldgen = F_ISSET(session, WT_SESSION_NO_CACHE) ? 1 : 0;
continue;
case WT_REF_LOCKED:
case WT_REF_READING:
/*
* The page is being read or considered for eviction --
* wait for that to be resolved.
*/
break;
case WT_REF_EVICT_WALK:
case WT_REF_MEM:
/*
* The page is in memory: get a hazard pointer, update
* the page's LRU and return. The expected reason we
* can't get a hazard pointer is because the page is
* being evicted; yield and 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)
break;
page = ref->page;
WT_ASSERT(session,
page != NULL && !WT_PAGE_IS_ROOT(page));
/*
* Make sure the page isn't too big. Only do this
* check once per transaction: it is not a common case,
* and we don't want to get stuck if it isn't possible
* to evict the page.
*/
if (!F_ISSET(txn, TXN_FORCE_EVICT) &&
__wt_eviction_page_force(session, page)) {
F_SET(txn, TXN_FORCE_EVICT);
page->read_gen = WT_READ_GEN_OLDEST;
WT_RET(__wt_page_release(session, page));
break;
}
/* Check if we need an autocommit transaction. */
if ((ret = __wt_txn_autocommit_check(session)) != 0) {
WT_TRET(__wt_hazard_clear(session, page));
return (ret);
}
/*
* If this page has ever been considered for eviction,
* and its generation is aging, update it.
*/
if (page->read_gen != WT_READ_GEN_NOTSET &&
page->read_gen < __wt_cache_read_gen(session))
page->read_gen =
__wt_cache_read_gen_set(session);
/*
* If we read the page and we are configured to not
* trash the cache, set the oldest read generation so
* the page is forcibly evicted as soon as possible.
*/
if (oldgen && page->read_gen == WT_READ_GEN_NOTSET)
page->read_gen = WT_READ_GEN_OLDEST;
return (0);
WT_ILLEGAL_VALUE(session);
}
/* We failed to get the page -- yield before retrying. */
__wt_yield();
}
}
