/*
* __wt_cond_signal --
* Signal a waiting thread.
*/
void
__wt_cond_signal(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
WT_DECL_RET;
__wt_verbose(session, WT_VERB_MUTEX, "signal %s", cond->name);
/*
* Our callers often set flags to cause a thread to exit. Add a barrier
* to ensure exit flags are seen by the sleeping threads, otherwise we
* can wake up a thread, it immediately goes back to sleep, and we'll
* hang. Use a full barrier (we may not write before waiting on thread
* join).
*/
WT_FULL_BARRIER();
/*
* Fast path if we are in (or can enter), a state where the next waiter
* will return immediately as already signaled.
*/
if (cond->waiters == -1 ||
(cond->waiters == 0 && __wt_atomic_casi32(&cond->waiters, 0, -1)))
return;
EnterCriticalSection(&cond->mtx);
WakeAllConditionVariable(&cond->cond);
LeaveCriticalSection(&cond->mtx);
}
/*
* __wt_yield --
* Yield the thread of control.
*/
void
__wt_yield(void)
{
/*
* Yielding the processor isn't documented as a memory barrier, and it's
* a reasonable expectation to have. There's no reason not to explicitly
* include a barrier since we're giving up the CPU, and ensures callers
* aren't ever surprised.
*/
WT_FULL_BARRIER();
SwitchToThread();
}
/*
* __wt_las_set_written --
* Flag that the lookaside table has been written.
*/
void
__wt_las_set_written(WT_SESSION_IMPL *session)
{
WT_CONNECTION_IMPL *conn;
conn = S2C(session);
if (!conn->las_written) {
conn->las_written = true;
/*
* Push the flag: unnecessary, but from now page reads must deal
* with lookaside table records, and we only do the write once.
*/
WT_FULL_BARRIER();
}
}
/*
* __wt_lsm_start_worker --
* Start the worker thread for an LSM tree.
*/
static int
__lsm_tree_start_worker(WT_SESSION_IMPL *session, WT_LSM_TREE *lsm_tree)
{
WT_CONNECTION *wt_conn;
WT_LSM_WORKER_ARGS *wargs;
WT_SESSION *wt_session;
WT_SESSION_IMPL *s;
uint32_t i;
wt_conn = &S2C(session)->iface;
WT_RET(wt_conn->open_session(wt_conn, NULL, NULL, &wt_session));
lsm_tree->ckpt_session = (WT_SESSION_IMPL *)wt_session;
F_SET(lsm_tree->ckpt_session, WT_SESSION_INTERNAL);
F_SET(lsm_tree, WT_LSM_TREE_WORKING);
/* The new thread will rely on the WORKING value being visible. */
WT_FULL_BARRIER();
if (F_ISSET(S2C(session), WT_CONN_LSM_MERGE))
for (i = 0; i < lsm_tree->merge_threads; i++) {
WT_RET(wt_conn->open_session(
wt_conn, NULL, NULL, &wt_session));
s = (WT_SESSION_IMPL *)wt_session;
F_SET(s, WT_SESSION_INTERNAL);
lsm_tree->worker_sessions[i] = s;
WT_RET(__wt_calloc_def(session, 1, &wargs));
wargs->lsm_tree = lsm_tree;
wargs->id = i;
WT_RET(__wt_thread_create(session,
&lsm_tree->worker_tids[i],
__wt_lsm_merge_worker, wargs));
}
if (FLD_ISSET(lsm_tree->bloom, WT_LSM_BLOOM_NEWEST)) {
WT_RET(wt_conn->open_session(wt_conn, NULL, NULL, &wt_session));
lsm_tree->bloom_session = (WT_SESSION_IMPL *)wt_session;
F_SET(lsm_tree->bloom_session, WT_SESSION_INTERNAL);
WT_RET(__wt_thread_create(session,
&lsm_tree->bloom_tid, __wt_lsm_bloom_worker, lsm_tree));
}
WT_RET(__wt_thread_create(session,
&lsm_tree->ckpt_tid, __wt_lsm_checkpoint_worker, lsm_tree));
return (0);
}
/*
* __lsm_tree_start_worker --
* Start the worker thread for an LSM tree.
*/
static int
__lsm_tree_start_worker(WT_SESSION_IMPL *session, WT_LSM_TREE *lsm_tree)
{
WT_CONNECTION *wt_conn;
WT_LSM_WORKER_ARGS *wargs;
WT_SESSION *wt_session;
WT_SESSION_IMPL *s;
uint32_t i;
wt_conn = &S2C(session)->iface;
/*
* All the LSM worker threads do their operations on read-only files.
* Use read-uncommitted isolation to avoid keeping updates in cache
* unnecessarily.
*/
WT_RET(wt_conn->open_session(
wt_conn, NULL, "isolation=read-uncommitted", &wt_session));
lsm_tree->ckpt_session = (WT_SESSION_IMPL *)wt_session;
F_SET(lsm_tree->ckpt_session, WT_SESSION_INTERNAL);
F_SET(lsm_tree, WT_LSM_TREE_WORKING);
/* The new thread will rely on the WORKING value being visible. */
WT_FULL_BARRIER();
if (F_ISSET(S2C(session), WT_CONN_LSM_MERGE))
for (i = 0; i < lsm_tree->merge_threads; i++) {
WT_RET(wt_conn->open_session(
wt_conn, NULL, "isolation=read-uncommitted",
&wt_session));
s = (WT_SESSION_IMPL *)wt_session;
F_SET(s, WT_SESSION_INTERNAL);
lsm_tree->worker_sessions[i] = s;
WT_RET(__wt_calloc_def(session, 1, &wargs));
wargs->lsm_tree = lsm_tree;
wargs->id = i;
WT_RET(__wt_thread_create(session,
&lsm_tree->worker_tids[i],
__wt_lsm_merge_worker, wargs));
}
WT_RET(__wt_thread_create(session,
&lsm_tree->ckpt_tid, __wt_lsm_checkpoint_worker, lsm_tree));
return (0);
}
/*
* __wt_thread_create --
* Create a new thread of control.
*/
int
__wt_thread_create(WT_SESSION_IMPL *session,
wt_thread_t *tidret, WT_THREAD_CALLBACK(*func)(void *), void *arg)
{
/*
* Creating a thread isn't a memory barrier, but WiredTiger commonly
* sets flags and or state and then expects worker threads to start.
* Include a barrier to ensure safety in those cases.
*/
WT_FULL_BARRIER();
/* Spawn a new thread of control. */
tidret->id = (HANDLE)_beginthreadex(NULL, 0, func, arg, 0, NULL);
if (tidret->id != 0) {
tidret->created = true;
return (0);
}
WT_RET_MSG(session, __wt_errno(), "thread create: _beginthreadex");
}
/*
* __wt_thread_join --
* Wait for a thread of control to exit.
*/
int
__wt_thread_join(WT_SESSION_IMPL *session, wt_thread_t *tid)
{
DWORD windows_error;
/* Only attempt to join if thread was created successfully */
if (!tid->created)
return (0);
tid->created = false;
/*
* Joining a thread isn't a memory barrier, but WiredTiger commonly
* sets flags and or state and then expects worker threads to halt.
* Include a barrier to ensure safety in those cases.
*/
WT_FULL_BARRIER();
if ((windows_error =
WaitForSingleObject(tid->id, INFINITE)) != WAIT_OBJECT_0) {
if (windows_error == WAIT_FAILED)
windows_error = __wt_getlasterror();
__wt_errx(session, "thread join: WaitForSingleObject: %s",
__wt_formatmessage(session, windows_error));
/* If we fail to wait, we will leak handles, do not continue. */
return (WT_PANIC);
}
if (CloseHandle(tid->id) == 0) {
windows_error = __wt_getlasterror();
__wt_errx(session, "thread join: CloseHandle: %s",
__wt_formatmessage(session, windows_error));
return (__wt_map_windows_error(windows_error));
}
return (0);
}
/*
* __wt_spin_lock_unregister_lock --
* Remove a lock from the connection's list.
*/
void
__wt_spin_lock_unregister_lock(WT_SESSION_IMPL *session, WT_SPINLOCK *t)
{
WT_CONNECTION_IMPL *conn;
u_int i;
conn = S2C(session);
for (i = 0; i < WT_SPINLOCK_MAX; i++)
if (conn->spinlock_list[i] == t)
conn->spinlock_list[i] = NULL;
/*
* XXX
* The statistics thread reads through this array, there's a possible
* race: if that thread reads the pointer then goes to sleep, then we
* free the spinlock, then the statistics thread wakes up, it can read
* free'd memory.
*
* This is performance debugging code, so we're not fixing the race for
* now, minimize the window.
*/
WT_FULL_BARRIER();
}
/*
* __sync_file --
* Flush pages for a specific file.
*/
static int
__sync_file(WT_SESSION_IMPL *session, int syncop)
{
struct timespec end, start;
WT_BTREE *btree;
WT_DECL_RET;
WT_PAGE *page;
WT_PAGE_MODIFY *mod;
WT_REF *walk;
WT_TXN *txn;
uint64_t internal_bytes, leaf_bytes;
uint64_t internal_pages, leaf_pages;
uint32_t flags;
bool evict_reset;
btree = S2BT(session);
flags = WT_READ_CACHE | WT_READ_NO_GEN;
walk = NULL;
txn = &session->txn;
internal_bytes = leaf_bytes = 0;
internal_pages = leaf_pages = 0;
if (WT_VERBOSE_ISSET(session, WT_VERB_CHECKPOINT))
WT_RET(__wt_epoch(session, &start));
switch (syncop) {
case WT_SYNC_WRITE_LEAVES:
/*
* Write all immediately available, dirty in-cache leaf pages.
*
* Writing the leaf pages is done without acquiring a high-level
* lock, serialize so multiple threads don't walk the tree at
* the same time.
*/
if (!btree->modified)
return (0);
__wt_spin_lock(session, &btree->flush_lock);
if (!btree->modified) {
__wt_spin_unlock(session, &btree->flush_lock);
return (0);
}
flags |= WT_READ_NO_WAIT | WT_READ_SKIP_INTL;
for (walk = NULL;;) {
WT_ERR(__wt_tree_walk(session, &walk, NULL, flags));
if (walk == NULL)
break;
/*
* Write dirty pages if nobody beat us to it. Don't
* try to write the hottest pages: checkpoint will have
* to visit them anyway.
*/
page = walk->page;
if (__wt_page_is_modified(page) &&
__wt_txn_visible_all(
session, page->modify->update_txn)) {
if (txn->isolation == WT_ISO_READ_COMMITTED)
__wt_txn_get_snapshot(session);
leaf_bytes += page->memory_footprint;
++leaf_pages;
WT_ERR(__wt_reconcile(session, walk, NULL, 0));
}
}
break;
case WT_SYNC_CHECKPOINT:
/*
* We cannot check the tree modified flag in the case of a
* checkpoint, the checkpoint code has already cleared it.
*
* Writing the leaf pages is done without acquiring a high-level
* lock, serialize so multiple threads don't walk the tree at
* the same time. We're holding the schema lock, but need the
* lower-level lock as well.
*/
__wt_spin_lock(session, &btree->flush_lock);
/*
* When internal pages are being reconciled by checkpoint their
* child pages cannot disappear from underneath them or be split
* into them, nor can underlying blocks be freed until the block
* lists for the checkpoint are stable. Set the checkpointing
* flag to block eviction of dirty pages until the checkpoint's
* internal page pass is complete, then wait for any existing
* eviction to complete.
*/
btree->checkpointing = 1;
WT_FULL_BARRIER();
WT_ERR(__wt_evict_file_exclusive_on(session, &evict_reset));
if (evict_reset)
__wt_evict_file_exclusive_off(session);
/* Write all dirty in-cache pages. */
flags |= WT_READ_NO_EVICT;
for (walk = NULL;;) {
/*
* If we have a page, and it was ever modified, track
* the highest transaction ID in the tree. We do this
* here because we want the value after reconciling
* dirty pages.
*/
if (walk != NULL && walk->page != NULL &&
(mod = walk->page->modify) != NULL &&
WT_TXNID_LT(btree->rec_max_txn, mod->rec_max_txn))
btree->rec_max_txn = mod->rec_max_txn;
WT_ERR(__wt_tree_walk(session, &walk, NULL, flags));
if (walk == NULL)
break;
page = walk->page;
mod = page->modify;
/* Skip clean pages. */
if (!__wt_page_is_modified(page))
continue;
/*
* Write dirty pages, unless we can be sure they only
* became dirty after the checkpoint started.
*
* We can skip dirty pages if:
* (1) they are leaf pages;
* (2) there is a snapshot transaction active (which
* is the case in ordinary application checkpoints
* but not all internal cases); and
* (3) the first dirty update on the page is
* sufficiently recent that the checkpoint
* transaction would skip them.
*
* Mark the tree dirty: the checkpoint marked it clean
* and we can't skip future checkpoints until this page
* is written.
*/
if (!WT_PAGE_IS_INTERNAL(page) &&
F_ISSET(txn, WT_TXN_HAS_SNAPSHOT) &&
WT_TXNID_LT(txn->snap_max, mod->first_dirty_txn) &&
mod->rec_result != WT_PM_REC_REWRITE) {
__wt_page_modify_set(session, page);
continue;
}
if (WT_PAGE_IS_INTERNAL(page)) {
internal_bytes += page->memory_footprint;
++internal_pages;
} else {
leaf_bytes += page->memory_footprint;
++leaf_pages;
}
WT_ERR(__wt_reconcile(session, walk, NULL, 0));
}
break;
}
if (WT_VERBOSE_ISSET(session, WT_VERB_CHECKPOINT)) {
WT_ERR(__wt_epoch(session, &end));
WT_ERR(__wt_verbose(session, WT_VERB_CHECKPOINT,
"__sync_file WT_SYNC_%s wrote:\n\t %" PRIu64
" bytes, %" PRIu64 " pages of leaves\n\t %" PRIu64
" bytes, %" PRIu64 " pages of internal\n\t"
"Took: %" PRIu64 "ms",
syncop == WT_SYNC_WRITE_LEAVES ?
"WRITE_LEAVES" : "CHECKPOINT",
leaf_bytes, leaf_pages, internal_bytes, internal_pages,
WT_TIMEDIFF(end, start) / WT_MILLION));
}
err: /* On error, clear any left-over tree walk. */
if (walk != NULL)
WT_TRET(__wt_page_release(session, walk, flags));
if (txn->isolation == WT_ISO_READ_COMMITTED && session->ncursors == 0)
__wt_txn_release_snapshot(session);
if (btree->checkpointing) {
/*
* Update the checkpoint generation for this handle so visible
* updates newer than the checkpoint can be evicted.
*
* This has to be published before eviction is enabled again,
* so that eviction knows that the checkpoint has completed.
*/
WT_PUBLISH(btree->checkpoint_gen,
S2C(session)->txn_global.checkpoint_gen);
WT_STAT_FAST_DATA_SET(session,
btree_checkpoint_generation, btree->checkpoint_gen);
/*
* Clear the checkpoint flag and push the change; not required,
* but publishing the change means stalled eviction gets moving
* as soon as possible.
*/
btree->checkpointing = 0;
WT_FULL_BARRIER();
/*
* If this tree was being skipped by the eviction server during
* the checkpoint, clear the wait.
*/
btree->evict_walk_period = 0;
/*
* Wake the eviction server, in case application threads have
* stalled while the eviction server decided it couldn't make
* progress. Without this, application threads will be stalled
* until the eviction server next wakes.
*/
WT_TRET(__wt_evict_server_wake(session));
}
__wt_spin_unlock(session, &btree->flush_lock);
/*
* Leaves are written before a checkpoint (or as part of a file close,
* before checkpointing the file). Start a flush to stable storage,
* but don't wait for it.
*/
if (ret == 0 && syncop == WT_SYNC_WRITE_LEAVES)
WT_RET(btree->bm->sync(btree->bm, session, true));
return (ret);
}
/*
* __sync_file --
* Flush pages for a specific file.
*/
static int
__sync_file(WT_SESSION_IMPL *session, WT_CACHE_OP syncop)
{
struct timespec end, start;
WT_BTREE *btree;
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_PAGE *page;
WT_PAGE_MODIFY *mod;
WT_REF *walk;
WT_TXN *txn;
uint64_t internal_bytes, internal_pages, leaf_bytes, leaf_pages;
uint64_t oldest_id, saved_snap_min;
uint32_t flags;
conn = S2C(session);
btree = S2BT(session);
walk = NULL;
txn = &session->txn;
saved_snap_min = WT_SESSION_TXN_STATE(session)->snap_min;
flags = WT_READ_CACHE | WT_READ_NO_GEN;
internal_bytes = leaf_bytes = 0;
internal_pages = leaf_pages = 0;
if (WT_VERBOSE_ISSET(session, WT_VERB_CHECKPOINT))
WT_RET(__wt_epoch(session, &start));
switch (syncop) {
case WT_SYNC_WRITE_LEAVES:
/*
* Write all immediately available, dirty in-cache leaf pages.
*
* Writing the leaf pages is done without acquiring a high-level
* lock, serialize so multiple threads don't walk the tree at
* the same time.
*/
if (!btree->modified)
return (0);
__wt_spin_lock(session, &btree->flush_lock);
if (!btree->modified) {
__wt_spin_unlock(session, &btree->flush_lock);
return (0);
}
/*
* Save the oldest transaction ID we need to keep around.
* Otherwise, in a busy system, we could be updating pages so
* fast that write leaves never catches up. We deliberately
* have no transaction running at this point that would keep
* the oldest ID from moving forwards as we walk the tree.
*/
oldest_id = __wt_txn_oldest_id(session);
flags |= WT_READ_NO_WAIT | WT_READ_SKIP_INTL;
for (walk = NULL;;) {
WT_ERR(__wt_tree_walk(session, &walk, flags));
if (walk == NULL)
break;
/*
* Write dirty pages if nobody beat us to it. Don't
* try to write hot pages (defined as pages that have
* been updated since the write phase leaves started):
* checkpoint will have to visit them anyway.
*/
page = walk->page;
if (__wt_page_is_modified(page) &&
WT_TXNID_LT(page->modify->update_txn, oldest_id)) {
if (txn->isolation == WT_ISO_READ_COMMITTED)
__wt_txn_get_snapshot(session);
leaf_bytes += page->memory_footprint;
++leaf_pages;
WT_ERR(__wt_reconcile(session, walk, NULL, 0));
}
}
break;
case WT_SYNC_CHECKPOINT:
/*
* If we are flushing a file at read-committed isolation, which
* is of particular interest for flushing the metadata to make
* schema-changing operation durable, get a transactional
* snapshot now.
*
* All changes committed up to this point should be included.
* We don't update the snapshot in between pages because (a)
* the metadata shouldn't be that big, and (b) if we do ever
*/
if (txn->isolation == WT_ISO_READ_COMMITTED)
__wt_txn_get_snapshot(session);
/*
* We cannot check the tree modified flag in the case of a
* checkpoint, the checkpoint code has already cleared it.
*
* Writing the leaf pages is done without acquiring a high-level
* lock, serialize so multiple threads don't walk the tree at
* the same time. We're holding the schema lock, but need the
* lower-level lock as well.
*/
__wt_spin_lock(session, &btree->flush_lock);
/*
* In the final checkpoint pass, child pages cannot be evicted
* from underneath internal pages nor can underlying blocks be
* freed until the checkpoint's block lists are stable. Also,
* we cannot split child pages into parents unless we know the
* final pass will write a consistent view of that namespace.
* Set the checkpointing flag to block such actions and wait for
* any problematic eviction or page splits to complete.
*/
WT_PUBLISH(btree->checkpointing, WT_CKPT_PREPARE);
WT_ERR(__wt_evict_file_exclusive_on(session));
__wt_evict_file_exclusive_off(session);
WT_PUBLISH(btree->checkpointing, WT_CKPT_RUNNING);
/* Write all dirty in-cache pages. */
flags |= WT_READ_NO_EVICT;
for (walk = NULL;;) {
WT_ERR(__wt_tree_walk(session, &walk, flags));
if (walk == NULL)
break;
/* Skip clean pages. */
if (!__wt_page_is_modified(walk->page))
continue;
/*
* Take a local reference to the page modify structure
* now that we know the page is dirty. It needs to be
* done in this order otherwise the page modify
* structure could have been created between taking the
* reference and checking modified.
*/
page = walk->page;
mod = page->modify;
/*
* Write dirty pages, unless we can be sure they only
* became dirty after the checkpoint started.
*
* We can skip dirty pages if:
* (1) they are leaf pages;
* (2) there is a snapshot transaction active (which
* is the case in ordinary application checkpoints
* but not all internal cases); and
* (3) the first dirty update on the page is
* sufficiently recent that the checkpoint
* transaction would skip them.
*
* Mark the tree dirty: the checkpoint marked it clean
* and we can't skip future checkpoints until this page
* is written.
*/
if (!WT_PAGE_IS_INTERNAL(page) &&
F_ISSET(txn, WT_TXN_HAS_SNAPSHOT) &&
WT_TXNID_LT(txn->snap_max, mod->first_dirty_txn)) {
__wt_page_modify_set(session, page);
continue;
}
if (WT_PAGE_IS_INTERNAL(page)) {
internal_bytes += page->memory_footprint;
++internal_pages;
} else {
leaf_bytes += page->memory_footprint;
++leaf_pages;
}
WT_ERR(__wt_reconcile(session, walk, NULL, 0));
}
break;
case WT_SYNC_CLOSE:
case WT_SYNC_DISCARD:
WT_ILLEGAL_VALUE_ERR(session);
}
if (WT_VERBOSE_ISSET(session, WT_VERB_CHECKPOINT)) {
WT_ERR(__wt_epoch(session, &end));
WT_ERR(__wt_verbose(session, WT_VERB_CHECKPOINT,
"__sync_file WT_SYNC_%s wrote:\n\t %" PRIu64
" bytes, %" PRIu64 " pages of leaves\n\t %" PRIu64
" bytes, %" PRIu64 " pages of internal\n\t"
"Took: %" PRIu64 "ms",
syncop == WT_SYNC_WRITE_LEAVES ?
"WRITE_LEAVES" : "CHECKPOINT",
leaf_bytes, leaf_pages, internal_bytes, internal_pages,
WT_TIMEDIFF_MS(end, start)));
}
err: /* On error, clear any left-over tree walk. */
if (walk != NULL)
WT_TRET(__wt_page_release(session, walk, flags));
/*
* If we got a snapshot in order to write pages, and there was no
* snapshot active when we started, release it.
*/
if (txn->isolation == WT_ISO_READ_COMMITTED &&
saved_snap_min == WT_TXN_NONE)
__wt_txn_release_snapshot(session);
if (btree->checkpointing != WT_CKPT_OFF) {
/*
* Update the checkpoint generation for this handle so visible
* updates newer than the checkpoint can be evicted.
*
* This has to be published before eviction is enabled again,
* so that eviction knows that the checkpoint has completed.
*/
WT_PUBLISH(btree->checkpoint_gen,
conn->txn_global.checkpoint_gen);
WT_STAT_FAST_DATA_SET(session,
btree_checkpoint_generation, btree->checkpoint_gen);
/*
* Clear the checkpoint flag and push the change; not required,
* but publishing the change means stalled eviction gets moving
* as soon as possible.
*/
btree->checkpointing = WT_CKPT_OFF;
WT_FULL_BARRIER();
/*
* If this tree was being skipped by the eviction server during
* the checkpoint, clear the wait.
*/
btree->evict_walk_period = 0;
/*
* Wake the eviction server, in case application threads have
* stalled while the eviction server decided it couldn't make
* progress. Without this, application threads will be stalled
* until the eviction server next wakes.
*/
WT_TRET(__wt_evict_server_wake(session));
}
__wt_spin_unlock(session, &btree->flush_lock);
/*
* Leaves are written before a checkpoint (or as part of a file close,
* before checkpointing the file). Start a flush to stable storage,
* but don't wait for it.
*/
if (ret == 0 &&
syncop == WT_SYNC_WRITE_LEAVES && F_ISSET(conn, WT_CONN_CKPT_SYNC))
WT_RET(btree->bm->sync(btree->bm, session, true));
return (ret);
}
/*
* __wt_hazard_set --
* Set a hazard pointer.
*/
int
__wt_hazard_set(WT_SESSION_IMPL *session, WT_REF *ref, bool *busyp
#ifdef HAVE_DIAGNOSTIC
, const char *file, int line
#endif
)
{
WT_BTREE *btree;
WT_CONNECTION_IMPL *conn;
WT_HAZARD *hp;
int restarts = 0;
btree = S2BT(session);
conn = S2C(session);
*busyp = false;
/* If a file can never be evicted, hazard pointers aren't required. */
if (F_ISSET(btree, WT_BTREE_IN_MEMORY))
return (0);
/*
* Do the dance:
*
* The memory location which makes a page "real" is the WT_REF's state
* of WT_REF_MEM, which can be set to WT_REF_LOCKED at any time by the
* page eviction server.
*
* Add the WT_REF reference to the session's hazard list and flush the
* write, then see if the page's state is still valid. If so, we can
* use the page because the page eviction server will see our hazard
* pointer before it discards the page (the eviction server sets the
* state to WT_REF_LOCKED, then flushes memory and checks the hazard
* pointers).
*
* For sessions with many active hazard pointers, skip most of the
* active slots: there may be a free slot in there, but checking is
* expensive. Most hazard pointers are released quickly: optimize
* for that case.
*/
for (hp = session->hazard + session->nhazard;; ++hp) {
/*
* If we get to the end of the array, either:
* 1. If we know there are free slots somewhere, and this is
* the first time through, continue the search from the
* start. Don't actually continue the loop because that
* will skip the first slot.
* 2. If we have searched all the way through and we have
* allocated the maximum number of slots, give up.
* 3. Allocate another increment of slots, up to the maximum.
* The slot we are on should now be available.
*/
if (hp >= session->hazard + session->hazard_size) {
if (session->nhazard < session->hazard_size &&
restarts++ == 0)
hp = session->hazard;
else if (session->hazard_size >= conn->hazard_max)
break;
else
WT_PUBLISH(session->hazard_size, WT_MIN(
session->hazard_size + WT_HAZARD_INCR,
conn->hazard_max));
}
if (hp->page != NULL)
continue;
hp->page = ref->page;
#ifdef HAVE_DIAGNOSTIC
hp->file = file;
hp->line = line;
#endif
/* Publish the hazard pointer before reading page's state. */
WT_FULL_BARRIER();
/*
* Check if the page state is still valid, where valid means a
* state of WT_REF_MEM and the pointer is unchanged. (The
* pointer can change, it means the page was evicted between
* the time we set our hazard pointer and the publication. It
* would theoretically be possible for the page to be evicted
* and a different page read into the same memory, so the
* pointer hasn't changed but the contents have. That's OK, we
* found this page using the tree's key space, whatever page we
* find here is the page for us to use.)
*/
if (ref->page == hp->page && ref->state == WT_REF_MEM) {
++session->nhazard;
return (0);
}
/*
* The page isn't available, it's being considered for eviction
* (or being evicted, for all we know). If the eviction server
* sees our hazard pointer before evicting the page, it will
* return the page to use, no harm done, if it doesn't, it will
* go ahead and complete the eviction.
*
* We don't bother publishing this update: the worst case is we
* prevent some random page from being evicted.
*/
hp->page = NULL;
*busyp = true;
return (0);
}
__wt_errx(session,
"session %p: hazard pointer table full", (void *)session);
#ifdef HAVE_DIAGNOSTIC
__hazard_dump(session);
#endif
return (ENOMEM);
}
/*
* __wt_statlog_dump_spinlock --
* Log the spin-lock statistics.
*/
int
__wt_statlog_dump_spinlock(WT_CONNECTION_IMPL *conn, const char *tag)
{
WT_SPINLOCK *spin;
WT_CONNECTION_STATS_SPINLOCK *p, *t;
uint64_t block_manager, btree_page, ignore;
u_int i, j;
/*
* Ignore rare acquisition of a spinlock using a base value of 10 per
* second so we don't create graphs we don't care about.
*/
ignore = (uint64_t)(conn->stat_usecs / 1000000) * 10;
/* Output the number of times each spinlock was acquired. */
block_manager = btree_page = 0;
for (i = 0; i < WT_ELEMENTS(conn->spinlock_list); ++i) {
if ((spin = conn->spinlock_list[i]) == NULL)
continue;
/*
* There are two sets of spinlocks we aggregate, the btree page
* locks and the block manager per-file locks. The reason is
* the block manager locks grow with the number of files open
* (and LSM and bloom filters can open a lot of files), and
* there are 16 btree page locks and splitting them out has not
* historically been that informative.
*/
if (strcmp(spin->name, "block manager") == 0) {
block_manager += spin->counter;
if (conn->stat_clear)
spin->counter = 0;
continue;
}
if (strcmp(spin->name, "btree page") == 0) {
btree_page += spin->counter;
if (conn->stat_clear)
spin->counter = 0;
continue;
}
WT_RET_TEST((fprintf(conn->stat_fp,
"%s %" PRIu64 " %s spinlock %s: acquisitions\n",
conn->stat_stamp,
spin->counter <= ignore ? 0 : spin->counter,
tag, spin->name) < 0),
__wt_errno());
if (conn->stat_clear)
spin->counter = 0;
}
WT_RET_TEST((fprintf(conn->stat_fp,
"%s %" PRIu64 " %s spinlock %s: acquisitions\n",
conn->stat_stamp,
block_manager <= ignore ? 0 : block_manager,
tag, "block manager") < 0),
__wt_errno());
WT_RET_TEST((fprintf(conn->stat_fp,
"%s %" PRIu64 " %s spinlock %s: acquisitions\n",
conn->stat_stamp,
btree_page <= ignore ? 0 : btree_page,
tag, "btree page") < 0),
__wt_errno());
/*
* Output the number of times each location acquires its spinlock and
* the blocking matrix.
*/
for (i = 0; i < WT_ELEMENTS(conn->spinlock_block); ++i) {
p = &conn->spinlock_block[i];
if (p->name == NULL)
continue;
WT_RET_TEST((fprintf(conn->stat_fp,
"%s %d %s spinlock %s acquired by %s(%d)\n",
conn->stat_stamp,
p->total <= ignore ? 0 : p->total,
tag,
p->name, p->file, p->line) < 0), __wt_errno());
if (conn->stat_clear)
p->total = 0;
for (j = 0; j < WT_ELEMENTS(conn->spinlock_block); ++j) {
t = &conn->spinlock_block[j];
if (t->name == NULL)
continue;
WT_RET_TEST((fprintf(conn->stat_fp,
"%s %d %s spinlock %s: %s(%d) blocked by %s(%d)\n",
conn->stat_stamp,
p->blocked[j] <= ignore ? 0 : p->blocked[j],
tag,
p->name, p->file, p->line,
t->file, t->line) < 0), __wt_errno());
if (conn->stat_clear)
p->blocked[j] = 0;
}
}
WT_FULL_BARRIER(); /* Minimize the window. */
return (0);
}
/*
* __wt_connection_close --
* Close a connection handle.
*/
int
__wt_connection_close(WT_CONNECTION_IMPL *conn)
{
WT_CONNECTION *wt_conn;
WT_DECL_RET;
WT_DLH *dlh;
WT_SESSION_IMPL *s, *session;
u_int i;
wt_conn = &conn->iface;
session = conn->default_session;
/* Shut down transactions (wait for in-flight operations to complete. */
WT_TRET(__wt_txn_global_shutdown(session));
/* Shut down the subsystems, ensuring workers see the state change. */
F_SET(conn, WT_CONN_CLOSING);
WT_FULL_BARRIER();
/*
* Clear any pending async operations and shut down the async worker
* threads and system before closing LSM.
*/
WT_TRET(__wt_async_flush(session));
WT_TRET(__wt_async_destroy(session));
/*
* Shut down server threads other than the eviction server, which is
* needed later to close btree handles. Some of these threads access
* btree handles, so take care in ordering shutdown to make sure they
* exit before files are closed.
*/
WT_TRET(__wt_lsm_manager_destroy(session));
/*
* Once the async and LSM threads exit, we shouldn't be opening any
* more files.
*/
F_SET(conn, WT_CONN_CLOSING_NO_MORE_OPENS);
WT_FULL_BARRIER();
WT_TRET(__wt_checkpoint_server_destroy(session));
WT_TRET(__wt_statlog_destroy(session, true));
WT_TRET(__wt_sweep_destroy(session));
/* The eviction server is shut down last. */
WT_TRET(__wt_evict_destroy(session));
/* Shut down the lookaside table, after all eviction is complete. */
WT_TRET(__wt_las_destroy(session));
/* Close open data handles. */
WT_TRET(__wt_conn_dhandle_discard(session));
/* Shut down metadata tracking. */
WT_TRET(__wt_meta_track_destroy(session));
/*
* Now that all data handles are closed, tell logging that a checkpoint
* has completed then shut down the log manager (only after closing
* data handles). The call to destroy the log manager is outside the
* conditional because we allocate the log path so that printlog can
* run without running logging or recovery.
*/
if (FLD_ISSET(conn->log_flags, WT_CONN_LOG_ENABLED) &&
FLD_ISSET(conn->log_flags, WT_CONN_LOG_RECOVER_DONE))
WT_TRET(__wt_txn_checkpoint_log(
session, true, WT_TXN_LOG_CKPT_STOP, NULL));
WT_TRET(__wt_logmgr_destroy(session));
/* Free memory for collators, compressors, data sources. */
WT_TRET(__wt_conn_remove_collator(session));
WT_TRET(__wt_conn_remove_compressor(session));
WT_TRET(__wt_conn_remove_data_source(session));
WT_TRET(__wt_conn_remove_encryptor(session));
WT_TRET(__wt_conn_remove_extractor(session));
/* Disconnect from shared cache - must be before cache destroy. */
WT_TRET(__wt_conn_cache_pool_destroy(session));
/* Discard the cache. */
WT_TRET(__wt_cache_destroy(session));
/* Discard transaction state. */
__wt_txn_global_destroy(session);
/* Close the lock file, opening up the database to other connections. */
if (conn->lock_fh != NULL)
WT_TRET(__wt_close(session, &conn->lock_fh));
/* Close any file handles left open. */
WT_TRET(__wt_close_connection_close(session));
/*
* Close the internal (default) session, and switch back to the dummy
* session in case of any error messages from the remaining operations
* while destroying the connection handle.
*/
if (session != &conn->dummy_session) {
WT_TRET(session->iface.close(&session->iface, NULL));
session = conn->default_session = &conn->dummy_session;
}
/*
* The session split stash, hazard information and handle arrays aren't
* discarded during normal session close, they persist past the life of
* the session. Discard them now.
*/
if (!F_ISSET(conn, WT_CONN_LEAK_MEMORY))
if ((s = conn->sessions) != NULL)
for (i = 0; i < conn->session_size; ++s, ++i) {
__wt_free(session, s->dhhash);
__wt_stash_discard_all(session, s);
__wt_free(session, s->hazard);
}
/* Destroy the file-system configuration. */
if (conn->file_system != NULL && conn->file_system->terminate != NULL)
WT_TRET(conn->file_system->terminate(
conn->file_system, (WT_SESSION *)session));
/* Close extensions, first calling any unload entry point. */
while ((dlh = TAILQ_FIRST(&conn->dlhqh)) != NULL) {
TAILQ_REMOVE(&conn->dlhqh, dlh, q);
if (dlh->terminate != NULL)
WT_TRET(dlh->terminate(wt_conn));
WT_TRET(__wt_dlclose(session, dlh));
}
/* Destroy the handle. */
__wt_connection_destroy(conn);
return (ret);
}
/*
* __wt_hazard_set --
* Set a hazard pointer.
*/
int
__wt_hazard_set(WT_SESSION_IMPL *session, WT_REF *ref, int *busyp
#ifdef HAVE_DIAGNOSTIC
, const char *file, int line
#endif
)
{
WT_BTREE *btree;
WT_HAZARD *hp;
int restarts = 0;
btree = S2BT(session);
*busyp = 0;
/* If a file can never be evicted, hazard pointers aren't required. */
if (F_ISSET(btree, WT_BTREE_NO_HAZARD))
return (0);
/*
* Do the dance:
*
* The memory location which makes a page "real" is the WT_REF's state
* of WT_REF_MEM, which can be set to WT_REF_LOCKED at any time by the
* page eviction server.
*
* Add the WT_REF reference to the session's hazard list and flush the
* write, then see if the page's state is still valid. If so, we can
* use the page because the page eviction server will see our hazard
* pointer before it discards the page (the eviction server sets the
* state to WT_REF_LOCKED, then flushes memory and checks the hazard
* pointers).
*
* For sessions with many active hazard pointers, skip most of the
* active slots: there may be a free slot in there, but checking is
* expensive. Most hazard pointers are released quickly: optimize
* for that case.
*/
for (hp = session->hazard + session->nhazard;; ++hp) {
/* Expand the number of hazard pointers if available.*/
if (hp >= session->hazard + session->hazard_size) {
if (session->hazard_size >= S2C(session)->hazard_max)
break;
/* Restart the search. */
if (session->nhazard < session->hazard_size &&
restarts++ == 0) {
hp = session->hazard;
continue;
}
WT_PUBLISH(session->hazard_size,
WT_MIN(session->hazard_size + WT_HAZARD_INCR,
S2C(session)->hazard_max));
}
if (hp->page != NULL)
continue;
hp->page = ref->page;
#ifdef HAVE_DIAGNOSTIC
hp->file = file;
hp->line = line;
#endif
/* Publish the hazard pointer before reading page's state. */
WT_FULL_BARRIER();
/*
* Check if the page state is still valid, where valid means a
* state of WT_REF_MEM or WT_REF_EVICT_WALK and the pointer is
* unchanged. (The pointer can change, it means the page was
* evicted between the time we set our hazard pointer and the
* publication. It would theoretically be possible for the
* page to be evicted and a different page read into the same
* memory, so the pointer hasn't changed but the contents have.
* That's OK, we found this page using the tree's key space,
* whatever page we find here is the page for us to use.)
*/
if (ref->page == hp->page &&
(ref->state == WT_REF_MEM ||
ref->state == WT_REF_EVICT_WALK)) {
WT_VERBOSE_RET(session, hazard,
"session %p hazard %p: set", session, ref->page);
++session->nhazard;
return (0);
}
/*
* The page isn't available, it's being considered for eviction
* (or being evicted, for all we know). If the eviction server
* sees our hazard pointer before evicting the page, it will
* return the page to use, no harm done, if it doesn't, it will
* go ahead and complete the eviction.
*
* We don't bother publishing this update: the worst case is we
* prevent some random page from being evicted.
*/
hp->page = NULL;
*busyp = 1;
return (0);
}
__wt_errx(session,
"session %p: hazard pointer table full", session);
#ifdef HAVE_DIAGNOSTIC
__hazard_dump(session);
#endif
return (ENOMEM);
}
/*
* __log_file_server --
* The log file server thread. This worker thread manages
* log file operations such as closing and syncing.
*/
static WT_THREAD_RET
__log_file_server(void *arg)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_FH *close_fh;
WT_LOG *log;
WT_LSN close_end_lsn, min_lsn;
WT_SESSION_IMPL *session;
uint32_t filenum;
bool locked;
session = arg;
conn = S2C(session);
log = conn->log;
locked = false;
while (F_ISSET(conn, WT_CONN_LOG_SERVER_RUN)) {
/*
* If there is a log file to close, make sure any outstanding
* write operations have completed, then fsync and close it.
*/
if ((close_fh = log->log_close_fh) != NULL) {
WT_ERR(__wt_log_extract_lognum(session, close_fh->name,
&filenum));
/*
* We update the close file handle before updating the
* close LSN when changing files. It is possible we
* could see mismatched settings. If we do, yield
* until it is set. This should rarely happen.
*/
while (log->log_close_lsn.l.file < filenum)
__wt_yield();
if (__wt_log_cmp(
&log->write_lsn, &log->log_close_lsn) >= 0) {
/*
* We've copied the file handle, clear out the
* one in the log structure to allow it to be
* set again. Copy the LSN before clearing
* the file handle.
* Use a barrier to make sure the compiler does
* not reorder the following two statements.
*/
close_end_lsn = log->log_close_lsn;
WT_FULL_BARRIER();
log->log_close_fh = NULL;
/*
* Set the close_end_lsn to the LSN immediately
* after ours. That is, the beginning of the
* next log file. We need to know the LSN
* file number of our own close in case earlier
* calls are still in progress and the next one
* to move the sync_lsn into the next file for
* later syncs.
*/
WT_ERR(__wt_fsync(session, close_fh, true));
/*
* We want to have the file size reflect actual
* data with minimal pre-allocated zeroed space.
* We can't truncate the file during hot backup,
* or the underlying file system may not support
* truncate: both are OK, it's just more work
* during cursor traversal.
*/
if (!conn->hot_backup) {
__wt_readlock(
session, conn->hot_backup_lock);
if (!conn->hot_backup)
WT_ERR_ERROR_OK(
__wt_ftruncate(session,
close_fh,
close_end_lsn.l.offset),
ENOTSUP);
__wt_readunlock(
session, conn->hot_backup_lock);
}
WT_SET_LSN(&close_end_lsn,
close_end_lsn.l.file + 1, 0);
__wt_spin_lock(session, &log->log_sync_lock);
locked = true;
WT_ERR(__wt_close(session, &close_fh));
WT_ASSERT(session, __wt_log_cmp(
&close_end_lsn, &log->sync_lsn) >= 0);
log->sync_lsn = close_end_lsn;
__wt_cond_signal(session, log->log_sync_cond);
locked = false;
__wt_spin_unlock(session, &log->log_sync_lock);
}
}
/*
* If a later thread asked for a background sync, do it now.
*/
if (__wt_log_cmp(&log->bg_sync_lsn, &log->sync_lsn) > 0) {
/*
* Save the latest write LSN which is the minimum
* we will have written to disk.
*/
min_lsn = log->write_lsn;
/*
* We have to wait until the LSN we asked for is
* written. If it isn't signal the wrlsn thread
* to get it written.
*
* We also have to wait for the written LSN and the
* sync LSN to be in the same file so that we know we
* have synchronized all earlier log files.
*/
if (__wt_log_cmp(&log->bg_sync_lsn, &min_lsn) <= 0) {
/*
* If the sync file is behind either the one
* wanted for a background sync or the write LSN
* has moved to another file continue to let
* this worker thread process that older file
* immediately.
*/
if ((log->sync_lsn.l.file <
log->bg_sync_lsn.l.file) ||
(log->sync_lsn.l.file < min_lsn.l.file))
continue;
WT_ERR(__wt_fsync(session, log->log_fh, true));
__wt_spin_lock(session, &log->log_sync_lock);
locked = true;
/*
* The sync LSN could have advanced while we
* were writing to disk.
*/
if (__wt_log_cmp(
&log->sync_lsn, &min_lsn) <= 0) {
WT_ASSERT(session,
min_lsn.l.file ==
log->sync_lsn.l.file);
log->sync_lsn = min_lsn;
__wt_cond_signal(
session, log->log_sync_cond);
}
locked = false;
__wt_spin_unlock(session, &log->log_sync_lock);
} else {
__wt_cond_auto_signal(
session, conn->log_wrlsn_cond);
/*
* We do not want to wait potentially a second
* to process this. Yield to give the wrlsn
* thread a chance to run and try again in
* this case.
*/
__wt_yield();
continue;
}
}
/* Wait until the next event. */
__wt_cond_wait(session, conn->log_file_cond, WT_MILLION / 10);
}
if (0) {
err: __wt_err(session, ret, "log close server error");
}
if (locked)
__wt_spin_unlock(session, &log->log_sync_lock);
return (WT_THREAD_RET_VALUE);
}
/*
* __log_file_server --
* The log file server thread. This worker thread manages
* log file operations such as closing and syncing.
*/
static WT_THREAD_RET
__log_file_server(void *arg)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_FH *close_fh;
WT_LOG *log;
WT_LSN close_end_lsn, min_lsn;
WT_SESSION_IMPL *session;
uint32_t filenum;
int locked;
session = arg;
conn = S2C(session);
log = conn->log;
locked = 0;
while (F_ISSET(conn, WT_CONN_LOG_SERVER_RUN)) {
/*
* If there is a log file to close, make sure any outstanding
* write operations have completed, then fsync and close it.
*/
if ((close_fh = log->log_close_fh) != NULL) {
WT_ERR(__wt_log_extract_lognum(session, close_fh->name,
&filenum));
/*
* We update the close file handle before updating the
* close LSN when changing files. It is possible we
* could see mismatched settings. If we do, yield
* until it is set. This should rarely happen.
*/
while (log->log_close_lsn.file < filenum)
__wt_yield();
if (__wt_log_cmp(
&log->write_lsn, &log->log_close_lsn) >= 0) {
/*
* We've copied the file handle, clear out the
* one in the log structure to allow it to be
* set again. Copy the LSN before clearing
* the file handle.
* Use a barrier to make sure the compiler does
* not reorder the following two statements.
*/
close_end_lsn = log->log_close_lsn;
WT_FULL_BARRIER();
log->log_close_fh = NULL;
/*
* Set the close_end_lsn to the LSN immediately
* after ours. That is, the beginning of the
* next log file. We need to know the LSN
* file number of our own close in case earlier
* calls are still in progress and the next one
* to move the sync_lsn into the next file for
* later syncs.
*/
close_end_lsn.file++;
close_end_lsn.offset = 0;
WT_ERR(__wt_fsync(session, close_fh));
__wt_spin_lock(session, &log->log_sync_lock);
locked = 1;
WT_ERR(__wt_close(session, &close_fh));
WT_ASSERT(session, __wt_log_cmp(
&close_end_lsn, &log->sync_lsn) >= 0);
log->sync_lsn = close_end_lsn;
WT_ERR(__wt_cond_signal(
session, log->log_sync_cond));
locked = 0;
__wt_spin_unlock(session, &log->log_sync_lock);
}
}
/*
* If a later thread asked for a background sync, do it now.
*/
if (__wt_log_cmp(&log->bg_sync_lsn, &log->sync_lsn) > 0) {
/*
* Save the latest write LSN which is the minimum
* we will have written to disk.
*/
min_lsn = log->write_lsn;
/*
* We have to wait until the LSN we asked for is
* written. If it isn't signal the wrlsn thread
* to get it written.
*/
if (__wt_log_cmp(&log->bg_sync_lsn, &min_lsn) <= 0) {
WT_ERR(__wt_fsync(session, log->log_fh));
__wt_spin_lock(session, &log->log_sync_lock);
locked = 1;
/*
* The sync LSN could have advanced while we
* were writing to disk.
*/
if (__wt_log_cmp(
&log->sync_lsn, &min_lsn) <= 0) {
log->sync_lsn = min_lsn;
WT_ERR(__wt_cond_signal(
session, log->log_sync_cond));
}
locked = 0;
__wt_spin_unlock(session, &log->log_sync_lock);
} else {
WT_ERR(__wt_cond_signal(
session, conn->log_wrlsn_cond));
/*
* We do not want to wait potentially a second
* to process this. Yield to give the wrlsn
* thread a chance to run and try again in
* this case.
*/
__wt_yield();
continue;
}
}
/* Wait until the next event. */
WT_ERR(__wt_cond_wait(
session, conn->log_file_cond, WT_MILLION));
}
if (0) {
err: __wt_err(session, ret, "log close server error");
}
if (locked)
__wt_spin_unlock(session, &log->log_sync_lock);
return (WT_THREAD_RET_VALUE);
}
/*
* __wt_compact_page_skip --
* Return if compaction requires we read this page.
*/
int
__wt_compact_page_skip(WT_SESSION_IMPL *session, WT_REF *ref, bool *skipp)
{
WT_BM *bm;
WT_DECL_RET;
size_t addr_size;
u_int type;
const uint8_t *addr;
/*
* Skip deleted pages, rewriting them doesn't seem useful; in a better
* world we'd write the parent to delete the page.
*/
if (ref->state == WT_REF_DELETED) {
*skipp = true;
return (0);
}
*skipp = false; /* Default to reading */
/*
* If the page is in-memory, we want to look at it (it may have been
* modified and written, and the current location is the interesting
* one in terms of compaction, not the original location).
*
* This test could be combined with the next one, but this is a cheap
* test and the next one is expensive.
*/
if (ref->state != WT_REF_DISK)
return (0);
/*
* There's nothing to prevent the WT_REF state from changing underfoot,
* which can change its address. For example, the WT_REF address might
* reference an on-page cell, and page eviction can free that memory.
* Lock the WT_REF so we can look at its address.
*/
if (!__wt_atomic_casv32(&ref->state, WT_REF_DISK, WT_REF_LOCKED))
return (0);
/*
* The page is on disk, so there had better be an address; assert that
* fact, test at run-time to avoid the core dump.
*
* Internal pages must be read to walk the tree; ask the block-manager
* if it's useful to rewrite leaf pages, don't do the I/O if a rewrite
* won't help.
*/
__wt_ref_info(ref, &addr, &addr_size, &type);
WT_ASSERT(session, addr != NULL);
if (addr != NULL && type != WT_CELL_ADDR_INT) {
bm = S2BT(session)->bm;
ret = bm->compact_page_skip(
bm, session, addr, addr_size, skipp);
}
/*
* Reset the WT_REF state and push the change. The full-barrier isn't
* necessary, but it's better to keep pages in circulation than not.
*/
ref->state = WT_REF_DISK;
WT_FULL_BARRIER();
return (ret);
}