/*
* __wt_log_slot_close --
* Close a slot and do not allow any other threads to join this slot.
* Remove this from the active slot array and move a new slot from
* the pool into its place. Set up the size of this group;
* Must be called with the logging spinlock held.
*/
int
__wt_log_slot_close(WT_SESSION_IMPL *session, WT_LOGSLOT *slot)
{
WT_CONNECTION_IMPL *conn;
WT_LOG *log;
WT_LOGSLOT *newslot;
int64_t old_state;
conn = S2C(session);
log = conn->log;
/*
* Find an unused slot in the pool.
*/
WT_RET(__log_slot_find_free(session, &newslot));
/*
* Swap out the slot we're going to use and put a free one in the
* slot array in its place so that threads can use it right away.
*/
WT_STAT_FAST_CONN_INCR(session, log_slot_closes);
newslot->slot_state = WT_LOG_SLOT_READY;
newslot->slot_index = slot->slot_index;
log->slot_array[newslot->slot_index] = newslot;
old_state = WT_ATOMIC_STORE8(slot->slot_state, WT_LOG_SLOT_PENDING);
slot->slot_group_size = (uint64_t)(old_state - WT_LOG_SLOT_READY);
/*
* Note that this statistic may be much bigger than in reality,
* especially when compared with the total bytes written in
* __log_fill. The reason is that this size reflects any
* rounding up that is needed and the total bytes in __log_fill
* is the amount of user bytes.
*/
WT_STAT_FAST_CONN_INCRV(session,
log_slot_consolidated, (uint64_t)slot->slot_group_size);
return (0);
}
/*
* __wt_log_slot_close --
* Close a slot and do not allow any other threads to join this slot.
* Remove this from the active slot array and move a new slot from
* the pool into its place. Set up the size of this group;
* Must be called with the logging spinlock held.
*/
int
__wt_log_slot_close(WT_SESSION_IMPL *session, WT_LOGSLOT *slot)
{
WT_CONNECTION_IMPL *conn;
WT_LOG *log;
WT_LOGSLOT *newslot;
int64_t old_state;
int32_t yields;
uint32_t pool_i, switch_fails;
conn = S2C(session);
log = conn->log;
switch_fails = 0;
retry:
/*
* Find an unused slot in the pool.
*/
pool_i = log->pool_index;
newslot = &log->slot_pool[pool_i];
if (++log->pool_index >= SLOT_POOL)
log->pool_index = 0;
if (newslot->slot_state != WT_LOG_SLOT_FREE) {
WT_STAT_FAST_CONN_INCR(session, log_slot_switch_fails);
/*
* If it takes a number of attempts to find an available slot
* it's likely all slots are waiting to be released. This
* churn is used to change how long we pause before closing
* the slot - which leads to more consolidation and less churn.
*/
if (++switch_fails % SLOT_POOL == 0 &&
switch_fails != 0 && slot->slot_churn < 5)
++slot->slot_churn;
__wt_yield();
goto retry;
} else if (slot->slot_churn > 0) {
--slot->slot_churn;
WT_ASSERT(session, slot->slot_churn >= 0);
}
/* Pause to allow other threads a chance to consolidate. */
for (yields = slot->slot_churn; yields >= 0; yields--)
__wt_yield();
/*
* Swap out the slot we're going to use and put a free one in the
* slot array in its place so that threads can use it right away.
*/
WT_STAT_FAST_CONN_INCR(session, log_slot_closes);
newslot->slot_state = WT_LOG_SLOT_READY;
newslot->slot_index = slot->slot_index;
log->slot_array[newslot->slot_index] = &log->slot_pool[pool_i];
old_state = WT_ATOMIC_STORE8(slot->slot_state, WT_LOG_SLOT_PENDING);
slot->slot_group_size = (uint64_t)(old_state - WT_LOG_SLOT_READY);
/*
* Note that this statistic may be much bigger than in reality,
* especially when compared with the total bytes written in
* __log_fill. The reason is that this size reflects any
* rounding up that is needed and the total bytes in __log_fill
* is the amount of user bytes.
*/
WT_STAT_FAST_CONN_INCRV(session,
log_slot_consolidated, (uint64_t)slot->slot_group_size);
return (0);
}
