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refs #5461 Some cleanup based on code review of cachetable

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git-svn-id: file:///svn/toku/tokudb@47729 c7de825b-a66e-492c-adef-691d508d4ae1
This commit is contained in:
Yoni Fogel 2013-04-17 00:01:06 -04:00
parent 31c3324c24
commit 3bd32d9fbc
2 changed files with 19 additions and 8 deletions
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4
ft/cachetable-internal.h
View file

@ -178,8 +178,12 @@ struct ctpair {
// A PAIR is stored in a pair_list (which happens to be PAIR->list). // A PAIR is stored in a pair_list (which happens to be PAIR->list).
// These variables are protected by the list lock in the pair_list // These variables are protected by the list lock in the pair_list
//
// clock_next,clock_prev represent a circular doubly-linked list.
PAIR clock_next,clock_prev; // In clock. PAIR clock_next,clock_prev; // In clock.
PAIR hash_chain; PAIR hash_chain;
// pending_next,pending_next represent a non-circular doubly-linked list.
PAIR pending_next; PAIR pending_next;
PAIR pending_prev; PAIR pending_prev;
}; };

23
ft/cachetable.cc
View file

@ -74,7 +74,7 @@ status_init(void) {
static void * const zero_value = 0; static void * const zero_value = nullptr;
static PAIR_ATTR const zero_attr = { static PAIR_ATTR const zero_attr = {
.size = 0, .size = 0,
.nonleaf_size = 0, .nonleaf_size = 0,
@ -1644,6 +1644,9 @@ beginning:
// we only want to sleep once per call to get_and_pin. If we have already // we only want to sleep once per call to get_and_pin. If we have already
// slept and there is still cache pressure, then we might as // slept and there is still cache pressure, then we might as
// well just complete the call, because the sleep did not help // well just complete the call, because the sleep did not help
// By sleeping only once per get_and_pin, we prevent starvation and ensure
// that we make progress (however slow) on each thread, which allows
// assumptions of the form 'x will eventually happen'.
// This happens in extreme scenarios. // This happens in extreme scenarios.
if (ct->ev.should_client_thread_sleep() && !already_slept) { if (ct->ev.should_client_thread_sleep() && !already_slept) {
wait = true; wait = true;
@ -1652,8 +1655,8 @@ beginning:
if (ct->ev.should_client_wake_eviction_thread()) { if (ct->ev.should_client_wake_eviction_thread()) {
ct->ev.signal_eviction_thread(); ct->ev.signal_eviction_thread();
} }
// Since we missed the pair, we need the write list // Since the pair was not found, we need the write list
// lock. So, we have to release the read list lock // lock to add it. So, we have to release the read list lock
// first. // first.
ct->list.read_list_unlock(); ct->list.read_list_unlock();
ct->list.write_list_lock(); ct->list.write_list_lock();
@ -1701,7 +1704,7 @@ beginning:
write_callback, write_callback,
CACHETABLE_CLEAN CACHETABLE_CLEAN
); );
assert(p); invariant_notnull(p);
// Pin the pair. // Pin the pair.
pair_lock(p); pair_lock(p);
@ -1710,7 +1713,7 @@ beginning:
if (lock_type != PL_READ) { if (lock_type != PL_READ) {
ct->list.read_pending_cheap_lock(); ct->list.read_pending_cheap_lock();
assert(!p->checkpoint_pending); invariant(!p->checkpoint_pending);
for (uint32_t i = 0; i < num_dependent_pairs; i++) { for (uint32_t i = 0; i < num_dependent_pairs; i++) {
dep_checkpoint_pending[i] = dependent_pairs[i]->checkpoint_pending; dep_checkpoint_pending[i] = dependent_pairs[i]->checkpoint_pending;
dependent_pairs[i]->checkpoint_pending = false; dependent_pairs[i]->checkpoint_pending = false;
@ -1745,6 +1748,10 @@ beginning:
// downgrading, because we would have to possibly resolve the // downgrading, because we would have to possibly resolve the
// checkpointing again, and that would just make this function even // checkpointing again, and that would just make this function even
// messier. // messier.
//
// TODO(yoni): in case of PL_WRITE_CHEAP, write and use
// p->value_rwlock.write_change_status_to_not_expensive(); (Also name it better)
// to downgrade from an expensive write lock to a cheap one
if (lock_type == PL_READ) { if (lock_type == PL_READ) {
pair_lock(p); pair_lock(p);
p->value_rwlock.write_unlock(); p->value_rwlock.write_unlock();
@ -3343,9 +3350,9 @@ PAIR pair_list::remove_from_hash_chain (PAIR remove_me, PAIR list) {
// //
void pair_list::pair_remove (PAIR p) { void pair_list::pair_remove (PAIR p) {
if (p->clock_prev == p) { if (p->clock_prev == p) {
assert(m_clock_head == p); invariant(m_clock_head == p);
assert(p->clock_next == p); invariant(p->clock_next == p);
assert(m_cleaner_head == p); invariant(m_cleaner_head == p);
m_clock_head = NULL; m_clock_head = NULL;
m_cleaner_head = NULL; m_cleaner_head = NULL;
} }