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rocksdb/utilities/transactions/lock/point/point_lock_manager.cc

720 lines
24 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#ifndef ROCKSDB_LITE
#include "utilities/transactions/lock/point/point_lock_manager.h"
#include <algorithm>
#include <cinttypes>
#include <mutex>
#include "monitoring/perf_context_imp.h"
#include "rocksdb/slice.h"
#include "rocksdb/utilities/transaction_db_mutex.h"
#include "test_util/sync_point.h"
#include "util/cast_util.h"
Consolidate hash function used for non-persistent data in a new function (#5155) Summary: Create new function NPHash64() and GetSliceNPHash64(), which are currently implemented using murmurhash. Replace the current direct call of murmurhash() to use the new functions if the hash results are not used in on-disk format. This will make it easier to try out or switch to alternative functions in the uses where data format compatibility doesn't need to be considered. This part shouldn't have any performance impact. Also, the sharded cache hash function is changed to the new format, because it falls into this categoery. It doesn't show visible performance impact in db_bench results. CPU showed by perf is increased from about 0.2% to 0.4% in an extreme benchmark setting (4KB blocks, no-compression, everything cached in block cache). We've known that the current hash function used, our own Hash() has serious hash quality problem. It can generate a lots of conflicts with similar input. In this use case, it means extra lock contention for reads from the same file. This slight CPU regression is worthy to me to counter the potential bad performance with hot keys. And hopefully this will get further improved in the future with a better hash function. cache_test's condition is relaxed a little bit to. The new hash is slightly more skewed in this use case, but I manually checked the data and see the hash results are still in a reasonable range. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5155 Differential Revision: D14834821 Pulled By: siying fbshipit-source-id: ec9a2c0a2f8ae4b54d08b13a5c2e9cc97aa80cb5
6 years ago
#include "util/hash.h"
#include "util/thread_local.h"
#include "utilities/transactions/pessimistic_transaction_db.h"
#include "utilities/transactions/transaction_db_mutex_impl.h"
namespace ROCKSDB_NAMESPACE {
struct LockInfo {
bool exclusive;
autovector<TransactionID> txn_ids;
// Transaction locks are not valid after this time in us
uint64_t expiration_time;
LockInfo(TransactionID id, uint64_t time, bool ex)
: exclusive(ex), expiration_time(time) {
txn_ids.push_back(id);
}
LockInfo(const LockInfo& lock_info)
: exclusive(lock_info.exclusive),
txn_ids(lock_info.txn_ids),
expiration_time(lock_info.expiration_time) {}
void operator=(const LockInfo& lock_info) {
exclusive = lock_info.exclusive;
txn_ids = lock_info.txn_ids;
expiration_time = lock_info.expiration_time;
}
Meta-internal folly integration with F14FastMap (#9546) Summary: Especially after updating to C++17, I don't see a compelling case for *requiring* any folly components in RocksDB. I was able to purge the existing hard dependencies, and it can be quite difficult to strip out non-trivial components from folly for use in RocksDB. (The prospect of doing that on F14 has changed my mind on the best approach here.) But this change creates an optional integration where we can plug in components from folly at compile time, starting here with F14FastMap to replace std::unordered_map when possible (probably no public APIs for example). I have replaced the biggest CPU users of std::unordered_map with compile-time pluggable UnorderedMap which will use F14FastMap when USE_FOLLY is set. USE_FOLLY is always set in the Meta-internal buck build, and a simulation of that is in the Makefile for public CI testing. A full folly build is not needed, but checking out the full folly repo is much simpler for getting the dependency, and anything else we might want to optionally integrate in the future. Some picky details: * I don't think the distributed mutex stuff is actually used, so it was easy to remove. * I implemented an alternative to `folly::constexpr_log2` (which is much easier in C++17 than C++11) so that I could pull out the hard dependencies on `ConstexprMath.h` * I had to add noexcept move constructors/operators to some types to make F14's complainUnlessNothrowMoveAndDestroy check happy, and I added a macro to make that easier in some common cases. * Updated Meta-internal buck build to use folly F14Map (always) No updates to HISTORY.md nor INSTALL.md as this is not (yet?) considered a production integration for open source users. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9546 Test Plan: CircleCI tests updated so that a couple of them use folly. Most internal unit & stress/crash tests updated to use Meta-internal latest folly. (Note: they should probably use buck but they currently use Makefile.) Example performance improvement: when filter partitions are pinned in cache, they are tracked by PartitionedFilterBlockReader::filter_map_ and we can build a test that exercises that heavily. Build DB with ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=30000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters ``` and test with (simultaneous runs with & without folly, ~20 times each to see convergence) ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench_folly -readonly -use_existing_db -benchmarks=readrandom -num=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters -duration=40 -pin_l0_filter_and_index_blocks_in_cache ``` Average ops/s no folly: 26229.2 Average ops/s with folly: 26853.3 (+2.4%) Reviewed By: ajkr Differential Revision: D34181736 Pulled By: pdillinger fbshipit-source-id: ffa6ad5104c2880321d8a1aa7187e00ab0d02e94
3 years ago
DECLARE_DEFAULT_MOVES(LockInfo);
};
struct LockMapStripe {
explicit LockMapStripe(std::shared_ptr<TransactionDBMutexFactory> factory) {
stripe_mutex = factory->AllocateMutex();
stripe_cv = factory->AllocateCondVar();
assert(stripe_mutex);
assert(stripe_cv);
}
// Mutex must be held before modifying keys map
std::shared_ptr<TransactionDBMutex> stripe_mutex;
// Condition Variable per stripe for waiting on a lock
std::shared_ptr<TransactionDBCondVar> stripe_cv;
// Locked keys mapped to the info about the transactions that locked them.
// TODO(agiardullo): Explore performance of other data structures.
Meta-internal folly integration with F14FastMap (#9546) Summary: Especially after updating to C++17, I don't see a compelling case for *requiring* any folly components in RocksDB. I was able to purge the existing hard dependencies, and it can be quite difficult to strip out non-trivial components from folly for use in RocksDB. (The prospect of doing that on F14 has changed my mind on the best approach here.) But this change creates an optional integration where we can plug in components from folly at compile time, starting here with F14FastMap to replace std::unordered_map when possible (probably no public APIs for example). I have replaced the biggest CPU users of std::unordered_map with compile-time pluggable UnorderedMap which will use F14FastMap when USE_FOLLY is set. USE_FOLLY is always set in the Meta-internal buck build, and a simulation of that is in the Makefile for public CI testing. A full folly build is not needed, but checking out the full folly repo is much simpler for getting the dependency, and anything else we might want to optionally integrate in the future. Some picky details: * I don't think the distributed mutex stuff is actually used, so it was easy to remove. * I implemented an alternative to `folly::constexpr_log2` (which is much easier in C++17 than C++11) so that I could pull out the hard dependencies on `ConstexprMath.h` * I had to add noexcept move constructors/operators to some types to make F14's complainUnlessNothrowMoveAndDestroy check happy, and I added a macro to make that easier in some common cases. * Updated Meta-internal buck build to use folly F14Map (always) No updates to HISTORY.md nor INSTALL.md as this is not (yet?) considered a production integration for open source users. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9546 Test Plan: CircleCI tests updated so that a couple of them use folly. Most internal unit & stress/crash tests updated to use Meta-internal latest folly. (Note: they should probably use buck but they currently use Makefile.) Example performance improvement: when filter partitions are pinned in cache, they are tracked by PartitionedFilterBlockReader::filter_map_ and we can build a test that exercises that heavily. Build DB with ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=30000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters ``` and test with (simultaneous runs with & without folly, ~20 times each to see convergence) ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench_folly -readonly -use_existing_db -benchmarks=readrandom -num=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters -duration=40 -pin_l0_filter_and_index_blocks_in_cache ``` Average ops/s no folly: 26229.2 Average ops/s with folly: 26853.3 (+2.4%) Reviewed By: ajkr Differential Revision: D34181736 Pulled By: pdillinger fbshipit-source-id: ffa6ad5104c2880321d8a1aa7187e00ab0d02e94
3 years ago
UnorderedMap<std::string, LockInfo> keys;
};
// Map of #num_stripes LockMapStripes
struct LockMap {
explicit LockMap(size_t num_stripes,
std::shared_ptr<TransactionDBMutexFactory> factory)
: num_stripes_(num_stripes) {
lock_map_stripes_.reserve(num_stripes);
for (size_t i = 0; i < num_stripes; i++) {
LockMapStripe* stripe = new LockMapStripe(factory);
lock_map_stripes_.push_back(stripe);
}
}
~LockMap() {
for (auto stripe : lock_map_stripes_) {
delete stripe;
}
}
// Number of sepearate LockMapStripes to create, each with their own Mutex
const size_t num_stripes_;
// Count of keys that are currently locked in this column family.
// (Only maintained if PointLockManager::max_num_locks_ is positive.)
std::atomic<int64_t> lock_cnt{0};
std::vector<LockMapStripe*> lock_map_stripes_;
size_t GetStripe(const std::string& key) const;
};
namespace {
void UnrefLockMapsCache(void* ptr) {
// Called when a thread exits or a ThreadLocalPtr gets destroyed.
auto lock_maps_cache =
Meta-internal folly integration with F14FastMap (#9546) Summary: Especially after updating to C++17, I don't see a compelling case for *requiring* any folly components in RocksDB. I was able to purge the existing hard dependencies, and it can be quite difficult to strip out non-trivial components from folly for use in RocksDB. (The prospect of doing that on F14 has changed my mind on the best approach here.) But this change creates an optional integration where we can plug in components from folly at compile time, starting here with F14FastMap to replace std::unordered_map when possible (probably no public APIs for example). I have replaced the biggest CPU users of std::unordered_map with compile-time pluggable UnorderedMap which will use F14FastMap when USE_FOLLY is set. USE_FOLLY is always set in the Meta-internal buck build, and a simulation of that is in the Makefile for public CI testing. A full folly build is not needed, but checking out the full folly repo is much simpler for getting the dependency, and anything else we might want to optionally integrate in the future. Some picky details: * I don't think the distributed mutex stuff is actually used, so it was easy to remove. * I implemented an alternative to `folly::constexpr_log2` (which is much easier in C++17 than C++11) so that I could pull out the hard dependencies on `ConstexprMath.h` * I had to add noexcept move constructors/operators to some types to make F14's complainUnlessNothrowMoveAndDestroy check happy, and I added a macro to make that easier in some common cases. * Updated Meta-internal buck build to use folly F14Map (always) No updates to HISTORY.md nor INSTALL.md as this is not (yet?) considered a production integration for open source users. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9546 Test Plan: CircleCI tests updated so that a couple of them use folly. Most internal unit & stress/crash tests updated to use Meta-internal latest folly. (Note: they should probably use buck but they currently use Makefile.) Example performance improvement: when filter partitions are pinned in cache, they are tracked by PartitionedFilterBlockReader::filter_map_ and we can build a test that exercises that heavily. Build DB with ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=30000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters ``` and test with (simultaneous runs with & without folly, ~20 times each to see convergence) ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench_folly -readonly -use_existing_db -benchmarks=readrandom -num=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters -duration=40 -pin_l0_filter_and_index_blocks_in_cache ``` Average ops/s no folly: 26229.2 Average ops/s with folly: 26853.3 (+2.4%) Reviewed By: ajkr Differential Revision: D34181736 Pulled By: pdillinger fbshipit-source-id: ffa6ad5104c2880321d8a1aa7187e00ab0d02e94
3 years ago
static_cast<UnorderedMap<uint32_t, std::shared_ptr<LockMap>>*>(ptr);
delete lock_maps_cache;
}
} // anonymous namespace
PointLockManager::PointLockManager(PessimisticTransactionDB* txn_db,
const TransactionDBOptions& opt)
: txn_db_impl_(txn_db),
default_num_stripes_(opt.num_stripes),
max_num_locks_(opt.max_num_locks),
lock_maps_cache_(new ThreadLocalPtr(&UnrefLockMapsCache)),
dlock_buffer_(opt.max_num_deadlocks),
mutex_factory_(opt.custom_mutex_factory
? opt.custom_mutex_factory
: std::make_shared<TransactionDBMutexFactoryImpl>()) {}
size_t LockMap::GetStripe(const std::string& key) const {
assert(num_stripes_ > 0);
return FastRange64(GetSliceNPHash64(key), num_stripes_);
}
void PointLockManager::AddColumnFamily(const ColumnFamilyHandle* cf) {
InstrumentedMutexLock l(&lock_map_mutex_);
if (lock_maps_.find(cf->GetID()) == lock_maps_.end()) {
lock_maps_.emplace(cf->GetID(), std::make_shared<LockMap>(
default_num_stripes_, mutex_factory_));
} else {
// column_family already exists in lock map
assert(false);
}
}
void PointLockManager::RemoveColumnFamily(const ColumnFamilyHandle* cf) {
// Remove lock_map for this column family. Since the lock map is stored
// as a shared ptr, concurrent transactions can still keep using it
// until they release their references to it.
{
InstrumentedMutexLock l(&lock_map_mutex_);
auto lock_maps_iter = lock_maps_.find(cf->GetID());
if (lock_maps_iter == lock_maps_.end()) {
return;
}
lock_maps_.erase(lock_maps_iter);
} // lock_map_mutex_
// Clear all thread-local caches
autovector<void*> local_caches;
lock_maps_cache_->Scrape(&local_caches, nullptr);
for (auto cache : local_caches) {
delete static_cast<LockMaps*>(cache);
}
}
// Look up the LockMap std::shared_ptr for a given column_family_id.
// Note: The LockMap is only valid as long as the caller is still holding on
// to the returned std::shared_ptr.
std::shared_ptr<LockMap> PointLockManager::GetLockMap(
ColumnFamilyId column_family_id) {
// First check thread-local cache
if (lock_maps_cache_->Get() == nullptr) {
lock_maps_cache_->Reset(new LockMaps());
}
auto lock_maps_cache = static_cast<LockMaps*>(lock_maps_cache_->Get());
auto lock_map_iter = lock_maps_cache->find(column_family_id);
if (lock_map_iter != lock_maps_cache->end()) {
// Found lock map for this column family.
return lock_map_iter->second;
}
// Not found in local cache, grab mutex and check shared LockMaps
InstrumentedMutexLock l(&lock_map_mutex_);
lock_map_iter = lock_maps_.find(column_family_id);
if (lock_map_iter == lock_maps_.end()) {
return std::shared_ptr<LockMap>(nullptr);
} else {
// Found lock map. Store in thread-local cache and return.
std::shared_ptr<LockMap>& lock_map = lock_map_iter->second;
lock_maps_cache->insert({column_family_id, lock_map});
return lock_map;
}
}
// Returns true if this lock has expired and can be acquired by another
// transaction.
// If false, sets *expire_time to the expiration time of the lock according
// to Env->GetMicros() or 0 if no expiration.
bool PointLockManager::IsLockExpired(TransactionID txn_id,
const LockInfo& lock_info, Env* env,
uint64_t* expire_time) {
if (lock_info.expiration_time == 0) {
*expire_time = 0;
return false;
}
auto now = env->NowMicros();
bool expired = lock_info.expiration_time <= now;
if (!expired) {
// return how many microseconds until lock will be expired
*expire_time = lock_info.expiration_time;
} else {
for (auto id : lock_info.txn_ids) {
if (txn_id == id) {
continue;
}
bool success = txn_db_impl_->TryStealingExpiredTransactionLocks(id);
if (!success) {
expired = false;
*expire_time = 0;
break;
}
}
}
return expired;
}
Status PointLockManager::TryLock(PessimisticTransaction* txn,
ColumnFamilyId column_family_id,
const std::string& key, Env* env,
bool exclusive) {
// Lookup lock map for this column family id
std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(column_family_id);
LockMap* lock_map = lock_map_ptr.get();
if (lock_map == nullptr) {
char msg[255];
snprintf(msg, sizeof(msg), "Column family id not found: %" PRIu32,
column_family_id);
return Status::InvalidArgument(msg);
}
// Need to lock the mutex for the stripe that this key hashes to
size_t stripe_num = lock_map->GetStripe(key);
assert(lock_map->lock_map_stripes_.size() > stripe_num);
LockMapStripe* stripe = lock_map->lock_map_stripes_.at(stripe_num);
LockInfo lock_info(txn->GetID(), txn->GetExpirationTime(), exclusive);
int64_t timeout = txn->GetLockTimeout();
return AcquireWithTimeout(txn, lock_map, stripe, column_family_id, key, env,
timeout, std::move(lock_info));
}
// Helper function for TryLock().
Status PointLockManager::AcquireWithTimeout(
PessimisticTransaction* txn, LockMap* lock_map, LockMapStripe* stripe,
ColumnFamilyId column_family_id, const std::string& key, Env* env,
int64_t timeout, LockInfo&& lock_info) {
Status result;
uint64_t end_time = 0;
if (timeout > 0) {
uint64_t start_time = env->NowMicros();
end_time = start_time + timeout;
}
if (timeout < 0) {
// If timeout is negative, we wait indefinitely to acquire the lock
result = stripe->stripe_mutex->Lock();
} else {
result = stripe->stripe_mutex->TryLockFor(timeout);
}
if (!result.ok()) {
// failed to acquire mutex
return result;
}
// Acquire lock if we are able to
uint64_t expire_time_hint = 0;
autovector<TransactionID> wait_ids;
result = AcquireLocked(lock_map, stripe, key, env, std::move(lock_info),
&expire_time_hint, &wait_ids);
if (!result.ok() && timeout != 0) {
PERF_TIMER_GUARD(key_lock_wait_time);
PERF_COUNTER_ADD(key_lock_wait_count, 1);
// If we weren't able to acquire the lock, we will keep retrying as long
// as the timeout allows.
bool timed_out = false;
do {
// Decide how long to wait
int64_t cv_end_time = -1;
if (expire_time_hint > 0 && end_time > 0) {
cv_end_time = std::min(expire_time_hint, end_time);
} else if (expire_time_hint > 0) {
cv_end_time = expire_time_hint;
} else if (end_time > 0) {
cv_end_time = end_time;
}
assert(result.IsBusy() || wait_ids.size() != 0);
// We are dependent on a transaction to finish, so perform deadlock
// detection.
if (wait_ids.size() != 0) {
if (txn->IsDeadlockDetect()) {
if (IncrementWaiters(txn, wait_ids, key, column_family_id,
lock_info.exclusive, env)) {
result = Status::Busy(Status::SubCode::kDeadlock);
stripe->stripe_mutex->UnLock();
return result;
}
}
txn->SetWaitingTxn(wait_ids, column_family_id, &key);
}
TEST_SYNC_POINT("PointLockManager::AcquireWithTimeout:WaitingTxn");
if (cv_end_time < 0) {
// Wait indefinitely
result = stripe->stripe_cv->Wait(stripe->stripe_mutex);
} else {
uint64_t now = env->NowMicros();
if (static_cast<uint64_t>(cv_end_time) > now) {
result = stripe->stripe_cv->WaitFor(stripe->stripe_mutex,
cv_end_time - now);
}
}
if (wait_ids.size() != 0) {
txn->ClearWaitingTxn();
if (txn->IsDeadlockDetect()) {
DecrementWaiters(txn, wait_ids);
}
}
if (result.IsTimedOut()) {
timed_out = true;
// Even though we timed out, we will still make one more attempt to
// acquire lock below (it is possible the lock expired and we
// were never signaled).
}
if (result.ok() || result.IsTimedOut()) {
result = AcquireLocked(lock_map, stripe, key, env, std::move(lock_info),
&expire_time_hint, &wait_ids);
}
} while (!result.ok() && !timed_out);
}
stripe->stripe_mutex->UnLock();
return result;
}
void PointLockManager::DecrementWaiters(
const PessimisticTransaction* txn,
const autovector<TransactionID>& wait_ids) {
std::lock_guard<std::mutex> lock(wait_txn_map_mutex_);
DecrementWaitersImpl(txn, wait_ids);
}
void PointLockManager::DecrementWaitersImpl(
const PessimisticTransaction* txn,
const autovector<TransactionID>& wait_ids) {
auto id = txn->GetID();
assert(wait_txn_map_.Contains(id));
wait_txn_map_.Delete(id);
for (auto wait_id : wait_ids) {
rev_wait_txn_map_.Get(wait_id)--;
if (rev_wait_txn_map_.Get(wait_id) == 0) {
rev_wait_txn_map_.Delete(wait_id);
}
}
}
bool PointLockManager::IncrementWaiters(
const PessimisticTransaction* txn,
const autovector<TransactionID>& wait_ids, const std::string& key,
const uint32_t& cf_id, const bool& exclusive, Env* const env) {
auto id = txn->GetID();
std::vector<int> queue_parents(static_cast<size_t>(txn->GetDeadlockDetectDepth()));
std::vector<TransactionID> queue_values(static_cast<size_t>(txn->GetDeadlockDetectDepth()));
std::lock_guard<std::mutex> lock(wait_txn_map_mutex_);
assert(!wait_txn_map_.Contains(id));
wait_txn_map_.Insert(id, {wait_ids, cf_id, exclusive, key});
for (auto wait_id : wait_ids) {
if (rev_wait_txn_map_.Contains(wait_id)) {
rev_wait_txn_map_.Get(wait_id)++;
} else {
rev_wait_txn_map_.Insert(wait_id, 1);
}
}
// No deadlock if nobody is waiting on self.
if (!rev_wait_txn_map_.Contains(id)) {
return false;
}
const auto* next_ids = &wait_ids;
int parent = -1;
int64_t deadlock_time = 0;
for (int tail = 0, head = 0; head < txn->GetDeadlockDetectDepth(); head++) {
int i = 0;
if (next_ids) {
for (; i < static_cast<int>(next_ids->size()) &&
tail + i < txn->GetDeadlockDetectDepth();
i++) {
queue_values[tail + i] = (*next_ids)[i];
queue_parents[tail + i] = parent;
}
tail += i;
}
// No more items in the list, meaning no deadlock.
if (tail == head) {
return false;
}
auto next = queue_values[head];
if (next == id) {
std::vector<DeadlockInfo> path;
while (head != -1) {
assert(wait_txn_map_.Contains(queue_values[head]));
auto extracted_info = wait_txn_map_.Get(queue_values[head]);
path.push_back({queue_values[head], extracted_info.m_cf_id,
extracted_info.m_exclusive,
extracted_info.m_waiting_key});
head = queue_parents[head];
}
if (!env->GetCurrentTime(&deadlock_time).ok()) {
/*
TODO(AR) this preserves the current behaviour whilst checking the
status of env->GetCurrentTime to ensure that ASSERT_STATUS_CHECKED
passes. Should we instead raise an error if !ok() ?
*/
deadlock_time = 0;
}
std::reverse(path.begin(), path.end());
dlock_buffer_.AddNewPath(DeadlockPath(path, deadlock_time));
deadlock_time = 0;
DecrementWaitersImpl(txn, wait_ids);
return true;
} else if (!wait_txn_map_.Contains(next)) {
next_ids = nullptr;
continue;
} else {
parent = head;
next_ids = &(wait_txn_map_.Get(next).m_neighbors);
}
}
// Wait cycle too big, just assume deadlock.
if (!env->GetCurrentTime(&deadlock_time).ok()) {
/*
TODO(AR) this preserves the current behaviour whilst checking the status
of env->GetCurrentTime to ensure that ASSERT_STATUS_CHECKED passes.
Should we instead raise an error if !ok() ?
*/
deadlock_time = 0;
}
dlock_buffer_.AddNewPath(DeadlockPath(deadlock_time, true));
DecrementWaitersImpl(txn, wait_ids);
return true;
}
// Try to lock this key after we have acquired the mutex.
// Sets *expire_time to the expiration time in microseconds
// or 0 if no expiration.
// REQUIRED: Stripe mutex must be held.
Status PointLockManager::AcquireLocked(LockMap* lock_map, LockMapStripe* stripe,
const std::string& key, Env* env,
LockInfo&& txn_lock_info,
uint64_t* expire_time,
autovector<TransactionID>* txn_ids) {
assert(txn_lock_info.txn_ids.size() == 1);
Status result;
// Check if this key is already locked
auto stripe_iter = stripe->keys.find(key);
if (stripe_iter != stripe->keys.end()) {
// Lock already held
LockInfo& lock_info = stripe_iter->second;
assert(lock_info.txn_ids.size() == 1 || !lock_info.exclusive);
if (lock_info.exclusive || txn_lock_info.exclusive) {
if (lock_info.txn_ids.size() == 1 &&
lock_info.txn_ids[0] == txn_lock_info.txn_ids[0]) {
// The list contains one txn and we're it, so just take it.
lock_info.exclusive = txn_lock_info.exclusive;
lock_info.expiration_time = txn_lock_info.expiration_time;
} else {
// Check if it's expired. Skips over txn_lock_info.txn_ids[0] in case
// it's there for a shared lock with multiple holders which was not
// caught in the first case.
if (IsLockExpired(txn_lock_info.txn_ids[0], lock_info, env,
expire_time)) {
// lock is expired, can steal it
lock_info.txn_ids = txn_lock_info.txn_ids;
lock_info.exclusive = txn_lock_info.exclusive;
lock_info.expiration_time = txn_lock_info.expiration_time;
// lock_cnt does not change
} else {
result = Status::TimedOut(Status::SubCode::kLockTimeout);
*txn_ids = lock_info.txn_ids;
}
}
} else {
// We are requesting shared access to a shared lock, so just grant it.
lock_info.txn_ids.push_back(txn_lock_info.txn_ids[0]);
// Using std::max means that expiration time never goes down even when
// a transaction is removed from the list. The correct solution would be
// to track expiry for every transaction, but this would also work for
// now.
lock_info.expiration_time =
std::max(lock_info.expiration_time, txn_lock_info.expiration_time);
}
} else { // Lock not held.
// Check lock limit
if (max_num_locks_ > 0 &&
lock_map->lock_cnt.load(std::memory_order_acquire) >= max_num_locks_) {
result = Status::Busy(Status::SubCode::kLockLimit);
} else {
// acquire lock
stripe->keys.emplace(key, std::move(txn_lock_info));
// Maintain lock count if there is a limit on the number of locks
if (max_num_locks_) {
lock_map->lock_cnt++;
}
}
}
return result;
}
void PointLockManager::UnLockKey(PessimisticTransaction* txn,
const std::string& key, LockMapStripe* stripe,
LockMap* lock_map, Env* env) {
#ifdef NDEBUG
(void)env;
#endif
TransactionID txn_id = txn->GetID();
auto stripe_iter = stripe->keys.find(key);
if (stripe_iter != stripe->keys.end()) {
auto& txns = stripe_iter->second.txn_ids;
auto txn_it = std::find(txns.begin(), txns.end(), txn_id);
// Found the key we locked. unlock it.
if (txn_it != txns.end()) {
if (txns.size() == 1) {
stripe->keys.erase(stripe_iter);
} else {
auto last_it = txns.end() - 1;
if (txn_it != last_it) {
*txn_it = *last_it;
}
txns.pop_back();
}
if (max_num_locks_ > 0) {
// Maintain lock count if there is a limit on the number of locks.
assert(lock_map->lock_cnt.load(std::memory_order_relaxed) > 0);
lock_map->lock_cnt--;
}
}
} else {
// This key is either not locked or locked by someone else. This should
// only happen if the unlocking transaction has expired.
assert(txn->GetExpirationTime() > 0 &&
txn->GetExpirationTime() < env->NowMicros());
}
}
void PointLockManager::UnLock(PessimisticTransaction* txn,
ColumnFamilyId column_family_id,
const std::string& key, Env* env) {
std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(column_family_id);
LockMap* lock_map = lock_map_ptr.get();
if (lock_map == nullptr) {
// Column Family must have been dropped.
return;
}
// Lock the mutex for the stripe that this key hashes to
size_t stripe_num = lock_map->GetStripe(key);
assert(lock_map->lock_map_stripes_.size() > stripe_num);
LockMapStripe* stripe = lock_map->lock_map_stripes_.at(stripe_num);
stripe->stripe_mutex->Lock().PermitUncheckedError();
UnLockKey(txn, key, stripe, lock_map, env);
stripe->stripe_mutex->UnLock();
// Signal waiting threads to retry locking
stripe->stripe_cv->NotifyAll();
}
void PointLockManager::UnLock(PessimisticTransaction* txn,
const LockTracker& tracker, Env* env) {
Replace tracked_keys with a new LockTracker interface in TransactionDB (#7013) Summary: We're going to support more locking protocols such as range lock in transaction. However, in current design, `TransactionBase` has a member `tracked_keys` which assumes that point lock (lock a single key) is used, and is used in snapshot checking (isolation protocol). When using range lock, we may use read committed instead of snapshot checking as the isolation protocol. The most significant usage scenarios of `tracked_keys` are: 1. pessimistic transaction uses it to track the locked keys, and unlock these keys when commit or rollback. 2. optimistic transaction does not lock keys upfront, it only tracks the lock intentions in tracked_keys, and do write conflict checking when commit. 3. each `SavePoint` tracks the keys that are locked since the `SavePoint`, `RollbackToSavePoint` or `PopSavePoint` relies on both the tracked keys in `SavePoint`s and `tracked_keys`. Based on these scenarios, if we can abstract out a `LockTracker` interface to hold a set of tracked locks (can be keys or key ranges), and have methods that can be composed together to implement the scenarios, then `tracked_keys` can be an internal data structure of one implementation of `LockTracker`. See `utilities/transactions/lock/lock_tracker.h` for the detailed interface design, and `utilities/transactions/lock/point_lock_tracker.cc` for the implementation. In the future, a `RangeLockTracker` can be implemented to track range locks without affecting other components. After this PR, a clean interface for lock manager should be possible, and then ideally, we can have pluggable locking protocols. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7013 Test Plan: Run `transaction_test` and `optimistic_transaction_test`. Reviewed By: ajkr Differential Revision: D22163706 Pulled By: cheng-chang fbshipit-source-id: f2860577b5334e31dd2994f5bc6d7c40d502b1b4
4 years ago
std::unique_ptr<LockTracker::ColumnFamilyIterator> cf_it(
tracker.GetColumnFamilyIterator());
assert(cf_it != nullptr);
while (cf_it->HasNext()) {
ColumnFamilyId cf = cf_it->Next();
std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(cf);
LockMap* lock_map = lock_map_ptr.get();
Replace tracked_keys with a new LockTracker interface in TransactionDB (#7013) Summary: We're going to support more locking protocols such as range lock in transaction. However, in current design, `TransactionBase` has a member `tracked_keys` which assumes that point lock (lock a single key) is used, and is used in snapshot checking (isolation protocol). When using range lock, we may use read committed instead of snapshot checking as the isolation protocol. The most significant usage scenarios of `tracked_keys` are: 1. pessimistic transaction uses it to track the locked keys, and unlock these keys when commit or rollback. 2. optimistic transaction does not lock keys upfront, it only tracks the lock intentions in tracked_keys, and do write conflict checking when commit. 3. each `SavePoint` tracks the keys that are locked since the `SavePoint`, `RollbackToSavePoint` or `PopSavePoint` relies on both the tracked keys in `SavePoint`s and `tracked_keys`. Based on these scenarios, if we can abstract out a `LockTracker` interface to hold a set of tracked locks (can be keys or key ranges), and have methods that can be composed together to implement the scenarios, then `tracked_keys` can be an internal data structure of one implementation of `LockTracker`. See `utilities/transactions/lock/lock_tracker.h` for the detailed interface design, and `utilities/transactions/lock/point_lock_tracker.cc` for the implementation. In the future, a `RangeLockTracker` can be implemented to track range locks without affecting other components. After this PR, a clean interface for lock manager should be possible, and then ideally, we can have pluggable locking protocols. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7013 Test Plan: Run `transaction_test` and `optimistic_transaction_test`. Reviewed By: ajkr Differential Revision: D22163706 Pulled By: cheng-chang fbshipit-source-id: f2860577b5334e31dd2994f5bc6d7c40d502b1b4
4 years ago
if (!lock_map) {
// Column Family must have been dropped.
return;
}
// Bucket keys by lock_map_ stripe
Meta-internal folly integration with F14FastMap (#9546) Summary: Especially after updating to C++17, I don't see a compelling case for *requiring* any folly components in RocksDB. I was able to purge the existing hard dependencies, and it can be quite difficult to strip out non-trivial components from folly for use in RocksDB. (The prospect of doing that on F14 has changed my mind on the best approach here.) But this change creates an optional integration where we can plug in components from folly at compile time, starting here with F14FastMap to replace std::unordered_map when possible (probably no public APIs for example). I have replaced the biggest CPU users of std::unordered_map with compile-time pluggable UnorderedMap which will use F14FastMap when USE_FOLLY is set. USE_FOLLY is always set in the Meta-internal buck build, and a simulation of that is in the Makefile for public CI testing. A full folly build is not needed, but checking out the full folly repo is much simpler for getting the dependency, and anything else we might want to optionally integrate in the future. Some picky details: * I don't think the distributed mutex stuff is actually used, so it was easy to remove. * I implemented an alternative to `folly::constexpr_log2` (which is much easier in C++17 than C++11) so that I could pull out the hard dependencies on `ConstexprMath.h` * I had to add noexcept move constructors/operators to some types to make F14's complainUnlessNothrowMoveAndDestroy check happy, and I added a macro to make that easier in some common cases. * Updated Meta-internal buck build to use folly F14Map (always) No updates to HISTORY.md nor INSTALL.md as this is not (yet?) considered a production integration for open source users. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9546 Test Plan: CircleCI tests updated so that a couple of them use folly. Most internal unit & stress/crash tests updated to use Meta-internal latest folly. (Note: they should probably use buck but they currently use Makefile.) Example performance improvement: when filter partitions are pinned in cache, they are tracked by PartitionedFilterBlockReader::filter_map_ and we can build a test that exercises that heavily. Build DB with ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench -benchmarks=fillrandom -num=10000000 -disable_wal=1 -write_buffer_size=30000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters ``` and test with (simultaneous runs with & without folly, ~20 times each to see convergence) ``` TEST_TMPDIR=/dev/shm/rocksdb ./db_bench_folly -readonly -use_existing_db -benchmarks=readrandom -num=10000000 -bloom_bits=16 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=0 -partition_index_and_filters -duration=40 -pin_l0_filter_and_index_blocks_in_cache ``` Average ops/s no folly: 26229.2 Average ops/s with folly: 26853.3 (+2.4%) Reviewed By: ajkr Differential Revision: D34181736 Pulled By: pdillinger fbshipit-source-id: ffa6ad5104c2880321d8a1aa7187e00ab0d02e94
3 years ago
UnorderedMap<size_t, std::vector<const std::string*>> keys_by_stripe(
Replace tracked_keys with a new LockTracker interface in TransactionDB (#7013) Summary: We're going to support more locking protocols such as range lock in transaction. However, in current design, `TransactionBase` has a member `tracked_keys` which assumes that point lock (lock a single key) is used, and is used in snapshot checking (isolation protocol). When using range lock, we may use read committed instead of snapshot checking as the isolation protocol. The most significant usage scenarios of `tracked_keys` are: 1. pessimistic transaction uses it to track the locked keys, and unlock these keys when commit or rollback. 2. optimistic transaction does not lock keys upfront, it only tracks the lock intentions in tracked_keys, and do write conflict checking when commit. 3. each `SavePoint` tracks the keys that are locked since the `SavePoint`, `RollbackToSavePoint` or `PopSavePoint` relies on both the tracked keys in `SavePoint`s and `tracked_keys`. Based on these scenarios, if we can abstract out a `LockTracker` interface to hold a set of tracked locks (can be keys or key ranges), and have methods that can be composed together to implement the scenarios, then `tracked_keys` can be an internal data structure of one implementation of `LockTracker`. See `utilities/transactions/lock/lock_tracker.h` for the detailed interface design, and `utilities/transactions/lock/point_lock_tracker.cc` for the implementation. In the future, a `RangeLockTracker` can be implemented to track range locks without affecting other components. After this PR, a clean interface for lock manager should be possible, and then ideally, we can have pluggable locking protocols. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7013 Test Plan: Run `transaction_test` and `optimistic_transaction_test`. Reviewed By: ajkr Differential Revision: D22163706 Pulled By: cheng-chang fbshipit-source-id: f2860577b5334e31dd2994f5bc6d7c40d502b1b4
4 years ago
lock_map->num_stripes_);
std::unique_ptr<LockTracker::KeyIterator> key_it(
tracker.GetKeyIterator(cf));
assert(key_it != nullptr);
while (key_it->HasNext()) {
const std::string& key = key_it->Next();
size_t stripe_num = lock_map->GetStripe(key);
keys_by_stripe[stripe_num].push_back(&key);
}
// For each stripe, grab the stripe mutex and unlock all keys in this stripe
for (auto& stripe_iter : keys_by_stripe) {
size_t stripe_num = stripe_iter.first;
auto& stripe_keys = stripe_iter.second;
assert(lock_map->lock_map_stripes_.size() > stripe_num);
LockMapStripe* stripe = lock_map->lock_map_stripes_.at(stripe_num);
stripe->stripe_mutex->Lock().PermitUncheckedError();
for (const std::string* key : stripe_keys) {
UnLockKey(txn, *key, stripe, lock_map, env);
}
stripe->stripe_mutex->UnLock();
// Signal waiting threads to retry locking
stripe->stripe_cv->NotifyAll();
}
}
}
PointLockManager::PointLockStatus PointLockManager::GetPointLockStatus() {
PointLockStatus data;
// Lock order here is important. The correct order is lock_map_mutex_, then
// for every column family ID in ascending order lock every stripe in
// ascending order.
InstrumentedMutexLock l(&lock_map_mutex_);
std::vector<uint32_t> cf_ids;
for (const auto& map : lock_maps_) {
cf_ids.push_back(map.first);
}
std::sort(cf_ids.begin(), cf_ids.end());
for (auto i : cf_ids) {
const auto& stripes = lock_maps_[i]->lock_map_stripes_;
// Iterate and lock all stripes in ascending order.
for (const auto& j : stripes) {
j->stripe_mutex->Lock().PermitUncheckedError();
for (const auto& it : j->keys) {
struct KeyLockInfo info;
info.exclusive = it.second.exclusive;
info.key = it.first;
for (const auto& id : it.second.txn_ids) {
info.ids.push_back(id);
}
data.insert({i, info});
}
}
}
// Unlock everything. Unlocking order is not important.
for (auto i : cf_ids) {
const auto& stripes = lock_maps_[i]->lock_map_stripes_;
for (const auto& j : stripes) {
j->stripe_mutex->UnLock();
}
}
return data;
}
std::vector<DeadlockPath> PointLockManager::GetDeadlockInfoBuffer() {
return dlock_buffer_.PrepareBuffer();
}
void PointLockManager::Resize(uint32_t target_size) {
dlock_buffer_.Resize(target_size);
}
PointLockManager::RangeLockStatus PointLockManager::GetRangeLockStatus() {
return {};
}
Status PointLockManager::TryLock(PessimisticTransaction* /* txn */,
ColumnFamilyId /* cf_id */,
const Endpoint& /* start */,
const Endpoint& /* end */, Env* /* env */,
bool /* exclusive */) {
return Status::NotSupported(
"PointLockManager does not support range locking");
}
void PointLockManager::UnLock(PessimisticTransaction* /* txn */,
ColumnFamilyId /* cf_id */,
const Endpoint& /* start */,
const Endpoint& /* end */, Env* /* env */) {
// no-op
}
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE