rocksdb/utilities/transactions/transaction_lock_mgr.h
agiardullo 5e94f68f35 TransactionDB Custom Locking API
Summary:
Prototype of API to allow MyRocks to override default Mutex/CondVar used by transactions with their own implementations.  They would simply need to pass their own implementations of Mutex/CondVar to the templated TransactionDB::Open().

Default implementation of TransactionDBMutex/TransactionDBCondVar provided (but the code is not currently changed to use this).

Let me know if this API makes sense or if it should be changed

Test Plan: n/a

Reviewers: yhchiang, rven, igor, sdong, spetrunia

Reviewed By: spetrunia

Subscribers: maykov, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43761
2015-09-08 17:03:57 -07:00

95 lines
3.2 KiB
C++

// Copyright (c) 2015, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#ifndef ROCKSDB_LITE
#include <chrono>
#include <string>
#include <unordered_map>
#include <vector>
#include "rocksdb/utilities/transaction.h"
#include "util/instrumented_mutex.h"
#include "util/thread_local.h"
#include "utilities/transactions/transaction_impl.h"
namespace rocksdb {
class ColumnFamilyHandle;
struct LockInfo;
struct LockMap;
struct LockMapStripe;
class Slice;
class TransactionLockMgr {
public:
TransactionLockMgr(size_t default_num_stripes, int64_t max_num_locks,
std::shared_ptr<TransactionDBMutexFactory> factory);
~TransactionLockMgr();
// Creates a new LockMap for this column family. Caller should guarantee
// that this column family does not already exist.
void AddColumnFamily(uint32_t column_family_id);
// Deletes the LockMap for this column family. Caller should guarantee that
// this column family is no longer in use.
void RemoveColumnFamily(uint32_t column_family_id);
// Attempt to lock key. If OK status is returned, the caller is responsible
// for calling UnLock() on this key.
Status TryLock(const TransactionImpl* txn, uint32_t column_family_id,
const std::string& key, Env* env);
// Unlock a key locked by TryLock(). txn must be the same Transaction that
// locked this key.
void UnLock(const TransactionImpl* txn, const TransactionKeyMap* keys,
Env* env);
void UnLock(TransactionImpl* txn, uint32_t column_family_id,
const std::string& key, Env* env);
private:
// Default number of lock map stripes per column family
const size_t default_num_stripes_;
// Limit on number of keys locked per column family
const int64_t max_num_locks_;
// Used to allocate mutexes/condvars to use when locking keys
std::shared_ptr<TransactionDBMutexFactory> mutex_factory_;
// Must be held when accessing/modifying lock_maps_
InstrumentedMutex lock_map_mutex_;
// Map of ColumnFamilyId to locked key info
using LockMaps = std::unordered_map<uint32_t, std::shared_ptr<LockMap>>;
LockMaps lock_maps_;
// Thread-local cache of entries in lock_maps_. This is an optimization
// to avoid acquiring a mutex in order to look up a LockMap
std::unique_ptr<ThreadLocalPtr> lock_maps_cache_;
bool IsLockExpired(const LockInfo& lock_info, Env* env, uint64_t* wait_time);
std::shared_ptr<LockMap> GetLockMap(uint32_t column_family_id);
Status AcquireWithTimeout(LockMap* lock_map, LockMapStripe* stripe,
const std::string& key, Env* env, int64_t timeout,
const LockInfo& lock_info);
Status AcquireLocked(LockMap* lock_map, LockMapStripe* stripe,
const std::string& key, Env* env,
const LockInfo& lock_info, uint64_t* wait_time);
// No copying allowed
TransactionLockMgr(const TransactionLockMgr&);
void operator=(const TransactionLockMgr&);
};
} // namespace rocksdb
#endif // ROCKSDB_LITE