a58d48de79
Summary: Implement ReadWrite locks for leveldb. These will be helpful to implement a read-modify-write operation (e.g. atomic increments). Test Plan: does not modify any existing code Reviewers: heyongqiang Reviewed By: heyongqiang CC: MarkCallaghan Differential Revision: https://reviews.facebook.net/D5787
79 lines
1.8 KiB
C++
79 lines
1.8 KiB
C++
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#ifndef STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_
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#define STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_
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#include "port/port.h"
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namespace leveldb {
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// Helper class that locks a mutex on construction and unlocks the mutex when
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// the destructor of the MutexLock object is invoked.
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//
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// Typical usage:
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//
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// void MyClass::MyMethod() {
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// MutexLock l(&mu_); // mu_ is an instance variable
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// ... some complex code, possibly with multiple return paths ...
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// }
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class MutexLock {
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public:
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explicit MutexLock(port::Mutex *mu) : mu_(mu) {
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this->mu_->Lock();
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}
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~MutexLock() { this->mu_->Unlock(); }
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private:
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port::Mutex *const mu_;
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// No copying allowed
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MutexLock(const MutexLock&);
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void operator=(const MutexLock&);
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};
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//
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// Acquire a ReadLock on the specified RWMutex.
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// The Lock will be automatically released then the
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// object goes out of scope.
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//
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class ReadLock {
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public:
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explicit ReadLock(port::RWMutex *mu) : mu_(mu) {
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this->mu_->ReadLock();
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}
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~ReadLock() { this->mu_->Unlock(); }
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private:
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port::RWMutex *const mu_;
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// No copying allowed
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ReadLock(const ReadLock&);
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void operator=(const ReadLock&);
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};
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//
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// Acquire a WriteLock on the specified RWMutex.
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// The Lock will be automatically released then the
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// object goes out of scope.
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//
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class WriteLock {
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public:
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explicit WriteLock(port::RWMutex *mu) : mu_(mu) {
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this->mu_->WriteLock();
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}
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~WriteLock() { this->mu_->Unlock(); }
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private:
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port::RWMutex *const mu_;
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// No copying allowed
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WriteLock(const WriteLock&);
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void operator=(const WriteLock&);
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_
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