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rocksdb/thrift/lib/cpp/concurrency/Monitor.h

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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
#ifndef _THRIFT_CONCURRENCY_MONITOR_H_
#define _THRIFT_CONCURRENCY_MONITOR_H_ 1
#include "thrift/lib/cpp/concurrency/Exception.h"
#include "thrift/lib/cpp/concurrency/Mutex.h"
#include <boost/utility.hpp>
namespace apache { namespace thrift { namespace concurrency {
/**
* A monitor is a combination mutex and condition-event. Waiting and
* notifying condition events requires that the caller own the mutex. Mutex
* lock and unlock operations can be performed independently of condition
* events. This is more or less analogous to java.lang.Object multi-thread
* operations.
*
* Note the Monitor can create a new, internal mutex; alternatively, a
* separate Mutex can be passed in and the Monitor will re-use it without
* taking ownership. It's the user's responsibility to make sure that the
* Mutex is not deallocated before the Monitor.
*
* Note that all methods are const. Monitors implement logical constness, not
* bit constness. This allows const methods to call monitor methods without
* needing to cast away constness or change to non-const signatures.
*
* @version $Id:$
*/
class Monitor : boost::noncopyable {
public:
/** Creates a new mutex, and takes ownership of it. */
Monitor();
/** Uses the provided mutex without taking ownership. */
explicit Monitor(Mutex* mutex);
/** Uses the mutex inside the provided Monitor without taking ownership. */
explicit Monitor(Monitor* monitor);
/** Deallocates the mutex only if we own it. */
virtual ~Monitor();
Mutex& mutex() const;
virtual void lock() const;
virtual void unlock() const;
/**
* Waits a maximum of the specified timeout in milliseconds for the condition
* to occur, or waits forever if timeout_ms == 0.
*
* Returns 0 if condition occurs, ETIMEDOUT on timeout, or an error code.
*/
int waitForTimeRelative(int64_t timeout_ms) const;
/**
* Waits until the absolute time specified using struct timespec.
* Returns 0 if condition occurs, ETIMEDOUT on timeout, or an error code.
*/
int waitForTime(const timespec* abstime) const;
/**
* Waits forever until the condition occurs.
* Returns 0 if condition occurs, or an error code otherwise.
*/
int waitForever() const;
/**
* Exception-throwing version of waitForTimeRelative(), called simply
* wait(int64) for historical reasons. Timeout is in milliseconds.
*
* If the condition occurs, this function returns cleanly; on timeout or
* error an exception is thrown.
*/
void wait(int64_t timeout_ms = 0LL) const;
/** Wakes up one thread waiting on this monitor. */
virtual void notify() const;
/** Wakes up all waiting threads on this monitor. */
virtual void notifyAll() const;
private:
class Impl;
Impl* impl_;
};
class Synchronized {
public:
Synchronized(const Monitor* monitor) : g(monitor->mutex()) { }
Synchronized(const Monitor& monitor) : g(monitor.mutex()) { }
private:
Guard g;
};
}}} // apache::thrift::concurrency
#endif // #ifndef _THRIFT_CONCURRENCY_MONITOR_H_