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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
/**
* @class document::Runnable
* @ingroup util
*
* @brief Implementation of FastOS_Runnable that implements threadsafe stop.
*
* FastOS_Runnable can easily be used unsafe. If you use the thread pointer for
* anything after your runnable had returned from Run(), it could affect another
* runnable now using that thread.
*
* Using this class should be foolproof to avoid synchronization issues during
* thread starting and stopping :)
*
* @author H�kon Humberset
* @date 2005-09-19
* @version $Id$
*/
#pragma once
#include <vespa/vespalib/util/sync.h>
#include <vespa/fastos/thread.h>
namespace document {
class Runnable : private FastOS_Runnable {
public:
enum State { NOT_RUNNING, STARTING, RUNNING, STOPPING };
private:
mutable vespalib::Monitor _stateLock;
State _state;
void Run(FastOS_ThreadInterface*, void*) override;
Runnable(const Runnable&);
Runnable& operator=(const Runnable&);
public:
/**
* Create a runnable.
* @param pool If set, runnable will be started in constructor.
*/
Runnable(FastOS_ThreadPool* pool = 0);
/**
* Start this runnable.
* @param pool The threadpool from which a thread is acquired.
* @return True if thread was started, false if thread was already running.
*/
bool start(FastOS_ThreadPool& pool);
/**
* Stop this runnable.
* @return True if thread was stopped, false if thread was not running.
*/
bool stop();
/**
* Called in stop(). Implement, to for instance notify any monitors that
* can be waiting.
*/
virtual bool onStop();
/**
* Wait for this thread to finish, if it is in the process of stopping.
* @return True if thread finished (or not running), false if thread is
* running normally and no stop is scheduled.
*/
bool join() const;
/**
* Implement this to make the runnable actually do something.
*/
virtual void run() = 0;
/** Get the current state of this runnable. */
State getState() const { return _state; }
/** Check if system is in the process of stopping. */
bool stopping() const
{
State s(getState());
return (s == STOPPING) ||
(s == RUNNING && GetThread()->GetBreakFlag());
}
/**
* Checks if runnable is running or not. (Started is considered running)
*/
bool running() const
{
State s(getState());
// Must check breakflag too, as threadpool will use that to close
// down.
return (s == STARTING ||
(s == RUNNING && !GetThread()->GetBreakFlag()));
}
};
}
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