lib/cpp/src/concurrency/Thread.h

// Copyright (c) 2006- Facebook
// Distributed under the Thrift Software License
//
// See accompanying file LICENSE or visit the Thrift site at:
// http://developers.facebook.com/thrift/

#ifndef _THRIFT_CONCURRENCY_THREAD_H_
#define _THRIFT_CONCURRENCY_THREAD_H_ 1

#include <boost/shared_ptr.hpp>
#include <boost/weak_ptr.hpp>

namespace facebook { namespace thrift { namespace concurrency {

class Thread;

/**
 * Minimal runnable class.  More or less analogous to java.lang.Runnable.
 *
 * @author marc
 * @version $Id:$
 */
class Runnable {

 public:
  virtual ~Runnable() {};
  virtual void run() = 0;

  /**
   * Gets the thread object that is hosting this runnable object  - can return
   * an empty boost::shared pointer if no references remain on thet thread  object
   */
  virtual boost::shared_ptr<Thread> thread() { return thread_.lock(); }

  /**
   * Sets the thread that is executing this object.  This is only meant for
   * use by concrete implementations of Thread.
   */
  virtual void thread(boost::shared_ptr<Thread> value) { thread_ = value; }

 private:
  boost::weak_ptr<Thread> thread_;
};

/**
 * Minimal thread class. Returned by thread factory bound to a Runnable object
 * and ready to start execution.  More or less analogous to java.lang.Thread
 * (minus all the thread group, priority, mode and other baggage, since that
 * is difficult to abstract across platforms and is left for platform-specific
 * ThreadFactory implemtations to deal with
 *
 * @see facebook::thrift::concurrency::ThreadFactory)
 */
class Thread {

 public:

  typedef unsigned long long id_t;

  virtual ~Thread() {};

  /**
   * Starts the thread. Does platform specific thread creation and
   * configuration then invokes the run method of the Runnable object bound
   * to this thread.
   */
  virtual void start() = 0;

  /**
   * Join this thread. Current thread blocks until this target thread
   * completes.
   */
  virtual void join() = 0;

  /**
   * Gets the thread's platform-specific ID
   */
  virtual id_t id() = 0;

  /**
   * Gets the runnable object this thread is hosting
   */
  virtual boost::shared_ptr<Runnable> runnable() const { return _runnable; }

 protected:
  virtual void runnable(boost::shared_ptr<Runnable> value) { _runnable = value; }

 private:
  boost::shared_ptr<Runnable> _runnable;

};

/**
 * Factory to create platform-specific thread object and bind them to Runnable
 * object for execution
 */
class ThreadFactory {

 public:
  virtual ~ThreadFactory() {}
  virtual boost::shared_ptr<Thread> newThread(boost::shared_ptr<Runnable> runnable) const = 0;

  /** Gets the current thread id or unknown_thread_id if the current thread is not a thrift thread */

  static const Thread::id_t unknown_thread_id;

  virtual Thread::id_t currentThreadId() const = 0;
};

}}} // facebook::thrift::concurrency

#endif // #ifndef _THRIFT_CONCURRENCY_THREAD_H_