webrtc/system_wrappers/interface/thread_wrapper.h

/*
 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

// System independant wrapper for spawning threads
// Note: the spawned thread will loop over the callback function until stopped.
// Note: The callback function is expected to return every 2 seconds or more
// often.

#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_THREAD_WRAPPER_H_
#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_THREAD_WRAPPER_H_

#include "common_types.h"
#include "typedefs.h"

namespace webrtc {
// Object that will be passed by the spawned thread when it enters the callback
// function.
#define ThreadObj void*

// Callback function that the spawned thread will enter once spawned.
// A return value of false is interpreted as that the function has no
// more work to do and that the thread can be released.
typedef  bool(*ThreadRunFunction)(ThreadObj);

enum ThreadPriority
{
    kLowPriority = 1,
    kNormalPriority = 2,
    kHighPriority = 3,
    kHighestPriority = 4,
    kRealtimePriority = 5
};

class ThreadWrapper
{
public:
    enum {kThreadMaxNameLength = 64};

    virtual ~ThreadWrapper() {};

    // Factory method. Constructor disabled.
    //
    // func        Pointer to a, by user, specified callback function.
    // obj         Object associated with the thread. Passed in the callback
    //             function.
    // prio        Thread priority. May require root/admin rights.
    // threadName  NULL terminated thread name, will be visable in the Windows
    //             debugger.
    static ThreadWrapper* CreateThread(ThreadRunFunction func = 0,
                                       ThreadObj obj= 0,
                                       ThreadPriority prio = kNormalPriority,
                                       const char* threadName = 0);

    // Get the current thread's kernel thread ID.
    static uint32_t GetThreadId();

    // Non blocking termination of the spawned thread. Note that it is not safe
    // to delete this class until the spawned thread has been reclaimed.
    virtual void SetNotAlive() = 0;

    // Tries to spawns a thread and returns true if that was successful.
    // Additionally, it tries to set thread priority according to the priority
    // from when CreateThread was called. However, failure to set priority will
    // not result in a false return value.
    // TODO(henrike): add a function for polling whether priority was set or
    //                not.
    virtual bool Start(unsigned int& id) = 0;

    // Sets the threads CPU affinity. CPUs are listed 0 - (number of CPUs - 1).
    // The numbers in processorNumbers specify which CPUs are allowed to run the
    // thread. processorNumbers should not contain any duplicates and elements
    // should be lower than (number of CPUs - 1). amountOfProcessors should be
    // equal to the number of processors listed in processorNumbers
    virtual bool SetAffinity(const int* /*processorNumbers*/,
                             const unsigned int /*amountOfProcessors*/) {
      return false;
    }

    // Stops the spawned thread and waits for it to be reclaimed with a timeout
    // of two seconds. Will return false if the thread was not reclaimed.
    // Multiple tries to Stop are allowed (e.g. to wait longer than 2 seconds).
    // It's ok to call Stop() even if the spawned thread has been reclaimed.
    virtual bool Stop() = 0;
};
} // namespace webrtc

#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_THREAD_WRAPPER_H_