src/third_party/WebKit/Source/WTF/wtf/ThreadIdentifierDataStarboard.h

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef ThreadIdentifierDataStarboard_h
#define ThreadIdentifierDataStarboard_h

#include <map>

#include <wtf/Threading.h>
#include <wtf/ThreadingPrimitives.h>

#include "starboard/thread.h"

namespace WTF {

// Holds ThreadIdentifier in the thread-specific storage and employs 2-pass
// destruction to reliably remove ThreadIdentifier from threadMap. It assumes
// regular ThreadSpecific types don't use multiple-pass destruction.
//
// NOTE: I have no real idea what this multi-pass destruction is trying to
// do, but it is replicated here on Starboard. It's unclear whether this is a
// good idea or not -- if the underlying threads implementation does not have
// the same call-twice behavior as pthreads, it might ultimately leak the
// ThreadIdentifierData. That said, I don't think threads are being created and
// destroyed often, so it's probably not particularly important.
class ThreadIdentifierData {
    WTF_MAKE_NONCOPYABLE(ThreadIdentifierData);
public:
    ~ThreadIdentifierData();

    // One time initialization for this class as a whole.
    // This method must be called before initialize() and it is not thread-safe.
    static void initializeOnce();

    // Creates and puts an instance of ThreadIdentifierData into thread-specific storage.
    static void initialize(ThreadIdentifier identifier);

    // Returns 0 if thread-specific storage was not initialized.
    static ThreadIdentifier identifier();

private:
    ThreadIdentifierData(ThreadIdentifier identifier)
        : m_identifier(identifier)
        , m_isDestroyedOnce(false)
    {
    }

    static std::map<ThreadIdentifier, ThreadIdentifierData*> local_handle;
    static Mutex lock_local_handle;

    // This thread-specific destructor is called 2 times when thread terminates:
    //
    // * First, when all the other thread-specific destructors are called, it
    //   simply remembers it was 'destroyed once' and re-sets itself into the
    //   thread-specific slot to make the destructed be called again later.
    //
    // * Second, after all thread-specific destructors were invoked, it gets
    //   called again - this time, we remove the ThreadIdentifier from the
    //   threadMap, completing the cleanup.
    static void destruct(void* data);

    ThreadIdentifier m_identifier;
    bool m_isDestroyedOnce;
    static SbThreadLocalKey m_key;
};

} // namespace WTF

#endif // ThreadIdentifierDataStarboard_h