src/v8threads.h

// Copyright 2008 the V8 project authors. 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 V8_V8THREADS_H_
#define V8_V8THREADS_H_

namespace v8 { namespace internal {


class ThreadState {
 public:
  // Iterate over in-use states.
  static ThreadState* FirstInUse();
  // Returns NULL after the last one.
  ThreadState* Next();

  enum List {FREE_LIST, IN_USE_LIST};

  void LinkInto(List list);
  void Unlink();

  static ThreadState* GetFree();

  // Get data area for archiving a thread.
  char* data() { return data_; }
 private:
  ThreadState();

  void AllocateSpace();

  char* data_;
  ThreadState* next_;
  ThreadState* previous_;
  // In the following two lists there is always at least one object on the list.
  // The first object is a flying anchor that is only there to simplify linking
  // and unlinking.
  // Head of linked list of free states.
  static ThreadState* free_anchor_;
  // Head of linked list of states in use.
  static ThreadState* in_use_anchor_;
};


class ThreadManager : public AllStatic {
 public:
  static void Lock();
  static void Unlock();

  static void ArchiveThread();
  static bool RestoreThread();

  static void Iterate(ObjectVisitor* v);
  static void MarkCompactPrologue();
  static void MarkCompactEpilogue();
  static bool IsLockedByCurrentThread() { return mutex_owner_.IsSelf(); }
 private:
  static void EagerlyArchiveThread();

  static Mutex* mutex_;
  static ThreadHandle mutex_owner_;
  static ThreadHandle lazily_archived_thread_;
  static ThreadState* lazily_archived_thread_state_;
};


class ContextSwitcher: public Thread {
 public:
  void Run();
  static void StartPreemption(int every_n_ms);
  static void StopPreemption();
  static void PreemptionReceived();
 private:
  explicit ContextSwitcher(int every_n_ms);
  void WaitForPreemption();
  void Stop();
  Semaphore* preemption_semaphore_;
  bool keep_going_;
  int sleep_ms_;
};

} }  // namespace v8::internal

#endif  // V8_V8THREADS_H_