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 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 #ifndef SANDBOX_SRC_WIN2K_THREADPOOL_H_

 #define SANDBOX_SRC_WIN2K_THREADPOOL_H_

 #include <list>

 #include <algorithm>

 #include "sandbox/win/src/crosscall_server.h"

 namespace sandbox {

 // Win2kThreadPool a simple implementation of a thread provider as required

 // for the sandbox IPC subsystem. See sandbox\crosscall_server.h for the details

 // and requirements of this interface.

 //

 // Implementing the thread provider as a thread pool is desirable in the case

 // of shared memory IPC because it can generate a large number of waitable

 // events: as many as channels. A thread pool does not create a thread per

 // event, instead maintains a few idle threads but can create more if the need

 // arises.

 //

 // This implementation simply thunks to the nice thread pool API of win2k.

 class Win2kThreadPool : public ThreadProvider {

  public:

   Win2kThreadPool() {

     ::InitializeCriticalSection(&lock_);

   }

   virtual ~Win2kThreadPool();

   virtual bool RegisterWait(const void* cookie, HANDLE waitable_object,

                             CrossCallIPCCallback callback,

                             void* context);

   virtual bool UnRegisterWaits(void* cookie);

   // Returns the total number of wait objects associated with

   // the thread pool.

   size_t OutstandingWaits();

  private:

   // record to keep track of a wait and its associated cookie.

   struct PoolObject {

     const void* cookie;

     HANDLE wait;

   };

   // The list of pool wait objects.

   typedef std::list<PoolObject> PoolObjects;

   PoolObjects pool_objects_;

   // This lock protects the list of pool wait objects.

   CRITICAL_SECTION lock_;

   DISALLOW_COPY_AND_ASSIGN(Win2kThreadPool);

 };

 }  // namespace sandbox

 #endif  // SANDBOX_SRC_WIN2K_THREADPOOL_H_