sandbox/win/src/win2k_threadpool.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SANDBOX_SRC_WIN2K_THREADPOOL_H_
   6 #define SANDBOX_SRC_WIN2K_THREADPOOL_H_
   7
   8 #include <list>
   9 #include <algorithm>
  10 #include "sandbox/win/src/crosscall_server.h"
  11
  12 namespace sandbox {
  13
  14 // Win2kThreadPool a simple implementation of a thread provider as required
  15 // for the sandbox IPC subsystem. See sandbox\crosscall_server.h for the details
  16 // and requirements of this interface.
  17 //
  18 // Implementing the thread provider as a thread pool is desirable in the case
  19 // of shared memory IPC because it can generate a large number of waitable
  20 // events: as many as channels. A thread pool does not create a thread per
  21 // event, instead maintains a few idle threads but can create more if the need
  22 // arises.
  23 //
  24 // This implementation simply thunks to the nice thread pool API of win2k.
  25 class Win2kThreadPool : public ThreadProvider {
  26  public:
  27   Win2kThreadPool() {
  28     ::InitializeCriticalSection(&lock_);
  29   }
  30   virtual ~Win2kThreadPool();
  31
  32   virtual bool RegisterWait(const void* cookie, HANDLE waitable_object,
  33                             CrossCallIPCCallback callback,
  34                             void* context);
  35
  36   virtual bool UnRegisterWaits(void* cookie);
  37
  38   // Returns the total number of wait objects associated with
  39   // the thread pool.
  40   size_t OutstandingWaits();
  41
  42  private:
  43   // record to keep track of a wait and its associated cookie.
  44   struct PoolObject {
  45     const void* cookie;
  46     HANDLE wait;
  47   };
  48   // The list of pool wait objects.
  49   typedef std::list<PoolObject> PoolObjects;
  50   PoolObjects pool_objects_;
  51   // This lock protects the list of pool wait objects.
  52   CRITICAL_SECTION lock_;
  53   DISALLOW_COPY_AND_ASSIGN(Win2kThreadPool);
  54 };
  55
  56 }  // namespace sandbox
  57
  58 #endif  // SANDBOX_SRC_WIN2K_THREADPOOL_H_