text: // LevelDB Copyright (c) 2011 The LevelDB Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file. See the AUTHORS file for names of contributors.
  //
  // See port_example.h for documentation for the following types/functions.
  
  // 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 the University of California, Berkeley 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 REGENTS 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 REGENTS AND 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.
  //
  
  #include "port/port_win.h"
  
  #include <windows.h>
  #include <cassert>
  
  #define ZLIB
  
  #ifdef SNAPPY
  	#include <snappy/snappy.h>
  #elif defined(ZLIB)
  	#include <zlib/zlib.h>
  #endif
  
  namespace leveldb {
  namespace port {
  
  CondVar::CondVar(Mutex* mu) :
      waiting_(0), 
      mu_(mu), 
      sem1_(::CreateSemaphore(NULL, 0, 10000, NULL)), 
      sem2_(::CreateSemaphore(NULL, 0, 10000, NULL)) {
    assert(mu_);
  }
  
  CondVar::~CondVar() {
    ::CloseHandle(sem1_);
    ::CloseHandle(sem2_);
  }
  
  void CondVar::Wait() {
    mu_->AssertHeld();
  
    wait_mtx_.Lock();
    ++waiting_;
    wait_mtx_.Unlock();
  
    mu_->Unlock();
  
    // initiate handshake
    ::WaitForSingleObject(sem1_, INFINITE);
    ::ReleaseSemaphore(sem2_, 1, NULL);
    mu_->Lock();
  }
  
  void CondVar::Signal() {
    wait_mtx_.Lock();
    if (waiting_ > 0) {
      --waiting_;
  
      // finalize handshake
      ::ReleaseSemaphore(sem1_, 1, NULL);
      ::WaitForSingleObject(sem2_, INFINITE);
    }
    wait_mtx_.Unlock();
  }
  
  void CondVar::SignalAll() {
    wait_mtx_.Lock();
    for(long i = 0; i < waiting_; ++i) {
      ::ReleaseSemaphore(sem1_, 1, NULL);
      while(waiting_ > 0) {
        --waiting_;
        ::WaitForSingleObject(sem2_, INFINITE);
      }
    }
    wait_mtx_.Unlock();
  }
  
  AtomicPointer::AtomicPointer(void* v) {
    Release_Store(v);
  }
  
  void* AtomicPointer::Acquire_Load() const {
    void * p = nullptr;
    InterlockedExchangePointer(&p, rep_);
    return p;
  }
  
  void AtomicPointer::Release_Store(void* v) {
    InterlockedExchangePointer(&rep_, v);
  }
  
  void* AtomicPointer::NoBarrier_Load() const {
    return rep_;
  }
  
  void AtomicPointer::NoBarrier_Store(void* v) {
    rep_ = v;
  }
  
  }
  }
  