talk/base/sharedexclusivelock.cc

/*
 * libjingle
 * Copyright 2011, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. 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.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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,
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 */

#include "talk/base/sharedexclusivelock.h"

namespace talk_base {

SharedExclusiveLock::SharedExclusiveLock()
    : shared_count_is_zero_(true, true),
      shared_count_(0) {
}

void SharedExclusiveLock::LockExclusive() {
  cs_exclusive_.Enter();
  shared_count_is_zero_.Wait(talk_base::kForever);
}

void SharedExclusiveLock::UnlockExclusive() {
  cs_exclusive_.Leave();
}

void SharedExclusiveLock::LockShared() {
  CritScope exclusive_scope(&cs_exclusive_);
  CritScope shared_scope(&cs_shared_);
  if (++shared_count_ == 1) {
    shared_count_is_zero_.Reset();
  }
}

void SharedExclusiveLock::UnlockShared() {
  CritScope shared_scope(&cs_shared_);
  if (--shared_count_ == 0) {
    shared_count_is_zero_.Set();
  }
}

}  // namespace talk_base