spinlock.h

/*
 * Copyright (c) 2014, Siemens AG. All rights reserved.
 *
 * 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.
 *
 * 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 HOLDER 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 EMBB_DATAFLOW_INTERNAL_SPINLOCK_H_
#define EMBB_DATAFLOW_INTERNAL_SPINLOCK_H_

#include <embb/base/atomic.h>

namespace embb {
namespace dataflow {
namespace internal {

class SpinLock {
 public:
  SpinLock() : lock_(0) {}
  void Lock() {
    int expected = 0;
    while (!lock_.CompareAndSwap(expected, 1)) {
      expected = 0;
    }
  }
  bool TryLock(int spins = 0) {
    int expected = 0;
    while (spins > 0 && !lock_.CompareAndSwap(expected, 1)) {
      expected = 0;
      spins--;
    }
    return spins > 0;
  }
  void Unlock() {
    lock_ = 0;
  }

 private:
  embb::base::Atomic<int> lock_;
};

} // namespace internal
} // namespace dataflow
} // namespace embb

#endif // EMBB_DATAFLOW_INTERNAL_SPINLOCK_H_