text: ////////////////////////////////////////////////////////////////////////////////
  /// DISCLAIMER
  ///
  /// Copyright 2014-2021 ArangoDB GmbH, Cologne, Germany
  /// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
  ///
  /// Licensed under the Apache License, Version 2.0 (the "License");
  /// you may not use this file except in compliance with the License.
  /// You may obtain a copy of the License at
  ///
  ///     http://www.apache.org/licenses/LICENSE-2.0
  ///
  /// Unless required by applicable law or agreed to in writing, software
  /// distributed under the License is distributed on an "AS IS" BASIS,
  /// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  /// See the License for the specific language governing permissions and
  /// limitations under the License.
  ///
  /// Copyright holder is ArangoDB GmbH, Cologne, Germany
  ///
  /// @author Dr. Frank Celler
  /// @author Achim Brandt
  ////////////////////////////////////////////////////////////////////////////////
  
  #ifndef ARANGODB_BASICS_CONDITION_LOCKER_H
  #define ARANGODB_BASICS_CONDITION_LOCKER_H 1
  
  #include "Basics/Common.h"
  #include "Basics/Locking.h"
  
  #include <chrono>
  
  /// @brief construct locker with file and line information
  #ifdef ARANGODB_SHOW_LOCK_TIME
  
  #define CONDITION_LOCKER(a, b) \
    arangodb::basics::ConditionLocker a(&(b), __FILE__, __LINE__)
  
  #else
  
  #define CONDITION_LOCKER(a, b) \
    ::arangodb::basics::ConditionLocker a(&(b))
  
  #endif
  
  namespace arangodb {
  namespace basics {
  class ConditionVariable;
  
  /// @brief condition locker
  ///
  /// A ConditionLocker locks a condition when constructed and releases the lock
  /// when destroyed. It is possible the wait for an event in which case the lock
  /// is released or to broadcast an event.
  class ConditionLocker {
    ConditionLocker(ConditionLocker const&);
    ConditionLocker& operator=(ConditionLocker const&);
  
   public:
  /// @brief locks the condition variable
  ///
  /// The constructor locks the condition variable, the destructor unlocks
  /// the condition variable
  #ifdef ARANGODB_SHOW_LOCK_TIME
  
    ConditionLocker(ConditionVariable* conditionVariable, char const* file,
                    int line, bool showLockTime = true);
  
  #else
  
    explicit ConditionLocker(ConditionVariable* conditionVariable);
  
  #endif
  
    /// @brief unlocks the condition variable
    ~ConditionLocker();
  
   public:
    /// @brief whether or not the condition is locked
    bool isLocked() const { return _isLocked; }
  
    /// @brief waits for an event to occur
    void wait();
  
    /// @brief waits for an event to occur, using a timeout in micro seconds
    /// returns true when the condition was signaled, false on timeout
    bool wait(uint64_t);
  
    /// @brief waits for an event to occur, using a timeout
    /// returns true when the condition was signaled, false on timeout
    bool wait(std::chrono::microseconds);
  
    /// @brief broadcasts an event
    void broadcast();
  
    /// @brief signals an event
    void signal();
  
    /// @brief unlocks the variable (handle with care, no exception allowed)
    void unlock();
  
    /// @brief relock the variable after unlock
    void lock();
  
   private:
    /// @brief the condition
    ConditionVariable* _conditionVariable;
  
    /// @brief lock state
    bool _isLocked;
  
  #ifdef ARANGODB_SHOW_LOCK_TIME
  
    /// @brief file
    char const* _file;
  
    /// @brief line number
    int _line;
  
    bool _showLockTime;
  
    /// @brief lock time
    double _time;
  
  #endif
  };
  }  // namespace basics
  }  // namespace arangodb
  
  #endif
  