itkThreadLogger.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  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.
 *
 *=========================================================================*/
#ifndef itkThreadLogger_h
#define itkThreadLogger_h
 
#include "itkLogger.h"
#include <mutex>
#include <atomic>
 
#include <string>
#include <queue>
#include <thread>
 
namespace itk
{
 
class ITKCommon_EXPORT ThreadLogger : public Logger
{
public:
  using Self = ThreadLogger;
  using Superclass = Logger;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkOverrideGetNameOfClassMacro(ThreadLogger);

  itkNewMacro(Self);
 
  using OutputType = Logger::OutputType;
 
  using PriorityLevelEnum = Logger::PriorityLevelEnum;
 
  using DelayType = unsigned int;

  enum OperationType
  {
    SET_PRIORITY_LEVEL,
    SET_LEVEL_FOR_FLUSHING,
    ADD_LOG_OUTPUT,
    WRITE,
    FLUSH
  };

  void
  SetPriorityLevel(PriorityLevelEnum level) override;

  PriorityLevelEnum
  GetPriorityLevel() const override;
 
  void
  SetLevelForFlushing(PriorityLevelEnum level) override;
 
  PriorityLevelEnum
  GetLevelForFlushing() const override;

  virtual void
  SetDelay(DelayType delay);

  virtual DelayType
  GetDelay() const;

  void
  AddLogOutput(OutputType * output) override;
 
  void
  Write(PriorityLevelEnum level, const std::string & content) override;
 
  void
  Flush() override;
 
protected:
  ThreadLogger();

  ~ThreadLogger() override;

  void
  PrintSelf(std::ostream & os, Indent indent) const override;
 
  void
  ThreadFunction();
 
private:
  void
  InternalFlush();
 
  std::thread m_Thread{};
 
  std::atomic<bool> m_TerminationRequested{};
 
  std::queue<OperationType> m_OperationQ{};
 
  std::queue<std::string> m_MessageQ{};
 
  std::queue<PriorityLevelEnum> m_LevelQ{};
 
  std::queue<OutputType::Pointer> m_OutputQ{};
 
  mutable std::mutex m_Mutex{};
 
  DelayType m_Delay{};
 
}; // class ThreadLogger
} // namespace itk
 
#endif // itkThreadLogger_h