/********************************************************************
**                Image Component Library (ICL)                    **
**                                                                 **
** Copyright (C) 2006-2013 CITEC, University of Bielefeld          **
**                         Neuroinformatics Group                  **
** Website: www.iclcv.org and                                      **
**          http://opensource.cit-ec.de/projects/icl               **
**                                                                 **
** File   : ICLUtils/src/ICLUtils/ProcessMonitor.h                 **
** Module : ICLUtils                                               **
** Authors: Christof Elbrechter                                    **
**                                                                 **
**                                                                 **
** GNU LESSER GENERAL PUBLIC LICENSE                               **
** This file may be used under the terms of the GNU Lesser General **
** Public License version 3.0 as published by the                  **
**                                                                 **
** Free Software Foundation and appearing in the file LICENSE.LGPL **
** included in the packaging of this file.  Please review the      **
** following information to ensure the license requirements will   **
** be met: http://www.gnu.org/licenses/lgpl-3.0.txt                **
**                                                                 **
** The development of this software was supported by the           **
** Excellence Cluster EXC 277 Cognitive Interaction Technology.    **
** The Excellence Cluster EXC 277 is a grant of the Deutsche       **
** Forschungsgemeinschaft (DFG) in the context of the German       **
** Excellence Initiative.                                          **
**                                                                 **
********************************************************************/

#pragma once

#include <ICLUtils/CompatMacros.h>
#include <ICLUtils/Thread.h>
#include <ICLUtils/Mutex.h>
#include <ICLUtils/Uncopyable.h>
#include <ICLUtils/Function.h>
#include <iostream>

namespace icl{
  namespace utils{
    
    /// The ProcessMonitor class grants access to processes memory and CPU usage
    /** Since querying process specific information is not standardized in C++,
        Only a Linux solution is provided yet. 
  
        \section SRC Source of the Information
        
        * The pid is obtained via getpid() 
        * numThreads and memoryUsage is obtained by parsing /proc/self/stats 
        * memoryUsage is obtained by reading a piped 'ps' processes output
        * since querying information an in particular waiting for 'ps' output
          takes some time, all the information is collected in a dedicated 
          thread. 
        * numCPUs is queried once at construction time by parsing /proc/processor
        * allCPU usage is also queried by parsing the piped 'ps' output
  
        \section CB Callbacks
        Since sometimes, an application wants to do something, when new information
        is available, a callback mechanism is provided as well. Simply register
        an icl::Function instance that is then called whenever a new set of 
        data is available.
    */
    class ICLUtils_API ProcessMonitor : protected Thread, public Uncopyable{
      /// internal data structure (pimpl)
      struct Data;
      
      /// internal data pointer
      Data *m_data;
      
      public:
      
      /// Utility struct, that is used to pass available information at once
      struct Info{
        int pid;            // current process ID
        int numThreads;     // number of threads of the current process
        float cpuUsage;     // percent 0-numCPUs*100
        float allCpuUsage;  // percent 0-100
        float memoryUsage;  // used memory in MB
        int numCPUs;        // sometimes, this helps for visualization
      };
      
      protected:
      /// Create a new instance
      ProcessMonitor();
      
      public:
      
      /// returns the singelton instance
      static ProcessMonitor *getInstance();
      
      /// Destructor
      ~ProcessMonitor();
      
      /// implements the Thread::run method
      virtual void run();
      
      /// synchronized access to last queried data
      Info getInfo() const;
      
      /// callback function/functor type 
      typedef Function<void,const Info&> Callback;
  
      /// registers a callback instance that is automatically called when new data is available
      /** returns a callback ID */
      int registerCallback(Callback cb);
      
      /// removes a callback registered before
      void removeCallback(int id);
      
      /// removes all registered callbacks
      void removeAllCallbacks();
    };
  
    /// overloaded ostream operator for the ProcessMonitor's Info data type
    ICLUtils_API std::ostream &operator<<(std::ostream &s, const ProcessMonitor::Info &info);
  } // namespace utils
}