Guard.h

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/*
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   Copyright (c) 2009 Scientific Computing and Imaging Institute,
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///
///@file   Guard.h
///@brief  Automatically lock/unlock a mutex or crowdmonitor.
///
///@author Steve Parker
///        Department of Computer Science
///        University of Utah
///@date   June 1997
///

#ifndef Core_Thread_Guard_h
#define Core_Thread_Guard_h

#include <Core/Thread/Legacy/share.h>

namespace SCIRun {

class Mutex;
class RecursiveMutex;
class CrowdMonitor;

/**************************************

@class
  Guard

  KEYWORDS
  Thread

@details
  Utility class to lock and unlock a <b>Mutex</b> or a <b>CrowdMonitor</b>.
  The constructor of the <b>Guard</b> object will lock the mutex
  (or <b>CrowdMonitor</b>), and the destructor will unlock it.
  <p>
  This would be used like this:
  <blockquote><pre>
  {
  <blockquote>Guard mlock(&mutex);  // Acquire the mutex
  ... critical section ...</blockquote>
  } // mutex is released when mlock goes out of scope
  </pre></blockquote>
   
****************************************/
class SCISHARE Guard {
public:
  //////////
  /// Attach the <b>Guard</b> object to the <i>mutex</i>, and
  /// acquire the mutex.
  Guard(Mutex* mutex);

  Guard(RecursiveMutex* rmutex);

  enum Which {
    Read,
    Write
  };
    
  //////////
  /// Attach the <b>Guard</b> to the <i>CrowdMonitor</pre> and
  /// acquire one of the locks.  If <i>action</i> is
  /// <b>Guard::Read</b>, the read lock will be acquired, and if
  /// <i>action</i> is <b>Write</b>, then the write lock will be
  /// acquired.  The appropriate lock will then be released by the
  /// destructor
  Guard(CrowdMonitor* crowdMonitor, Which action);
    
  //////////
  /// Release the lock acquired by the constructor.
  ~Guard();
private:
  Mutex* mutex_;
  RecursiveMutex* rmutex_;
  CrowdMonitor* monitor_;
  Which action_;

  // Cannot copy them
  Guard(const Guard&);
  Guard& operator=(const Guard&);
};
} // End namespace SCIRun

#endif