oct-mutex.h

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2008-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////
 
#if ! defined (octave_oct_mutex_h)
#define octave_oct_mutex_h 1
 
#include "octave-config.h"
 
#include "oct-refcount.h"
 
namespace octave
{
  class mutex;
 
  class
  base_mutex
  {
  public:
    friend class mutex;
 
    base_mutex (void) : m_count (1) { }
 
    virtual ~base_mutex (void) = default;
 
    virtual void lock (void);
 
    virtual void unlock (void);
 
    virtual bool try_lock (void);
 
  private:
    refcount<octave_idx_type> m_count;
  };
 
  class
  OCTAVE_API
  mutex
  {
  public:
    mutex (void);
 
    mutex (const mutex& m)
      : m_rep (m.m_rep)
    {
      m_rep->m_count++;
    }
 
    ~mutex (void)
    {
      if (--m_rep->m_count == 0)
        delete m_rep;
    }
 
    mutex& operator = (const mutex& m)
    {
      if (m_rep != m.m_rep)
        {
          if (--m_rep->m_count == 0)
            delete m_rep;
 
          m_rep = m.m_rep;
          m_rep->m_count++;
        }
 
      return *this;
    }
 
    void lock (void)
    {
      m_rep->lock ();
    }
 
    void unlock (void)
    {
      m_rep->unlock ();
    }
 
    bool try_lock (void)
    {
      return m_rep->try_lock ();
    }
 
  protected:
    base_mutex *m_rep;
  };
 
  class
  autolock
  {
  public:
    autolock (const mutex& m, bool block = true)
      : m_mutex (m), m_lock_result (false)
    {
      if (block)
        {
          m_mutex.lock ();
          m_lock_result = true;
        }
      else
        m_lock_result = m_mutex.try_lock ();
    }
 
    // No copying.
 
    autolock (const autolock&) = delete;
 
    autolock& operator = (const autolock&) = delete;
 
    ~autolock (void)
    {
      if (m_lock_result)
        m_mutex.unlock ();
    }
 
    bool ok (void) const { return m_lock_result; }
 
    operator bool (void) const { return ok (); }
 
  private:
 
    mutex m_mutex;
 
    bool m_lock_result;
  };
 
 
  class
  OCTAVE_API
  thread
  {
  public:
 
    static void init (void);
 
    static bool is_thread (void);
  };
}
 
#endif