ImfThreading.h

Go to the documentation of this file.

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////

#ifndef INCLUDED_IMF_THREADING_H
#define INCLUDED_IMF_THREADING_H

#include "ImfExport.h"
#include "ImfNamespace.h"

//-----------------------------------------------------------------------------
//
//      Threading support for the IlmImf library
//
//      The IlmImf library uses threads to perform reading and writing
//      of OpenEXR files in parallel.  The thread that calls the library
//      always performs the actual file IO (this is usually the main
//      application thread) whereas a several worker threads perform
//      data compression and decompression.  The number of worker
//      threads can be any non-negative value (a value of zero reverts
//      to single-threaded operation).  As long as there is at least
//      one worker thread, file IO and compression can potentially be
//      done concurrently through pinelining.  If there are two or more
//      worker threads, then pipelining as well as concurrent compression
//      of multiple blocks can be performed.
// 
//      Threading in the Imf library is controllable at two granularities:
//
//      * The functions in this file query and control the total number
//        of worker threads, which will be created globally for the whole
//        library.  Regardless of how many input or output files are
//        opened simultaneously, the library will use at most this number
//        of worker threads to perform all work.  The default number of
//        global worker threads is zero (i.e. single-threaded operation;
//        everything happens in the thread that calls the library).
//
//      * Furthermore, it is possible to set the number of threads that
//        each input or output file should keep busy.  This number can
//        be explicitly set for each file.  The default behavior is for
//        each file to try to occupy all worker threads in the library's
//        thread pool.
//
//-----------------------------------------------------------------------------

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER


//-----------------------------------------------------------------------------
// Return the number of Imf-global worker threads used for parallel
// compression and decompression of OpenEXR files.
//-----------------------------------------------------------------------------
    
IMF_EXPORT int     globalThreadCount ();


//-----------------------------------------------------------------------------
// Change the number of Imf-global worker threads
//-----------------------------------------------------------------------------

IMF_EXPORT void    setGlobalThreadCount (int count);


OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT

#endif