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ImfThreading.h

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
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///////////////////////////////////////////////////////////////////////////

#ifndef INCLUDED_IMF_THREADING_H
#define INCLUDED_IMF_THREADING_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.
//
//-----------------------------------------------------------------------------

namespace Imf {


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


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

void    setGlobalThreadCount (int count);


} // namespace Imf

#endif

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