1 ///////////////////////////////////////////////////////////////////////////
3 // Copyright (c) 2005, Industrial Light & Magic, a division of Lucas
6 // All rights reserved.
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9 // modification, are permitted provided that the following conditions are
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33 ///////////////////////////////////////////////////////////////////////////
35 #ifndef INCLUDED_IMF_THREADING_H
36 #define INCLUDED_IMF_THREADING_H
38 //-----------------------------------------------------------------------------
40 // Threading support for the IlmImf library
42 // The IlmImf library uses threads to perform reading and writing
43 // of OpenEXR files in parallel. The thread that calls the library
44 // always performs the actual file IO (this is usually the main
45 // application thread) whereas a several worker threads perform
46 // data compression and decompression. The number of worker
47 // threads can be any non-negative value (a value of zero reverts
48 // to single-threaded operation). As long as there is at least
49 // one worker thread, file IO and compression can potentially be
50 // done concurrently through pinelining. If there are two or more
51 // worker threads, then pipelining as well as concurrent compression
52 // of multiple blocks can be performed.
54 // Threading in the Imf library is controllable at two granularities:
56 // * The functions in this file query and control the total number
57 // of worker threads, which will be created globally for the whole
58 // library. Regardless of how many input or output files are
59 // opened simultaneously, the library will use at most this number
60 // of worker threads to perform all work. The default number of
61 // global worker threads is zero (i.e. single-threaded operation;
62 // everything happens in the thread that calls the library).
64 // * Furthermore, it is possible to set the number of threads that
65 // each input or output file should keep busy. This number can
66 // be explicitly set for each file. The default behavior is for
67 // each file to try to occupy all worker threads in the library's
70 //-----------------------------------------------------------------------------
75 //-----------------------------------------------------------------------------
76 // Return the number of Imf-global worker threads used for parallel
77 // compression and decompression of OpenEXR files.
78 //-----------------------------------------------------------------------------
80 int globalThreadCount ();
83 //-----------------------------------------------------------------------------
84 // Change the number of Imf-global worker threads
85 //-----------------------------------------------------------------------------
87 void setGlobalThreadCount (int count);