1 | ///////////////////////////////////////////////////////////////////////////  |
2 | //  |
3 | // Copyright (c) 2005, Industrial Light & Magic, a division of Lucas  |
4 | // Digital Ltd. LLC  |
5 | //   |
6 | // All rights reserved.  |
7 | //   |
8 | // Redistribution and use in source and binary forms, with or without  |
9 | // modification, are permitted provided that the following conditions are  |
10 | // met:  |
11 | // * Redistributions of source code must retain the above copyright  |
12 | // notice, this list of conditions and the following disclaimer.  |
13 | // * Redistributions in binary form must reproduce the above  |
14 | // copyright notice, this list of conditions and the following disclaimer  |
15 | // in the documentation and/or other materials provided with the  |
16 | // distribution.  |
17 | // * Neither the name of Industrial Light & Magic nor the names of  |
18 | // its contributors may be used to endorse or promote products derived  |
19 | // from this software without specific prior written permission.   |
20 | //   |
21 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS  |
22 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT  |
23 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR  |
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32 | //  |
33 | ///////////////////////////////////////////////////////////////////////////  |
34 |   |
35 | #ifndef INCLUDED_IMF_THREADING_H  |
36 | #define INCLUDED_IMF_THREADING_H  |
37 |   |
38 | #include "ImfExport.h"  |
39 | #include "ImfNamespace.h"  |
40 |   |
41 | //-----------------------------------------------------------------------------  |
42 | //  |
43 | // Threading support for the IlmImf library  |
44 | //  |
45 | // The IlmImf library uses threads to perform reading and writing  |
46 | // of OpenEXR files in parallel. The thread that calls the library  |
47 | // always performs the actual file IO (this is usually the main  |
48 | // application thread) whereas a several worker threads perform  |
49 | // data compression and decompression. The number of worker  |
50 | // threads can be any non-negative value (a value of zero reverts  |
51 | // to single-threaded operation). As long as there is at least  |
52 | // one worker thread, file IO and compression can potentially be  |
53 | // done concurrently through pinelining. If there are two or more  |
54 | // worker threads, then pipelining as well as concurrent compression  |
55 | // of multiple blocks can be performed.  |
56 | //   |
57 | // Threading in the Imf library is controllable at two granularities:  |
58 | //  |
59 | // * The functions in this file query and control the total number  |
60 | // of worker threads, which will be created globally for the whole  |
61 | // library. Regardless of how many input or output files are  |
62 | // opened simultaneously, the library will use at most this number  |
63 | // of worker threads to perform all work. The default number of  |
64 | // global worker threads is zero (i.e. single-threaded operation;  |
65 | // everything happens in the thread that calls the library).  |
66 | //  |
67 | // * Furthermore, it is possible to set the number of threads that  |
68 | // each input or output file should keep busy. This number can  |
69 | // be explicitly set for each file. The default behavior is for  |
70 | // each file to try to occupy all worker threads in the library's  |
71 | // thread pool.  |
72 | //  |
73 | //-----------------------------------------------------------------------------  |
74 |   |
75 | OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER  |
76 |   |
77 |   |
78 | //-----------------------------------------------------------------------------  |
79 | // Return the number of Imf-global worker threads used for parallel  |
80 | // compression and decompression of OpenEXR files.  |
81 | //-----------------------------------------------------------------------------  |
82 |   |
83 | IMF_EXPORT int globalThreadCount ();  |
84 |   |
85 |   |
86 | //-----------------------------------------------------------------------------  |
87 | // Change the number of Imf-global worker threads  |
88 | //-----------------------------------------------------------------------------  |
89 |   |
90 | IMF_EXPORT void setGlobalThreadCount (int count);  |
91 |   |
92 |   |
93 | OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT  |
94 |   |
95 | #endif  |
96 | |