| 1 | // |
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| 2 | // SPDX-License-Identifier: BSD-3-Clause |
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| 3 | // Copyright (c) Contributors to the OpenEXR Project. |
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| 4 | // |
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| 5 | |
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| 6 | #ifndef INCLUDED_IMF_THREADING_H |
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| 7 | #define INCLUDED_IMF_THREADING_H |
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| 8 | |
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| 9 | #include "ImfExport.h" |
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| 10 | #include "ImfNamespace.h" |
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| 11 | |
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| 12 | //----------------------------------------------------------------------------- |
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| 13 | // |
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| 14 | // Threading support for the OpenEXR library |
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| 15 | // |
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| 16 | // The OpenEXR library uses threads to perform reading and writing |
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| 17 | // of OpenEXR files in parallel. The thread that calls the library |
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| 18 | // always performs the actual file IO (this is usually the main |
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| 19 | // application thread) whereas a several worker threads perform |
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| 20 | // data compression and decompression. The number of worker |
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| 21 | // threads can be any non-negative value (a value of zero reverts |
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| 22 | // to single-threaded operation). As long as there is at least |
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| 23 | // one worker thread, file IO and compression can potentially be |
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| 24 | // done concurrently through pinelining. If there are two or more |
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| 25 | // worker threads, then pipelining as well as concurrent compression |
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| 26 | // of multiple blocks can be performed. |
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| 27 | // |
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| 28 | // Threading in the EXR library is controllable at two granularities: |
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| 29 | // |
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| 30 | // * The functions in this file query and control the total number |
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| 31 | // of worker threads, which will be created globally for the whole |
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| 32 | // library. Regardless of how many input or output files are |
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| 33 | // opened simultaneously, the library will use at most this number |
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| 34 | // of worker threads to perform all work. The default number of |
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| 35 | // global worker threads is zero (i.e. single-threaded operation; |
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| 36 | // everything happens in the thread that calls the library). |
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| 37 | // |
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| 38 | // * Furthermore, it is possible to set the number of threads that |
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| 39 | // each input or output file should keep busy. This number can |
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| 40 | // be explicitly set for each file. The default behavior is for |
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| 41 | // each file to try to occupy all worker threads in the library's |
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| 42 | // thread pool. |
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| 43 | // |
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| 44 | //----------------------------------------------------------------------------- |
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| 45 | |
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| 46 | OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER |
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| 47 | |
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| 48 | |
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| 49 | //----------------------------------------------------------------------------- |
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| 50 | // Return the number of Imf-global worker threads used for parallel |
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| 51 | // compression and decompression of OpenEXR files. |
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| 52 | //----------------------------------------------------------------------------- |
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| 53 | |
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| 54 | IMF_EXPORT int globalThreadCount (); |
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| 55 | |
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| 56 | |
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| 57 | //----------------------------------------------------------------------------- |
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| 58 | // Change the number of Imf-global worker threads |
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| 59 | //----------------------------------------------------------------------------- |
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| 60 | |
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| 61 | IMF_EXPORT void setGlobalThreadCount (int count); |
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| 62 | |
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| 63 | |
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| 64 | OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT |
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| 65 | |
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| 66 | #endif |
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| 67 | |
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