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| 1 // Copyright 2011 Google Inc. All Rights Reserved. |
| 2 // |
| 3 // Use of this source code is governed by a BSD-style license |
| 4 // that can be found in the COPYING file in the root of the source |
| 5 // tree. An additional intellectual property rights grant can be found |
| 6 // in the file PATENTS. All contributing project authors may |
| 7 // be found in the AUTHORS file in the root of the source tree. |
| 8 // ----------------------------------------------------------------------------- |
| 9 // |
| 10 // Multi-threaded worker |
| 11 // |
| 12 // Author: Skal (pascal.massimino@gmail.com) |
| 13 |
| 14 #ifndef WEBP_UTILS_THREAD_H_ |
| 15 #define WEBP_UTILS_THREAD_H_ |
| 16 |
| 17 #ifdef HAVE_CONFIG_H |
| 18 #include "../webp/config.h" |
| 19 #endif |
| 20 |
| 21 #include "../webp/types.h" |
| 22 |
| 23 #ifdef __cplusplus |
| 24 extern "C" { |
| 25 #endif |
| 26 |
| 27 // State of the worker thread object |
| 28 typedef enum { |
| 29 NOT_OK = 0, // object is unusable |
| 30 OK, // ready to work |
| 31 WORK // busy finishing the current task |
| 32 } WebPWorkerStatus; |
| 33 |
| 34 // Function to be called by the worker thread. Takes two opaque pointers as |
| 35 // arguments (data1 and data2), and should return false in case of error. |
| 36 typedef int (*WebPWorkerHook)(void*, void*); |
| 37 |
| 38 // Platform-dependent implementation details for the worker. |
| 39 typedef struct WebPWorkerImpl WebPWorkerImpl; |
| 40 |
| 41 // Synchronization object used to launch job in the worker thread |
| 42 typedef struct { |
| 43 WebPWorkerImpl* impl_; |
| 44 WebPWorkerStatus status_; |
| 45 WebPWorkerHook hook; // hook to call |
| 46 void* data1; // first argument passed to 'hook' |
| 47 void* data2; // second argument passed to 'hook' |
| 48 int had_error; // return value of the last call to 'hook' |
| 49 } WebPWorker; |
| 50 |
| 51 // The interface for all thread-worker related functions. All these functions |
| 52 // must be implemented. |
| 53 typedef struct { |
| 54 // Must be called first, before any other method. |
| 55 void (*Init)(WebPWorker* const worker); |
| 56 // Must be called to initialize the object and spawn the thread. Re-entrant. |
| 57 // Will potentially launch the thread. Returns false in case of error. |
| 58 int (*Reset)(WebPWorker* const worker); |
| 59 // Makes sure the previous work is finished. Returns true if worker->had_error |
| 60 // was not set and no error condition was triggered by the working thread. |
| 61 int (*Sync)(WebPWorker* const worker); |
| 62 // Triggers the thread to call hook() with data1 and data2 arguments. These |
| 63 // hook/data1/data2 values can be changed at any time before calling this |
| 64 // function, but not be changed afterward until the next call to Sync(). |
| 65 void (*Launch)(WebPWorker* const worker); |
| 66 // This function is similar to Launch() except that it calls the |
| 67 // hook directly instead of using a thread. Convenient to bypass the thread |
| 68 // mechanism while still using the WebPWorker structs. Sync() must |
| 69 // still be called afterward (for error reporting). |
| 70 void (*Execute)(WebPWorker* const worker); |
| 71 // Kill the thread and terminate the object. To use the object again, one |
| 72 // must call Reset() again. |
| 73 void (*End)(WebPWorker* const worker); |
| 74 } WebPWorkerInterface; |
| 75 |
| 76 // Install a new set of threading functions, overriding the defaults. This |
| 77 // should be done before any workers are started, i.e., before any encoding or |
| 78 // decoding takes place. The contents of the interface struct are copied, it |
| 79 // is safe to free the corresponding memory after this call. This function is |
| 80 // not thread-safe. Return false in case of invalid pointer or methods. |
| 81 WEBP_EXTERN(int) WebPSetWorkerInterface( |
| 82 const WebPWorkerInterface* const interface); |
| 83 |
| 84 // Retrieve the currently set thread worker interface. |
| 85 WEBP_EXTERN(const WebPWorkerInterface*) WebPGetWorkerInterface(void); |
| 86 |
| 87 //------------------------------------------------------------------------------ |
| 88 |
| 89 #ifdef __cplusplus |
| 90 } // extern "C" |
| 91 #endif |
| 92 |
| 93 #endif /* WEBP_UTILS_THREAD_H_ */ |
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