thread_utils.h (3689B)
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_UTILS_H_ 15 #define WEBP_UTILS_THREAD_UTILS_H_ 16 17 #ifdef HAVE_CONFIG_H 18 #include "src/webp/config.h" 19 #endif 20 21 #include "src/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 // Synchronization object used to launch job in the worker thread 39 typedef struct { 40 void* impl; // platform-dependent implementation worker details 41 WebPWorkerStatus status; 42 WebPWorkerHook hook; // hook to call 43 void* data1; // first argument passed to 'hook' 44 void* data2; // second argument passed to 'hook' 45 int had_error; // return value of the last call to 'hook' 46 } WebPWorker; 47 48 // The interface for all thread-worker related functions. All these functions 49 // must be implemented. 50 typedef struct { 51 // Must be called first, before any other method. 52 void (*Init)(WebPWorker* const worker); 53 // Must be called to initialize the object and spawn the thread. Re-entrant. 54 // Will potentially launch the thread. Returns false in case of error. 55 int (*Reset)(WebPWorker* const worker); 56 // Makes sure the previous work is finished. Returns true if worker->had_error 57 // was not set and no error condition was triggered by the working thread. 58 int (*Sync)(WebPWorker* const worker); 59 // Triggers the thread to call hook() with data1 and data2 arguments. These 60 // hook/data1/data2 values can be changed at any time before calling this 61 // function, but not be changed afterward until the next call to Sync(). 62 void (*Launch)(WebPWorker* const worker); 63 // This function is similar to Launch() except that it calls the 64 // hook directly instead of using a thread. Convenient to bypass the thread 65 // mechanism while still using the WebPWorker structs. Sync() must 66 // still be called afterward (for error reporting). 67 void (*Execute)(WebPWorker* const worker); 68 // Kill the thread and terminate the object. To use the object again, one 69 // must call Reset() again. 70 void (*End)(WebPWorker* const worker); 71 } WebPWorkerInterface; 72 73 // Install a new set of threading functions, overriding the defaults. This 74 // should be done before any workers are started, i.e., before any encoding or 75 // decoding takes place. The contents of the interface struct are copied, it 76 // is safe to free the corresponding memory after this call. This function is 77 // not thread-safe. Return false in case of invalid pointer or methods. 78 WEBP_EXTERN int WebPSetWorkerInterface( 79 const WebPWorkerInterface* const winterface); 80 81 // Retrieve the currently set thread worker interface. 82 WEBP_EXTERN const WebPWorkerInterface* WebPGetWorkerInterface(void); 83 84 //------------------------------------------------------------------------------ 85 86 #ifdef __cplusplus 87 } // extern "C" 88 #endif 89 90 #endif // WEBP_UTILS_THREAD_UTILS_H_