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 (at) gmail.com) 13 14 #ifndef WEBP_UTILS_THREAD_H_ 15 #define WEBP_UTILS_THREAD_H_ 16 17 #ifdef HAVE_CONFIG_H 18 #include "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_ */ 94
