github.com/cellofellow/gopkg@v0.0.0-20140722061823-eec0544a62ad/image/webp/libwebp/src/utils/thread.h (about)

     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 "config.h"
    19  #endif
    20  
    21  #ifdef __cplusplus
    22  extern "C" {
    23  #endif
    24  
    25  #ifdef WEBP_USE_THREAD
    26  
    27  #if defined(_WIN32)
    28  
    29  #include <windows.h>
    30  typedef HANDLE pthread_t;
    31  typedef CRITICAL_SECTION pthread_mutex_t;
    32  typedef struct {
    33    HANDLE waiting_sem_;
    34    HANDLE received_sem_;
    35    HANDLE signal_event_;
    36  } pthread_cond_t;
    37  
    38  #else
    39  
    40  #include <pthread.h>
    41  
    42  #endif    /* _WIN32 */
    43  #endif    /* WEBP_USE_THREAD */
    44  
    45  // State of the worker thread object
    46  typedef enum {
    47    NOT_OK = 0,   // object is unusable
    48    OK,           // ready to work
    49    WORK          // busy finishing the current task
    50  } WebPWorkerStatus;
    51  
    52  // Function to be called by the worker thread. Takes two opaque pointers as
    53  // arguments (data1 and data2), and should return false in case of error.
    54  typedef int (*WebPWorkerHook)(void*, void*);
    55  
    56  // Synchronize object used to launch job in the worker thread
    57  typedef struct {
    58  #ifdef WEBP_USE_THREAD
    59    pthread_mutex_t mutex_;
    60    pthread_cond_t  condition_;
    61    pthread_t       thread_;
    62  #endif
    63    WebPWorkerStatus status_;
    64    WebPWorkerHook hook;    // hook to call
    65    void* data1;            // first argument passed to 'hook'
    66    void* data2;            // second argument passed to 'hook'
    67    int had_error;          // return value of the last call to 'hook'
    68  } WebPWorker;
    69  
    70  // Must be called first, before any other method.
    71  void WebPWorkerInit(WebPWorker* const worker);
    72  // Must be called to initialize the object and spawn the thread. Re-entrant.
    73  // Will potentially launch the thread. Returns false in case of error.
    74  int WebPWorkerReset(WebPWorker* const worker);
    75  // Makes sure the previous work is finished. Returns true if worker->had_error
    76  // was not set and no error condition was triggered by the working thread.
    77  int WebPWorkerSync(WebPWorker* const worker);
    78  // Triggers the thread to call hook() with data1 and data2 argument. These
    79  // hook/data1/data2 can be changed at any time before calling this function,
    80  // but not be changed afterward until the next call to WebPWorkerSync().
    81  void WebPWorkerLaunch(WebPWorker* const worker);
    82  // This function is similar to WebPWorkerLaunch() except that it calls the
    83  // hook directly instead of using a thread. Convenient to bypass the thread
    84  // mechanism while still using the WebPWorker structs. WebPWorkerSync() must
    85  // still be called afterward (for error reporting).
    86  void WebPWorkerExecute(WebPWorker* const worker);
    87  // Kill the thread and terminate the object. To use the object again, one
    88  // must call WebPWorkerReset() again.
    89  void WebPWorkerEnd(WebPWorker* const worker);
    90  
    91  //------------------------------------------------------------------------------
    92  
    93  #ifdef __cplusplus
    94  }    // extern "C"
    95  #endif
    96  
    97  #endif  /* WEBP_UTILS_THREAD_H_ */