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
24extern "C" {
25#endif
26
27// State of the worker thread object
28typedef 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.
36typedef int (*WebPWorkerHook)(void*, void*);
37
38// Synchronization object used to launch job in the worker thread
39typedef 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.
50typedef 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.
78WEBP_EXTERN int WebPSetWorkerInterface(
79 const WebPWorkerInterface* const winterface);
80
81// Retrieve the currently set thread worker interface.
82WEBP_EXTERN const WebPWorkerInterface* WebPGetWorkerInterface(void);
83
84//------------------------------------------------------------------------------
85
86#ifdef __cplusplus
87} // extern "C"
88#endif
89
90#endif // WEBP_UTILS_THREAD_UTILS_H_
91