94 lines
3.6 KiB
C
94 lines
3.6 KiB
C
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// Copyright 2011 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Multi-threaded worker
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#ifndef WEBP_UTILS_THREAD_H_
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#define WEBP_UTILS_THREAD_H_
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#ifdef HAVE_CONFIG_H
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#include "../webp/config.h"
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#endif
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#include "../webp/types.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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// State of the worker thread object
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typedef enum {
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NOT_OK = 0, // object is unusable
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OK, // ready to work
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WORK // busy finishing the current task
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} WebPWorkerStatus;
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// Function to be called by the worker thread. Takes two opaque pointers as
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// arguments (data1 and data2), and should return false in case of error.
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typedef int (*WebPWorkerHook)(void*, void*);
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// Platform-dependent implementation details for the worker.
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typedef struct WebPWorkerImpl WebPWorkerImpl;
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// Synchronization object used to launch job in the worker thread
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typedef struct {
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WebPWorkerImpl* impl_;
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WebPWorkerStatus status_;
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WebPWorkerHook hook; // hook to call
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void* data1; // first argument passed to 'hook'
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void* data2; // second argument passed to 'hook'
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int had_error; // return value of the last call to 'hook'
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} WebPWorker;
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// The interface for all thread-worker related functions. All these functions
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// must be implemented.
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typedef struct {
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// Must be called first, before any other method.
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void (*Init)(WebPWorker* const worker);
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// Must be called to initialize the object and spawn the thread. Re-entrant.
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// Will potentially launch the thread. Returns false in case of error.
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int (*Reset)(WebPWorker* const worker);
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// Makes sure the previous work is finished. Returns true if worker->had_error
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// was not set and no error condition was triggered by the working thread.
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int (*Sync)(WebPWorker* const worker);
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// Triggers the thread to call hook() with data1 and data2 arguments. These
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// hook/data1/data2 values can be changed at any time before calling this
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// function, but not be changed afterward until the next call to Sync().
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void (*Launch)(WebPWorker* const worker);
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// This function is similar to Launch() except that it calls the
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// hook directly instead of using a thread. Convenient to bypass the thread
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// mechanism while still using the WebPWorker structs. Sync() must
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// still be called afterward (for error reporting).
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void (*Execute)(WebPWorker* const worker);
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// Kill the thread and terminate the object. To use the object again, one
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// must call Reset() again.
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void (*End)(WebPWorker* const worker);
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} WebPWorkerInterface;
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// Install a new set of threading functions, overriding the defaults. This
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// should be done before any workers are started, i.e., before any encoding or
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// decoding takes place. The contents of the interface struct are copied, it
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// is safe to free the corresponding memory after this call. This function is
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// not thread-safe. Return false in case of invalid pointer or methods.
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WEBP_EXTERN(int) WebPSetWorkerInterface(
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const WebPWorkerInterface* const interface);
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// Retrieve the currently set thread worker interface.
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WEBP_EXTERN(const WebPWorkerInterface*) WebPGetWorkerInterface(void);
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//------------------------------------------------------------------------------
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif /* WEBP_UTILS_THREAD_H_ */
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