// Copyright 2011 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// -----------------------------------------------------------------------------

//

// Multi-threaded worker

//

// Author: Skal (pascal.massimino@gmail.com)

#ifndef WEBP_UTILS_THREAD_UTILS_H_

#define WEBP_UTILS_THREAD_UTILS_H_

#ifdef HAVE_CONFIG_H

#include "src/webp/config.h"

#endif

#include "src/webp/types.h"

#ifdef __cplusplus

extern "C" {

#endif

// State of the worker thread object

typedef enum {

  NOT_OK = 0,   // object is unusable

  OK,           // ready to work

  WORK          // busy finishing the current task

} WebPWorkerStatus;

// Function to be called by the worker thread. Takes two opaque pointers as

// arguments (data1 and data2), and should return false in case of error.

typedef int (*WebPWorkerHook)(void*, void*);

// Synchronization object used to launch job in the worker thread

typedef struct {

  void* impl_;            // platform-dependent implementation worker details

  WebPWorkerStatus status_;

  WebPWorkerHook hook;    // hook to call

  void* data1;            // first argument passed to 'hook'

  void* data2;            // second argument passed to 'hook'

  int had_error;          // return value of the last call to 'hook'

} WebPWorker;

// The interface for all thread-worker related functions. All these functions

// must be implemented.

typedef struct {

  // Must be called first, before any other method.

  void (*Init)(WebPWorker* const worker);

  // Must be called to initialize the object and spawn the thread. Re-entrant.

  // Will potentially launch the thread. Returns false in case of error.

  int (*Reset)(WebPWorker* const worker);

  // Makes sure the previous work is finished. Returns true if worker->had_error

  // was not set and no error condition was triggered by the working thread.

  int (*Sync)(WebPWorker* const worker);

  // Triggers the thread to call hook() with data1 and data2 arguments. These

  // hook/data1/data2 values can be changed at any time before calling this

  // function, but not be changed afterward until the next call to Sync().

  void (*Launch)(WebPWorker* const worker);

  // This function is similar to Launch() except that it calls the

  // hook directly instead of using a thread. Convenient to bypass the thread

  // mechanism while still using the WebPWorker structs. Sync() must

  // still be called afterward (for error reporting).

  void (*Execute)(WebPWorker* const worker);

  // Kill the thread and terminate the object. To use the object again, one

  // must call Reset() again.

  void (*End)(WebPWorker* const worker);

} WebPWorkerInterface;

// Install a new set of threading functions, overriding the defaults. This

// should be done before any workers are started, i.e., before any encoding or

// decoding takes place. The contents of the interface struct are copied, it

// is safe to free the corresponding memory after this call. This function is

// not thread-safe. Return false in case of invalid pointer or methods.

WEBP_EXTERN int WebPSetWorkerInterface(

    const WebPWorkerInterface* const winterface);

// Retrieve the currently set thread worker interface.

WEBP_EXTERN const WebPWorkerInterface* WebPGetWorkerInterface(void);

//------------------------------------------------------------------------------

#ifdef __cplusplus

}    // extern "C"

#endif

#endif  /* WEBP_UTILS_THREAD_UTILS_H_ */