vpx_thread.h - mozsearch

// Copyright 2013 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

//

// Original source:

//  https://chromium.googlesource.com/webm/libwebp

#ifndef VPX_VPX_UTIL_VPX_THREAD_H_

#define VPX_VPX_UTIL_VPX_THREAD_H_

#ifdef __cplusplus

extern "C" {

#endif

// State of the worker thread object

typedef enum {

  VPX_WORKER_STATUS_NOT_OK = 0,  // object is unusable

  VPX_WORKER_STATUS_OK,          // ready to work

  VPX_WORKER_STATUS_WORKING      // busy finishing the current task

} VPxWorkerStatus;

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

// arguments (data1 and data2). Should return true on success and return false

// in case of error.

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

// Platform-dependent implementation details for the worker.

typedef struct VPxWorkerImpl VPxWorkerImpl;

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

typedef struct {

  VPxWorkerImpl *impl_;

  VPxWorkerStatus status_;

  // Thread name for the debugger. If not NULL, must point to a string that

  // outlives the worker thread. For portability, use a name <= 15 characters

  // long (not including the terminating NUL character).

  const char *thread_name;

  VPxWorkerHook hook;  // hook to call

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

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

  int had_error;       // true if a call to 'hook' returned false

} VPxWorker;

// 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)(VPxWorker *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)(VPxWorker *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)(VPxWorker *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)(VPxWorker *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 VPxWorker structs. sync() must

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

  void (*execute)(VPxWorker *const worker);

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

  // must call reset() again.

  void (*end)(VPxWorker *const worker);

} VPxWorkerInterface;

// 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.

int vpx_set_worker_interface(const VPxWorkerInterface *const winterface);

// Retrieve the currently set thread worker interface.

const VPxWorkerInterface *vpx_get_worker_interface(void);

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

#ifdef __cplusplus

}  // extern "C"

#endif

#endif  // VPX_VPX_UTIL_VPX_THREAD_H_