// 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

// Enable GNU extensions in glibc so that we can call pthread_setname_np().

// This must be before any #include statements.

#ifndef _GNU_SOURCE

#define _GNU_SOURCE

#endif

#include <assert.h>

#include <string.h>  // for memset()

#include "./vpx_config.h"

#include "./vpx_thread.h"

#include "vpx_mem/vpx_mem.h"

#include "vpx_util/vpx_pthread.h"

#if CONFIG_MULTITHREAD

struct VPxWorkerImpl {

  pthread_mutex_t mutex_;

  pthread_cond_t condition_;

  pthread_t thread_;

};

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

static void execute(VPxWorker *const worker);  // Forward declaration.

static THREADFN thread_loop(void *ptr) {

  VPxWorker *const worker = (VPxWorker *)ptr;

#ifdef __APPLE__

  if (worker->thread_name != NULL) {

    // Apple's version of pthread_setname_np takes one argument and operates on

    // the current thread only. The maximum size of the thread_name buffer was

    // noted in the Chromium source code and was confirmed by experiments. If

    // thread_name is too long, pthread_setname_np returns -1 with errno

    // ENAMETOOLONG (63).

    char thread_name[64];

    strncpy(thread_name, worker->thread_name, sizeof(thread_name) - 1);

    thread_name[sizeof(thread_name) - 1] = '\0';

    pthread_setname_np(thread_name);

  }

#elif (defined(__GLIBC__) && !defined(__GNU__)) || defined(__BIONIC__)

  if (worker->thread_name != NULL) {

    // Linux and Android require names (with nul) fit in 16 chars, otherwise

    // pthread_setname_np() returns ERANGE (34).

    char thread_name[16];

    strncpy(thread_name, worker->thread_name, sizeof(thread_name) - 1);

    thread_name[sizeof(thread_name) - 1] = '\0';

    pthread_setname_np(pthread_self(), thread_name);

  }

#endif

  pthread_mutex_lock(&worker->impl_->mutex_);

  for (;;) {

    while (worker->status_ == VPX_WORKER_STATUS_OK) {  // wait in idling mode

      pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);

    }

    if (worker->status_ == VPX_WORKER_STATUS_WORKING) {

      // When worker->status_ is VPX_WORKER_STATUS_WORKING, the main thread

      // doesn't change worker->status_ and will wait until the worker changes

      // worker->status_ to VPX_WORKER_STATUS_OK. See change_state(). So the

      // worker can safely call execute() without holding worker->impl_->mutex_.

      // When the worker reacquires worker->impl_->mutex_, worker->status_ must

      // still be VPX_WORKER_STATUS_WORKING.

      pthread_mutex_unlock(&worker->impl_->mutex_);

      execute(worker);

      pthread_mutex_lock(&worker->impl_->mutex_);

      assert(worker->status_ == VPX_WORKER_STATUS_WORKING);

      worker->status_ = VPX_WORKER_STATUS_OK;

      // signal to the main thread that we're done (for sync())

      pthread_cond_signal(&worker->impl_->condition_);

    } else {

      assert(worker->status_ == VPX_WORKER_STATUS_NOT_OK);  // finish the worker

      break;

    }

  }

  pthread_mutex_unlock(&worker->impl_->mutex_);

  return THREAD_EXIT_SUCCESS;  // Thread is finished

}

// main thread state control

static void change_state(VPxWorker *const worker, VPxWorkerStatus new_status) {

  // No-op when attempting to change state on a thread that didn't come up.

  // Checking status_ without acquiring the lock first would result in a data

  // race.

  if (worker->impl_ == NULL) return;

  pthread_mutex_lock(&worker->impl_->mutex_);

  if (worker->status_ >= VPX_WORKER_STATUS_OK) {

    // wait for the worker to finish

    while (worker->status_ != VPX_WORKER_STATUS_OK) {

      pthread_cond_wait(&worker->impl_->condition_, &worker->impl_->mutex_);

    }

    // assign new status and release the working thread if needed

    if (new_status != VPX_WORKER_STATUS_OK) {

      worker->status_ = new_status;

      pthread_cond_signal(&worker->impl_->condition_);

    }

  }

  pthread_mutex_unlock(&worker->impl_->mutex_);

}

#endif  // CONFIG_MULTITHREAD

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

static void init(VPxWorker *const worker) {

  memset(worker, 0, sizeof(*worker));

  worker->status_ = VPX_WORKER_STATUS_NOT_OK;

}

static int sync(VPxWorker *const worker) {

#if CONFIG_MULTITHREAD

  change_state(worker, VPX_WORKER_STATUS_OK);

#endif

  assert(worker->status_ <= VPX_WORKER_STATUS_OK);

  return !worker->had_error;

}

static int reset(VPxWorker *const worker) {

  int ok = 1;

  worker->had_error = 0;

  if (worker->status_ < VPX_WORKER_STATUS_OK) {

#if CONFIG_MULTITHREAD

    worker->impl_ = (VPxWorkerImpl *)vpx_calloc(1, sizeof(*worker->impl_));

    if (worker->impl_ == NULL) {

      return 0;

    }

    if (pthread_mutex_init(&worker->impl_->mutex_, NULL)) {

      goto Error;

    }

    if (pthread_cond_init(&worker->impl_->condition_, NULL)) {

      pthread_mutex_destroy(&worker->impl_->mutex_);

      goto Error;

    }

    pthread_mutex_lock(&worker->impl_->mutex_);

    ok = !pthread_create(&worker->impl_->thread_, NULL, thread_loop, worker);

    if (ok) worker->status_ = VPX_WORKER_STATUS_OK;

    pthread_mutex_unlock(&worker->impl_->mutex_);

    if (!ok) {

      pthread_mutex_destroy(&worker->impl_->mutex_);

      pthread_cond_destroy(&worker->impl_->condition_);

    Error:

      vpx_free(worker->impl_);

      worker->impl_ = NULL;

      return 0;

    }

#else

    worker->status_ = VPX_WORKER_STATUS_OK;

#endif

  } else if (worker->status_ > VPX_WORKER_STATUS_OK) {

    ok = sync(worker);

  }

  assert(!ok || (worker->status_ == VPX_WORKER_STATUS_OK));

  return ok;

}

static void execute(VPxWorker *const worker) {

  if (worker->hook != NULL) {

    worker->had_error |= !worker->hook(worker->data1, worker->data2);

  }

}

static void launch(VPxWorker *const worker) {

#if CONFIG_MULTITHREAD

  change_state(worker, VPX_WORKER_STATUS_WORKING);

#else

  execute(worker);

#endif

}

static void end(VPxWorker *const worker) {

#if CONFIG_MULTITHREAD

  if (worker->impl_ != NULL) {

    change_state(worker, VPX_WORKER_STATUS_NOT_OK);

    pthread_join(worker->impl_->thread_, NULL);

    pthread_mutex_destroy(&worker->impl_->mutex_);

    pthread_cond_destroy(&worker->impl_->condition_);

    vpx_free(worker->impl_);

    worker->impl_ = NULL;

  }

#else

  worker->status_ = VPX_WORKER_STATUS_NOT_OK;

  assert(worker->impl_ == NULL);

#endif

  assert(worker->status_ == VPX_WORKER_STATUS_NOT_OK);

}

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

static VPxWorkerInterface g_worker_interface = { init,   reset,   sync,

                                                 launch, execute, end };

int vpx_set_worker_interface(const VPxWorkerInterface *const winterface) {

  if (winterface == NULL || winterface->init == NULL ||

      winterface->reset == NULL || winterface->sync == NULL ||

      winterface->launch == NULL || winterface->execute == NULL ||

      winterface->end == NULL) {

    return 0;

  }

  g_worker_interface = *winterface;

  return 1;

}

const VPxWorkerInterface *vpx_get_worker_interface(void) {

  return &g_worker_interface;

}

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