// 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)

#include <assert.h>

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

#include "src/utils/thread_utils.h"

#include "src/utils/utils.h"

#ifdef WEBP_USE_THREAD

#if defined(_WIN32)

#include <windows.h>

typedef HANDLE pthread_t;

typedef CRITICAL_SECTION pthread_mutex_t;

#if _WIN32_WINNT >= 0x0600  // Windows Vista / Server 2008 or greater

#define USE_WINDOWS_CONDITION_VARIABLE

typedef CONDITION_VARIABLE pthread_cond_t;

#else

typedef struct {

  HANDLE waiting_sem;

  HANDLE received_sem;

  HANDLE signal_event;

} pthread_cond_t;

#endif  // _WIN32_WINNT >= 0x600

#ifndef WINAPI_FAMILY_PARTITION

#define WINAPI_PARTITION_DESKTOP 1

#define WINAPI_FAMILY_PARTITION(x) x

#endif

#if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)

#define USE_CREATE_THREAD

#endif

#else  // !_WIN32

#include <pthread.h>

#endif  // _WIN32

typedef struct {

  pthread_mutex_t mutex;

  pthread_cond_t  condition;

  pthread_t       thread;

} WebPWorkerImpl;

#if defined(_WIN32)

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

// simplistic pthread emulation layer

#include <process.h>

// _beginthreadex requires __stdcall

#define THREADFN unsigned int __stdcall

#define THREAD_RETURN(val) (unsigned int)((DWORD_PTR)val)

#if _WIN32_WINNT >= 0x0501  // Windows XP or greater

#define WaitForSingleObject(obj, timeout) \

  WaitForSingleObjectEx(obj, timeout, FALSE /*bAlertable*/)

#endif

static int pthread_create(pthread_t* const thread, const void* attr,

                          unsigned int (__stdcall* start)(void*), void* arg) {

  (void)attr;

#ifdef USE_CREATE_THREAD

  *thread = CreateThread(NULL,   /* lpThreadAttributes */

                         0,      /* dwStackSize */

                         start,

                         arg,

                         0,      /* dwStackSize */

                         NULL);  /* lpThreadId */

#else

  *thread = (pthread_t)_beginthreadex(NULL,   /* void *security */

                                      0,      /* unsigned stack_size */

                                      start,

                                      arg,

                                      0,      /* unsigned initflag */

                                      NULL);  /* unsigned *thrdaddr */

#endif

  if (*thread == NULL) return 1;

  SetThreadPriority(*thread, THREAD_PRIORITY_ABOVE_NORMAL);

  return 0;

}

static int pthread_join(pthread_t thread, void** value_ptr) {

  (void)value_ptr;

  return (WaitForSingleObject(thread, INFINITE) != WAIT_OBJECT_0 ||

          CloseHandle(thread) == 0);

}

// Mutex

static int pthread_mutex_init(pthread_mutex_t* const mutex, void* mutexattr) {

  (void)mutexattr;

#if _WIN32_WINNT >= 0x0600  // Windows Vista / Server 2008 or greater

  InitializeCriticalSectionEx(mutex, 0 /*dwSpinCount*/, 0 /*Flags*/);

#else

  InitializeCriticalSection(mutex);

#endif

  return 0;

}

static int pthread_mutex_lock(pthread_mutex_t* const mutex) {

  EnterCriticalSection(mutex);

  return 0;

}

static int pthread_mutex_unlock(pthread_mutex_t* const mutex) {

  LeaveCriticalSection(mutex);

  return 0;

}

static int pthread_mutex_destroy(pthread_mutex_t* const mutex) {

  DeleteCriticalSection(mutex);

  return 0;

}

// Condition

static int pthread_cond_destroy(pthread_cond_t* const condition) {

  int ok = 1;

#ifdef USE_WINDOWS_CONDITION_VARIABLE

  (void)condition;

#else

  ok &= (CloseHandle(condition->waiting_sem) != 0);

  ok &= (CloseHandle(condition->received_sem) != 0);

  ok &= (CloseHandle(condition->signal_event) != 0);

#endif

  return !ok;

}

static int pthread_cond_init(pthread_cond_t* const condition, void* cond_attr) {

  (void)cond_attr;

#ifdef USE_WINDOWS_CONDITION_VARIABLE

  InitializeConditionVariable(condition);

#else

  condition->waiting_sem = CreateSemaphore(NULL, 0, 1, NULL);

  condition->received_sem = CreateSemaphore(NULL, 0, 1, NULL);

  condition->signal_event = CreateEvent(NULL, FALSE, FALSE, NULL);

  if (condition->waiting_sem == NULL ||

      condition->received_sem == NULL ||

      condition->signal_event == NULL) {

    pthread_cond_destroy(condition);

    return 1;

  }

#endif

  return 0;

}

static int pthread_cond_signal(pthread_cond_t* const condition) {

  int ok = 1;

#ifdef USE_WINDOWS_CONDITION_VARIABLE

  WakeConditionVariable(condition);

#else

  if (WaitForSingleObject(condition->waiting_sem, 0) == WAIT_OBJECT_0) {

    // a thread is waiting in pthread_cond_wait: allow it to be notified

    ok = SetEvent(condition->signal_event);

    // wait until the event is consumed so the signaler cannot consume

    // the event via its own pthread_cond_wait.

    ok &= (WaitForSingleObject(condition->received_sem, INFINITE) !=

           WAIT_OBJECT_0);

  }

#endif

  return !ok;

}

static int pthread_cond_wait(pthread_cond_t* const condition,

                             pthread_mutex_t* const mutex) {

  int ok;

#ifdef USE_WINDOWS_CONDITION_VARIABLE

  ok = SleepConditionVariableCS(condition, mutex, INFINITE);

#else

  // note that there is a consumer available so the signal isn't dropped in

  // pthread_cond_signal

  if (!ReleaseSemaphore(condition->waiting_sem, 1, NULL)) return 1;

  // now unlock the mutex so pthread_cond_signal may be issued

  pthread_mutex_unlock(mutex);

  ok = (WaitForSingleObject(condition->signal_event, INFINITE) ==

        WAIT_OBJECT_0);

  ok &= ReleaseSemaphore(condition->received_sem, 1, NULL);

  pthread_mutex_lock(mutex);

#endif

  return !ok;

}

#else  // !_WIN32

# define THREADFN void*

# define THREAD_RETURN(val) val

#endif  // _WIN32

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

static THREADFN ThreadLoop(void* ptr) {

  WebPWorker* const worker = (WebPWorker*)ptr;

  WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl;

  int done = 0;

  while (!done) {

    pthread_mutex_lock(&impl->mutex);

    while (worker->status == OK) {   // wait in idling mode

      pthread_cond_wait(&impl->condition, &impl->mutex);

    }

    if (worker->status == WORK) {

      WebPGetWorkerInterface()->Execute(worker);

      worker->status = OK;

    } else if (worker->status == NOT_OK) {   // finish the worker

      done = 1;

    }

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

    // Note the associated mutex does not need to be held when signaling the

    // condition. Unlocking the mutex first may improve performance in some

    // implementations, avoiding the case where the waiting thread can't

    // reacquire the mutex when woken.

    pthread_mutex_unlock(&impl->mutex);

    pthread_cond_signal(&impl->condition);

  }

  return THREAD_RETURN(NULL);    // Thread is finished

}

// main thread state control

static void ChangeState(WebPWorker* const worker, WebPWorkerStatus 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.

  WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl;

  if (impl == NULL) return;

  pthread_mutex_lock(&impl->mutex);

  if (worker->status >= OK) {

    // wait for the worker to finish

    while (worker->status != OK) {

      pthread_cond_wait(&impl->condition, &impl->mutex);

    }

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

    if (new_status != OK) {

      worker->status = new_status;

      // Note the associated mutex does not need to be held when signaling the

      // condition. Unlocking the mutex first may improve performance in some

      // implementations, avoiding the case where the waiting thread can't

      // reacquire the mutex when woken.

      pthread_mutex_unlock(&impl->mutex);

      pthread_cond_signal(&impl->condition);

      return;

    }

  }

  pthread_mutex_unlock(&impl->mutex);

}

#endif  // WEBP_USE_THREAD

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

static void Init(WebPWorker* const worker) {

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

  worker->status = NOT_OK;

}

static int Sync(WebPWorker* const worker) {

#ifdef WEBP_USE_THREAD

  ChangeState(worker, OK);

#endif

  assert(worker->status <= OK);

  return !worker->had_error;

}

static int Reset(WebPWorker* const worker) {

  int ok = 1;

  worker->had_error = 0;

  if (worker->status < OK) {

#ifdef WEBP_USE_THREAD

    WebPWorkerImpl* const impl =

        (WebPWorkerImpl*)WebPSafeCalloc(1, sizeof(WebPWorkerImpl));

    worker->impl = (void*)impl;

    if (worker->impl == NULL) {

      return 0;

    }

    if (pthread_mutex_init(&impl->mutex, NULL)) {

      goto Error;

    }

    if (pthread_cond_init(&impl->condition, NULL)) {

      pthread_mutex_destroy(&impl->mutex);

      goto Error;

    }

    pthread_mutex_lock(&impl->mutex);

    ok = !pthread_create(&impl->thread, NULL, ThreadLoop, worker);

    if (ok) worker->status = OK;

    pthread_mutex_unlock(&impl->mutex);

    if (!ok) {

      pthread_mutex_destroy(&impl->mutex);

      pthread_cond_destroy(&impl->condition);

 Error:

      WebPSafeFree(impl);

      worker->impl = NULL;

      return 0;

    }

#else

    worker->status = OK;

#endif

  } else if (worker->status > OK) {

    ok = Sync(worker);

  }

  assert(!ok || (worker->status == OK));

  return ok;

}

static void Execute(WebPWorker* const worker) {

  if (worker->hook != NULL) {

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

  }

}

static void Launch(WebPWorker* const worker) {

#ifdef WEBP_USE_THREAD

  ChangeState(worker, WORK);

#else

  Execute(worker);

#endif

}

static void End(WebPWorker* const worker) {

#ifdef WEBP_USE_THREAD

  if (worker->impl != NULL) {

    WebPWorkerImpl* const impl = (WebPWorkerImpl*)worker->impl;

    ChangeState(worker, NOT_OK);

    pthread_join(impl->thread, NULL);

    pthread_mutex_destroy(&impl->mutex);

    pthread_cond_destroy(&impl->condition);

    WebPSafeFree(impl);

    worker->impl = NULL;

  }

#else

  worker->status = NOT_OK;

  assert(worker->impl == NULL);

#endif

  assert(worker->status == NOT_OK);

}

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

static WebPWorkerInterface g_worker_interface = {

  Init, Reset, Sync, Launch, Execute, End

};

int WebPSetWorkerInterface(const WebPWorkerInterface* 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 WebPWorkerInterface* WebPGetWorkerInterface(void) {

  return &g_worker_interface;

}

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