gthreadpool.c

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 * to do.  
 **/
void 
g_thread_pool_push (GThreadPool     *pool,
		    gpointer         data,
		    GError         **error)
{
  GRealThreadPool *real = (GRealThreadPool*) pool;

  g_return_if_fail (real);

  g_async_queue_lock (real->queue);
  
  if (!real->running)
    {
      g_async_queue_unlock (real->queue);
      g_return_if_fail (real->running);
    }

  if (g_async_queue_length_unlocked (real->queue) >= 0)
    /* No thread is waiting in the queue */
    g_thread_pool_start_thread (real, error);

  g_async_queue_push_unlocked (real->queue, data);
  g_async_queue_unlock (real->queue);
}

/**
 * g_thread_pool_set_max_threads:
 * @pool: a #GThreadPool
 * @max_threads: a new maximal number of threads for @pool
 * @error: return location for error
 * 
 * Sets the maximal allowed number of threads for @pool. A value of -1
 * means, that the maximal number of threads is unlimited.
 *
 * Setting @max_threads to 0 means stopping all work for @pool. It is
 * effectively frozen until @max_threads is set to a non-zero value
 * again.
 * 
 * A thread is never terminated while calling @func, as supplied by
 * g_thread_pool_new (). Instead the maximal number of threads only
 * has effect for the allocation of new threads in g_thread_pool_push(). 
 * A new thread is allocated, whenever the number of currently
 * running threads in @pool is smaller than the maximal number.
 *
 * @error can be %NULL to ignore errors, or non-%NULL to report
 * errors. An error can only occur when a new thread couldn't be
 * created. 
 **/
void
g_thread_pool_set_max_threads (GThreadPool     *pool,
			       gint             max_threads,
			       GError         **error)
{
  GRealThreadPool *real = (GRealThreadPool*) pool;
  gint to_start;

  g_return_if_fail (real);
  g_return_if_fail (real->running);
  g_return_if_fail (!real->pool.exclusive || max_threads != -1);
  g_return_if_fail (max_threads >= -1);

  g_async_queue_lock (real->queue);

  real->max_threads = max_threads;
  
  if (pool->exclusive)
    to_start = real->max_threads - real->num_threads;
  else
    to_start = g_async_queue_length_unlocked (real->queue);
  
  for ( ; to_start > 0; to_start--)
    {
      GError *local_error = NULL;
      g_thread_pool_start_thread (real, &local_error);
      if (local_error)
	{
	  g_propagate_error (error, local_error);
	  break;
	}
    }
   
  g_async_queue_unlock (real->queue);
}

/**
 * g_thread_pool_get_max_threads:
 * @pool: a #GThreadPool
 *
 * Returns the maximal number of threads for @pool.
 *
 * Return value: the maximal number of threads
 **/
gint
g_thread_pool_get_max_threads (GThreadPool     *pool)
{
  GRealThreadPool *real = (GRealThreadPool*) pool;
  gint retval;

  g_return_val_if_fail (real, 0);
  g_return_val_if_fail (real->running, 0);

  g_async_queue_lock (real->queue);

  retval = real->max_threads;
    
  g_async_queue_unlock (real->queue);

  return retval;
}

/**
 * g_thread_pool_get_num_threads:
 * @pool: a #GThreadPool
 *
 * Returns the number of threads currently running in @pool.
 *
 * Return value: the number of threads currently running
 **/
guint
g_thread_pool_get_num_threads (GThreadPool     *pool)
{
  GRealThreadPool *real = (GRealThreadPool*) pool;
  guint retval;

  g_return_val_if_fail (real, 0);
  g_return_val_if_fail (real->running, 0);

  g_async_queue_lock (real->queue);

  retval = real->num_threads;
    
  g_async_queue_unlock (real->queue);

  return retval;
}

/**
 * g_thread_pool_unprocessed:
 * @pool: a #GThreadPool
 *
 * Returns the number of tasks still unprocessed in @pool.
 *
 * Return value: the number of unprocessed tasks
 **/
guint
g_thread_pool_unprocessed (GThreadPool     *pool)
{
  GRealThreadPool *real = (GRealThreadPool*) pool;
  gint unprocessed;

  g_return_val_if_fail (real, 0);
  g_return_val_if_fail (real->running, 0);

  unprocessed = g_async_queue_length (real->queue);

  return MAX (unprocessed, 0);
}

/**
 * g_thread_pool_free:
 * @pool: a #GThreadPool
 * @immediate: should @pool shut down immediately?
 * @wait: should the function wait for all tasks to be finished?
 *
 * Frees all resources allocated for @pool.
 *
 * If @immediate is %TRUE, no new task is processed for
 * @pool. Otherwise @pool is not freed before the last task is
 * processed. Note however, that no thread of this pool is
 * interrupted, while processing a task. Instead at least all still
 * running threads can finish their tasks before the @pool is freed.
 *
 * If @wait is %TRUE, the functions does not return before all tasks
 * to be processed (dependent on @immediate, whether all or only the
 * currently running) are ready. Otherwise the function returns immediately.
 *
 * After calling this function @pool must not be used anymore. 
 **/
void
g_thread_pool_free (GThreadPool     *pool,
		    gboolean         immediate,
		    gboolean         wait)
{
  GRealThreadPool *real = (GRealThreadPool*) pool;

  g_return_if_fail (real);
  g_return_if_fail (real->running);
  /* It there's no thread allowed here, there is not much sense in
   * not stopping this pool immediately, when it's not empty */
  g_return_if_fail (immediate || real->max_threads != 0 || 
		    g_async_queue_length (real->queue) == 0);

  g_async_queue_lock (real->queue);

  real->running = FALSE;
  real->immediate = immediate;
  real->waiting = wait;

  if (wait)
    {
      g_mutex_lock (inform_mutex);
      while (g_async_queue_length_unlocked (real->queue) != -real->num_threads)
	{
	  g_async_queue_unlock (real->queue); 
	  g_cond_wait (inform_cond, inform_mutex); 
	  g_async_queue_lock (real->queue); 
	}
      g_mutex_unlock (inform_mutex); 
    }

  if (g_async_queue_length_unlocked (real->queue) == -real->num_threads)
    {
      /* No thread is currently doing something (and nothing is left
       * to process in the queue) */
      if (real->num_threads == 0) /* No threads left, we clean up */
	{
	  g_async_queue_unlock (real->queue);
	  g_thread_pool_free_internal (real);
	  return;
	}

      g_thread_pool_wakeup_and_stop_all (real);
    }
  
  real->waiting = FALSE; /* The last thread should cleanup the pool */
  g_async_queue_unlock (real->queue);
}

static void
g_thread_pool_free_internal (GRealThreadPool* pool)
{
  g_return_if_fail (pool);
  g_return_if_fail (!pool->running);
  g_return_if_fail (pool->num_threads == 0);

  g_async_queue_unref (pool->queue);

  g_free (pool);
}

static void
g_thread_pool_wakeup_and_stop_all (GRealThreadPool* pool)
{
  guint i;
  
  g_return_if_fail (pool);
  g_return_if_fail (!pool->running);
  g_return_if_fail (pool->num_threads != 0);
  g_return_if_fail (g_async_queue_length_unlocked (pool->queue) == 
		    -pool->num_threads);

  pool->immediate = TRUE; 
  for (i = 0; i < pool->num_threads; i++)
    g_async_queue_push_unlocked (pool->queue, GUINT_TO_POINTER (1));
}

/**
 * g_thread_pool_set_max_unused_threads:
 * @max_threads: maximal number of unused threads
 *
 * Sets the maximal number of unused threads to @max_threads. If
 * @max_threads is -1, no limit is imposed on the number of unused
 * threads.
 **/
void
g_thread_pool_set_max_unused_threads (gint max_threads)
{
  g_return_if_fail (max_threads >= -1);  

  G_LOCK (unused_threads);
  
  max_unused_threads = max_threads;

  if (max_unused_threads < unused_threads && max_unused_threads != -1)
    {
      guint i;

      g_async_queue_lock (unused_thread_queue);
      for (i = unused_threads - max_unused_threads; i > 0; i--)
	g_async_queue_push_unlocked (unused_thread_queue, 
				     stop_this_thread_marker);
      g_async_queue_unlock (unused_thread_queue);
    }
    
  G_UNLOCK (unused_threads);
}

/**
 * g_thread_pool_get_max_unused_threads:
 * 
 * Returns the maximal allowed number of unused threads.
 *
 * Return value: the maximal number of unused threads
 **/
gint
g_thread_pool_get_max_unused_threads (void)
{
  gint retval;
  
  G_LOCK (unused_threads);
  retval = max_unused_threads;
  G_UNLOCK (unused_threads);

  return retval;
}

/**
 * g_thread_pool_get_num_unused_threads:
 * 
 * Returns the number of currently unused threads.
 *
 * Return value: the number of currently unused threads
 **/
guint g_thread_pool_get_num_unused_threads (void)
{
  guint retval;
  
  G_LOCK (unused_threads);
  retval = unused_threads;
  G_UNLOCK (unused_threads);

  return retval;
}

/**
 * g_thread_pool_stop_unused_threads:
 * 
 * Stops all currently unused threads. This does not change the
 * maximal number of unused threads. This function can be used to
 * regularly stop all unused threads e.g. from g_timeout_add().
 **/
void g_thread_pool_stop_unused_threads (void)
{ 
  guint oldval = g_thread_pool_get_max_unused_threads ();
  g_thread_pool_set_max_unused_threads (0);
  g_thread_pool_set_max_unused_threads (oldval);
}