#ifndef _GLIBMM_THREADPOOL_H
#define _GLIBMM_THREADPOOL_H
/* Copyright (C) 2002 The gtkmm Development Team
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <glibmmconfig.h>
#ifndef GLIBMM_DISABLE_DEPRECATED
#include <sigc++/sigc++.h>
extern "C" {
using GThreadPool = struct _GThreadPool;
}
namespace Glib
{
/** @defgroup ThreadPools Thread Pools
* Pools of threads to execute work concurrently.
*
* @deprecated This is deprecated in favor of the standard C++ concurrency API in C++11 and C++14.
*
* @{
*/
// TODO: Is std::async() an appropriate replacement to mention for this deprecated API?
/** A pool of threads to execute work concurrently.
*
* @deprecated This is deprecated in favor of the standard C++ concurrency API in C++11 and C++14.
*/
class GLIBMM_API ThreadPool
{
public:
/** Constructs a new thread pool.
* Whenever you call ThreadPool::push(), either a new thread is created or an
* unused one is reused. At most @a max_threads threads are running
* concurrently for this thread pool. @a max_threads = -1 allows
* unlimited threads to be created for this thread pool.
*
* The parameter @a exclusive determines, whether the thread pool owns all
* threads exclusive or whether the threads are shared globally. If @a
* exclusive is <tt>true</tt>, @a max_threads threads are started immediately
* and they will run exclusively for this thread pool until it is destroyed
* by ~ThreadPool(). If @a exclusive is <tt>false</tt>, threads are created
* when needed and shared between all non-exclusive thread pools. This
* implies that @a max_threads may not be -1 for exclusive thread pools.
*
* @param max_threads The maximal number of threads to execute concurrently
* in the new thread pool, -1 means no limit.
* @param exclusive Should this thread pool be exclusive?
* @throw Glib::ThreadError An error can only occur when @a exclusive is
* set to <tt>true</tt> and not all @a max_threads threads could be created.
*/
explicit ThreadPool(int max_threads = -1, bool exclusive = false);
virtual ~ThreadPool() noexcept;
// See http://bugzilla.gnome.org/show_bug.cgi?id=512348 about the sigc::trackable issue.
// TODO: At the next ABI break, consider changing const sigc::slot<void>& slot
// to const std::function<void()>& func, if it can be assumed that all supported
// compilers understand the C++11 template class std::function<>.
/** Inserts @a slot into the list of tasks to be executed by the pool.
* When the number of currently running threads is lower than the maximal
* allowed number of threads, a new thread is started (or reused). Otherwise
* @a slot stays in the queue until a thread in this pool finishes its
* previous task and processes @a slot.
*
* Because sigc::trackable is not thread-safe, if the slot represents a
* non-static class method and is created by sigc::mem_fun(), the class concerned
* should not derive from sigc::trackable. You can use, say, boost::bind() or,
* in C++11, std::bind() or a C++11 lambda expression instead of sigc::mem_fun().
*
* @param slot A new task for the thread pool.
* @throw Glib::ThreadError An error can only occur when a new thread
* couldn't be created. In that case @a slot is simply appended to the
* queue of work to do.
*/
void push(const sigc::slot<void>& slot);
/** Sets the maximal allowed number of threads for the pool.
* A value of -1 means that the maximal number of threads is unlimited.
* Setting @a max_threads to 0 means stopping all work for pool. It is
* effectively frozen until @a max_threads is set to a non-zero value again.
*
* A thread is never terminated while it is still running. Instead the
* maximal number of threads only has effect for the allocation of new
* threads in ThreadPool::push(). A new thread is allocated whenever the
* number of currently running threads in the pool is smaller than the
* maximal number.
*
* @param max_threads A new maximal number of threads for the pool.
* @throw Glib::ThreadError An error can only occur when a new thread
* couldn't be created.
*/
void set_max_threads(int max_threads);
/** Returns the maximal number of threads for the pool.
* @return The maximal number of threads.
*/
int get_max_threads() const;
/** Returns the number of threads currently running in the pool.
* @return The number of threads currently running.
*/
unsigned int get_num_threads() const;
/** Returns the number of tasks still unprocessed in the pool.
* @return The number of unprocessed tasks.
*/
unsigned int unprocessed() const;
/** Returns whether all threads are exclusive to this pool.
* @return Whether all threads are exclusive to this pool.
*/
bool get_exclusive() const;
/** Frees all resources allocated for the pool.
* If @a immediately is <tt>true</tt>, no new task is processed. Otherwise the
* 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.
*
* This method does not return before all tasks to be processed (dependent on
* @a immediately, whether all or only the currently running) are ready.
* After calling shutdown() the pool must not be used anymore.
*
* @param immediately Should the pool shut down immediately?
*/
void shutdown(bool immediately = false);
/** Sets the maximal number of unused threads to @a max_threads.
* If @a max_threads is -1, no limit is imposed on the number of unused threads.
* @param max_threads Maximal number of unused threads.
*/
static void set_max_unused_threads(int max_threads);
/** Returns the maximal allowed number of unused threads.
* @return The maximal number of unused threads.
*/
static int get_max_unused_threads();
/** Returns the number of currently unused threads.
* @return The number of currently unused threads.
*/
static unsigned int get_num_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 Glib::signal_timeout().
*/
static void stop_unused_threads();
GThreadPool* gobj() { return gobject_; }
const GThreadPool* gobj() const { return gobject_; }
#ifndef DOXYGEN_SHOULD_SKIP_THIS
class SlotList;
#endif
private:
GThreadPool* gobject_;
SlotList* slot_list_;
ThreadPool(const ThreadPool&);
ThreadPool& operator=(const ThreadPool&);
};
/** @} group ThreadPools */
/***************************************************************************/
/* inline implementation */
/***************************************************************************/
#ifndef DOXYGEN_SHOULD_SKIP_THIS
/**** Glib::Private ********************************************************/
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
} // namespace Glib
#endif // GLIBMM_DISABLE_DEPRECATED
#endif /* _GLIBMM_THREADPOOL_H */