event_loop.h

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/*
 * Copyright (C) 2009-2016 Paul Davis <paul@linuxaudiosystems.com>
 * Copyright (C) 2015-2017 Robin Gareus <robin@gareus.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#pragma once
 
#include <sigc++/trackable.h>
#include <sigc++/connection.h>
 
#include <atomic>
#include <functional>
#include <string>
#include <list>
#include <vector>
#include <stdint.h>
#include <pthread.h>
 
#include "pbd/libpbd_visibility.h"
#include "pbd/mutex.h"
#include "pbd/private.h"
#include "pbd/rwlock.h"
 
namespace PBD
{
 
class LIBPBD_API EventLoop
{
public:
        EventLoop (std::string const&);
        virtual ~EventLoop();
 
        enum RequestType {
                range_guarantee = ~0
        };
 
        struct BaseRequestObject;
 
        struct InvalidationRecord {
                std::list<BaseRequestObject*> requests;
                PBD::EventLoop* event_loop;
                std::atomic<int> _valid;
                std::atomic<int> _ref;
                const char* file;
                int line;
 
                InvalidationRecord() : event_loop (0), _valid (1), _ref (0) {}
                void invalidate () { _valid.store (0); }
                bool valid () { return _valid.load () == 1; }
 
                void ref ()    { _ref.fetch_add (1); }
                void unref ()  { (void) _ref.fetch_sub (1); }
                bool in_use () { return _ref.load () > 0; }
                int  use_count () { return _ref.load (); }
        };
 
        static void* invalidate_request (void* data);
 
        struct BaseRequestObject {
                RequestType             type;
                InvalidationRecord*     invalidation;
                std::function<void()> the_slot;
 
                BaseRequestObject() : invalidation (0) {}
                ~BaseRequestObject() {
                        if (invalidation) {
                                invalidation->unref ();
                        }
                }
        };
 
        virtual bool call_slot (InvalidationRecord*, const std::function<void()>&) = 0;
        virtual PBD::RWLock& slot_invalidation_rwlock() = 0;
 
        std::string event_loop_name() const { return _name; }
 
        static EventLoop* get_event_loop_for_thread();
        static void set_event_loop_for_thread (EventLoop* ui);
 
        struct ThreadBufferMapping {
                pthread_t emitting_thread;
                size_t num_requests;
        };
 
        static std::vector<ThreadBufferMapping> get_request_buffers_for_target_thread (const std::string&);
 
        static void pre_register (const std::string& emitting_thread_name, uint32_t num_requests);
        static void remove_request_buffer_from_map (pthread_t);
 
        std::list<InvalidationRecord*> trash;
 
        static InvalidationRecord* __invalidator (sigc::trackable& trackable, const char*, int);
 
private:
        static PBD::Private<EventLoop> thread_event_loop;
        std::string _name;
 
        typedef std::vector<ThreadBufferMapping> ThreadRequestBufferList;
        static ThreadRequestBufferList thread_buffer_requests;
        static PBD::Mutex   thread_buffer_requests_lock;
 
        struct RequestBufferSupplier {
 
                /* @param name : name of object/entity that will/may accept
                 * requests from other threads, via a request buffer.
                 */
                std::string name;
 
                /* @param factory : a function that can be called (with an
                 * argument specifying the @param number_of_requests) to create and
                 * return a request buffer for communicating with @p name)
                 */
                void* (*factory)(uint32_t nunber_of_requests);
        };
        typedef std::vector<RequestBufferSupplier> RequestBufferSuppliers;
        static RequestBufferSuppliers request_buffer_suppliers;
};
 
}
 
#define MISSING_INVALIDATOR nullptr // used to mark places where we fail to provide an invalidator