1 /*
2  * Copyright (C) 2009-2016 Paul Davis <paul@linuxaudiosystems.com>
3  * Copyright (C) 2015-2017 Robin Gareus <robin@gareus.org>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation; either version 2 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License along
16  * with this program; if not, write to the Free Software Foundation, Inc.,
17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18  */
19 
20 #ifndef __pbd_event_loop_h__
21 #define __pbd_event_loop_h__
22 
23 #include <string>
24 #include <vector>
25 #include <map>
26 #include <boost/function.hpp>
27 #include <boost/bind.hpp> /* we don't need this here, but anything calling call_slot() probably will, so this is convenient */
28 #include <stdint.h>
29 #include <pthread.h>
30 #include <glibmm/threads.h>
31 
32 #include "pbd/libpbd_visibility.h"
33 
34 namespace PBD
35 {
36 
37 /** An EventLoop is as basic abstraction designed to be used with any "user
38  * interface" (not necessarily graphical) that needs to wait on
39  * events/requests and dispatch/process them as they arrive.
40  *
41  * This is a very basic class that doesn't by itself provide an actual
42  * event loop or thread. See BaseUI for the "real" object to be used
43  * when something like this is needed (it inherits from EventLoop).
44  */
45 
46 class LIBPBD_API EventLoop
47 {
48 public:
49 	EventLoop (std::string const&);
50 	virtual ~EventLoop();
51 
52 	enum RequestType {
53 		range_guarantee = ~0
54 	};
55 
56 	struct BaseRequestObject;
57 
58 	struct InvalidationRecord {
59 		std::list<BaseRequestObject*> requests;
60 		PBD::EventLoop* event_loop;
61 		gint _valid;
62 		gint _ref;
63 		const char* file;
64 		int line;
65 
InvalidationRecordInvalidationRecord66 		InvalidationRecord() : event_loop (0), _valid (1), _ref (0) {}
invalidateInvalidationRecord67 		void invalidate () { g_atomic_int_set (&_valid, 0); }
validInvalidationRecord68 		bool valid () { return g_atomic_int_get (&_valid) == 1; }
69 
refInvalidationRecord70 		void ref ()    { g_atomic_int_inc (&_ref); }
unrefInvalidationRecord71 		void unref ()  { (void) g_atomic_int_dec_and_test (&_ref); }
in_useInvalidationRecord72 		bool in_use () { return g_atomic_int_get (&_ref) > 0; }
use_countInvalidationRecord73 		int  use_count () { return g_atomic_int_get (&_ref); }
74 	};
75 
76 	static void* invalidate_request (void* data);
77 
78 	struct BaseRequestObject {
79 		RequestType             type;
80 		InvalidationRecord*     invalidation;
81 		boost::function<void()> the_slot;
82 
BaseRequestObjectBaseRequestObject83 		BaseRequestObject() : invalidation (0) {}
~BaseRequestObjectBaseRequestObject84 		~BaseRequestObject() {
85 			if (invalidation) {
86 				invalidation->unref ();
87 			}
88 		}
89 	};
90 
91 	virtual void call_slot (InvalidationRecord*, const boost::function<void()>&) = 0;
92 	virtual Glib::Threads::Mutex& slot_invalidation_mutex() = 0;
93 
event_loop_name()94 	std::string event_loop_name() const { return _name; }
95 
96 	static EventLoop* get_event_loop_for_thread();
97 	static void set_event_loop_for_thread (EventLoop* ui);
98 
99 	struct ThreadBufferMapping {
100 		pthread_t emitting_thread;
101 		std::string target_thread_name;
102 		void* request_buffer;
103 	};
104 
105 	static std::vector<ThreadBufferMapping> get_request_buffers_for_target_thread (const std::string&);
106 
107 	static void register_request_buffer_factory (const std::string& target_thread_name, void* (*factory) (uint32_t));
108 	static void pre_register (const std::string& emitting_thread_name, uint32_t num_requests);
109 	static void remove_request_buffer_from_map (void* ptr);
110 
111 	std::list<InvalidationRecord*> trash;
112 
113 private:
114 	static Glib::Threads::Private<EventLoop> thread_event_loop;
115 	std::string _name;
116 
117 	typedef std::map<std::string,ThreadBufferMapping> ThreadRequestBufferList;
118 	static ThreadRequestBufferList thread_buffer_requests;
119 	static Glib::Threads::RWLock   thread_buffer_requests_lock;
120 
121 	struct RequestBufferSupplier {
122 
123 		/* @param name : name of object/entity that will/may accept
124 		 * requests from other threads, via a request buffer.
125 		 */
126 		std::string name;
127 
128 		/* @param factory : a function that can be called (with an
129 		 * argument specifying the @param number_of_requests) to create and
130 		 * return a request buffer for communicating with @param name)
131 		 */
132 		void* (*factory)(uint32_t nunber_of_requests);
133 	};
134 	typedef std::vector<RequestBufferSupplier> RequestBufferSuppliers;
135 	static RequestBufferSuppliers request_buffer_suppliers;
136 };
137 
138 }
139 
140 #define MISSING_INVALIDATOR 0 // used to mark places where we fail to provide an invalidator
141 
142 #endif /* __pbd_event_loop_h__ */
143