2 Copyright (C) 2012 Paul Davis
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include "pbd/compose.h"
25 #include "pbd/debug.h"
26 #include "pbd/event_loop.h"
27 #include "pbd/error.h"
28 #include "pbd/stacktrace.h"
35 static void do_not_delete_the_loop_pointer (void*) { }
37 Glib::Threads::Private<EventLoop> EventLoop::thread_event_loop (do_not_delete_the_loop_pointer);
39 Glib::Threads::RWLock EventLoop::thread_buffer_requests_lock;
40 EventLoop::ThreadRequestBufferList EventLoop::thread_buffer_requests;
41 EventLoop::RequestBufferSuppliers EventLoop::request_buffer_suppliers;
43 EventLoop::EventLoop (string const& name)
49 EventLoop::get_event_loop_for_thread()
51 return thread_event_loop.get ();
55 EventLoop::set_event_loop_for_thread (EventLoop* loop)
57 thread_event_loop.set (loop);
61 EventLoop::invalidate_request (void* data)
63 InvalidationRecord* ir = (InvalidationRecord*) data;
65 /* Some of the requests queued with an EventLoop may involve functors
66 * that make method calls to objects whose lifetime is shorter
67 * than the EventLoop's. We do not want to make those calls if the
68 * object involve has been destroyed. To prevent this, we
69 * provide a way to invalidate those requests when the object is
72 * An object was passed to __invalidator() which added a callback to
73 * EventLoop::invalidate_request() to its "notify when destroyed"
74 * list. __invalidator() returned an InvalidationRecord that has been
75 * to passed to this function as data.
77 * The object is currently being destroyed and so we want to
78 * mark all requests involving this object that are queued with
79 * any EventLoop as invalid.
81 * As of April 2012, we are usign sigc::trackable as the base object
82 * used to queue calls to ::invalidate_request() to be made upon
83 * destruction, via its ::add_destroy_notify_callback() API. This is
84 * not necessarily ideal, but it is very close to precisely what we
85 * want, and many of the objects we want to do this with already
86 * inherit (indirectly) from sigc::trackable.
90 Glib::Threads::Mutex::Lock lm (ir->event_loop->slot_invalidation_mutex());
91 for (list<BaseRequestObject*>::iterator i = ir->requests.begin(); i != ir->requests.end(); ++i) {
93 (*i)->invalidation = 0;
101 vector<EventLoop::ThreadBufferMapping>
102 EventLoop::get_request_buffers_for_target_thread (const std::string& target_thread)
104 vector<ThreadBufferMapping> ret;
105 Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
107 for (ThreadRequestBufferList::const_iterator x = thread_buffer_requests.begin();
108 x != thread_buffer_requests.end(); ++x) {
110 if (x->second.target_thread_name == target_thread) {
111 ret.push_back (x->second);
115 DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("for thread \"%1\", found %2 request buffers\n", target_thread, ret.size()));
121 EventLoop::register_request_buffer_factory (const string& target_thread_name,
122 void* (*factory)(uint32_t))
125 RequestBufferSupplier trs;
126 trs.name = target_thread_name;
127 trs.factory = factory;
130 Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
131 request_buffer_suppliers.push_back (trs);
136 EventLoop::pre_register (const string& emitting_thread_name, uint32_t num_requests)
138 /* Threads that need to emit signals "towards" other threads, but with
139 RT safe behavior may be created before the receiving threads
140 exist. This makes it impossible for them to use the
141 ThreadCreatedWithRequestSize signal to notify receiving threads of
144 This function creates a request buffer for them to use with
145 the (not yet) created threads, and stores it where the receiving
146 thread can find it later.
149 ThreadBufferMapping mapping;
150 Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
152 for (RequestBufferSuppliers::iterator trs = request_buffer_suppliers.begin(); trs != request_buffer_suppliers.end(); ++trs) {
155 /* no factory - no request buffer required or expected */
159 if (emitting_thread_name == trs->name) {
160 /* no need to register an emitter with itself */
164 mapping.emitting_thread = pthread_self();
165 mapping.target_thread_name = trs->name;
167 /* Allocate a suitably sized request buffer. This will set the
168 * thread-local variable that holds a pointer to this request
171 mapping.request_buffer = trs->factory (num_requests);
173 /* now store it where the receiving thread (trs->name) can find
174 it if and when it is created. (Discovery happens in the
175 AbstractUI constructor. Note that if
178 const string key = string_compose ("%1/%2", emitting_thread_name, mapping.target_thread_name);
180 /* management of the thread_request_buffers map works as
183 * when the factory method was called above, the pointer to the
184 * created buffer is set as a thread-local-storage (TLS) value
185 * for this (the emitting) thread.
187 * The TLS value is set up with a destructor that marks the
188 * request buffer as "dead" when the emitting thread exits.
190 * An entry will remain in the map after the thread exits.
192 * The receiving thread may (if it receives requests from other
193 * threads) notice the dead buffer. If it does, it will delete
194 * the request buffer, and call
195 * ::remove_request_buffer_from_map() to get rid of it from the map.
197 * This does mean that the lifetime of the request buffer is
198 * indeterminate: if the receiving thread were to receive no
199 * further requests, the request buffer will live on
200 * forever. But this is OK, because if there are no requests
201 * arriving, the receiving thread is not attempting to use the
202 * request buffer(s) in any way.
204 * Note, however, that *if* an emitting thread is recreated
205 * with the same name (e.g. when a control surface is
206 * enabled/disabled/enabled), then the request buffer for the
207 * new thread will replace the map entry for the key, because
208 * of the matching thread names. This does mean that
209 * potentially the request buffer can leak in this case, but
210 * (a) these buffers are not really that large anyway (b) the
211 * scenario is not particularly common (c) the buffers would
212 * typically last across a session instance if not program
216 thread_buffer_requests[key] = mapping;
217 DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("pre-registered request buffer for \"%1\" to send to \"%2\", buffer @ %3 (key was %4)\n",
218 emitting_thread_name, trs->name, mapping.request_buffer, key));
223 EventLoop::remove_request_buffer_from_map (void* ptr)
225 Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
227 for (ThreadRequestBufferList::iterator x = thread_buffer_requests.begin(); x != thread_buffer_requests.end(); ++x) {
228 if (x->second.request_buffer == ptr) {
229 thread_buffer_requests.erase (x);