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.
23 #include "pbd/stacktrace.h"
24 #include "pbd/abstract_ui.h"
25 #include "pbd/pthread_utils.h"
26 #include "pbd/failed_constructor.h"
27 #include "pbd/debug.h"
32 #include <ardourext/misc.h> // Needed for 'DECLARE_DEFAULT_COMPARISONS'. Objects in an STL container can be
33 // searched and sorted. Thus, when instantiating the container, MSVC complains
34 // if the type of object being contained has no appropriate comparison operators
35 // defined (specifically, if operators '<' and '==' are undefined). This seems
36 // to be the case with ptw32 'pthread_t' which is a simple struct.
37 DECLARE_DEFAULT_COMPARISONS(ptw32_handle_t)
42 template<typename RequestBuffer> void
43 cleanup_request_buffer (void* ptr)
45 RequestBuffer* rb = (RequestBuffer*) ptr;
47 /* this is called when the thread for which this request buffer was
48 * allocated dies. That could be before or after the end of the UI
49 * event loop for which this request buffer provides communication.
51 * We are not modifying the UI's thread/buffer map, just marking it
52 * dead. If the UI is currently processing the buffers and misses
53 * this "dead" signal, it will find it the next time it receives
54 * a request. If the UI has finished processing requests, then
55 * we will leak this buffer object.
57 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("thread \"%1\" exits: marking request buffer as dead @ %2\n", pthread_name(), rb));
62 Glib::Threads::Private<typename AbstractUI<R>::RequestBuffer> AbstractUI<R>::per_thread_request_buffer (cleanup_request_buffer<AbstractUI<R>::RequestBuffer>);
64 template <typename RequestObject>
65 AbstractUI<RequestObject>::AbstractUI (const string& name)
68 void (AbstractUI<RequestObject>::*pmf)(pthread_t,string,uint32_t) = &AbstractUI<RequestObject>::register_thread;
70 /* better to make this connect a handler that runs in the UI event loop but the syntax seems hard, and
71 register_thread() is thread safe anyway.
74 PBD::ThreadCreatedWithRequestSize.connect_same_thread (new_thread_connection, boost::bind (pmf, this, _1, _2, _3));
76 /* find pre-registerer threads */
78 vector<EventLoop::ThreadBufferMapping> tbm = EventLoop::get_request_buffers_for_target_thread (event_loop_name());
81 Glib::Threads::Mutex::Lock rbml (request_buffer_map_lock);
82 for (vector<EventLoop::ThreadBufferMapping>::iterator t = tbm.begin(); t != tbm.end(); ++t) {
83 request_buffers[t->emitting_thread] = static_cast<RequestBuffer*> (t->request_buffer);
88 template <typename RequestObject> void
89 AbstractUI<RequestObject>::register_thread (pthread_t thread_id, string thread_name, uint32_t num_requests)
91 /* the calling thread wants to register with the thread that runs this
92 * UI's event loop, so that it will have its own per-thread queue of
93 * requests. this means that when it makes a request to this UI it can
94 * do so in a realtime-safe manner (no locks).
97 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("in %1 (thread name %4), %2 (%5) wants to register with UIs\n", event_loop_name(), thread_name, pthread_name(), DEBUG_THREAD_SELF));
99 /* the per_thread_request_buffer is a thread-private variable.
100 See pthreads documentation for more on these, but the key
101 thing is that it is a variable that as unique value for
102 each thread, guaranteed. Note that the thread in question
103 is the caller of this function, which is assumed to be the
104 thread from which signals will be emitted that this UI's
105 event loop will catch.
108 RequestBuffer* b = per_thread_request_buffer.get();
112 /* create a new request queue/ringbuffer */
114 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("create new request buffer for %1 in %2\n", thread_name, event_loop_name()));
116 b = new RequestBuffer (num_requests);
117 /* set this thread's per_thread_request_buffer to this new
118 queue/ringbuffer. remember that only this thread will
119 get this queue when it calls per_thread_request_buffer.get()
121 the second argument is a function that will be called
122 when the thread exits, and ensures that the buffer is marked
123 dead. it will then be deleted during a call to handle_ui_requests()
126 per_thread_request_buffer.set (b);
128 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 : %2 is already registered\n", event_loop_name(), thread_name));
132 /* add the new request queue (ringbuffer) to our map
133 so that we can iterate over it when the time is right.
134 This step is not RT-safe, but is assumed to be called
135 only at thread initialization time, not repeatedly,
136 and so this is of little consequence.
138 Glib::Threads::Mutex::Lock rbml (request_buffer_map_lock);
139 request_buffers[thread_id] = b;
144 template <typename RequestObject> RequestObject*
145 AbstractUI<RequestObject>::get_request (RequestType rt)
147 RequestBuffer* rbuf = per_thread_request_buffer.get ();
148 RequestBufferVector vec;
150 /* see comments in ::register_thread() above for an explanation of
151 the per_thread_request_buffer variable
156 /* the calling thread has registered with this UI and therefore
157 * we have a per-thread request queue/ringbuffer. use it. this
158 * "allocation" of a request is RT-safe.
161 rbuf->get_write_vector (&vec);
163 if (vec.len[0] == 0) {
164 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: no space in per thread pool for request of type %2\n", event_loop_name(), rt));
168 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated per-thread request of type %2, caller %3\n", event_loop_name(), rt, pthread_name()));
170 vec.buf[0]->type = rt;
174 /* calling thread has not registered, so just allocate a new request on
175 * the heap. the lack of registration implies that realtime constraints
179 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated normal heap request of type %2, caller %3\n", event_loop_name(), rt, pthread_name()));
181 RequestObject* req = new RequestObject;
187 template <typename RequestObject> void
188 AbstractUI<RequestObject>::handle_ui_requests ()
190 RequestBufferMapIterator i;
191 RequestBufferVector vec;
193 /* check all registered per-thread buffers first */
194 Glib::Threads::Mutex::Lock rbml (request_buffer_map_lock);
196 /* clean up any dead invalidation records (object was deleted) */
199 for (std::list<InvalidationRecord*>::iterator r = trash.begin(); r != trash.end();) {
200 if (!(*r)->in_use ()) {
201 assert (!(*r)->valid ());
202 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 drop invalidation trash %2\n", event_loop_name(), *r));
203 std::list<InvalidationRecord*>::iterator tmp = r;
213 if (trash.size() > 0) {
214 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 items in trash: %2\n", event_loop_name(), trash.size()));
218 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 check %2 request buffers for requests\n", event_loop_name(), request_buffers.size()));
220 for (i = request_buffers.begin(); i != request_buffers.end(); ++i) {
222 while (!(*i).second->dead) {
224 /* we must process requests 1 by 1 because
225 * the request may run a recursive main
226 * event loop that will itself call
227 * handle_ui_requests. when we return
228 * from the request handler, we cannot
229 * expect that the state of queued requests
230 * is even remotely consistent with
231 * the condition before we called it.
234 i->second->get_read_vector (&vec);
236 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 reading requests from RB[%2] @ %5, requests = %3 + %4\n",
237 event_loop_name(), std::distance (request_buffers.begin(), i), vec.len[0], vec.len[1], i->second));
239 if (vec.len[0] == 0) {
242 if (vec.buf[0]->invalidation && !vec.buf[0]->invalidation->valid ()) {
243 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: skipping invalidated request\n", event_loop_name()));
247 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: valid request, unlocking before calling\n", event_loop_name()));
250 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: valid request, calling ::do_request()\n", event_loop_name()));
251 do_request (vec.buf[0]);
254 /* if the request was CallSlot, then we need to ensure that we reset the functor in the request, in case it
255 * held a shared_ptr<>. Failure to do so can lead to dangling references to objects passed to PBD::Signals.
257 * Note that this method (::handle_ui_requests()) is by definition called from the event loop thread, so
258 * caller_is_self() is true, which means that the execution of the functor has definitely happened after
259 * do_request() returns and we no longer need the functor for any reason.
262 if (vec.buf[0]->type == CallSlot) {
263 vec.buf[0]->the_slot = 0;
267 if (vec.buf[0]->invalidation) {
268 vec.buf[0]->invalidation->unref ();
270 vec.buf[0]->invalidation = NULL;
271 i->second->increment_read_ptr (1);
276 assert (rbml.locked ());
277 for (i = request_buffers.begin(); i != request_buffers.end(); ) {
278 if ((*i).second->dead) {
279 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 deleting dead per-thread request buffer for %3 @ %4 (%5 requests)\n", event_loop_name(), pthread_name(), i->second, (*i).second->read_space()));
280 RequestBufferMapIterator tmp = i;
282 /* remove it from the EventLoop static map of all request buffers */
283 EventLoop::remove_request_buffer_from_map ((*i).second);
286 * Deleting the ringbuffer destroys all RequestObjects
287 * and thereby drops any InvalidationRecord references of
288 * requests that have not been processed.
291 /* remove it from this thread's list of request buffers */
292 request_buffers.erase (i);
299 /* and now, the generic request buffer. same rules as above apply */
301 while (!request_list.empty()) {
302 assert (rbml.locked ());
303 RequestObject* req = request_list.front ();
304 request_list.pop_front ();
306 /* we're about to execute this request, so its
307 * too late for any invalidation. mark
308 * the request as "done" before we start.
311 if (req->invalidation && !req->invalidation->valid()) {
312 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 handling invalid heap request, type %3, deleting\n", event_loop_name(), pthread_name(), req->type));
317 /* at this point, an object involved in a functor could be
318 * deleted before we actually execute the functor. so there is
319 * a race condition that makes the invalidation architecture
320 * somewhat pointless.
322 * really, we should only allow functors containing shared_ptr
323 * references to objects to enter into the request queue.
326 /* unlock the request lock while we execute the request, so
327 * that we don't needlessly block other threads (note: not RT
328 * threads since they have their own queue) from making requests.
331 /* also the request may destroy the object itself resulting in a direct
332 * path to EventLoop::invalidate_request () from here
333 * which takes the lock */
337 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 execute request type %3\n", event_loop_name(), pthread_name(), req->type));
339 /* and lets do it ... this is a virtual call so that each
340 * specific type of UI can have its own set of requests without
341 * some kind of central request type registration logic
346 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 delete heap request type %3\n", event_loop_name(), pthread_name(), req->type));
349 /* re-acquire the list lock so that we check again */
357 template <typename RequestObject> void
358 AbstractUI<RequestObject>::send_request (RequestObject *req)
360 /* This is called to ask a given UI to carry out a request. It may be
361 * called from the same thread that runs the UI's event loop (see the
362 * caller_is_self() case below), or from any other thread.
365 if (base_instance() == 0) {
367 return; /* XXX is this the right thing to do ? */
370 if (caller_is_self ()) {
371 /* the thread that runs this UI's event loop is sending itself
372 a request: we dispatch it immediately and inline.
374 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 direct dispatch of request type %3\n", event_loop_name(), pthread_name(), req->type));
379 /* If called from a different thread, we first check to see if
380 * the calling thread is registered with this UI. If so, there
381 * is a per-thread ringbuffer of requests that ::get_request()
382 * just set up a new request in. If so, all we need do here is
383 * to advance the write ptr in that ringbuffer so that the next
384 * request by this calling thread will use the next slot in
385 * the ringbuffer. The ringbuffer has
386 * single-reader/single-writer semantics because the calling
387 * thread is the only writer, and the UI event loop is the only
391 RequestBuffer* rbuf = per_thread_request_buffer.get ();
394 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 send per-thread request type %3 using ringbuffer @ %4 IR: %5\n", event_loop_name(), pthread_name(), req->type, rbuf, req->invalidation));
395 rbuf->increment_write_ptr (1);
397 /* no per-thread buffer, so just use a list with a lock so that it remains
398 * single-reader/single-writer semantics
400 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 send heap request type %3 IR %4\n", event_loop_name(), pthread_name(), req->type, req->invalidation));
401 Glib::Threads::Mutex::Lock lm (request_buffer_map_lock);
402 request_list.push_back (req);
405 /* send the UI event loop thread a wakeup so that it will look
406 at the per-thread and generic request lists.
409 signal_new_request ();
413 template<typename RequestObject> void
414 AbstractUI<RequestObject>::call_slot (InvalidationRecord* invalidation, const boost::function<void()>& f)
416 if (caller_is_self()) {
417 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 direct dispatch of call slot via functor @ %3, invalidation %4\n", event_loop_name(), pthread_name(), &f, invalidation));
422 /* object destruction may race with realtime signal emission.
424 * There may be a concurrent event-loop in progress of deleting
425 * the slot-object. That's perfectly fine. But we need to mark
426 * the invalidation record itself as being used by the request.
428 * The IR needs to be kept around until the last signal using
429 * it is disconnected and then it can be deleted in the event-loop
433 if (!invalidation->valid()) {
434 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 ignoring call-slot using functor @ %3, dead invalidation %4\n", event_loop_name(), pthread_name(), &f, invalidation));
437 invalidation->ref ();
438 invalidation->event_loop = this;
441 RequestObject *req = get_request (BaseUI::CallSlot);
445 invalidation->unref ();
450 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 queue call-slot using functor @ %3, invalidation %4\n", event_loop_name(), pthread_name(), &f, invalidation));
452 /* copy semantics: copy the functor into the request object */
456 /* the invalidation record is an object which will carry out
457 * invalidation of any requests associated with it when it is
458 * destroyed. it can be null. if its not null, associate this
459 * request with the invalidation record. this allows us to
460 * "cancel" requests submitted to the UI because they involved
461 * a functor that uses an object that is being deleted.
464 req->invalidation = invalidation;
469 template<typename RequestObject> void*
470 AbstractUI<RequestObject>::request_buffer_factory (uint32_t num_requests)
472 RequestBuffer* mcr = new RequestBuffer (num_requests); // leaks
473 per_thread_request_buffer.set (mcr);