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*>::const_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));
210 if (trash.size() > 0) {
211 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 items in trash: %2\n", event_loop_name(), trash.size()));
215 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 check %2 request buffers for requests\n", event_loop_name(), request_buffers.size()));
217 for (i = request_buffers.begin(); i != request_buffers.end(); ++i) {
219 while (!(*i).second->dead) {
221 /* we must process requests 1 by 1 because
222 * the request may run a recursive main
223 * event loop that will itself call
224 * handle_ui_requests. when we return
225 * from the request handler, we cannot
226 * expect that the state of queued requests
227 * is even remotely consistent with
228 * the condition before we called it.
231 i->second->get_read_vector (&vec);
233 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 reading requests from RB[%2] @ %5, requests = %3 + %4\n",
234 event_loop_name(), std::distance (request_buffers.begin(), i), vec.len[0], vec.len[1], i->second));
236 if (vec.len[0] == 0) {
239 if (vec.buf[0]->invalidation && !vec.buf[0]->invalidation->valid ()) {
240 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: skipping invalidated request\n", event_loop_name()));
244 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: valid request, unlocking before calling\n", event_loop_name()));
247 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: valid request, calling ::do_request()\n", event_loop_name()));
248 do_request (vec.buf[0]);
251 /* if the request was CallSlot, then we need to ensure that we reset the functor in the request, in case it
252 * held a shared_ptr<>. Failure to do so can lead to dangling references to objects passed to PBD::Signals.
254 * Note that this method (::handle_ui_requests()) is by definition called from the event loop thread, so
255 * caller_is_self() is true, which means that the execution of the functor has definitely happened after
256 * do_request() returns and we no longer need the functor for any reason.
259 if (vec.buf[0]->type == CallSlot) {
260 vec.buf[0]->the_slot = 0;
264 if (vec.buf[0]->invalidation) {
265 vec.buf[0]->invalidation->unref ();
267 i->second->increment_read_ptr (1);
272 assert (rbml.locked ());
273 for (i = request_buffers.begin(); i != request_buffers.end(); ) {
274 if ((*i).second->dead) {
275 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()));
276 RequestBufferMapIterator tmp = i;
278 /* remove it from the EventLoop static map of all request buffers */
279 EventLoop::remove_request_buffer_from_map ((*i).second);
282 * Deleting the ringbuffer destroys all RequestObjects
283 * and thereby drops any InvalidationRecord references of
284 * requests that have not been processed.
287 /* remove it from this thread's list of request buffers */
288 request_buffers.erase (i);
295 /* and now, the generic request buffer. same rules as above apply */
297 while (!request_list.empty()) {
298 assert (rbml.locked ());
299 RequestObject* req = request_list.front ();
300 request_list.pop_front ();
302 /* we're about to execute this request, so its
303 * too late for any invalidation. mark
304 * the request as "done" before we start.
307 if (req->invalidation && !req->invalidation->valid()) {
308 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 handling invalid heap request, type %3, deleting\n", event_loop_name(), pthread_name(), req->type));
313 /* at this point, an object involved in a functor could be
314 * deleted before we actually execute the functor. so there is
315 * a race condition that makes the invalidation architecture
316 * somewhat pointless.
318 * really, we should only allow functors containing shared_ptr
319 * references to objects to enter into the request queue.
322 /* unlock the request lock while we execute the request, so
323 * that we don't needlessly block other threads (note: not RT
324 * threads since they have their own queue) from making requests.
327 /* also the request may destroy the object itself resulting in a direct
328 * path to EventLoop::invalidate_request () from here
329 * which takes the lock */
333 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 execute request type %3\n", event_loop_name(), pthread_name(), req->type));
335 /* and lets do it ... this is a virtual call so that each
336 * specific type of UI can have its own set of requests without
337 * some kind of central request type registration logic
342 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 delete heap request type %3\n", event_loop_name(), pthread_name(), req->type));
345 /* re-acquire the list lock so that we check again */
353 template <typename RequestObject> void
354 AbstractUI<RequestObject>::send_request (RequestObject *req)
356 /* This is called to ask a given UI to carry out a request. It may be
357 * called from the same thread that runs the UI's event loop (see the
358 * caller_is_self() case below), or from any other thread.
361 if (base_instance() == 0) {
363 return; /* XXX is this the right thing to do ? */
366 if (caller_is_self ()) {
367 /* the thread that runs this UI's event loop is sending itself
368 a request: we dispatch it immediately and inline.
370 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 direct dispatch of request type %3\n", event_loop_name(), pthread_name(), req->type));
375 /* If called from a different thread, we first check to see if
376 * the calling thread is registered with this UI. If so, there
377 * is a per-thread ringbuffer of requests that ::get_request()
378 * just set up a new request in. If so, all we need do here is
379 * to advance the write ptr in that ringbuffer so that the next
380 * request by this calling thread will use the next slot in
381 * the ringbuffer. The ringbuffer has
382 * single-reader/single-writer semantics because the calling
383 * thread is the only writer, and the UI event loop is the only
387 RequestBuffer* rbuf = per_thread_request_buffer.get ();
390 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));
391 rbuf->increment_write_ptr (1);
393 /* no per-thread buffer, so just use a list with a lock so that it remains
394 * single-reader/single-writer semantics
396 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));
397 Glib::Threads::Mutex::Lock lm (request_buffer_map_lock);
398 request_list.push_back (req);
401 /* send the UI event loop thread a wakeup so that it will look
402 at the per-thread and generic request lists.
405 signal_new_request ();
409 template<typename RequestObject> void
410 AbstractUI<RequestObject>::call_slot (InvalidationRecord* invalidation, const boost::function<void()>& f)
412 if (caller_is_self()) {
413 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));
419 Glib::Threads::Mutex::Lock lm (request_buffer_map_lock); // -- remove this once signal connect/disconnect uses ir->un/ref()
420 if (!invalidation->valid()) {
421 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));
424 invalidation->ref ();
425 assert (invalidation->event_loop == this);
426 invalidation->event_loop = this; // XXX is this needed, PBD::signal::connect sets it
429 RequestObject *req = get_request (BaseUI::CallSlot);
433 invalidation->unref ();
438 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));
440 /* copy semantics: copy the functor into the request object */
444 /* the invalidation record is an object which will carry out
445 * invalidation of any requests associated with it when it is
446 * destroyed. it can be null. if its not null, associate this
447 * request with the invalidation record. this allows us to
448 * "cancel" requests submitted to the UI because they involved
449 * a functor that uses an object that is being deleted.
452 req->invalidation = invalidation;
457 template<typename RequestObject> void*
458 AbstractUI<RequestObject>::request_buffer_factory (uint32_t num_requests)
460 RequestBuffer* mcr = new RequestBuffer (num_requests); // leaks
461 per_thread_request_buffer.set (mcr);