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.
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)(string,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, _4));
77 template <typename RequestObject> void
78 AbstractUI<RequestObject>::register_thread (string target_gui, pthread_t thread_id, string thread_name, uint32_t num_requests)
80 /* the calling thread wants to register with the thread that runs this
81 * UI's event loop, so that it will have its own per-thread queue of
82 * requests. this means that when it makes a request to this UI it can
83 * do so in a realtime-safe manner (no locks).
86 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("in %1 (thread name %4), %2 (%5) wants to register with %3\n", event_loop_name(), thread_name, target_gui, pthread_name(), DEBUG_THREAD_SELF));
88 if (target_gui != event_loop_name()) {
89 /* this UI is not the UI that the calling thread is trying to
92 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 : not the registration target\n", event_loop_name()));
96 /* the per_thread_request_buffer is a thread-private variable.
97 See pthreads documentation for more on these, but the key
98 thing is that it is a variable that as unique value for
99 each thread, guaranteed.
102 RequestBuffer* b = per_thread_request_buffer.get();
105 /* thread already registered with this UI
107 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 : %2 is already registered\n", event_loop_name(), thread_name));
111 /* create a new request queue/ringbuffer */
113 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("create new request buffer for %1 in %2\n", thread_name, event_loop_name()));
115 b = new RequestBuffer (num_requests, *this);
118 /* add the new request queue (ringbuffer) to our map
119 so that we can iterate over it when the time is right.
120 This step is not RT-safe, but is assumed to be called
121 only at thread initialization time, not repeatedly,
122 and so this is of little consequence.
124 Glib::Threads::Mutex::Lock lm (request_buffer_map_lock);
125 request_buffers[thread_id] = b;
128 /* set this thread's per_thread_request_buffer to this new
129 queue/ringbuffer. remember that only this thread will
130 get this queue when it calls per_thread_request_buffer.get()
132 the second argument is a function that will be called
133 when the thread exits, and ensures that the buffer is marked
134 dead. it will then be deleted during a call to handle_ui_requests()
137 per_thread_request_buffer.set (b);
140 template <typename RequestObject> RequestObject*
141 AbstractUI<RequestObject>::get_request (RequestType rt)
143 RequestBuffer* rbuf = per_thread_request_buffer.get ();
144 RequestBufferVector vec;
146 /* see comments in ::register_thread() above for an explanation of
147 the per_thread_request_buffer variable
152 /* the calling thread has registered with this UI and therefore
153 * we have a per-thread request queue/ringbuffer. use it. this
154 * "allocation" of a request is RT-safe.
157 rbuf->get_write_vector (&vec);
159 if (vec.len[0] == 0) {
160 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: no space in per thread pool for request of type %2\n", event_loop_name(), rt));
164 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated per-thread request of type %2, caller %3\n", event_loop_name(), rt, pthread_name()));
166 vec.buf[0]->type = rt;
167 vec.buf[0]->valid = true;
171 /* calling thread has not registered, so just allocate a new request on
172 * the heap. the lack of registration implies that realtime constraints
176 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated normal heap request of type %2, caller %3\n", event_loop_name(), rt, pthread_name()));
178 RequestObject* req = new RequestObject;
184 template <typename RequestObject> void
185 AbstractUI<RequestObject>::handle_ui_requests ()
187 RequestBufferMapIterator i;
188 RequestBufferVector vec;
190 /* check all registered per-thread buffers first */
192 request_buffer_map_lock.lock ();
194 for (i = request_buffers.begin(); i != request_buffers.end(); ++i) {
198 /* we must process requests 1 by 1 because
199 * the request may run a recursive main
200 * event loop that will itself call
201 * handle_ui_requests. when we return
202 * from the request handler, we cannot
203 * expect that the state of queued requests
204 * is even remotely consistent with
205 * the condition before we called it.
208 i->second->get_read_vector (&vec);
210 if (vec.len[0] == 0) {
213 if (vec.buf[0]->valid) {
214 request_buffer_map_lock.unlock ();
215 do_request (vec.buf[0]);
216 request_buffer_map_lock.lock ();
217 if (vec.buf[0]->invalidation) {
218 vec.buf[0]->invalidation->requests.remove (vec.buf[0]);
221 i->second->increment_read_ptr (1);
226 /* clean up any dead request buffers (their thread has exited) */
228 for (i = request_buffers.begin(); i != request_buffers.end(); ) {
229 if ((*i).second->dead) {
230 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 deleting dead per-thread request buffer for %3 @ %4\n",
231 event_loop_name(), pthread_name(), i->second));
233 RequestBufferMapIterator tmp = i;
235 request_buffers.erase (i);
242 request_buffer_map_lock.unlock ();
244 /* and now, the generic request buffer. same rules as above apply */
246 Glib::Threads::Mutex::Lock lm (request_list_lock);
248 while (!request_list.empty()) {
249 RequestObject* req = request_list.front ();
250 request_list.pop_front ();
252 /* We need to use this lock, because its the one
253 * returned by slot_invalidation_mutex() and protects
254 * against request invalidation.
257 request_buffer_map_lock.lock ();
259 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 handling invalid heap request, type %3, deleting\n", event_loop_name(), pthread_name(), req->type));
261 request_buffer_map_lock.unlock ();
265 /* we're about to execute this request, so its
266 * too late for any invalidation. mark
267 * the request as "done" before we start.
270 if (req->invalidation) {
271 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 remove request from its invalidation list\n", event_loop_name(), pthread_name()));
273 /* after this call, if the object referenced by the
274 * invalidation record is deleted, it will no longer
275 * try to mark the request as invalid.
278 req->invalidation->requests.remove (req);
281 /* at this point, an object involved in a functor could be
282 * deleted before we actually execute the functor. so there is
283 * a race condition that makes the invalidation architecture
284 * somewhat pointless.
286 * really, we should only allow functors containing shared_ptr
287 * references to objects to enter into the request queue.
290 request_buffer_map_lock.unlock ();
292 /* unlock the request lock while we execute the request, so
293 * that we don't needlessly block other threads (note: not RT
294 * threads since they have their own queue) from making requests.
299 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 execute request type %3\n", event_loop_name(), pthread_name(), req->type));
301 /* and lets do it ... this is a virtual call so that each
302 * specific type of UI can have its own set of requests without
303 * some kind of central request type registration logic
308 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 delete heap request type %3\n", event_loop_name(), pthread_name(), req->type));
311 /* re-acquire the list lock so that we check again */
317 template <typename RequestObject> void
318 AbstractUI<RequestObject>::send_request (RequestObject *req)
320 /* This is called to ask a given UI to carry out a request. It may be
321 * called from the same thread that runs the UI's event loop (see the
322 * caller_is_self() case below), or from any other thread.
325 if (base_instance() == 0) {
326 return; /* XXX is this the right thing to do ? */
329 if (caller_is_self ()) {
330 /* the thread that runs this UI's event loop is sending itself
331 a request: we dispatch it immediately and inline.
333 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 direct dispatch of request type %3\n", event_loop_name(), pthread_name(), req->type));
338 /* If called from a different thread, we first check to see if
339 * the calling thread is registered with this UI. If so, there
340 * is a per-thread ringbuffer of requests that ::get_request()
341 * just set up a new request in. If so, all we need do here is
342 * to advance the write ptr in that ringbuffer so that the next
343 * request by this calling thread will use the next slot in
344 * the ringbuffer. The ringbuffer has
345 * single-reader/single-writer semantics because the calling
346 * thread is the only writer, and the UI event loop is the only
350 RequestBuffer* rbuf = per_thread_request_buffer.get ();
353 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 send per-thread request type %3\n", event_loop_name(), pthread_name(), req->type));
354 rbuf->increment_write_ptr (1);
356 /* no per-thread buffer, so just use a list with a lock so that it remains
357 single-reader/single-writer semantics
359 DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 send heap request type %3\n", event_loop_name(), pthread_name(), req->type));
360 Glib::Threads::Mutex::Lock lm (request_list_lock);
361 request_list.push_back (req);
364 /* send the UI event loop thread a wakeup so that it will look
365 at the per-thread and generic request lists.
368 signal_new_request ();
372 template<typename RequestObject> void
373 AbstractUI<RequestObject>::call_slot (InvalidationRecord* invalidation, const boost::function<void()>& f)
375 if (caller_is_self()) {
376 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));
381 RequestObject *req = get_request (BaseUI::CallSlot);
387 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));
389 /* copy semantics: copy the functor into the request object */
393 /* the invalidation record is an object which will carry out
394 * invalidation of any requests associated with it when it is
395 * destroyed. it can be null. if its not null, associate this
396 * request with the invalidation record. this allows us to
397 * "cancel" requests submitted to the UI because they involved
398 * a functor that uses an object that is being deleted.
401 req->invalidation = invalidation;
404 invalidation->requests.push_back (req);
405 invalidation->event_loop = this;