+/*
+ Copyright (C) 2012 Paul Davis
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
#include <unistd.h>
#include <iostream>
+#include <algorithm>
#include "pbd/stacktrace.h"
#include "pbd/abstract_ui.h"
#include "pbd/pthread_utils.h"
#include "pbd/failed_constructor.h"
+#include "pbd/debug.h"
-#include "i18n.h"
+#include "pbd/i18n.h"
+
+#ifdef COMPILER_MSVC
+#include <ardourext/misc.h> // Needed for 'DECLARE_DEFAULT_COMPARISONS'. Objects in an STL container can be
+ // searched and sorted. Thus, when instantiating the container, MSVC complains
+ // if the type of object being contained has no appropriate comparison operators
+ // defined (specifically, if operators '<' and '==' are undefined). This seems
+ // to be the case with ptw32 'pthread_t' which is a simple struct.
+DECLARE_DEFAULT_COMPARISONS(ptw32_handle_t)
+#endif
using namespace std;
-static void do_not_delete_the_request_buffer (void*) { }
+template<typename RequestBuffer> void
+cleanup_request_buffer (void* ptr)
+{
+ RequestBuffer* rb = (RequestBuffer*) ptr;
+
+ /* this is called when the thread for which this request buffer was
+ * allocated dies. That could be before or after the end of the UI
+ * event loop for which this request buffer provides communication.
+ *
+ * We are not modifying the UI's thread/buffer map, just marking it
+ * dead. If the UI is currently processing the buffers and misses
+ * this "dead" signal, it will find it the next time it receives
+ * a request. If the UI has finished processing requests, then
+ * we will leak this buffer object.
+ */
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("thread \"%1\" exits: marking request buffer as dead @ %2\n", pthread_name(), rb));
+ rb->dead = true;
+}
template<typename R>
-Glib::StaticPrivate<typename AbstractUI<R>::RequestBuffer> AbstractUI<R>::per_thread_request_buffer;
+Glib::Threads::Private<typename AbstractUI<R>::RequestBuffer> AbstractUI<R>::per_thread_request_buffer (cleanup_request_buffer<AbstractUI<R>::RequestBuffer>);
template <typename RequestObject>
AbstractUI<RequestObject>::AbstractUI (const string& name)
: BaseUI (name)
{
- void (AbstractUI<RequestObject>::*pmf)(string,pthread_t,string,uint32_t) = &AbstractUI<RequestObject>::register_thread;
+ void (AbstractUI<RequestObject>::*pmf)(pthread_t,string,uint32_t) = &AbstractUI<RequestObject>::register_thread;
- /* better to make this connect a handler that runs in the UI event loop but the syntax seems hard, and
+ /* better to make this connect a handler that runs in the UI event loop but the syntax seems hard, and
register_thread() is thread safe anyway.
*/
- PBD::ThreadCreatedWithRequestSize.connect_same_thread (new_thread_connection, boost::bind (pmf, this, _1, _2, _3, _4));
+ PBD::ThreadCreatedWithRequestSize.connect_same_thread (new_thread_connection, boost::bind (pmf, this, _1, _2, _3));
+
+ /* find pre-registerer threads */
+
+ vector<EventLoop::ThreadBufferMapping> tbm = EventLoop::get_request_buffers_for_target_thread (event_loop_name());
+
+ {
+ Glib::Threads::Mutex::Lock lm (request_buffer_map_lock);
+ for (vector<EventLoop::ThreadBufferMapping>::iterator t = tbm.begin(); t != tbm.end(); ++t) {
+ request_buffers[t->emitting_thread] = static_cast<RequestBuffer*> (t->request_buffer);
+ }
+ }
}
template <typename RequestObject> void
-AbstractUI<RequestObject>::register_thread (string target_gui, pthread_t thread_id, string /*thread name*/, uint32_t num_requests)
+AbstractUI<RequestObject>::register_thread (pthread_t thread_id, string thread_name, uint32_t num_requests)
{
- if (target_gui != name()) {
- return;
- }
+ /* the calling thread wants to register with the thread that runs this
+ * UI's event loop, so that it will have its own per-thread queue of
+ * requests. this means that when it makes a request to this UI it can
+ * do so in a realtime-safe manner (no locks).
+ */
+
+ 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));
+
+ /* the per_thread_request_buffer is a thread-private variable.
+ See pthreads documentation for more on these, but the key
+ thing is that it is a variable that as unique value for
+ each thread, guaranteed. Note that the thread in question
+ is the caller of this function, which is assumed to be the
+ thread from which signals will be emitted that this UI's
+ event loop will catch.
+ */
+
+ RequestBuffer* b = per_thread_request_buffer.get();
+
+ if (!b) {
+
+ /* create a new request queue/ringbuffer */
+
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("create new request buffer for %1 in %2\n", thread_name, event_loop_name()));
+
+ b = new RequestBuffer (num_requests);
+ /* set this thread's per_thread_request_buffer to this new
+ queue/ringbuffer. remember that only this thread will
+ get this queue when it calls per_thread_request_buffer.get()
+
+ the second argument is a function that will be called
+ when the thread exits, and ensures that the buffer is marked
+ dead. it will then be deleted during a call to handle_ui_requests()
+ */
- RequestBuffer* b = new RequestBuffer (num_requests);
+ per_thread_request_buffer.set (b);
+ } else {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 : %2 is already registered\n", event_loop_name(), thread_name));
+ }
{
- Glib::Mutex::Lock lm (request_buffer_map_lock);
+ /* add the new request queue (ringbuffer) to our map
+ so that we can iterate over it when the time is right.
+ This step is not RT-safe, but is assumed to be called
+ only at thread initialization time, not repeatedly,
+ and so this is of little consequence.
+ */
+ Glib::Threads::Mutex::Lock lm (request_buffer_map_lock);
request_buffers[thread_id] = b;
}
- per_thread_request_buffer.set (b, do_not_delete_the_request_buffer);
}
template <typename RequestObject> RequestObject*
RequestBuffer* rbuf = per_thread_request_buffer.get ();
RequestBufferVector vec;
+ /* see comments in ::register_thread() above for an explanation of
+ the per_thread_request_buffer variable
+ */
+
if (rbuf != 0) {
- /* we have a per-thread FIFO, use it */
+
+ /* the calling thread has registered with this UI and therefore
+ * we have a per-thread request queue/ringbuffer. use it. this
+ * "allocation" of a request is RT-safe.
+ */
rbuf->get_write_vector (&vec);
if (vec.len[0] == 0) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: no space in per thread pool for request of type %2\n", event_loop_name(), rt));
return 0;
}
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated per-thread request of type %2, caller %3\n", event_loop_name(), rt, pthread_name()));
+
vec.buf[0]->type = rt;
- vec.buf[0]->valid = true;
+ vec.buf[0]->valid = true;
return vec.buf[0];
}
+ /* calling thread has not registered, so just allocate a new request on
+ * the heap. the lack of registration implies that realtime constraints
+ * are not at work.
+ */
+
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated normal heap request of type %2, caller %3\n", event_loop_name(), rt, pthread_name()));
+
RequestObject* req = new RequestObject;
req->type = rt;
RequestBufferMapIterator i;
RequestBufferVector vec;
- /* per-thread buffers first */
+ /* check all registered per-thread buffers first */
request_buffer_map_lock.lock ();
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 check %2 request buffers for requests\n", event_loop_name(), request_buffers.size()));
+
for (i = request_buffers.begin(); i != request_buffers.end(); ++i) {
while (true) {
/* we must process requests 1 by 1 because
- the request may run a recursive main
- event loop that will itself call
- handle_ui_requests. when we return
- from the request handler, we cannot
- expect that the state of queued requests
- is even remotely consistent with
- the condition before we called it.
- */
+ * the request may run a recursive main
+ * event loop that will itself call
+ * handle_ui_requests. when we return
+ * from the request handler, we cannot
+ * expect that the state of queued requests
+ * is even remotely consistent with
+ * the condition before we called it.
+ */
i->second->get_read_vector (&vec);
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1 reading requests from RB[%2] @ %5, requests = %3 + %4\n",
+ event_loop_name(), std::distance (request_buffers.begin(), i), vec.len[0], vec.len[1], i->second));
+
if (vec.len[0] == 0) {
break;
} else {
- if (vec.buf[0]->valid) {
- request_buffer_map_lock.unlock ();
- do_request (vec.buf[0]);
- request_buffer_map_lock.lock ();
- if (vec.buf[0]->invalidation) {
- vec.buf[0]->invalidation->requests.remove (vec.buf[0]);
- }
- i->second->increment_read_ptr (1);
- }
- }
+ if (vec.buf[0]->valid) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: valid request, unlocking before calling\n", event_loop_name()));
+ request_buffer_map_lock.unlock ();
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: valid request, calling ::do_request()\n", event_loop_name()));
+ do_request (vec.buf[0]);
+
+ /* if the request was CallSlot, then we need to ensure that we reset the functor in the request, in case it
+ * held a shared_ptr<>. Failure to do so can lead to dangling references to objects passed to PBD::Signals.
+ *
+ * Note that this method (::handle_ui_requests()) is by definition called from the event loop thread, so
+ * caller_is_self() is true, which means that the execution of the functor has definitely happened after
+ * do_request() returns and we no longer need the functor for any reason.
+ */
+
+ if (vec.buf[0]->type == CallSlot) {
+ vec.buf[0]->the_slot = 0;
+ }
+
+ request_buffer_map_lock.lock ();
+ if (vec.buf[0]->invalidation) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: removing invalidation record for that request\n", event_loop_name()));
+ vec.buf[0]->invalidation->requests.remove (vec.buf[0]);
+ } else {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: no invalidation record for that request\n", event_loop_name()));
+ }
+ } else {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, "invalid request, ignoring\n");
+ }
+ i->second->increment_read_ptr (1);
+ }
+ }
+ }
+
+ /* clean up any dead request buffers (their thread has exited) */
+
+ for (i = request_buffers.begin(); i != request_buffers.end(); ) {
+ if ((*i).second->dead) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 deleting dead per-thread request buffer for %3 @ %4\n",
+ event_loop_name(), pthread_name(), i->second));
+ /* remove it from the EventLoop static map of all request buffers */
+ EventLoop::remove_request_buffer_from_map ((*i).second);
+ /* delete it */
+ delete (*i).second;
+ RequestBufferMapIterator tmp = i;
+ ++tmp;
+ /* remove it from this thread's list of request buffers */
+ request_buffers.erase (i);
+ i = tmp;
+ } else {
+ ++i;
}
}
/* and now, the generic request buffer. same rules as above apply */
- Glib::Mutex::Lock lm (request_list_lock);
+ Glib::Threads::Mutex::Lock lm (request_list_lock);
while (!request_list.empty()) {
RequestObject* req = request_list.front ();
request_list.pop_front ();
- /* We need to use this lock, because its the one
- returned by slot_invalidation_mutex() and protects
- against request invalidation.
- */
+ /* We need to use this lock, because its the one
+ * returned by slot_invalidation_mutex() and protects
+ * against request invalidation.
+ */
+
+ request_buffer_map_lock.lock ();
+ if (!req->valid) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 handling invalid heap request, type %3, deleting\n", event_loop_name(), pthread_name(), req->type));
+ delete req;
+ request_buffer_map_lock.unlock ();
+ continue;
+ }
+
+ /* we're about to execute this request, so its
+ * too late for any invalidation. mark
+ * the request as "done" before we start.
+ */
- request_buffer_map_lock.lock ();
- if (!req->valid) {
- delete req;
- request_buffer_map_lock.unlock ();
- continue;
- }
+ if (req->invalidation) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 remove request from its invalidation list\n", event_loop_name(), pthread_name()));
- /* we're about to execute this request, so its
- too late for any invalidation. mark
- the request as "done" before we start.
- */
+ /* after this call, if the object referenced by the
+ * invalidation record is deleted, it will no longer
+ * try to mark the request as invalid.
+ */
+
+ req->invalidation->requests.remove (req);
+ }
- if (req->invalidation) {
- req->invalidation->requests.remove (req);
- }
+ /* at this point, an object involved in a functor could be
+ * deleted before we actually execute the functor. so there is
+ * a race condition that makes the invalidation architecture
+ * somewhat pointless.
+ *
+ * really, we should only allow functors containing shared_ptr
+ * references to objects to enter into the request queue.
+ */
- request_buffer_map_lock.unlock ();
+ request_buffer_map_lock.unlock ();
+
+ /* unlock the request lock while we execute the request, so
+ * that we don't needlessly block other threads (note: not RT
+ * threads since they have their own queue) from making requests.
+ */
lm.release ();
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 execute request type %3\n", event_loop_name(), pthread_name(), req->type));
+
+ /* and lets do it ... this is a virtual call so that each
+ * specific type of UI can have its own set of requests without
+ * some kind of central request type registration logic
+ */
+
do_request (req);
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 delete heap request type %3\n", event_loop_name(), pthread_name(), req->type));
delete req;
+ /* re-acquire the list lock so that we check again */
+
lm.acquire();
}
}
template <typename RequestObject> void
AbstractUI<RequestObject>::send_request (RequestObject *req)
{
+ /* This is called to ask a given UI to carry out a request. It may be
+ * called from the same thread that runs the UI's event loop (see the
+ * caller_is_self() case below), or from any other thread.
+ */
+
if (base_instance() == 0) {
return; /* XXX is this the right thing to do ? */
}
if (caller_is_self ()) {
+ /* the thread that runs this UI's event loop is sending itself
+ a request: we dispatch it immediately and inline.
+ */
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 direct dispatch of request type %3\n", event_loop_name(), pthread_name(), req->type));
do_request (req);
- } else {
+ delete req;
+ } else {
+
+ /* If called from a different thread, we first check to see if
+ * the calling thread is registered with this UI. If so, there
+ * is a per-thread ringbuffer of requests that ::get_request()
+ * just set up a new request in. If so, all we need do here is
+ * to advance the write ptr in that ringbuffer so that the next
+ * request by this calling thread will use the next slot in
+ * the ringbuffer. The ringbuffer has
+ * single-reader/single-writer semantics because the calling
+ * thread is the only writer, and the UI event loop is the only
+ * reader.
+ */
+
RequestBuffer* rbuf = per_thread_request_buffer.get ();
if (rbuf != 0) {
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 send per-thread request type %3 using ringbuffer @ %4\n", event_loop_name(), pthread_name(), req->type, rbuf));
rbuf->increment_write_ptr (1);
} else {
/* no per-thread buffer, so just use a list with a lock so that it remains
single-reader/single-writer semantics
*/
- Glib::Mutex::Lock lm (request_list_lock);
+ DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 send heap request type %3\n", event_loop_name(), pthread_name(), req->type));
+ Glib::Threads::Mutex::Lock lm (request_list_lock);
request_list.push_back (req);
}
- request_channel.wakeup ();
+ /* send the UI event loop thread a wakeup so that it will look
+ at the per-thread and generic request lists.
+ */
+
+ signal_new_request ();
}
}
AbstractUI<RequestObject>::call_slot (InvalidationRecord* invalidation, const boost::function<void()>& f)
{
if (caller_is_self()) {
+ 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));
f ();
return;
}
RequestObject *req = get_request (BaseUI::CallSlot);
-
+
if (req == 0) {
return;
}
+ 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));
+
+ /* copy semantics: copy the functor into the request object */
+
req->the_slot = f;
- req->invalidation = invalidation;
- if (invalidation) {
- invalidation->requests.push_back (req);
- invalidation->event_loop = this;
- }
+ /* the invalidation record is an object which will carry out
+ * invalidation of any requests associated with it when it is
+ * destroyed. it can be null. if its not null, associate this
+ * request with the invalidation record. this allows us to
+ * "cancel" requests submitted to the UI because they involved
+ * a functor that uses an object that is being deleted.
+ */
+
+ req->invalidation = invalidation;
+
+ if (invalidation) {
+ invalidation->requests.push_back (req);
+ invalidation->event_loop = this;
+ }
send_request (req);
-}
+}
+template<typename RequestObject> void*
+AbstractUI<RequestObject>::request_buffer_factory (uint32_t num_requests)
+{
+ RequestBuffer* mcr = new RequestBuffer (num_requests); // leaks
+ per_thread_request_buffer.set (mcr);
+ return mcr;
+}
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