X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fpbd%2Fpbd%2Fabstract_ui.cc;h=52dc3fa12aa44a901d07f1ff0d1d357b8960522a;hb=f6a621346c97b37d45620f9caa8f3da6a64d6e5e;hp=e5319c21079e6d258a6ba7a13b8b857bf9bc45e4;hpb=401c7091c805b24b926acb2b393070d3a32628a6;p=ardour.git diff --git a/libs/pbd/pbd/abstract_ui.cc b/libs/pbd/pbd/abstract_ui.cc index e5319c2107..52dc3fa12a 100644 --- a/libs/pbd/pbd/abstract_ui.cc +++ b/libs/pbd/pbd/abstract_ui.cc @@ -1,36 +1,144 @@ +/* + 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 +#include +#include #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" +#ifdef COMPILER_MSVC +#include // 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; +template 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 +Glib::Threads::Private::RequestBuffer> AbstractUI::per_thread_request_buffer (cleanup_request_buffer::RequestBuffer>); + template AbstractUI::AbstractUI (const string& name) : BaseUI (name) { - PBD::ThreadCreatedWithRequestSize.connect (mem_fun (*this, &AbstractUI::register_thread)); + void (AbstractUI::*pmf)(pthread_t,string,uint32_t) = &AbstractUI::register_thread; + + /* 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)); + + /* find pre-registerer threads */ + + vector tbm = EventLoop::get_request_buffers_for_target_thread (event_loop_name()); + + { + Glib::Threads::Mutex::Lock lm (request_buffer_map_lock); + for (vector::iterator t = tbm.begin(); t != tbm.end(); ++t) { + request_buffers[t->emitting_thread] = static_cast (t->request_buffer); + } + } } template void -AbstractUI::register_thread (string target_gui, pthread_t thread_id, string thread_name, uint32_t num_requests) +AbstractUI::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) { - RequestBuffer* b = new RequestBuffer (num_requests); + /* 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() + */ + + 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); } template RequestObject* @@ -39,21 +147,41 @@ AbstractUI::get_request (RequestType rt) 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; 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; + return req; } @@ -63,34 +191,84 @@ AbstractUI::handle_ui_requests () 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 { - request_buffer_map_lock.unlock (); - do_request (vec.buf[0]); - request_buffer_map_lock.lock (); + 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; } } @@ -98,17 +276,73 @@ AbstractUI::handle_ui_requests () /* 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. + */ + + 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. + */ + + if (req->invalidation) { + DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 remove request from its invalidation list\n", event_loop_name(), pthread_name())); + + /* 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); + } + + /* 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 (); + + /* 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(); } } @@ -116,44 +350,101 @@ AbstractUI::handle_ui_requests () template void AbstractUI::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 (); } } template void -AbstractUI::call_slot (const boost::function& f) +AbstractUI::call_slot (InvalidationRecord* invalidation, const boost::function& 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; + + /* 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 void* +AbstractUI::request_buffer_factory (uint32_t num_requests) +{ + RequestBuffer* mcr = new RequestBuffer (num_requests); // leaks + per_thread_request_buffer.set (mcr); + return mcr; +}