X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fpbd%2Fpbd%2Fabstract_ui.cc;h=d43bc64f6352a8e3071a6cbc525cdf89eebde418;hb=54bf06e63cee78dfa218f604d862e577d0f5754c;hp=cc7010a4155770983116a9668c2478d62baa71ef;hpb=c83389b8ec5fef9553a401e6123b7e55702af9e2;p=ardour.git diff --git a/libs/pbd/pbd/abstract_ui.cc b/libs/pbd/pbd/abstract_ui.cc index cc7010a415..d43bc64f63 100644 --- a/libs/pbd/pbd/abstract_ui.cc +++ b/libs/pbd/pbd/abstract_ui.cc @@ -1,3 +1,22 @@ +/* + 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 @@ -5,15 +24,33 @@ #include "pbd/abstract_ui.h" #include "pbd/pthread_utils.h" #include "pbd/failed_constructor.h" +#include "pbd/debug.h" #include "i18n.h" using namespace std; -static void do_not_delete_the_request_buffer (void*) { } +template void +cleanup_request_buffer (void* ptr) +{ + RequestBuffer* rb = (RequestBuffer*) ptr; + + /* there is the question of why we don't simply erase the request + * buffer and delete it right here, since we have to take the lock + * anyway. + * + * as of april 24th 2012, i don't have a good answer to that. + */ + + + { + Glib::Threads::Mutex::Lock lm (rb->ui.request_buffer_map_lock); + rb->dead = true; + } +} template -Glib::StaticPrivate::RequestBuffer> AbstractUI::per_thread_request_buffer; +Glib::Threads::Private::RequestBuffer> AbstractUI::per_thread_request_buffer (cleanup_request_buffer::RequestBuffer>); template AbstractUI::AbstractUI (const string& name) @@ -31,18 +68,58 @@ AbstractUI::AbstractUI (const string& name) template void AbstractUI::register_thread (string target_gui, pthread_t thread_id, string /*thread name*/, uint32_t num_requests) { + /* 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). + */ + if (target_gui != name()) { + /* this UI is not the UI that the calling thread is trying to + register with + */ return; } - RequestBuffer* b = new RequestBuffer (num_requests); + /* 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. + */ + + RequestBuffer* b = per_thread_request_buffer.get(); + + if (b) { + /* thread already registered with this UI + */ + return; + } + + /* create a new request queue/ringbuffer */ + + b = new RequestBuffer (num_requests, *this); { - 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); + /* 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); } template RequestObject* @@ -51,21 +128,41 @@ 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", name(), rt)); return 0; } + DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1: allocated per-thread request of type %2, caller %3\n", name(), rt, pthread_self())); + 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", name(), rt, pthread_self())); + RequestObject* req = new RequestObject; req->type = rt; + return req; } @@ -75,52 +172,129 @@ AbstractUI::handle_ui_requests () RequestBufferMapIterator i; RequestBufferVector vec; - /* per-thread buffers first */ + /* check all registered per-thread buffers first */ request_buffer_map_lock.lock (); 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. - */ - - i->second->get_read_vector (&vec); - - if (vec.len[0] == 0) { - break; - } else { - request_buffer_map_lock.unlock (); - do_request (vec.buf[0]); - request_buffer_map_lock.lock (); - i->second->increment_read_ptr (1); - } - } - } + 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. + */ + + i->second->get_read_vector (&vec); + + 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); + } + } + } + } + + /* 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", + name(), pthread_self(), i->first, i->second)); + delete (*i).second; + RequestBufferMapIterator tmp = i; + ++tmp; + request_buffers.erase (i); + i = tmp; + } else { + ++i; + } + } request_buffer_map_lock.unlock (); /* 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", name(), pthread_self(), 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", name(), pthread_self())); + + /* 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", name(), pthread_self(), 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", name(), pthread_self(), req->type)); delete req; + /* re-acquire the list lock so that we check again */ + lm.acquire(); } } @@ -128,38 +302,62 @@ 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", name(), pthread_self(), req->type)); do_request (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\n", name(), pthread_self(), req->type)); 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", name(), pthread_self(), req->type)); + Glib::Threads::Mutex::Lock lm (request_list_lock); request_list.push_back (req); } + /* send the UI event loop thread a wakeup so that it will look + at the per-thread and generic request lists. + */ + request_channel.wakeup (); } } template void -AbstractUI::call_slot (const boost::function& f) +AbstractUI::call_slot (InvalidationRecord* invalidation, const boost::function& f) { if (caller_is_self()) { -#ifndef NDEBUG - if (getenv ("DEBUG_THREADED_SIGNALS")) { - std::cerr << "functor called in correct thread for " << name() << " , execute ...\n"; - } -#endif + DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 direct dispatch of call slot via functor @ %3, invalidation %4\n", name(), pthread_self(), &f, invalidation)); f (); return; } @@ -170,12 +368,27 @@ AbstractUI::call_slot (const boost::function& f) return; } + DEBUG_TRACE (PBD::DEBUG::AbstractUI, string_compose ("%1/%2 queue call-slot using functor @ %3, invalidation %4\n", name(), pthread_self(), &f, invalidation)); + + /* copy semantics: copy the functor into the request object */ + req->the_slot = f; -#ifndef NDEBUG - if (getenv ("DEBUG_THREADED_SIGNALS")) { - std::cerr << "functor called in wrong thread for " << name() << " (from " << pthread_name() << ") send request ...\n"; - } -#endif + + /* 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); }