246 lines
8.2 KiB
C++
246 lines
8.2 KiB
C++
/*
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* Copyright (C) 2009-2018 Paul Davis <paul@linuxaudiosystems.com>
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* Copyright (C) 2010 Carl Hetherington <carl@carlh.net>
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* Copyright (C) 2015-2017 Robin Gareus <robin@gareus.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <cstring>
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#include <pthread.h>
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#include "pbd/compose.h"
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#include "pbd/debug.h"
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#include "pbd/event_loop.h"
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#include "pbd/error.h"
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#include "pbd/pthread_utils.h"
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#include "pbd/stacktrace.h"
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#include "pbd/i18n.h"
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using namespace PBD;
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using namespace std;
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static void do_not_delete_the_loop_pointer (void*) { }
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Glib::Threads::Private<EventLoop> EventLoop::thread_event_loop (do_not_delete_the_loop_pointer);
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Glib::Threads::RWLock EventLoop::thread_buffer_requests_lock;
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EventLoop::ThreadRequestBufferList EventLoop::thread_buffer_requests;
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EventLoop::RequestBufferSuppliers EventLoop::request_buffer_suppliers;
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EventLoop::EventLoop (string const& name)
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: _name (name)
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{
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}
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EventLoop::~EventLoop ()
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{
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trash.sort();
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trash.unique();
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for (std::list<InvalidationRecord*>::iterator r = trash.begin(); r != trash.end(); ++r) {
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if (!(*r)->in_use ()) {
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delete *r;
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}
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}
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trash.clear ();
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}
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EventLoop*
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EventLoop::get_event_loop_for_thread()
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{
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return thread_event_loop.get ();
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}
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void
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EventLoop::set_event_loop_for_thread (EventLoop* loop)
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{
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thread_event_loop.set (loop);
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}
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void*
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EventLoop::invalidate_request (void* data)
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{
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InvalidationRecord* ir = (InvalidationRecord*) data;
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/* Some of the requests queued with an EventLoop may involve functors
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* that make method calls to objects whose lifetime is shorter
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* than the EventLoop's. We do not want to make those calls if the
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* object involve has been destroyed. To prevent this, we
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* provide a way to invalidate those requests when the object is
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* destroyed.
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*
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* An object was passed to __invalidator() which added a callback to
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* EventLoop::invalidate_request() to its "notify when destroyed"
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* list. __invalidator() returned an InvalidationRecord that has been
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* to passed to this function as data.
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*
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* The object is currently being destroyed and so we want to
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* mark all requests involving this object that are queued with
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* any EventLoop as invalid.
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*
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* As of April 2012, we are usign sigc::trackable as the base object
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* used to queue calls to ::invalidate_request() to be made upon
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* destruction, via its ::add_destroy_notify_callback() API. This is
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* not necessarily ideal, but it is very close to precisely what we
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* want, and many of the objects we want to do this with already
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* inherit (indirectly) from sigc::trackable.
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*/
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if (ir->event_loop) {
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DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("%1: invalidating request from %2 (%3) @ %4\n", pthread_name(), ir->event_loop, ir->event_loop->event_loop_name(), ir));
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Glib::Threads::Mutex::Lock lm (ir->event_loop->slot_invalidation_mutex());
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ir->invalidate ();
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ir->event_loop->trash.push_back(ir);
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}
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return 0;
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}
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vector<EventLoop::ThreadBufferMapping>
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EventLoop::get_request_buffers_for_target_thread (const std::string& target_thread)
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{
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vector<ThreadBufferMapping> ret;
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Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
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for (ThreadRequestBufferList::const_iterator x = thread_buffer_requests.begin();
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x != thread_buffer_requests.end(); ++x) {
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if (x->second.target_thread_name == target_thread) {
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ret.push_back (x->second);
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}
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}
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DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("for thread \"%1\", found %2 request buffers\n", target_thread, ret.size()));
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return ret;
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}
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void
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EventLoop::register_request_buffer_factory (const string& target_thread_name,
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void* (*factory)(uint32_t))
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{
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RequestBufferSupplier trs;
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trs.name = target_thread_name;
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trs.factory = factory;
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{
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Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
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request_buffer_suppliers.push_back (trs);
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}
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}
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void
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EventLoop::pre_register (const string& emitting_thread_name, uint32_t num_requests)
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{
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/* Threads that need to emit signals "towards" other threads, but with
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RT safe behavior may be created before the receiving threads
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exist. This makes it impossible for them to use the
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ThreadCreatedWithRequestSize signal to notify receiving threads of
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their existence.
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This function creates a request buffer for them to use with
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the (not yet) created threads, and stores it where the receiving
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thread can find it later.
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*/
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ThreadBufferMapping mapping;
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Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
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for (RequestBufferSuppliers::iterator trs = request_buffer_suppliers.begin(); trs != request_buffer_suppliers.end(); ++trs) {
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if (!trs->factory) {
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/* no factory - no request buffer required or expected */
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continue;
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}
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if (emitting_thread_name == trs->name) {
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/* no need to register an emitter with itself */
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continue;
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}
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mapping.emitting_thread = pthread_self();
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mapping.target_thread_name = trs->name;
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/* Allocate a suitably sized request buffer. This will set the
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* thread-local variable that holds a pointer to this request
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* buffer.
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*/
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mapping.request_buffer = trs->factory (num_requests);
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/* now store it where the receiving thread (trs->name) can find
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it if and when it is created. (Discovery happens in the
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AbstractUI constructor. Note that if
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*/
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const string key = string_compose ("%1/%2", emitting_thread_name, mapping.target_thread_name);
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/* management of the thread_request_buffers map works as
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* follows:
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*
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* when the factory method was called above, the pointer to the
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* created buffer is set as a thread-local-storage (TLS) value
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* for this (the emitting) thread.
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*
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* The TLS value is set up with a destructor that marks the
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* request buffer as "dead" when the emitting thread exits.
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*
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* An entry will remain in the map after the thread exits.
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*
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* The receiving thread may (if it receives requests from other
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* threads) notice the dead buffer. If it does, it will delete
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* the request buffer, and call
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* ::remove_request_buffer_from_map() to get rid of it from the map.
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*
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* This does mean that the lifetime of the request buffer is
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* indeterminate: if the receiving thread were to receive no
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* further requests, the request buffer will live on
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* forever. But this is OK, because if there are no requests
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* arriving, the receiving thread is not attempting to use the
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* request buffer(s) in any way.
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*
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* Note, however, that *if* an emitting thread is recreated
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* with the same name (e.g. when a control surface is
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* enabled/disabled/enabled), then the request buffer for the
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* new thread will replace the map entry for the key, because
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* of the matching thread names. This does mean that
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* potentially the request buffer can leak in this case, but
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* (a) these buffers are not really that large anyway (b) the
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* scenario is not particularly common (c) the buffers would
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* typically last across a session instance if not program
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* lifetime anyway.
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*/
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thread_buffer_requests[key] = mapping;
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DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("pre-registered request buffer for \"%1\" to send to \"%2\", buffer @ %3 (key was %4)\n",
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emitting_thread_name, trs->name, mapping.request_buffer, key));
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}
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}
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void
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EventLoop::remove_request_buffer_from_map (void* ptr)
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{
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Glib::Threads::RWLock::WriterLock lm (thread_buffer_requests_lock);
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for (ThreadRequestBufferList::iterator x = thread_buffer_requests.begin(); x != thread_buffer_requests.end(); ++x) {
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if (x->second.request_buffer == ptr) {
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thread_buffer_requests.erase (x);
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break;
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}
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}
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}
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