1 files changed, 308 insertions, 0 deletions
diff --git a/src/libcamera/base/event_dispatcher_poll.cpp b/src/libcamera/base/event_dispatcher_poll.cpp
new file mode 100644
index 00000000..d76ca7fc
--- /dev/null
+++ b/src/libcamera/base/event_dispatcher_poll.cpp
@@ -0,0 +1,308 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * event_dispatcher_poll.cpp - Poll-based event dispatcher
+ */
+
+#include <libcamera/base/event_dispatcher_poll.h>
+
+#include <algorithm>
+#include <chrono>
+#include <iomanip>
+#include <poll.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/thread.h>
+#include <libcamera/base/timer.h>
+#include <libcamera/base/utils.h>
+
+#include "libcamera/internal/event_notifier.h"
+
+/**
+ * \file base/event_dispatcher_poll.h
+ */
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(Event)
+
+static const char *notifierType(EventNotifier::Type type)
+{
+	if (type == EventNotifier::Read)
+		return "read";
+	if (type == EventNotifier::Write)
+		return "write";
+	if (type == EventNotifier::Exception)
+		return "exception";
+
+	return "";
+}
+
+/**
+ * \class EventDispatcherPoll
+ * \brief A poll-based event dispatcher
+ */
+
+EventDispatcherPoll::EventDispatcherPoll()
+	: processingEvents_(false)
+{
+	/*
+	 * Create the event fd. Failures are fatal as we can't implement an
+	 * interruptible dispatcher without the fd.
+	 */
+	eventfd_ = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
+	if (eventfd_ < 0)
+		LOG(Event, Fatal) << "Unable to create eventfd";
+}
+
+EventDispatcherPoll::~EventDispatcherPoll()
+{
+	close(eventfd_);
+}
+
+void EventDispatcherPoll::registerEventNotifier(EventNotifier *notifier)
+{
+	EventNotifierSetPoll &set = notifiers_[notifier->fd()];
+	EventNotifier::Type type = notifier->type();
+
+	if (set.notifiers[type] && set.notifiers[type] != notifier) {
+		LOG(Event, Warning)
+			<< "Ignoring duplicate " << notifierType(type)
+			<< " notifier for fd " << notifier->fd();
+		return;
+	}
+
+	set.notifiers[type] = notifier;
+}
+
+void EventDispatcherPoll::unregisterEventNotifier(EventNotifier *notifier)
+{
+	auto iter = notifiers_.find(notifier->fd());
+	if (iter == notifiers_.end())
+		return;
+
+	EventNotifierSetPoll &set = iter->second;
+	EventNotifier::Type type = notifier->type();
+
+	if (!set.notifiers[type])
+		return;
+
+	if (set.notifiers[type] != notifier) {
+		LOG(Event, Warning)
+			<< notifierType(type) << " notifier for fd "
+			<< notifier->fd() << " is not registered";
+		return;
+	}
+
+	set.notifiers[type] = nullptr;
+
+	/*
+	 * Don't race with event processing if this method is called from an
+	 * event notifier. The notifiers_ entry will be erased by
+	 * processEvents().
+	 */
+	if (processingEvents_)
+		return;
+
+	if (!set.notifiers[0] && !set.notifiers[1] && !set.notifiers[2])
+		notifiers_.erase(iter);
+}
+
+void EventDispatcherPoll::registerTimer(Timer *timer)
+{
+	for (auto iter = timers_.begin(); iter != timers_.end(); ++iter) {
+		if ((*iter)->deadline() > timer->deadline()) {
+			timers_.insert(iter, timer);
+			return;
+		}
+	}
+
+	timers_.push_back(timer);
+}
+
+void EventDispatcherPoll::unregisterTimer(Timer *timer)
+{
+	for (auto iter = timers_.begin(); iter != timers_.end(); ++iter) {
+		if (*iter == timer) {
+			timers_.erase(iter);
+			return;
+		}
+
+		/*
+		 * As the timers list is ordered, we can stop as soon as we go
+		 * past the deadline.
+		 */
+		if ((*iter)->deadline() > timer->deadline())
+			break;
+	}
+}
+
+void EventDispatcherPoll::processEvents()
+{
+	int ret;
+
+	Thread::current()->dispatchMessages();
+
+	/* Create the pollfd array. */
+	std::vector<struct pollfd> pollfds;
+	pollfds.reserve(notifiers_.size() + 1);
+
+	for (auto notifier : notifiers_)
+		pollfds.push_back({ notifier.first, notifier.second.events(), 0 });
+
+	pollfds.push_back({ eventfd_, POLLIN, 0 });
+
+	/* Wait for events and process notifiers and timers. */
+	do {
+		ret = poll(&pollfds);
+	} while (ret == -1 && errno == EINTR);
+
+	if (ret < 0) {
+		ret = -errno;
+		LOG(Event, Warning) << "poll() failed with " << strerror(-ret);
+	} else if (ret > 0) {
+		processInterrupt(pollfds.back());
+		pollfds.pop_back();
+		processNotifiers(pollfds);
+	}
+
+	processTimers();
+}
+
+void EventDispatcherPoll::interrupt()
+{
+	uint64_t value = 1;
+	ssize_t ret = write(eventfd_, &value, sizeof(value));
+	if (ret != sizeof(value)) {
+		if (ret < 0)
+			ret = -errno;
+		LOG(Event, Error)
+			<< "Failed to interrupt event dispatcher ("
+			<< ret << ")";
+	}
+}
+
+short EventDispatcherPoll::EventNotifierSetPoll::events() const
+{
+	short events = 0;
+
+	if (notifiers[EventNotifier::Read])
+		events |= POLLIN;
+	if (notifiers[EventNotifier::Write])
+		events |= POLLOUT;
+	if (notifiers[EventNotifier::Exception])
+		events |= POLLPRI;
+
+	return events;
+}
+
+int EventDispatcherPoll::poll(std::vector<struct pollfd> *pollfds)
+{
+	/* Compute the timeout. */
+	Timer *nextTimer = !timers_.empty() ? timers_.front() : nullptr;
+	struct timespec timeout;
+
+	if (nextTimer) {
+		utils::time_point now = utils::clock::now();
+
+		if (nextTimer->deadline() > now)
+			timeout = utils::duration_to_timespec(nextTimer->deadline() - now);
+		else
+			timeout = { 0, 0 };
+
+		LOG(Event, Debug)
+			<< "timeout " << timeout.tv_sec << "."
+			<< std::setfill('0') << std::setw(9)
+			<< timeout.tv_nsec;
+	}
+
+	return ppoll(pollfds->data(), pollfds->size(),
+		     nextTimer ? &timeout : nullptr, nullptr);
+}
+
+void EventDispatcherPoll::processInterrupt(const struct pollfd &pfd)
+{
+	if (!(pfd.revents & POLLIN))
+		return;
+
+	uint64_t value;
+	ssize_t ret = read(eventfd_, &value, sizeof(value));
+	if (ret != sizeof(value)) {
+		if (ret < 0)
+			ret = -errno;
+		LOG(Event, Error)
+			<< "Failed to process interrupt (" << ret << ")";
+	}
+}
+
+void EventDispatcherPoll::processNotifiers(const std::vector<struct pollfd> &pollfds)
+{
+	static const struct {
+		EventNotifier::Type type;
+		short events;
+	} events[] = {
+		{ EventNotifier::Read, POLLIN },
+		{ EventNotifier::Write, POLLOUT },
+		{ EventNotifier::Exception, POLLPRI },
+	};
+
+	processingEvents_ = true;
+
+	for (const pollfd &pfd : pollfds) {
+		auto iter = notifiers_.find(pfd.fd);
+		ASSERT(iter != notifiers_.end());
+
+		EventNotifierSetPoll &set = iter->second;
+
+		for (const auto &event : events) {
+			EventNotifier *notifier = set.notifiers[event.type];
+
+			if (!notifier)
+				continue;
+
+			/*
+			 * If the file descriptor is invalid, disable the
+			 * notifier immediately.
+			 */
+			if (pfd.revents & POLLNVAL) {
+				LOG(Event, Warning)
+					<< "Disabling " << notifierType(event.type)
+					<< " due to invalid file descriptor "
+					<< pfd.fd;
+				unregisterEventNotifier(notifier);
+				continue;
+			}
+
+			if (pfd.revents & event.events)
+				notifier->activated.emit(notifier);
+		}
+
+		/* Erase the notifiers_ entry if it is now empty. */
+		if (!set.notifiers[0] && !set.notifiers[1] && !set.notifiers[2])
+			notifiers_.erase(iter);
+	}
+
+	processingEvents_ = false;
+}
+
+void EventDispatcherPoll::processTimers()
+{
+	utils::time_point now = utils::clock::now();
+
+	while (!timers_.empty()) {
+		Timer *timer = timers_.front();
+		if (timer->deadline() > now)
+			break;
+
+		timers_.pop_front();
+		timer->stop();
+		timer->timeout.emit(timer);
+	}
+}
+
+} /* namespace libcamera */