libcamera/base: Move extended base functionality

Move the functionality for the following components to the new
base support library:

 - BoundMethod
 - EventDispatcher
 - EventDispatcherPoll
 - Log
 - Message
 - Object
 - Signal
 - Semaphore
 - Thread
 - Timer

While it would be preferable to see these split to move one component
per commit, these components are all interdependent upon each other,
which leaves us with one big change performing the move for all of them.

Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/src/libcamera/base/event_dispatcher.cpp b/src/libcamera/base/event_dispatcher.cpp
new file mode 100644
index 00000000..4be89e81
--- /dev/null
+++ b/src/libcamera/base/event_dispatcher.cpp
@@ -0,0 +1,116 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * event_dispatcher.cpp - Event dispatcher
+ */
+
+#include <libcamera/base/event_dispatcher.h>
+#include <libcamera/base/log.h>
+
+/**
+ * \file base/event_dispatcher.h
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(Event)
+
+/**
+ * \class EventDispatcher
+ * \brief Interface to manage the libcamera events and timers
+ *
+ * The EventDispatcher class allows the integration of the application event
+ * loop with libcamera by abstracting how events and timers are managed and
+ * processed.
+ *
+ * To listen to events, libcamera creates EventNotifier instances and registers
+ * them with the dispatcher with registerEventNotifier(). The event notifier
+ * \ref EventNotifier::activated signal is then emitted by the dispatcher
+ * whenever the event is detected.
+ *
+ * To set timers, libcamera creates Timer instances and registers them with the
+ * dispatcher with registerTimer(). The timer \ref Timer::timeout signal is then
+ * emitted by the dispatcher when the timer times out.
+ */
+
+EventDispatcher::~EventDispatcher()
+{
+}
+
+/**
+ * \fn EventDispatcher::registerEventNotifier()
+ * \brief Register an event notifier
+ * \param[in] notifier The event notifier to register
+ *
+ * Once the \a notifier is registered with the dispatcher, the dispatcher will
+ * emit the notifier \ref EventNotifier::activated signal whenever a
+ * corresponding event is detected on the notifier's file descriptor. The event
+ * is monitored until the notifier is unregistered with
+ * unregisterEventNotifier().
+ *
+ * Registering multiple notifiers for the same file descriptor and event type is
+ * not allowed and results in undefined behaviour.
+ */
+
+/**
+ * \fn EventDispatcher::unregisterEventNotifier()
+ * \brief Unregister an event notifier
+ * \param[in] notifier The event notifier to unregister
+ *
+ * After this function returns the \a notifier is guaranteed not to emit the
+ * \ref EventNotifier::activated signal.
+ *
+ * If the notifier isn't registered, this function performs no operation.
+ */
+
+/**
+ * \fn EventDispatcher::registerTimer()
+ * \brief Register a timer
+ * \param[in] timer The timer to register
+ *
+ * Once the \a timer is registered with the dispatcher, the dispatcher will emit
+ * the timer \ref Timer::timeout signal when the timer times out. The timer can
+ * be unregistered with unregisterTimer() before it times out, in which case the
+ * signal will not be emitted.
+ *
+ * When the \a timer times out, it is automatically unregistered by the
+ * dispatcher and can be registered back as early as from the \ref Timer::timeout
+ * signal handlers.
+ *
+ * Registering the same timer multiple times is not allowed and results in
+ * undefined behaviour.
+ */
+
+/**
+ * \fn EventDispatcher::unregisterTimer()
+ * \brief Unregister a timer
+ * \param[in] timer The timer to unregister
+ *
+ * After this function returns the \a timer is guaranteed not to emit the
+ * \ref Timer::timeout signal.
+ *
+ * If the timer isn't registered, this function performs no operation.
+ */
+
+/**
+ * \fn EventDispatcher::processEvents()
+ * \brief Wait for and process pending events
+ *
+ * This function processes all pending events associated with registered event
+ * notifiers and timers and signals the corresponding EventNotifier and Timer
+ * objects. If no events are pending, it waits for the first event and processes
+ * it before returning.
+ */
+
+/**
+ * \fn EventDispatcher::interrupt()
+ * \brief Interrupt any running processEvents() call as soon as possible
+ *
+ * Calling this function interrupts any blocking processEvents() call in
+ * progress. The processEvents() function will return as soon as possible,
+ * after processing pending timers and events. If processEvents() isn't in
+ * progress, it will be interrupted immediately the next time it gets called.
+ */
+
+} /* namespace libcamera */