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, 166 insertions, 0 deletions

diff --git a/src/libcamera/base/message.cpp b/src/libcamera/base/message.cpp
new file mode 100644
index 00000000..f1d772e4
--- /dev/null
+++ b/src/libcamera/base/message.cpp
@@ -0,0 +1,166 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * message.cpp - Message queue support
+ */
+
+#include <libcamera/base/message.h>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/signal.h>
+
+/**
+ * \file base/message.h
+ * \brief Message queue support
+ *
+ * The messaging API enables inter-thread communication through message
+ * posting. Messages can be sent from any thread to any recipient deriving from
+ * the Object class.
+ *
+ * To post a message, the sender allocates it dynamically as instance of a class
+ * derived from Message. It then posts the message to an Object recipient
+ * through Object::postMessage(). Message ownership is passed to the object,
+ * thus the message shall not store any temporary data.
+ *
+ * The message is delivered in the context of the object's thread, through the
+ * Object::message() virtual method. After delivery the message is
+ * automatically deleted.
+ */
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(Message)
+
+std::atomic_uint Message::nextUserType_{ Message::UserMessage };
+
+/**
+ * \class Message
+ * \brief A message that can be posted to a Thread
+ */
+
+/**
+ * \enum Message::Type
+ * \brief The message type
+ * \var Message::None
+ * \brief Invalid message type
+ * \var Message::InvokeMessage
+ * \brief Asynchronous method invocation across threads
+ * \var Message::ThreadMoveMessage
+ * \brief Object is being moved to a different thread
+ * \var Message::DeferredDelete
+ * \brief Object is scheduled for deletion
+ * \var Message::UserMessage
+ * \brief First value available for user-defined messages
+ */
+
+/**
+ * \brief Construct a message object of type \a type
+ * \param[in] type The message type
+ */
+Message::Message(Message::Type type)
+	: type_(type)
+{
+}
+
+Message::~Message()
+{
+}
+
+/**
+ * \fn Message::type()
+ * \brief Retrieve the message type
+ * \return The message type
+ */
+
+/**
+ * \fn Message::receiver()
+ * \brief Retrieve the message receiver
+ * \return The message receiver
+ */
+
+/**
+ * \brief Reserve and register a custom user-defined message type
+ *
+ * Custom message types use values starting at Message::UserMessage. Assigning
+ * custom types manually may lead to accidental duplicated types. To avoid this
+ * problem, this method reserves and returns the next available user-defined
+ * message type.
+ *
+ * The recommended way to use this method is to subclass Message and provide a
+ * static accessor for the custom message type.
+ *
+ * \code{.cpp}
+ * class MyCustomMessage : public Message
+ * {
+ * public:
+ *	MyCustomMessage() : Message(type()) {}
+ *
+ *	static Message::Type type()
+ *	{
+ *		static MessageType type = registerMessageType();
+ *		return type;
+ *	}
+ * };
+ * \endcode
+ *
+ * \return A new unique message type
+ */
+Message::Type Message::registerMessageType()
+{
+	return static_cast<Message::Type>(nextUserType_++);
+}
+
+/**
+ * \class InvokeMessage
+ * \brief A message carrying a method invocation across threads
+ */
+
+/**
+ * \brief Construct an InvokeMessage for method invocation on an Object
+ * \param[in] method The bound method
+ * \param[in] pack The packed method arguments
+ * \param[in] semaphore The semaphore used to signal message delivery
+ * \param[in] deleteMethod True to delete the \a method when the message is
+ * destroyed
+ */
+InvokeMessage::InvokeMessage(BoundMethodBase *method,
+			     std::shared_ptr<BoundMethodPackBase> pack,
+			     Semaphore *semaphore, bool deleteMethod)
+	: Message(Message::InvokeMessage), method_(method), pack_(pack),
+	  semaphore_(semaphore), deleteMethod_(deleteMethod)
+{
+}
+
+InvokeMessage::~InvokeMessage()
+{
+	if (deleteMethod_)
+		delete method_;
+}
+
+/**
+ * \fn InvokeMessage::semaphore()
+ * \brief Retrieve the message semaphore passed to the constructor
+ * \return The message semaphore
+ */
+
+/**
+ * \brief Invoke the method bound to InvokeMessage::method_ with arguments
+ * InvokeMessage::pack_
+ */
+void InvokeMessage::invoke()
+{
+	method_->invokePack(pack_.get());
+}
+
+/**
+ * \var InvokeMessage::method_
+ * \brief The method to be invoked
+ */
+
+/**
+ * \var InvokeMessage::pack_
+ * \brief The packed method invocation arguments
+ */
+
+} /* namespace libcamera */