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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* message.cpp - Message queue support
*/
#include "libcamera/internal/message.h"
#include <libcamera/signal.h>
#include "libcamera/internal/log.h"
/**
* \file 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 */
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