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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* bound_method.cpp - Method bind and invocation
*/
#include <libcamera/bound_method.h>
#include "message.h"
#include "semaphore.h"
#include "thread.h"
#include "utils.h"
/**
* \file bound_method.h
* \brief Method bind and invocation
*/
namespace libcamera {
/**
* \enum ConnectionType
* \brief Connection type for asynchronous communication
*
* This enumeration describes the possible types of asynchronous communication
* between a sender and a receiver. It applies to Signal::emit() and
* Object::invokeMethod().
*
* \var ConnectionType::ConnectionTypeAuto
* \brief If the sender and the receiver live in the same thread,
* ConnectionTypeDirect is used. Otherwise ConnectionTypeQueued is used.
*
* \var ConnectionType::ConnectionTypeDirect
* \brief The receiver is invoked immediately and synchronously in the sender's
* thread.
*
* \var ConnectionType::ConnectionTypeQueued
* \brief The receiver is invoked asynchronously in its thread when control
* returns to the thread's event loop. The sender proceeds without waiting for
* the invocation to complete.
*
* \var ConnectionType::ConnectionTypeBlocking
* \brief The receiver is invoked asynchronously in its thread when control
* returns to the thread's event loop. The sender blocks until the receiver
* signals the completion of the invocation. This connection type shall not be
* used when the sender and receiver live in the same thread, otherwise
* deadlock will occur.
*/
/**
* \brief Invoke the bound method with packed arguments
* \param[in] pack Packed arguments
* \param[in] deleteMethod True to delete \a this bound method instance when
* method invocation completes
*
* The bound method stores its return value, if any, in the arguments \a pack.
* For direct and blocking invocations, this is performed synchronously, and
* the return value contained in the pack may be used. For queued invocations,
* the return value is stored at an undefined point of time and shall thus not
* be used by the caller.
*
* \return True if the return value contained in the \a pack may be used by the
* caller, false otherwise
*/
bool BoundMethodBase::activatePack(std::shared_ptr<BoundMethodPackBase> pack,
bool deleteMethod)
{
ConnectionType type = connectionType_;
if (type == ConnectionTypeAuto) {
if (Thread::current() == object_->thread())
type = ConnectionTypeDirect;
else
type = ConnectionTypeQueued;
}
switch (type) {
case ConnectionTypeDirect:
default:
invokePack(pack.get());
if (deleteMethod)
delete this;
return true;
case ConnectionTypeQueued: {
std::unique_ptr<Message> msg =
utils::make_unique<InvokeMessage>(this, pack, nullptr, deleteMethod);
object_->postMessage(std::move(msg));
return false;
}
case ConnectionTypeBlocking: {
Semaphore semaphore;
std::unique_ptr<Message> msg =
utils::make_unique<InvokeMessage>(this, pack, &semaphore, deleteMethod);
object_->postMessage(std::move(msg));
semaphore.acquire();
return true;
}
}
}
} /* namespace libcamera */
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