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//
// AsyncChannel.h
//
// Library: Foundation
// Package: Logging
// Module: AsyncChannel
//
// Definition of the AsyncChannel class.
//
// Copyright (c) 2004-2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_AsyncChannel_INCLUDED
#define Foundation_AsyncChannel_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/Channel.h"
#include "Poco/Thread.h"
#include "Poco/Mutex.h"
#include "Poco/Runnable.h"
#include "Poco/AutoPtr.h"
#include "Poco/NotificationQueue.h"
#include <atomic>
namespace Poco {
class Foundation_API AsyncChannel: public Channel, public Runnable
/// A channel uses a separate thread for logging.
///
/// Using this channel can help to improve the performance of
/// applications that produce huge amounts of log messages or
/// that write log messages to multiple channels simultaneously.
///
/// All log messages are put into a queue and this queue is
/// then processed by a separate thread.
{
public:
using Ptr = AutoPtr<AsyncChannel>;
AsyncChannel(Channel::Ptr pChannel = 0, Thread::Priority prio = Thread::PRIO_NORMAL);
/// Creates the AsyncChannel and connects it to
/// the given channel.
void setChannel(Channel::Ptr pChannel);
/// Connects the AsyncChannel to the given target channel.
/// All messages will be forwarded to this channel.
Channel::Ptr getChannel() const;
/// Returns the target channel.
void open();
/// Opens the channel and creates the
/// background logging thread.
void close();
/// Closes the channel and stops the background
/// logging thread.
void log(const Message& msg);
/// Queues the message for processing by the
/// background thread.
void setProperty(const std::string& name, const std::string& value);
/// Sets or changes a configuration property.
///
/// The "channel" property allows setting the target
/// channel via the LoggingRegistry.
/// The "channel" property is set-only.
///
/// The "priority" property allows setting the thread
/// priority. The following values are supported:
/// * lowest
/// * low
/// * normal (default)
/// * high
/// * highest
///
/// The "priority" property is set-only.
///
/// The "queueSize" property allows to limit the number
/// of messages in the queue. If the queue is full and
/// new messages are logged, these are dropped until the
/// queue has free capacity again. The number of dropped
/// messages is recorded, and a log message indicating the
/// number of dropped messages will be generated when the
/// queue has free capacity again.
/// In addition to an unsigned integer specifying the size,
/// this property can have the values "none" or "unlimited",
/// which disable the queue size limit. A size of 0 also
/// removes the limit.
///
/// The "queueSize" property is set-only.
protected:
~AsyncChannel();
void run();
void setPriority(const std::string& value);
private:
Channel::Ptr _pChannel;
Thread _thread;
FastMutex _threadMutex;
FastMutex _channelMutex;
NotificationQueue _queue;
std::size_t _queueSize = 0;
std::size_t _dropCount = 0;
std::atomic<bool> _closed;
};
} // namespace Poco
#endif // Foundation_AsyncChannel_INCLUDED
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