ClickHouse/base/poco/Foundation/include/Poco/SimpleFileChannel.h

//
// SimpleFileChannel.h
//
// Library: Foundation
// Package: Logging
// Module:  SimpleFileChannel
//
// Definition of the SimpleFileChannel class.
//
// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_SimpleFileChannel_INCLUDED
#define Foundation_SimpleFileChannel_INCLUDED


#include "Poco/Channel.h"
#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include "Poco/Timestamp.h"


namespace Poco
{


class LogFile;


class Foundation_API SimpleFileChannel : public Channel
/// A Channel that writes to a file. This class only
/// supports simple log file rotation.
///
/// For more features, see the FileChannel class.
///
/// Only the message's text is written, followed
/// by a newline.
///
/// Chain this channel to a FormattingChannel with an
/// appropriate Formatter to control what is in the text.
///
/// Log file rotation based on log file size is supported.
///
/// If rotation is enabled, the SimpleFileChannel will
/// alternate between two log files. If the size of
/// the primary log file exceeds a specified limit,
/// the secondary log file will be used, and vice
/// versa.
///
/// Log rotation is configured with the "rotation"
/// property, which supports the following values:
///   * never:         no log rotation
///   * <n>:           the file is rotated when its size exceeds
///                    <n> bytes.
///   * <n> K:         the file is rotated when its size exceeds
///                    <n> Kilobytes.
///   * <n> M:         the file is rotated when its size exceeds
///                    <n> Megabytes.
///
/// The path of the (primary) log file can be specified with
/// the "path" property. Optionally, the path of the secondary
/// log file can be specified with the "secondaryPath" property.
///
/// If no secondary path is specified, the secondary path will
/// default to <primaryPath>.1.
///
/// The flush property specifies whether each log message is flushed
/// immediately to the log file (which may hurt application performance,
/// but ensures that everything is in the log in case of a system crash),
//  or whether it's allowed to stay in the system's file buffer for some time.
/// Valid values are:
///
///   * true:   Every essages is immediately flushed to the log file (default).
///   * false:  Messages are not immediately flushed to the log file.
///
{
public:
    SimpleFileChannel();
    /// Creates the FileChannel.

    SimpleFileChannel(const std::string & path);
    /// Creates the FileChannel for a file with the given path.

    void open();
    /// Opens the FileChannel and creates the log file if necessary.

    void close();
    /// Closes the FileChannel.

    void log(const Message & msg);
    /// Logs the given message to the file.

    void setProperty(const std::string & name, const std::string & value);
    /// Sets the property with the given name.
    ///
    /// The following properties are supported:
    ///   * path:          The primary log file's path.
    ///   * secondaryPath: The secondary log file's path.
    ///   * rotation:      The log file's rotation mode. See the
    ///                    SimpleFileChannel class for details.
    ///   * flush:         Specifies whether messages are immediately
    ///                    flushed to the log file. See the SimpleFileChannel
    ///                    class for details.

    std::string getProperty(const std::string & name) const;
    /// Returns the value of the property with the given name.
    /// See setProperty() for a description of the supported
    /// properties.

    Timestamp creationDate() const;
    /// Returns the log file's creation date.

    UInt64 size() const;
    /// Returns the log file's current size in bytes.

    const std::string & path() const;
    /// Returns the log file's primary path.

    const std::string & secondaryPath() const;
    /// Returns the log file's secondary path.

    static const std::string PROP_PATH;
    static const std::string PROP_SECONDARYPATH;
    static const std::string PROP_ROTATION;
    static const std::string PROP_FLUSH;

protected:
    ~SimpleFileChannel();
    void setRotation(const std::string & rotation);
    void setFlush(const std::string & flush);
    void rotate();

private:
    std::string _path;
    std::string _secondaryPath;
    std::string _rotation;
    UInt64 _limit;
    bool _flush;
    LogFile * _pFile;
    FastMutex _mutex;
};


} // namespace Poco


#endif // Foundation_SimpleFileChannel_INCLUDED