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

//
// FileChannel.h
//
// Library: Foundation
// Package: Logging
// Module:  FileChannel
//
// Definition of the FileChannel class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_FileChannel_INCLUDED
#define Foundation_FileChannel_INCLUDED


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


namespace Poco
{


class LogFile;
class RotateStrategy;
class ArchiveStrategy;
class PurgeStrategy;


class Foundation_API FileChannel : public Channel
/// A Channel that writes to a file. This class supports
/// flexible log file rotation and archiving, as well
/// as automatic purging of archived log files.
///
/// 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.
///
/// The FileChannel support log file rotation based
/// on log file size or time intervals.
/// Archived log files can be compressed in gzip format.
/// Older archived files can be automatically deleted
/// (purged).
///
/// The rotation strategy can be specified with the
/// "rotation" property, which can take one of the
/// following values:
///
///   * never:         no log rotation
///   * [day,][hh]:mm: the file is rotated on specified day/time
///                    day - day is specified as long or short day name (Monday|Mon, Tuesday|Tue, ... );
///                          day can be omitted, in which case log is rotated every day
///                    hh  - valid hour range is 00-23;
///                          hour can be omitted, in which case log is rotated every hour
///                    mm  - valid minute range is 00-59;
///                          minute must be specified
///   * daily:         the file is rotated daily
///   * weekly:        the file is rotated every seven days
///   * monthly:       the file is rotated every 30 days
///   * <n> minutes:   the file is rotated every <n> minutes,
///                    where <n> is an integer greater than zero.
///   * <n> hours:     the file is rotated every <n> hours, where
///                    <n> is an integer greater than zero.
///   * <n> days:      the file is rotated every <n> days, where
///                    <n> is an integer greater than zero.
///   * <n> weeks:     the file is rotated every <n> weeks, where
///                    <n> is an integer greater than zero.
///   * <n> months:    the file is rotated every <n> months, where
///                    <n> is an integer greater than zero and
///                    a month has 30 days.
///   * <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.
///
/// NOTE: For periodic log file rotation (daily, weekly, monthly, etc.),
/// the date and time of log file creation or last rotation is
/// written into the first line of the log file. This is because
/// there is no reliable way to find out the real creation date of
/// a file on many platforms (e.g., most Unix platforms do not
/// provide the creation date, and Windows has its own issues
/// with its "File System Tunneling Capabilities").
///
/// Using the "archive" property it is possible to specify
/// how archived log files are named. The following values
/// for the "archive" property are supported:
///
///   * number:     A number, starting with 0, is appended to
///                 the name of archived log files. The newest
///                 archived log file always has the number 0.
///                 For example, if the log file is named
///                 "access.log", and it fulfils the criteria
///                 for rotation, the file is renamed to
///                 "access.log.0". If a file named "access.log.0"
///                 already exists, it is renamed to "access.log.1",
///                 and so on.
///   * timestamp:  A timestamp is appended to the log file name.
///                 For example, if the log file is named
///                 "access.log", and it fulfils the criteria
///                 for rotation, the file is renamed to
///                 "access.log.20050802110300".
///
/// Using the "times" property it is possible to specify
/// time mode for the day/time based rotation. The following values
/// for the "times" property are supported:
///
///   * utc:        Rotation strategy is based on UTC time (default).
///   * local:      Rotation strategy is based on local time.
///
/// Archived log files can be compressed using the gzip compression
/// method. Compressing can be controlled with the "compress"
/// property. The following values for the "compress" property
/// are supported:
///
///   * true:       Compress archived log files.
///   * false:      Do not compress archived log files.
///
/// Archived log files can be automatically purged, either if
/// they reach a certain age, or if the number of archived
/// log files reaches a given maximum number. This is
/// controlled by the purgeAge and purgeCount properties.
///
/// The purgeAge property can have the following values:
///
///   * <n> [seconds]: the maximum age is <n> seconds.
///   * <n> minutes:   the maximum age is <n> minutes.
///   * <n> hours:     the maximum age is <n> hours.
///   * <n> days:      the maximum age is <n> days.
///   * <n> weeks:     the maximum age is <n> weeks.
///   * <n> months:    the maximum age is <n> months, where a month has 30 days.
///
/// The purgeCount property has an integer value that specifies the maximum number
/// of archived log files. If the number is exceeded, archived log files are
/// deleted, starting with the oldest. When "none" or empty string are
/// supplied, they reset purgeCount to none (no purging).
///
/// 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.
///
/// The rotateOnOpen property specifies whether an existing log file should be
/// rotated (and archived) when the channel is opened. Valid values are:
///
///   * true:  The log file is rotated (and archived) when the channel is opened.
///   * false: Log messages will be appended to an existing log file,
///            if it exists (unless other conditions for a rotation are met).
///            This is the default.
///
/// For a more lightweight file channel class, see SimpleFileChannel.
{
public:
    FileChannel();
    /// Creates the FileChannel.

    FileChannel(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 log file's path.
    ///   * rotation:     The log file's rotation mode. See the
    ///                   FileChannel class for details.
    ///   * archive:      The log file's archive mode. See the
    ///                   FileChannel class for details.
    ///   * times:        The log file's time mode. See the
    ///                   FileChannel class for details.
    ///   * compress:     Enable or disable compression of
    ///                   archived files. See the FileChannel class
    ///                   for details.
    ///   * purgeAge:     Maximum age of an archived log file before
    ///                   it is purged. See the FileChannel class for
    ///                   details.
    ///   * purgeCount:   Maximum number of archived log files before
    ///                   files are purged. See the FileChannel class
    ///                   for details.
    ///   * flush:        Specifies whether messages are immediately
    ///                   flushed to the log file. See the FileChannel class
    ///                   for details.
    ///   * rotateOnOpen: Specifies whether an existing log file should be
    ///                   rotated and archived when the channel is opened.

    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 path.

    static const std::string PROP_PATH;
    static const std::string PROP_ROTATION;
    static const std::string PROP_ARCHIVE;
    static const std::string PROP_TIMES;
    static const std::string PROP_COMPRESS;
    static const std::string PROP_STREAMCOMPRESS;
    static const std::string PROP_PURGEAGE;
    static const std::string PROP_PURGECOUNT;
    static const std::string PROP_FLUSH;
    static const std::string PROP_ROTATEONOPEN;

protected:
    ~FileChannel();
    void setRotation(const std::string & rotation);
    void setArchive(const std::string & archive);
    void setCompress(const std::string & compress);
    void setStreamCompress(const std::string & streamCompress);
    void setPurgeAge(const std::string & age);
    void setPurgeCount(const std::string & count);
    void setFlush(const std::string & flush);
    void setRotateOnOpen(const std::string & rotateOnOpen);
    void purge();
    void unsafeOpen();

private:
    LogFile * newLogFile();
    void archiveCorrupted(const std::string & path);
    bool setNoPurge(const std::string & value);
    int extractDigit(const std::string & value, std::string::const_iterator * nextToDigit = NULL) const;
    void setPurgeStrategy(PurgeStrategy * strategy);
    Timespan::TimeDiff extractFactor(const std::string & value, std::string::const_iterator start) const;

    std::string _path;
    std::string _times;
    std::string _rotation;
    std::string _archive;
    bool _compress;
    bool _streamCompress;
    std::string _purgeAge;
    std::string _purgeCount;
    bool _flush;
    bool _rotateOnOpen;
    LogFile * _pFile;
    RotateStrategy * _pRotateStrategy;
    ArchiveStrategy * _pArchiveStrategy;
    PurgeStrategy * _pPurgeStrategy;
    FastMutex _mutex;
};


} // namespace Poco


#endif // Foundation_FileChannel_INCLUDED