poco/Foundation/include/Poco/FileChannel.h

//
// FileChannel.h
//
// $Id: //poco/1.4/Foundation/include/Poco/FileChannel.h#5 $
//
// 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/Foundation.h"
#include "Poco/Channel.h"
#include "Poco/Timestamp.h"
#include "Poco/Mutex.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 message 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_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 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();

private:
	std::string      _path;
	std::string      _times;
	std::string      _rotation;
	std::string      _archive;
	bool             _compress;
	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