Parent

Logging::Appenders::RollingFile

An appender that writes to a file and ensures that the file size or age never exceeds some user specified level.

The goal of this class is to write log messages to a file. When the file age or size exceeds a given limit then the log file is copied and then truncated. The name of the copy indicates it is an older log file.

The name of the log file is changed by inserting the age of the log file (as a single number) between the log file name and the extension. If the file has no extension then the number is appended to the filename. Here is a simple example:

   /var/log/ruby.log   =>   /var/log/ruby.1.log

New log messages will continue to be appended to the same log file (/var/log/ruby.log in our example above). The age number for all older log files is incremented when the log file is rolled. The number of older log files to keep can be given, otherwise all the log files are kept.

The actual process of rolling all the log file names can be expensive if there are many, many older log files to process.

If you do not wish to use numbered files when rolling, you can specify the :roll_by option as ‘date’. This will use a date/time stamp to differentiate the older files from one another. If you configure your rolling file appender to roll daily and ignore the file size:

   /var/log/ruby.log   =>   /var/log/ruby.20091225.log

Where the date is expressed as %Y%m%d in the Time#strftime format.

NOTE: this class is not safe to use when log messages are written to files on NFS mounts or other remote file system. It should only be used for log files on the local file system. The exception to this is when a single process is writing to the log file; remote file systems are safe to use in this case but still not recommended.

Public Class Methods

new( name, opts ) click to toggle source

Creates a new Rolling File Appender. The name is the unique Appender name used to retrieve this appender from the Appender hash. The only required option is the filename to use for creating log files.

 [:filename]  The base filename to use when constructing new log
              filenames.

The following options are optional:

 [:layout]    The Layout that will be used by this appender. The Basic
              layout will be used if none is given.
 [:truncate]  When set to true any existing log files will be rolled
              immediately and a new, empty log file will be created.
 [:size]      The maximum allowed size (in bytes) of a log file before
              it is rolled.
 [:age]       The maximum age (in seconds) of a log file before it is
              rolled. The age can also be given as 'daily', 'weekly',
              or 'monthly'.
 [:keep]      The number of rolled log files to keep.
 [:roll_by]   How to name the rolled log files. This can be 'number' or
              'date'.
     # File lib/logging/appenders/rolling_file.rb, line 76
 76:     def initialize( name, opts = {} )
 77:       # raise an error if a filename was not given
 78:       @fn = opts.getopt(:filename, name)
 79:       raise ArgumentError, 'no filename was given' if @fn.nil?
 80: 
 81:       @fn = ::File.expand_path(@fn)
 82:       @fn_copy = @fn + '._copy_'
 83:       ::Logging::Appenders::File.assert_valid_logfile(@fn)
 84: 
 85:       # grab our options
 86:       @size = opts.getopt(:size, :as => Integer)
 87: 
 88:       code = 'def sufficiently_aged?() false end'
 89:       @age_fn = @fn + '.age'
 90:       @age_fn_mtime = nil
 91: 
 92:       case @age = opts.getopt(:age)
 93:       when 'daily'
 94:         code =         def sufficiently_aged?          @age_fn_mtime ||= ::File.mtime(@age_fn)          now = Time.now          if (now.day != @age_fn_mtime.day) or (now - @age_fn_mtime) > 86400            return true          end          false        end
 95:       when 'weekly'
 96:         code =         def sufficiently_aged?          @age_fn_mtime ||= ::File.mtime(@age_fn)          if (Time.now - @age_fn_mtime) > 604800            return true          end          false        end
 97:       when 'monthly'
 98:         code =         def sufficiently_aged?          @age_fn_mtime ||= ::File.mtime(@age_fn)          now = Time.now          if (now.month != @age_fn_mtime.month) or (now - @age_fn_mtime) > 2678400            return true          end          false        end
 99:       when Integer, String
100:         @age = Integer(@age)
101:         code =         def sufficiently_aged?          @age_fn_mtime ||= ::File.mtime(@age_fn)          if (Time.now - @age_fn_mtime) > @age            return true          end          false        end
102:       end
103: 
104:       FileUtils.touch(@age_fn) if @age and !test(ff, @age_fn)
105: 
106:       meta = class << self; self end
107:       meta.class_eval code, __FILE__, __LINE__
108: 
109:       # we are opening the file in read/write mode so that a shared lock can
110:       # be used on the file descriptor => http://pubs.opengroup.org/onlinepubs/009695399/functions/fcntl.html
111:       super(name, ::File.new(@fn, 'a+'), opts)
112: 
113:       # setup the file roller
114:       @roller =
115:           case opts.getopt(:roll_by)
116:           when 'number'; NumberedRoller.new(@fn, opts)
117:           when 'date'; DateRoller.new(@fn, opts)
118:           else
119:             (@age and !@size) ?
120:                 DateRoller.new(@fn, opts) :
121:                 NumberedRoller.new(@fn, opts)
122:           end
123: 
124:       # if the truncate flag was set to true, then roll
125:       roll_now = opts.getopt(:truncate, false)
126:       if roll_now
127:         copy_truncate
128:         @roller.roll_files
129:       end
130:     end

Public Instance Methods

filename() click to toggle source

Returns the path to the logfile.

     # File lib/logging/appenders/rolling_file.rb, line 168
168:     def filename() @fn.dup end
reopen() click to toggle source

Reopen the connection to the underlying logging destination. If the connection is currently closed then it will be opened. If the connection is currently open then it will be closed and immediately opened.

     # File lib/logging/appenders/rolling_file.rb, line 174
174:     def reopen
175:       @mutex.synchronize {
176:         if defined? @io and @io
177:           flush
178:           @io.close rescue nil
179:         end
180:         @io = ::File.new(@fn, 'a+')
181:       }
182:       super
183:       self
184:     end

Private Instance Methods

canonical_write( str ) click to toggle source

Write the given event to the log file. The log file will be rolled if the maximum file size is exceeded or if the file is older than the maximum age.

     # File lib/logging/appenders/rolling_file.rb, line 193
193:     def canonical_write( str )
194:       return self if @io.nil?
195: 
196:       @io.flock_sh { @io.syswrite(str) }
197: 
198:       if roll_required?
199:         @io.flock? {
200:           @age_fn_mtime = nil
201:           copy_truncate if roll_required?
202:         }
203:         @roller.roll_files
204:       end
205:       self
206:     rescue StandardError => err
207:       self.level = :off
208:       ::Logging.log_internal {"appender #{name.inspect} has been disabled"}
209:       ::Logging.log_internal(2) {err}
210:     end
copy_truncate() click to toggle source

Copy the contents of the logfile to another file. Truncate the logfile to zero length. This method will set the roll flag so that all the current logfiles will be rolled along with the copied file.

     # File lib/logging/appenders/rolling_file.rb, line 230
230:     def copy_truncate
231:       return unless ::File.exist?(@fn)
232:       FileUtils.concat @fn, @fn_copy
233:       @io.truncate 0
234: 
235:       # touch the age file if needed
236:       if @age
237:         FileUtils.touch @age_fn
238:         @age_fn_mtime = nil
239:       end
240: 
241:       @roller.roll = true
242:     end
roll_required?() click to toggle source

Returns true if the log file needs to be rolled.

     # File lib/logging/appenders/rolling_file.rb, line 214
214:     def roll_required?
215:       return false if ::File.exist?(@fn_copy) and (Time.now - ::File.mtime(@fn_copy)) < 180
216: 
217:       # check if max size has been exceeded
218:       s = @size ? ::File.size(@fn) > @size : false
219: 
220:       # check if max age has been exceeded
221:       a = sufficiently_aged?
222: 
223:       return (s || a)
224:     end

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