class 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
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 “rolling” portion of the filename can be configured via some simple pattern templates. For numbered rolling, you can use {{.%d}}
"logname{{.%d}}.log" => ["logname.log", "logname.1.log", "logname.2.log" ...] "logname.log{{-%d}}" => ["logname.log", "logname.log-1", "logname.log-2" ...]
And for date rolling you can use `strftime` patterns:
"logname{{.%Y%m%d}}.log" => ["logname.log, "logname.20130626.log" ...] "logname{{.%Y-%m-%dT%H:%M:%S}}.log" => ["logname.log, "logname.2013-06-26T22:03:31.log" ...]
If the defaults suit you fine, just pass in the :roll_by option and use your normal log filename without any pattern template.
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 86 def initialize( name, opts = {} ) @roller = Roller.new name, opts # grab our options @size = opts.fetch(:size, nil) @size = Integer(@size) unless @size.nil? @age_fn = filename + '.age' @age_fn_mtime = nil @age = opts.fetch(:age, nil) # create our `sufficiently_aged?` method build_singleton_methods FileUtils.touch(@age_fn) if @age && !test(?f, @age_fn) # we are opening the file in read/write mode so that a shared lock can # be used on the file descriptor => http://pubs.opengroup.org/onlinepubs/009695399/functions/fcntl.html @mode = encoding ? "a+:#{encoding}" : 'a+' super(name, ::File.new(filename, @mode), opts) # if the truncate flag was set to true, then roll roll_now = opts.fetch(:truncate, false) if roll_now copy_truncate @roller.roll_files end end
Public Instance Methods
Returns the path to the logfile.
# File lib/logging/appenders/rolling_file.rb, line 115 def filename @roller.filename end
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 122 def reopen @mutex.synchronize { if defined?(@io) && @io flush @io.close rescue nil end @io = ::File.new(filename, @mode) } super self end
Private Instance Methods
Returns the modification time of the age file.
# File lib/logging/appenders/rolling_file.rb, line 208 def age_fn_mtime @age_fn_mtime ||= ::File.mtime(@age_fn) end
We use meta-programming here to define the `sufficiently_aged?` method for the rolling appender. The `sufficiently_aged?` method is responsible for determining if the current log file is older than the rolling criteria - daily, weekly, etc.
Returns this rolling file appender instance
# File lib/logging/appenders/rolling_file.rb, line 218 def build_singleton_methods method = case @age when 'daily' -> { now = Time.now (now.day != age_fn_mtime.day) || (now - age_fn_mtime) > 86400 } when 'weekly' -> { (Time.now - age_fn_mtime) > 604800 } when 'monthly' -> { now = Time.now (now.month != age_fn_mtime.month) || (now - age_fn_mtime) > 2678400 } when Integer, String @age = Integer(@age) -> { (Time.now - age_fn_mtime) > @age } else -> { false } end self.define_singleton_method(:sufficiently_aged?, method) end
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 156 def canonical_write( str ) return self if @io.nil? str = str.force_encoding(encoding) if encoding && str.encoding != encoding @io.flock_sh { @io.write str } if roll_required? @io.flock? { @age_fn_mtime = nil copy_truncate if roll_required? } @roller.roll_files end self rescue StandardError => err self.level = :off ::Logging.log_internal {"appender #{name.inspect} has been disabled"} ::Logging.log_internal_error(err) end
Returns the file name to use as the temporary copy location. We are using copy-and-truncate semantics for rolling files so that the IO file descriptor remains valid during rolling.
# File lib/logging/appenders/rolling_file.rb, line 140 def copy_file @roller.copy_file end
Returns the modification time of the copy file if one exists. Otherwise returns `nil`.
# File lib/logging/appenders/rolling_file.rb, line 146 def copy_file_mtime return nil unless ::File.exist?(copy_file) ::File.mtime(copy_file) rescue Errno::ENOENT nil end
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 193 def copy_truncate return unless ::File.exist?(filename) FileUtils.concat filename, copy_file @io.truncate 0 # touch the age file if needed if @age FileUtils.touch @age_fn @age_fn_mtime = nil end @roller.roll = true end
Returns true
if the log file needs to be rolled.
# File lib/logging/appenders/rolling_file.rb, line 177 def roll_required? mtime = copy_file_mtime return false if mtime && (Time.now - mtime) < 180 # check if max size has been exceeded s = @size ? ::File.size(filename) > @size : false # check if max age has been exceeded a = sufficiently_aged? return (s || a) end