class Sawmill::Rotater::ShiftingLogFile

A rotation strategy that “shifts” log files by appending index numbers to the filename when the file reaches a certain size or age. So when the file “foo.log” is ready to rotate, it is renamed “foo.log.0”, and a new “foo.log” is started. When that one is ready to rotate, the oldest “foo.log.0” is shifted down to “foo.log.1”, “foo.log” is renamed to “foo.log.0”, and a new “foo.log” is started. So the oldest logfile is always the one with the largest number suffix, and the file currently being written to has no suffix. This is a common rotation strategy for many unix tools.

Public Class Methods

new(options_) click to toggle source

Create a new shifting log file rotation strategy.

Recognized options include:

:basedir: The base directory used if the filepath is a relative path. If not specified, the current working directory is used.
:file_path: The path to the log file. This may be an absolute path or a path relative to basedir. If not specified, defaults to “sawmill.log”.
:max_file_size: A logfile will try to rotate once it has reached this size in bytes. If not specified, the file size is not checked.
:shift_period: A logfile will try to rotate once it has been in service for this many seconds. This parameter also recognizes the values :yearly, :monthly, :daily, and :hourly. If not specified, the file’s age is not checked.
:history_size: The maximum number of old logfiles (files with indexes) to keep. Files beyond this history size will be automatically deleted. Default is 1. This value must be at least 1.

# File lib/sawmill/rotater/shifting_log_file.rb, line 80
def initialize(options_)
  @max_logfile_size = options_[:max_file_size] || options_[:max_logfile_size]
  @shift_period = options_[:shift_period]
  case @shift_period
  when :yearly
    @shift_period = 60*60*24*365
  when :monthly
    @shift_period = 60*60*24*30
  when :daily
    @shift_period = 60*60*24
  when :hourly
    @shift_period = 60*60
  end
  @history_size = options_[:history_size].to_i
  @history_size = 1 if @history_size < 1 && (@max_logfile_size || @shift_period)
  @normal_path = ::File.expand_path(options_[:file_path] || options_[:filepath] || 'sawmill.log',
                                    options_[:basedir] || ::Dir.getwd)
  @preferred_handle = 0
  @open_handles = {}
  @last_shift = ::Time.now
end

Public Instance Methods

before_write() click to toggle source

Implements the rotation strategy contract.

# File lib/sawmill/rotater/shifting_log_file.rb, line 139
def before_write
  return unless @max_logfile_size || @shift_period
  turnover_ = false
  if @max_logfile_size && ::File.file?(@normal_path) && ::File.size(@normal_path) > @max_logfile_size
    turnover_ = true
  end
  if @shift_period && (::Time.now - @last_shift) > @shift_period
    turnover_ = true
  end
  if turnover_
    max_ = @preferred_handle - @open_handles.keys.min + 1
    max_ = @history_size if max_ < @history_size
    ::File.delete("#{@normal_path}.#{max_-1}") rescue nil
    (max_-1).downto(1) do |index_|
      ::File.rename("#{@normal_path}.#{index_-1}", "#{@normal_path}.#{index_}") rescue nil
    end
    ::File.rename("#{@normal_path}", "#{@normal_path}.0") rescue nil
    @preferred_handle += 1
    @last_shift = ::Time.now
  end
end

close_handle(handle_, io_) click to toggle source

Implements the rotation strategy contract.

# File lib/sawmill/rotater/shifting_log_file.rb, line 127
def close_handle(handle_, io_)
  io_.close
  if @preferred_handle - handle_ > @history_size
    ::File.delete("#{@normal_path}.#{@preferred_handle-handle_-1}") rescue nil
  end
  @open_handles.delete(handle_)
  nil
end

open_handle(handle_) click to toggle source

Implements the rotation strategy contract.

# File lib/sawmill/rotater/shifting_log_file.rb, line 112
def open_handle(handle_)
  if handle_ == @preferred_handle
    path_ = @normal_path
  else
    path_ = "#{@normal_path}.#{@preferred_handle-handle_-1}"
  end
  file_ = ::File.open(path_, 'a')
  file_.sync = true
  @open_handles[handle_] = true
  file_
end

preferred_handle() click to toggle source

Implements the rotation strategy contract.

# File lib/sawmill/rotater/shifting_log_file.rb, line 105
def preferred_handle
  @preferred_handle
end