The Buffering module is used to implement buffering of the log messages in a given appender. The size of the buffer can be specified, and the buffer can be configured to auto-flush at a given threshold. The threshold can be a single message or a very large number of messages.
Log messages of a certain level can cause the buffer to be flushed immediately. If an error occurs, all previous messages and the error message will be written immediately to the logging destination if the buffer is configured to do so.
Default buffer size
Setup the message buffer and other variables for automatically and periodically flushing the buffer.
# File lib/logging/appenders/buffering.rb, line 37 37: def initialize( *args, &block ) 38: @buffer = [] 39: @immediate = [] 40: @auto_flushing = 1 41: @flush_period = @periodic_flusher = nil 42: 43: super(*args, &block) 44: end
Configure the auto-flushing threshold. Auto-flushing is used to flush the contents of the logging buffer to the logging destination automatically when the buffer reaches a certain threshold.
By default, the auto-flushing will be configured to flush after each log message.
The allowed settings are as follows:
N : flush after every N messages (N is an integer) true : flush after each log message false OR nil OR 0 : only flush when the buffer is full (500 messages)
If the default buffer size of 500 is too small, then you can manually configure it to be as large as you want. This will consume more memory.
auto_flushing = 42_000
# File lib/logging/appenders/buffering.rb, line 140 140: def auto_flushing=( period ) 141: @auto_flushing = 142: case period 143: when true; 1 144: when false, nil, 0; DEFAULT_BUFFER_SIZE 145: when Integer; period 146: when String; Integer(period) 147: else 148: raise ArgumentError, 149: "unrecognized auto_flushing period: #{period.inspect}" 150: end 151: 152: if @auto_flushing <= 0 153: raise ArgumentError, 154: "auto_flushing period must be greater than zero: #{period.inspect}" 155: end 156: 157: @auto_flushing = DEFAULT_BUFFER_SIZE if @flush_period and @auto_flushing <= 1 158: end
Close the message buffer by flushing all log events to the appender. If a periodic flusher thread is running, shut it down and allow it to exit.
# File lib/logging/appenders/buffering.rb, line 49 49: def close( *args ) 50: flush 51: 52: if @periodic_flusher 53: @periodic_flusher.stop 54: @periodic_flusher = nil 55: Thread.pass 56: end 57: 58: super(*args) 59: end
Call flush to force an appender to write out any buffered log events. Similar to IO#flush, so use in a similar fashion.
# File lib/logging/appenders/buffering.rb, line 73 73: def flush 74: return self if @buffer.empty? 75: 76: str = nil 77: sync { 78: str = @buffer.join 79: @buffer.clear 80: } 81: 82: canonical_write str unless str.empty? 83: self 84: end
Configure periodic flushing of the message buffer. Periodic flushing is used to flush the contents of the logging buffer at some regular interval. Periodic flushing is disabled by default.
When enabling periodic flushing the flush period should be set using one of the following formats: “HH:MM:SS” or seconds as an numeric or string.
"01:00:00" : every hour "00:05:00" : every 5 minutes "00:00:30" : every 30 seconds 60 : every 60 seconds (1 minute) "120" : every 120 seconds (2 minutes)
For the periodic flusher to work properly, the auto-flushing threshold will be set to the default value of 500. The auto-flushing threshold can be changed, but it must be greater than 1.
To disable the periodic flusher simply set the flush period to nil. The auto-flushing threshold will not be changed; it must be disabled manually if so desired.
# File lib/logging/appenders/buffering.rb, line 181 181: def flush_period=( period ) 182: period = 183: case period 184: when Integer, Float, nil; period 185: when String; 186: num = _parse_hours_minutes_seconds(period) || _parse_numeric(period) 187: num = ArgumentError.new("unrecognized flush period: #{period.inspect}") if num.nil? 188: num 189: else ArgumentError.new("unrecognized flush period: #{period.inspect}") end 190: 191: raise period if Exception === period 192: @flush_period = period 193: 194: _setup_periodic_flusher 195: end
Configure the levels that will trigger an immediate flush of the logging buffer. When a log event of the given level is seen, the buffer will be flushed immediately. Only the levels explicitly given in this assignment will flush the buffer; if an “error” message is configured to immediately flush the buffer, a “fatal” message will not even though it is a higher level. Both must be explicitly passed to this assignment.
You can pass in a single level name or number, an array of level names or numbers, or a string containing a comma separated list of level names or numbers.
immediate_at = :error immediate_at = [:error, :fatal] immediate_at = "warn, error"
# File lib/logging/appenders/buffering.rb, line 102 102: def immediate_at=( level ) 103: @immediate.clear 104: 105: # get the immediate levels -- no buffering occurs at these levels, and 106: # a log message is written to the logging destination immediately 107: immediate_at = 108: case level 109: when String; level.split(',').map {|x| x.strip} 110: when Array; level 111: else Array(level) end 112: 113: immediate_at.each do |lvl| 114: num = ::Logging.level_num(lvl) 115: next if num.nil? 116: @immediate[num] = true 117: end 118: end
Reopen the connection to the underlying logging destination. In addition if the appender is configured for periodic flushing, then the flushing thread will be stopped and restarted.
# File lib/logging/appenders/buffering.rb, line 65 65: def reopen 66: _setup_periodic_flusher 67: super 68: end
Configure the buffering using the arguments found in the give options hash. This method must be called in order to use the message buffer. The supported options are “immediate_at“ and “auto_flushing“. Please refer to the documentation for those methods to see the allowed options.
# File lib/logging/appenders/buffering.rb, line 205 205: def configure_buffering( opts ) 206: ::Logging.init unless ::Logging.initialized? 207: 208: self.immediate_at = opts.getopt(:immediate_at, '') 209: self.auto_flushing = opts.getopt(:auto_flushing, true) 210: self.flush_period = opts.getopt(:flush_period, nil) 211: end
Returns true if the event level matches one of the configured immediate logging levels. Otherwise returns false.
# File lib/logging/appenders/buffering.rb, line 216 216: def immediate?( event ) 217: return false unless event.respond_to? :level 218: @immediate[event.level] 219: end
Attempt to parse an hours/minutes/seconds value from the string and return an integer number of seconds.
_parse_hours_minutes_seconds("14:12:42") #=> 51162 _parse_hours_minutes_seconds("foo") #=> nil
# File lib/logging/appenders/buffering.rb, line 257 257: def _parse_hours_minutes_seconds( str ) 258: m = /^\s*(\d{2,}):(\d{2}):(\d{2}(?:\.\d+)?)\s*$/.match(str) 259: return if m.nil? 260: 261: (3600 * m[1].to_i) + (60 * m[2].to_i) + (m[3].to_f) 262: end
Convert the string into a numeric value. If the string does not represent a valid Integer or Float then nil is returned.
_parse_numeric("10") #=> 10 _parse_numeric("1.0") #=> 1.0 _parse_numeric("foo") #=> nil
# File lib/logging/appenders/buffering.rb, line 271 271: def _parse_numeric( str ) 272: Integer(str) rescue (Float(str) rescue nil) 273: end
Using the flush_period, create a new PeriodicFlusher attached to this appender. If the flush_period is nil, then no action will be taken. If a PeriodicFlusher already exists, it will be stopped and a new one will be created.
# File lib/logging/appenders/buffering.rb, line 280 280: def _setup_periodic_flusher 281: # stop and remove any existing periodic flusher instance 282: if @periodic_flusher 283: @periodic_flusher.stop 284: @periodic_flusher = nil 285: Thread.pass 286: end 287: 288: # create a new periodic flusher if we have a valid flush period 289: if @flush_period 290: @auto_flushing = DEFAULT_BUFFER_SIZE unless @auto_flushing > 1 291: @periodic_flusher = PeriodicFlusher.new(self, @flush_period) 292: @periodic_flusher.start 293: end 294: end
Writes the given event to the logging destination. The event can be either a LogEvent or a String. If a LogEvent, then it will be formatted using the layout given to the appender when it was created.
The event will be formatted and then buffered until the “auto_flushing“ level has been reached. At this time the canonical_write method will be used to log all events stored in the buffer.
# File lib/logging/appenders/buffering.rb, line 235 235: def write( event ) 236: str = event.instance_of?(::Logging::LogEvent) ? 237: layout.format(event) : event.to_s 238: return if str.empty? 239: 240: if @auto_flushing == 1 241: canonical_write(str) 242: else 243: sync { @buffer << str } 244: @periodic_flusher.signal if @periodic_flusher 245: flush if @buffer.length >= @auto_flushing || immediate?(event) 246: end 247: 248: self 249: end
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