Module: LogParser

Defined in:
lib/production_log/parser.rb

Overview

LogParser parses a Syslog log file looking for lines logged by the ‘rails’ program. A typical log line looks like this:

Mar  7 00:00:20 online1 rails[59600]: Person Load (0.001884)   SELECT * FROM people WHERE id = 10519 LIMIT 1

LogParser does not work with Rails’ default logger because there is no way to group all the log output of a single request. You must use SyslogLogger.

Defined Under Namespace

Classes: LogEntry

Class Method Summary collapse

Class Method Details

.parse(stream) ⇒ Object

Parses IO stream stream, creating a LogEntry for each recognizable log entry.

Log entries are recognised as starting with Processing, continuing with the same process id through Completed.



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# File 'lib/production_log/parser.rb', line 148

def self.parse(stream) # :yields: log_entry
  buckets = Hash.new { |h,k| h[k] = [] }
  comp_count = Hash.new 0

  stream.each_line do |line|
    line =~ / ([^ ]+) ([^ ]+)\[(\d+)\]: (.*)/
    next if $2.nil? or $2 == 'newsyslog'
    bucket = [$1, $2, $3].join '-'
    data = $4

    buckets[bucket] << data

    case data
    when /^Start rendering component / then
      comp_count[bucket] += 1
    when /^End of component rendering$/ then
      comp_count[bucket] -= 1
    when /^Completed/ then
      next unless comp_count[bucket] == 0
      entry = buckets.delete bucket
      next unless entry.any? { |l| l =~ /^Processing/ }
      yield LogEntry.new(entry)
    end
  end

  buckets.sort.each do |bucket, data|
    yield LogEntry.new(data)
  end
end