Class: LogMerge::Merger

Inherits:
Object
  • Object
show all
Defined in:
lib/logmerge/merger.rb

Overview

Merges multiple Apache log files by date.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(streams) ⇒ Merger

Creates a new Merger that will operate on an array of IO-like objects streams.



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# File 'lib/logmerge/merger.rb', line 30

def initialize(streams)
  @streams = streams
  @buf = []
  
  # The next line causes failure when a stream is empty in the
  # initial call to buf_fill. When @streams[slot].eof? == true buf_fill
  # removes the element from from @streams and @buf causing the each_index
  # iterator to terminate early.
  #
  #     @streams.each_index { |slot| buf_fill slot }
  #
  # Replace by
  #
  #     @streams.size.downto(1) { |slot| buf_fill slot-1 }
  #
  # which removes empty streams from the end of the @streams and @buf arrays
  # making sure we iterate over all elements of @streams and @buf.

  @streams.size.downto(1) { |slot| buf_fill slot-1 }

  @all_closed = @streams.empty?
end

Class Method Details

.merge(output = STDOUT, *files) ⇒ Object

Merges files into output. If files is nil, ARGV is used.



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# File 'lib/logmerge/merger.rb', line 14

def self.merge(output = STDOUT, *files)
  files = ARGV if files.empty?
  merger = LogMerge::Merger.new files.map { |file|
    if file =~ /\.gz$/
      Zlib::GzipReader.open file
    else
      File.open file
    end
  }
  merger.merge output
end

Instance Method Details

#all_closed? ⇒ Boolean

Are all the streams closed?

Returns:

  • (Boolean) 


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# File 'lib/logmerge/merger.rb', line 56

def all_closed?
  @all_closed
end

#buf_fill(slot) ⇒ Object

Adds a line to the buffer from input strem slot.



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# File 'lib/logmerge/merger.rb', line 63

def buf_fill(slot)
  line = @streams[slot].gets

  if line.nil? and @streams[slot].eof? then
    @streams.delete_at slot
    @buf.delete_at slot
  elsif line.nil? then
    raise "WTF? line.nil? and not eof?"
  else
    line =~ / \[(.+?)\] /
    time = Time.parse($1.sub(':', ' ').gsub('/', '-')).to_i
    @buf[slot] = [time, line]
  end
end

#merge(out_stream) ⇒ Object

Merges streams into out_stream.



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# File 'lib/logmerge/merger.rb', line 81

def merge(out_stream)
  index, min, line = nil

  until @streams.empty? do
    min = @buf.min { |a,b| a.first <=> b.first}
    slot = @buf.index min
    buf_fill slot
    out_stream.puts min.last
  end

  @all_closed = true
end