Class: LogMerge::IPResolver

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

Constant Summary collapse

FORMAT =

Marshal format version number.

0
THREADS =

Default number of threads.

$TESTING ? 2 : 100

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cache = {}) ⇒ IPResolver

Returns a new instance of IPResolver.



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# File 'lib/logmerge/resolver.rb', line 48

def initialize(cache = {})
  @cache = cache
  @failures = []
  @start_time = Time.now
  @dns = Resolv::DNS.new

  @output = nil
  @done = false
  @queue = SizedQueue.new THREADS
  @threads = ThreadGroup.new
  @buf = {}
  @cur = 0
end

Class Method Details

.create ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 17

def self.create
  resolver = nil

  if File.exists? '.name_cache' then
    data = File.read '.name_cache'
    begin
      resolver = Marshal.load data
    rescue ArgumentError
    end
  end

  resolver ||= self.new

  yield resolver

ensure
  begin
    File.open '.name_cache', 'w' do |fp|
      Marshal.dump resolver, fp
    end
  rescue Errno::EACCES
    # ignore
  end
end

.resolve(output = STDOUT, input = ARGF) ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 42

def self.resolve(output = STDOUT, input = ARGF)
  create do |resolver|
    resolver.run output, input
  end
end

Instance Method Details

#expire_entries(start_time) ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 62

def expire_entries(start_time)
  elapsed = (Time.now - start_time).to_i
  @cache.each { |ip, (name, ttl)| @cache[ip][1] = ttl - elapsed }
  @cache.delete_if { |ip, (name, ttl)| ttl <= 0 }
  return nil
end

#flush ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 69

def flush
  while @buf.has_key? @cur do
    @output.puts @buf.delete(@cur)
    @cur += 1
  end
end

#marshal_dump ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 76

def marshal_dump
  @failures.each { |ip| @cache.delete ip }

  expire_entries @start_time # compact

  return [FORMAT, @cache, @start_time]
end

#marshal_load(dumped) ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 84

def marshal_load(dumped)
  format, cache, start_time = dumped

  case format
  when 0 then
    send :initialize, cache
    expire_entries start_time # expire
  end
end

#resolve(ip) ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 94

def resolve(ip)
  name, = @cache[ip]

  return name unless name.nil?

  begin
    dns_name = Resolv::IPv4.create(ip).to_name
  rescue ArgumentError
    return ip
  end

  @dns.each_resource dns_name, Resolv::DNS::Resource::IN::PTR do |res|
    @cache[ip] = [res.name.to_s, res.ttl * 2]
    return res.name.to_s
  end

  @cache[ip] = [ip, 0]
  @failures << ip

  return ip
end

#run(output, input) ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 116

def run(output, input)
  start_threads
  line_no = 0
  @output = output

  input.each_line do |line|
    ip, rest = line.split ' ', 2
    record = [line_no, ip, rest]
    line_no += 1
    @queue << record
    flush if line_no % LogMerge::MAX_INFLIGHT == 0
  end

  @done = true

  Thread.pass until @queue.empty?

  @threads.enclose
  until @threads.list.empty? do
    @threads.list.first.join
  end

  flush
end

#start_threads ⇒ Object 



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# File 'lib/logmerge/resolver.rb', line 141

def start_threads
  THREADS.times do
    Thread.start do
      @threads.add Thread.current
      loop do
        begin
          line_no, ip, rest = @queue.pop true
        rescue ThreadError
          break if @done
          Thread.pass
          retry
        end

        name = resolve ip
        @buf[line_no] = "#{name} #{rest}"
      end
    end
  end
end