Class: Execache

Inherits:
Object
  • Object
show all
Defined in:
lib/execache.rb,
lib/execache/client.rb

Defined Under Namespace

Classes: Client

Instance Method Summary collapse

Constructor Details

#initialize(yaml) ⇒ Execache

Returns a new instance of Execache.



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# File 'lib/execache.rb', line 17

def initialize(yaml)
  options = YAML.load(File.read(yaml))
  parallel = options['parallel'] || 3

  puts "\nStarting execache server (redis @ #{options['redis']})..."

  redis = Redis.connect(:url => "redis://#{options['redis']}")
  retries = 0
  
  begin
    while true
      if request = redis.lpop('execache:request')
        Timeout.timeout(60) do
          request = Yajl::Parser.parse(request)

          # Options
          global_cache_key = request.delete('cache_key')
          channel = request.delete('channel')
          force = request.delete('force')
          ttl = request.delete('ttl')

          pending = false
          results = {}

          request.each do |cmd_type, cmd_options|
            cache_keys = []
            groups = []

            # Binary + preliminary arguments
            command = [
              options[cmd_type]['command'],
              cmd_options['args']
            ].join(' ')
            
            # For each argument group...
            cmd_options['groups'].each do |args|
              cache_key = Digest::SHA1.hexdigest(
                "#{global_cache_key || command} #{args}"
              )
              cache_key = "execache:cache:#{cache_key}"
              cache = redis.get(cache_key)

              # If force cache overwrite || no cache || pending cache
              if force || !cache || cache == '[PENDING]'
                pending = true
              
              # Else, store cache result
              else
                results[cmd_type] ||= []
                results[cmd_type] << Yajl::Parser.parse(cache)
              end

              # If force cache overwrite || no cache
              if force || !cache
                redis.set(cache_key, '[PENDING]')
                redis.expire(cache_key, 60) # Timeout incase execution fails

                cache_keys << cache_key
                groups << args
              end
            end
            
            # Add to command queue if commands present
            unless groups.empty?
              command = {
                :cache_keys => cache_keys,
                :cmd_type => cmd_type,
                :command => command,
                :groups => groups,
                :ttl => ttl
              }
              redis.rpush("execache:commands", Yajl::Encoder.encode(command))
            end
          end
          
          redis.publish(
            "execache:response:#{channel}",
            pending ? '[PENDING]' : Yajl::Encoder.encode(results)
          )
        end
      end

      # Execute queued commands
      if redis.get("execache:parallel").to_i <= parallel && cmd = redis.lpop("execache:commands")
        redis.incr("execache:parallel")
        Thread.new do
          Timeout.timeout(60) do
            cmd = Yajl::Parser.parse(cmd)

            cache_keys = cmd['cache_keys']
            cmd_type = cmd['cmd_type']
            command = cmd['command']
            groups = cmd['groups']
            ttl = cmd['ttl']

            separators = options[cmd_type]['separators'] || {}
            separators['group'] ||= "[END]"
            separators['result'] ||= "\n"

            results = `#{command} #{groups.join(' ')}`
            results = results.split(separators['group'] + separators['result'])
            results = results.collect { |r| r.split(separators['result']) }

            redis.decr("execache:parallel")

            results.each_with_index do |result, i|
              redis.set(
                cache_keys[i],
                Yajl::Encoder.encode(result)
              )
              redis.expire(cache_keys[i], ttl) if ttl
            end
          end
        end
      end

      sleep(1.0 / 1000.0)
    end
  rescue Interrupt
    shut_down
  rescue Exception => e
    puts "\nError: #{e.message}"
    puts "\t#{e.backtrace.join("\n\t")}"
    retries += 1
    shut_down if retries >= 10
    retry
  end
end

Instance Method Details

#shut_down ⇒ Object 



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# File 'lib/execache.rb', line 146

def shut_down
  puts "\nShutting down execache server..."
  exit
end