Class: Nutcracker::Wrapper

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ Wrapper

Initialize a new Nutcracker process wrappper

Options Hash (options):

  • :config_file (String) — default: conf/nutcracker.yaml —

    path to nutcracker’s configuration file

  • :stats_uri (String) —

    Nutcracker stats URI - tcp://localhost:22222

  • :max_memory (String) —

    use fixed max memory size ( ignore server configuration )

  • :args (Array) — default: [] —

    array with additional command line arguments



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# File 'lib/nutcracker.rb', line 45

def initialize options
  @options = validate defaults.merge options
  @options[:stats_uri] = URI @options[:stats_uri]
end

Instance Attribute Details

#pid ⇒ Object (readonly)

Returns the value of attribute pid.



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# File 'lib/nutcracker.rb', line 37

def pid
  @pid
end

Instance Method Details

#attached? ⇒ Boolean

Returns true if the current instance was initialize with the attached flag



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# File 'lib/nutcracker.rb', line 67

def attached?
  @options[:attached]
end

#config ⇒ Object

Returns Nutcracker’s configuration hash



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# File 'lib/nutcracker.rb', line 87

def config
  @config ||= YAML.load_file @options[:config_file]
end

#join ⇒ Object

Wait for the process to exit



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# File 'lib/nutcracker.rb', line 82

def join
  attached? ? sleep : (running! and ::Process.waitpid2 pid rescue nil)
end

#kill ⇒ Object

Kills the Nutcracker service



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# File 'lib/nutcracker.rb', line 77

def kill
  sig :KILL
end

#node_aliases(cluster) ⇒ Object

github.com/twitter/twemproxy/blob/master/notes/recommendation.md#node-names-for-consistent-hashing



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# File 'lib/nutcracker.rb', line 137

def node_aliases cluster
  Hash[config[cluster]["servers"].map(&:split).each {|o| o[0]=o[0].split(":")[0..1].join(":")}.map(&:reverse)]
end

#overview ⇒ Object

Returns hash with server and node statistics See example.json @ project root to get details about the structure



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# File 'lib/nutcracker.rb', line 98

def overview
  data = { :clusters => [], :config => config }

  stats.each do |cluster_name, cluster_data|
    # Setting global server attributes ( like hostname, version etc...)
    unless cluster_data.is_a? Hash
      data[cluster_name] = cluster_data
      next
    end

    #next unless redis? cluster_name # skip memcached clusters

    aliases = node_aliases cluster_name
    cluster = { nodes: [], name: cluster_name }
    cluster_data.each do |node, node_value|
      # Adding node
      if node_value.kind_of? Hash
        node_data = cluster_data[node]
        node = aliases[node] || node
        url = ( node =~ /redis\:\/\// ) ? node : "redis://#{node}"
        info = redis_info(url, config[cluster_name]["redis_auth"])
        cluster[:nodes] << {
          server_url: url, info: info, running: info.any?
        }.merge(node_data)
      else # Cluster attribute
        cluster[node] = node_value
      end
    end
    data[:clusters].push cluster
  end
  data
end

#redis?(cluster) ⇒ Boolean

Check if a given cluster name was configure as Redis



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# File 'lib/nutcracker.rb', line 132

def redis? cluster
  config[cluster]["redis"] rescue false
end

#redis_info(url, password) ⇒ Object

Returns hash with information about a given Redis



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# File 'lib/nutcracker.rb', line 142

def redis_info url, password
  begin
    r = Redis.new url: url, password: password
    info = r.info.merge 'dbsize' => r.dbsize
  rescue Exception => e
    STDERR.puts "[ERROR][#{__FILE__}:#{__LINE__}] Failed to get data from Redis - " +
      "#{url.inspect} (using password #{password.inspect}): #{e.message}\n#{e.backtrace.join("\n")}"
    return {}
  end

  begin
    info['maxmemory'] = @options.fetch(:max_memory) { r.config(:get, 'maxmemory')['maxmemory'] }
  rescue Exception
    info['maxmemory'] = info['used_memory_rss']
  end

  r.quit

  {
    'connections'     => info['connected_clients'].to_i,
    'used_memory'     => info['used_memory'].to_f,
    'used_memory_rss' => info['used_memory_rss'].to_f,
    'fragmentation'   => info['mem_fragmentation_ratio'].to_f,
    'expired_keys'    => info['expired_keys'].to_i,
    'evicted_keys'    => info['evicted_keys'].to_i,
    'hits'            => info['keyspace_hits'].to_i,
    'misses'          => info['keyspace_misses'].to_i,
    'keys'            => info['dbsize'].to_i,
    'max_memory'      => info['maxmemory'].to_i,
    'hit_ratio'       => 0
  }.tap {|d| d['hit_ratio'] = d['hits'].to_f / (d['hits']+d['misses']).to_f if d['hits'] > 0 }
end

#running? ⇒ Boolean

Returns the current running status



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# File 'lib/nutcracker.rb', line 62

def running?
  attached? ? stats.any? : !!(pid and ::Process.getpgid pid rescue nil)
end

#start(*args) ⇒ Object

launching the Nutcracker service



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# File 'lib/nutcracker.rb', line 51

def start *args
  return self if attached? or running?
  @pid = ::Process.spawn Nutcracker.executable, *command
  Process.detach(@pid)
  sleep 2
  raise "Nutcracker failed to start" unless running?
  Kernel.at_exit { kill if running? }
  self
end

#stats ⇒ Object

Returns a hash with server statistics



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# File 'lib/nutcracker.rb', line 176

def stats
  JSON.parse TCPSocket.new(@options[:stats_uri].host,@options[:stats_uri].port).read rescue {}
end

#stop ⇒ Object

Stops the Nutcracker service



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# File 'lib/nutcracker.rb', line 72

def stop
  sig :TERM
end

#use(plugin, *args) ⇒ Object

Syntactic sugar for initialize plugins



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# File 'lib/nutcracker.rb', line 92

def use plugin, *args
  Nutcracker.const_get(plugin.to_s.capitalize).start(self,*args)
end