Class: Emptyd::Connection

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

Constant Summary collapse

EXPIRE_INTERVAL =

10min

600
MAX_CONNECTIONS = 
30
HAPPY_RATIO = 
0.5
@@connections = 
{}
@@count = 
{}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, logger) ⇒ Connection

Returns a new instance of Connection.

Raises:

  • (IOError) 


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# File 'lib/emptyd.rb', line 22

def initialize(key, logger)
  raise IOError, "already registered" if @@connections[key]
  @key = key
  @logger = logger
  @sessions = []
  @user, @host = key.split('@', 2)
  @user, @host = "root", @user if @host.nil?
  @@connections[key] = self
  @run_queue = []
  self.start
  @timer = EM::PeriodicTimer.new(rand(5..15)) do
    start
    destroy if old? and free?
  end
end

Instance Attribute Details

#error ⇒ Object (readonly)

Returns the value of attribute error.



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# File 'lib/emptyd.rb', line 11

def error
  @error
end

#failed_at ⇒ Object (readonly)

Returns the value of attribute failed_at.



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# File 'lib/emptyd.rb', line 11

def failed_at
  @failed_at
end

#key ⇒ Object (readonly)

Returns the value of attribute key.



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# File 'lib/emptyd.rb', line 11

def key
  @key
end

#updated_at ⇒ Object (readonly)

Returns the value of attribute updated_at.



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# File 'lib/emptyd.rb', line 11

def updated_at
  @updated_at
end

Class Method Details

.[](key, logger) ⇒ Object 



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# File 'lib/emptyd.rb', line 18

def self.[](key, logger)
  @@connections[key] or Connection.new(key, logger)
end

Instance Method Details

#bind(session) ⇒ Object

Raises:

  • (IOError) 


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# File 'lib/emptyd.rb', line 147

def bind(session)
  raise IOError, "already bound" if @sessions.include? session
  @sessions << session
end

#connecting? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/emptyd.rb', line 226

def connecting?
  @connecting
end

#dead? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/emptyd.rb', line 230

def dead?
  @failed_at
end

#destroy ⇒ Object

Raises:

  • (IOError) 


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# File 'lib/emptyd.rb', line 38

def destroy
  raise IOError, "sessions are still alive" unless @sessions.empty?
  @timer.cancel
  @start_timer.cancel if @start_timer
  @@connections.delete @key
  if @conn
    @@count.delete self.key
    conn = @conn
    @conn = nil
    Fiber.new do
      conn.close
    end.resume
  end
  @logger.debug "Destroying connection #{@key}"
end

#errback(err) ⇒ Object 



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# File 'lib/emptyd.rb', line 128

def errback err
  @@count.delete self.key
  had_valid_conn = !!@conn
  @conn = nil
  STDERR.puts "Connection to #{@key} is broken: #{err}"
  @error = err
  @failed_at = Time.now
  @connecting = false
  if had_valid_conn
    @sessions.each do |session|
      session.queue.push [self, :error, @error]
    end
  else
    @run_queue.each do |cmd,session,callback|
      callback.call self, :error, @error
    end
  end
end

#free? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/emptyd.rb', line 222

def free?
  @sessions.empty?
end

#old? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/emptyd.rb', line 218

def old?
  @updated_at and Time.now - @updated_at > EXPIRE_INTERVAL
end

#run(cmd, session, &callback) ⇒ Object 



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# File 'lib/emptyd.rb', line 158

def run cmd, session, &callback
  unless @conn
    @run_queue << [cmd, session, callback]
    return
  end

  setup = proc do |ch|
    callback.call self, :init, ch

    ch.on_data do |c, data|
      EM.next_tick do
        @updated_at = Time.now
        session.queue.push [@key,nil,data]
      end
    end

    ch.on_extended_data do |c, type, data|
      EM.next_tick do
        @updated_at = Time.now
        session.queue.push [@key,type,data]
        @logger.debug [type,data]
      end
    end

    ch.on_request "exit-status" do |ch, data|
      EM.next_tick do
        @updated_at = Time.now
        session.queue.push [@key,:exit,data.read_long]
      end
    end

    ch.on_close do
      @updated_at = Time.now
      callback.call self, :close
    end

    ch.on_open_failed do |ch, code, desc|
      EM.next_tick do
        callback.call self, :error, desc
      end
    end
  end

  @conn.open_channel do |ch|
    if session.interactive?
      ch.request_pty do |ch, success|
        ch.exec cmd do |ch, success|
          STDERR.puts "exec failed: #{cmd}" unless success
          setup[ch]
        end
      end
    else
      ch.exec cmd do |ch, success|
        STDERR.puts "exec failed: #{cmd}" unless success
        setup[ch]
      end
    end
  end
end

#start ⇒ Object 



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# File 'lib/emptyd.rb', line 54

def start
  return if @conn or @connecting
  @connecting = true

  pressure = proc do
    if @@count.size >= MAX_CONNECTIONS # pressure
      c = @@count.select{|k,c| c.free?}.values.sample
      if c
        c.destroy
      else
        @logger.debug "pressure: no free connections: #{@@count.keys}"
      end
    end
  end

  starter = proc do
    begin
      pressure[]
      if @@count.size >= MAX_CONNECTIONS
        @logger.debug "Quota exceeded by #{@key}: #{@@count.size}"
        @start_timer = EM::PeriodicTimer.new(rand(1..10)) do
          pressure[]
          if @@count.size < MAX_CONNECTIONS
            @start_timer.cancel
            EM.next_tick starter
          else
            @logger.debug "No more connection quota, deferring #{@key}..."
          end
        end
      else
        @@count[self.key] = self
        @logger.debug "Created new conn: #{key}, quota = #{@@count.size}"
        options = { :user_known_hosts_file => [] }
        options[:password] = $PASSWORD if $PASSWORD
        EM::Ssh.start(@host, @user, options) do |conn|
          conn.errback { |err| errback err }
          conn.on(:closed) { errback "closed" }
          conn.callback do |ssh|
            @conn = ssh
            @error = nil
            @failed_at = nil
            @updated_at = Time.now
            @connecting = false
            @run_queue.each do |cmd,session,callback|
              if session.dead?
                @logger.debug "Dropping pending run request from a dead session"
                @error = "session is dead"
              else
                EM.next_tick { run cmd, session, &callback }
              end
            end
            @run_queue.clear
            if @error
              ssh.close
              @@count.delete self.key
            end
          end
        end
      end
    rescue EventMachine::ConnectionError => e
      @@count.delete self.key
      @conn = nil
      @error = e
      @failed_at = Time.now
      @connecting = false
      @run_queue.each do |cmd,session,callback|
        callback.call self, :error
      end
    end
  end

  EM.next_tick starter
end

#unbind(session) ⇒ Object

Raises:

  • (IOError) 


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# File 'lib/emptyd.rb', line 152

def unbind(session)
  raise IOError, "not bound" unless @sessions.include? session
  @run_queue.delete_if{|cmd,sess,cb| sess == session}
  @sessions.delete session
end