Class: Expedite::Server::AgentManager

Inherits:
Object
  • Object
show all
Defined in:
lib/expedite/server/agent_manager.rb

Overview

Locates agent processes and spawns them if necessary

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, env) ⇒ AgentManager

Returns a new instance of AgentManager.



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# File 'lib/expedite/server/agent_manager.rb', line 14

def initialize(name, env)
  @name  = name.to_s
  @env   = env
  @mutex = Mutex.new
  @state = :running
  @pid   = nil

  @agent = Expedite::Agents.lookup(@name)
end

Instance Attribute Details

#agent ⇒ Object (readonly)

Returns the value of attribute agent.



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# File 'lib/expedite/server/agent_manager.rb', line 12

def agent
  @agent
end

#child ⇒ Object (readonly)

Returns the value of attribute child.



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# File 'lib/expedite/server/agent_manager.rb', line 12

def child
  @child
end

#env ⇒ Object (readonly)

Returns the value of attribute env.



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# File 'lib/expedite/server/agent_manager.rb', line 12

def env
  @env
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/expedite/server/agent_manager.rb', line 12

def name
  @name
end

#pid ⇒ Object (readonly)

Returns the value of attribute pid.



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# File 'lib/expedite/server/agent_manager.rb', line 12

def pid
  @pid
end

#status ⇒ Object (readonly)

Returns the value of attribute status.



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# File 'lib/expedite/server/agent_manager.rb', line 12

def status
  @status
end

Instance Method Details

#alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/expedite/server/agent_manager.rb', line 46

def alive?
  @pid
end

#keep_alive ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 107

def keep_alive
  agent.keep_alive
end

#log(message) ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 24

def log(message)
  env.log "[application_manager:#{name}] #{message}"
end

#parent ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 111

def parent
  agent.parent
end

#restart ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 41

def restart
  return if @state == :stopping
  start_child(true)
end

#run(client) ⇒ Object

Returns the pid of the process running the command, or nil if the application process died.



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# File 'lib/expedite/server/agent_manager.rb', line 71

def run(client)
  with_child do |child|
    child.send_io client
    child.gets or raise Errno::EPIPE
  end

  pid = child.gets.to_i

  unless pid.zero?
    log "got worker pid #{pid}"
    pid
  end
rescue Exception => e
  # NotImplementedError is an Exception, not StandardError
  client.send_exception(e, env)
  return Process.pid
rescue Errno::ECONNRESET, Errno::EPIPE => e
  log "#{e} while reading from child; returning no pid"
  nil
ensure
  client.close
end

#start ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 37

def start
  start_child
end

#stop ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 94

def stop
  log "stopping"
  @state = :stopping

  _pid = self.pid
  if _pid
    Process.kill('TERM', _pid)
    Process.wait(_pid)
  end
rescue Errno::ESRCH, Errno::ECHILD
  # Don't care
end

#synchronize ⇒ Object

We’re not using @mutex.synchronize to avoid the weird “<internal:prelude>:10” line which messes with backtraces in e.g. rspec



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# File 'lib/expedite/server/agent_manager.rb', line 30

def synchronize
  @mutex.lock
  yield
ensure
  @mutex.unlock
end

#with_child ⇒ Object 



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# File 'lib/expedite/server/agent_manager.rb', line 50

def with_child
  synchronize do
    if alive?
      begin
        yield child
      rescue Errno::ECONNRESET, Errno::EPIPE
        # The child has died but has not been collected by the wait thread yet,
        # so start a new child and try again.
        log "child dead; starting"
        start
        yield child
      end
    else
      log "child not running; starting"
      start
      yield child
    end
  end
end