Module: EventMachine

Defined in:
lib/em/future.rb,
lib/em/streamer.rb,
lib/em/eventable.rb,
lib/em/processes.rb,
lib/em/spawnable.rb,
lib/eventmachine.rb,
lib/em/deferrable.rb,
lib/evma/callback.rb,
lib/jeventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/pr_eventmachine.rb,
lib/protocols/stomp.rb,
lib/protocols/tcptest.rb,
lib/protocols/httpcli2.rb,
lib/protocols/memcache.rb,
lib/protocols/postgres.rb,
lib/protocols/saslauth.rb,
lib/protocols/linetext2.rb,
lib/eventmachine_version.rb,
lib/protocols/httpclient.rb,
lib/protocols/smtpclient.rb,
lib/protocols/smtpserver.rb,
lib/protocols/line_and_text.rb,
lib/protocols/header_and_content.rb,
ext/rubymain.cpp,
ext/fastfilereader/rubymain.cpp

Overview

require ‘base64’

Defined Under Namespace

Modules: Deferrable, Eventable, Protocols, UuidGenerator Classes: Connection, ConnectionNotBound, DatagramObject, DefaultDeferrable, DeferrableChildProcess, Error, EvmaKeyboard, EvmaTCPClient, EvmaTCPServer, EvmaUDPSocket, EvmaUNIXClient, EvmaUNIXServer, FastFileReader, FileNotFoundException, FileStreamer, JEM, LoopbreakReader, PeriodicTimer, Reactor, Selectable, SpawnedProcess, StreamObject, SystemCmd, Timer, UnknownTimerFired, YieldBlockFromSpawnedProcess

Constant Summary collapse

P = 
EventMachine::Protocols
TimerFired =

TODO: These event numbers are defined in way too many places. DRY them up.

INT2NUM(100)
ConnectionData = 
INT2NUM(101)
ConnectionUnbound = 
INT2NUM(102)
ConnectionAccepted = 
INT2NUM(103)
ConnectionCompleted = 
INT2NUM(104)
LoopbreakSignalled = 
INT2NUM(105)
VERSION = 
"0.12.6"
ConnectionNotifyReadable = 
INT2NUM(106)
ConnectionNotifyWritable = 
INT2NUM(107)
SslHandshakeCompleted = 
INT2NUM(108)

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.threadpool ⇒ Object (readonly)

Returns the value of attribute threadpool.



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# File 'lib/eventmachine.rb', line 178

def threadpool
  @threadpool
end

Class Method Details

._open_file_for_writing(filename, handler = nil) ⇒ Object 



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# File 'lib/eventmachine.rb', line 1397

def _open_file_for_writing filename, handler=nil
  klass = if (handler and handler.is_a?(Class))
    raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
    handler
  else
    Class.new( Connection ) {handler and include handler}
  end

  s = _write_file filename
  c = klass.new s
  @conns[s] = c
  block_given? and yield c
  c
end

.add_oneshot_timer(interval) ⇒ Object

#add_oneshot_timer – Changed 04Oct06: intervals from the caller are now in milliseconds, but our native-ruby processor still wants them in seconds.



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# File 'lib/pr_eventmachine.rb', line 58

def self.add_oneshot_timer interval
	@em.installOneshotTimer interval
end

.add_periodic_timer(*args, &block) ⇒ Object

EventMachine#add_periodic_timer adds a periodic timer to the event loop. It takes the same parameters as the one-shot timer method, EventMachine#add_timer. This method schedules execution of the given block repeatedly, at intervals of time at least as great as the number of seconds given in the first parameter to the call.

Usage example

The following sample program will write a dollar-sign to stderr every five seconds. (Of course if the program defined network clients and/or servers, they would be doing their work while the periodic timer is counting off.)

EventMachine::run {
  EventMachine::add_periodic_timer( 5 ) { $stderr.write "$" }
}



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# File 'lib/eventmachine.rb', line 373

def EventMachine::add_periodic_timer *args, &block
  interval = args.shift
  code = args.shift || block
  if code
    block_1 = proc {
      code.call
      EventMachine::add_periodic_timer interval, code
    }
    add_timer interval, block_1
  end
end

.add_timer(*args, &block) ⇒ Object

EventMachine#add_timer adds a one-shot timer to the event loop. Call it with one or two parameters. The first parameters is a delay-time expressed in seconds (not milliseconds). The second parameter, if present, must be a proc object. If a proc object is not given, then you can also simply pass a block to the method call.

EventMachine#add_timer may be called from the block passed to EventMachine#run or from any callback method. It schedules execution of the proc or block passed to add_timer, after the passage of an interval of time equal to at least the number of seconds specified in the first parameter to the call.

EventMachine#add_timer is a non-blocking call. Callbacks can and will be called during the interval of time that the timer is in effect. There is no built-in limit to the number of timers that can be outstanding at any given time.

Usage example

This example shows how easy timers are to use. Observe that two timers are initiated simultaneously. Also, notice that the event loop will continue to run even after the second timer event is processed, since there was no call to EventMachine#stop_event_loop. There will be no activity, of course, since no network clients or servers are defined. Stop the program with Ctrl-C.

require 'rubygems'
require 'eventmachine'

EventMachine::run {
  puts "Starting the run now: #{Time.now}"
  EventMachine::add_timer 5, proc { puts "Executing timer event: #{Time.now}" }
  EventMachine::add_timer( 10 ) { puts "Executing timer event: #{Time.now}" }
}

– Changed 04Oct06: We now pass the interval as an integer number of milliseconds.



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# File 'lib/eventmachine.rb', line 346

def EventMachine::add_timer *args, &block
  interval = args.shift
  code = args.shift || block
  if code
    # check too many timers!
    s = add_oneshot_timer((interval * 1000).to_i)
    @timers[s] = code
    s
  end
end

.attach(io, handler = nil, *args) ⇒ Object

EventMachine::attach registers a given file descriptor or IO object with the eventloop

If the handler provided has the functions notify_readable or notify_writable defined, EventMachine will not read or write from the socket, and instead fire the corresponding callback on the handler.

To detach the file descriptor, use EventMachine::Connection#detach

Usage Example

module SimpleHttpClient
  def initialize sock
    @sock = sock
  end

  def notify_readable
    header = @sock.readline

    if header == "\r\n"
      # detach returns the file descriptor number (fd == @sock.fileno)
      fd = detach
    end
  rescue EOFError
    detach
  end

  def unbind
    EM.next_tick do
      # socket is detached from the eventloop, but still open
      data = @sock.read
    end
  end
end

EM.run{
  $sock = TCPSocket.new('site.com', 80)
  $sock.write("GET / HTTP/1.0\r\n\r\n")
  EM.attach $sock, SimpleHttpClient, $sock
}

– Thanks to Riham Aldakkak (eSpace Technologies) for the initial patch



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# File 'lib/eventmachine.rb', line 759

def  EventMachine::attach io, handler=nil, *args
  klass = if (handler and handler.is_a?(Class))
    raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
    handler
  else
    Class.new( Connection ) {handler and include handler}
  end

  arity = klass.instance_method(:initialize).arity
  expected = arity >= 0 ? arity : -(arity + 1)
  if (arity >= 0 and args.size != expected) or (arity < 0 and args.size < expected)
    raise ArgumentError, "wrong number of arguments for #{klass}#initialize (#{args.size} for #{expected})"
  end

  readmode  = klass.public_instance_methods.any?{|m| m.to_sym == :notify_readable }
  writemode = klass.public_instance_methods.any?{|m| m.to_sym == :notify_writable }

  s = attach_fd io.respond_to?(:fileno) ? io.fileno : io, readmode, writemode

  c = klass.new s, *args
  @conns[s] = c
  block_given? and yield c
  c
end

.cancel_timer(signature) ⇒ Object

–



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# File 'lib/eventmachine.rb', line 387

def EventMachine::cancel_timer signature
	@timers[signature] = proc{} if @timers.has_key?(signature)
end

.close_connection(target, after_writing) ⇒ Object

#close_connection The extension version does NOT raise any kind of an error if an attempt is made to close a non-existent connection. Not sure whether we should. For now, we’ll raise an error here in that case.



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

def self.close_connection sig, after_writing
	@em.closeConnection sig, after_writing
end

.connect(server, port = nil, handler = nil, *args) ⇒ Object

EventMachine#connect initiates a TCP connection to a remote server and sets up event-handling for the connection. You can call EventMachine#connect in the block supplied to EventMachine#run or in any callback method.

EventMachine#connect takes the IP address (or hostname) and port of the remote server you want to connect to. It also takes an optional handler Module which you must define, that contains the callbacks that will be invoked by the event loop on behalf of the connection.

See the description of EventMachine#start_server for a discussion of the handler Module. All of the details given in that description apply for connections created with EventMachine#connect.

Usage Example

Here’s a program which connects to a web server, sends a naive request, parses the HTTP header of the response, and then (antisocially) ends the event loop, which automatically drops the connection (and incidentally calls the connection’s unbind method).

require 'rubygems'
require 'eventmachine'

module DumbHttpClient

  def post_init
    send_data "GET / HTTP/1.1\r\nHost: _\r\n\r\n"
    @data = ""
  end

  def receive_data data
    @data << data
    if  @data =~ /[\n][\r]*[\n]/m
      puts "RECEIVED HTTP HEADER:"
      $`.each {|line| puts ">>> #{line}" }

      puts "Now we'll terminate the loop, which will also close the connection"
      EventMachine::stop_event_loop
    end
  end

  def unbind
    puts "A connection has terminated"
  end

end # DumbHttpClient

EventMachine::run {
  EventMachine::connect "www.bayshorenetworks.com", 80, DumbHttpClient
}
puts "The event loop has ended"

There are times when it’s more convenient to define a protocol handler as a Class rather than a Module. Here’s how to do this:

class MyProtocolHandler < EventMachine::Connection
  def initialize *args
    super
    # whatever else you want to do here
  end

  #.......your other class code
end # class MyProtocolHandler

If you do this, then an instance of your class will be instantiated to handle every network connection created by your code or accepted by servers that you create. If you redefine #post_init in your protocol-handler class, your #post_init method will be called inside the call to #super that you will make in your #initialize method (if you provide one).

– EventMachine::connect initiates a TCP connection to a remote server and sets up event-handling for the connection. It internally creates an object that should not be handled by the caller. HOWEVER, it’s often convenient to get the object to set up interfacing to other objects in the system. We return the newly-created anonymous-class object to the caller. It’s expected that a considerable amount of code will depend on this behavior, so don’t change it.

Ok, added support for a user-defined block, 13Apr06. This leads us to an interesting choice because of the presence of the post_init call, which happens in the initialize method of the new object. We call the user’s block and pass the new object to it. This is a great way to do protocol-specific initiation. It happens AFTER post_init has been called on the object, which I certainly hope is the right choice. Don’t change this lightly, because accepted connections are different from connected ones and we don’t want to have them behave differently with respect to post_init if at all possible.



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# File 'lib/eventmachine.rb', line 681

def EventMachine::connect server, port=nil, handler=nil, *args
  begin
    port = Integer(port)
  rescue ArgumentError, TypeError
    # there was no port, so server must be a unix domain socket
    # the port argument is actually the handler, and the handler is one of the args
    args.unshift handler if handler
    handler = port
    port = nil
  end if port

  klass = if (handler and handler.is_a?(Class))
    raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
    handler
  else
    Class.new( Connection ) {handler and include handler}
  end

  arity = klass.instance_method(:initialize).arity
  expected = arity >= 0 ? arity : -(arity + 1)
  if (arity >= 0 and args.size != expected) or (arity < 0 and args.size < expected)
    raise ArgumentError, "wrong number of arguments for #{klass}#initialize (#{args.size} for #{expected})"
  end

  s = if port
        connect_server server, port
      else
        connect_unix_server server
      end

  c = klass.new s, *args
  @conns[s] = c
  block_given? and yield c
  c
end

.connect_server(host, port) ⇒ Object

#connect_server. Return a connection descriptor to the caller. TODO, what do we return here if we can’t connect?



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# File 'lib/pr_eventmachine.rb', line 78

def self.connect_server server, port
	@em.connectTcpServer server, port
end

.connect_unix_domain(socketname, *args, &blk) ⇒ Object

Make a connection to a Unix-domain socket. This is not implemented on Windows platforms. The parameter socketname is a String which identifies the Unix-domain socket you want to connect to. socketname is the name of a file on your local system, and in most cases is a fully-qualified path name. Make sure that your process has enough local permissions to open the Unix-domain socket. See also the documentation for #connect_server. This method behaves like #connect_server in all respects except for the fact that it connects to a local Unix-domain socket rather than a TCP socket. NOTE: this functionality will soon be subsumed into the #connect method. This method will still be supported as an alias. – For making connections to Unix-domain sockets. Eventually this has to get properly documented and unified with the TCP-connect methods. Note how nearly identical this is to EventMachine#connect



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# File 'lib/eventmachine.rb', line 823

def EventMachine::connect_unix_domain socketname, *args, &blk
  connect socketname, *args, &blk
end

.connect_unix_server(chain) ⇒ Object

#connect_unix_server



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# File 'lib/pr_eventmachine.rb', line 116

def connect_unix_server chain
  EvmaUNIXClient.connect(chain).uuid
end

.connection_count ⇒ Object

Returns the total number of connections (file descriptors) currently held by the reactor. Note that a tick must pass after the ‘initiation’ of a connection for this number to increment.

For example, $count will be 0 in this case:

EM.run 

EM.connect("rubyeventmachine.com", 80)
$count = EM.connection_count

In this example, $count will be 1 since the connection has been established in the next loop of the reactor.

EM.run {

EM.connect("rubyeventmachine.com", 80)
EM.next_tick {
  $count = EM.connection_count
}

}



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# File 'lib/eventmachine.rb', line 963

def self::connection_count
  self::get_connection_count
end

.defer(op = nil, callback = nil, &blk) ⇒ Object

#defer is for integrating blocking operations into EventMachine’s control flow. Call #defer with one or two blocks, as shown below (the second block is optional):

operation = proc {
  # perform a long-running operation here, such as a database query.
  "result" # as usual, the last expression evaluated in the block will be the return value.
}
callback = proc {|result|
  # do something with result here, such as send it back to a network client.
}

EventMachine.defer( operation, callback )

The action of #defer is to take the block specified in the first parameter (the “operation”) and schedule it for asynchronous execution on an internal thread pool maintained by EventMachine. When the operation completes, it will pass the result computed by the block (if any) back to the EventMachine reactor. Then, EventMachine calls the block specified in the second parameter to #defer (the “callback”), as part of its normal, synchronous event handling loop. The result computed by the operation block is passed as a parameter to the callback. You may omit the callback parameter if you don’t need to execute any code after the operation completes.

Caveats: Note carefully that the code in your deferred operation will be executed on a separate thread from the main EventMachine processing and all other Ruby threads that may exist in your program. Also, multiple deferred operations may be running at once! Therefore, you are responsible for ensuring that your operation code is threadsafe. [Need more explanation and examples.] Don’t write a deferred operation that will block forever. If so, the current implementation will not detect the problem, and the thread will never be returned to the pool. EventMachine limits the number of threads in its pool, so if you do this enough times, your subsequent deferred operations won’t get a chance to run. [We might put in a timer to detect this problem.]

– OBSERVE that #next_tick hacks into this mechanism, so don’t make any changes here without syncing there.

Running with $VERBOSE set to true gives a warning unless all ivars are defined when they appear in rvalues. But we DON’T ever want to initialize @threadqueue unless we need it, because the Ruby threads are so heavyweight. We end up with this bizarre way of initializing @threadqueue because EventMachine is a Module, not a Class, and has no constructor.



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# File 'lib/eventmachine.rb', line 1047

def self::defer op = nil, callback = nil, &blk
	unless @threadpool
		require 'thread'
		@threadpool = []
		@threadqueue = Queue.new
		@resultqueue = Queue.new
		spawn_threadpool
	end

	@threadqueue << [op||blk,callback]
end

.epoll ⇒ Object

#epoll is a harmless no-op in the pure-Ruby implementation. This is intended to ensure that user code behaves properly across different EM implementations.



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

def self.epoll
	# Epoll is a no-op for Java.
	# The latest Java versions run epoll when possible in NIO.
end

.error_handler(cb = nil, &blk) ⇒ Object

Catch-all for errors raised during event loop callbacks.

EM.error_handler{ |e|

puts "Error raised during event loop: #{e.message}"

}



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# File 'lib/eventmachine.rb', line 1229

def EventMachine::error_handler cb = nil, &blk
	if cb or blk
		@error_handler = cb || blk
	elsif instance_variable_defined? :@error_handler
		remove_instance_variable :@error_handler
	end
end

.event_callback(target, opcode, data) ⇒ Object 



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# File 'lib/eventmachine.rb', line 1238

def EventMachine::event_callback conn_binding, opcode, data
	#
	# Changed 27Dec07: Eliminated the hookable error handling.
	# No one was using it, and it degraded performance significantly.
	# It's in original_event_callback, which is dead code.
	#
	# Changed 25Jul08: Added a partial solution to the problem of exceptions
	# raised in user-written event-handlers. If such exceptions are not caught,
	# we must cause the reactor to stop, and then re-raise the exception.
	# Otherwise, the reactor doesn't stop and it's left on the call stack.
	# This is partial because we only added it to #unbind, where it's critical
	# (to keep unbind handlers from being re-entered when a stopping reactor
	# runs down open connections). It should go on the other calls to user
	# code, but the performance impact may be too large.
	#
	if opcode == ConnectionUnbound
		if c = @conns.delete( conn_binding )
			begin
				c.unbind
			rescue
				@wrapped_exception = $!
				stop
			end
		elsif c = @acceptors.delete( conn_binding )
			# no-op
		else
			raise ConnectionNotBound, "recieved ConnectionUnbound for an unknown signature: #{conn_binding}"
		end
	elsif opcode == ConnectionAccepted
		accep,args,blk = @acceptors[conn_binding]
		raise NoHandlerForAcceptedConnection unless accep
		c = accep.new data, *args
		@conns[data] = c
		blk and blk.call(c)
		c # (needed?)
	elsif opcode == ConnectionCompleted
		c = @conns[conn_binding] or raise ConnectionNotBound, "received ConnectionCompleted for unknown signature: #{conn_binding}"
		c.connection_completed
	##
	# The remaining code is a fallback for the pure ruby reactor. Usually these events are handled in the C event_callback() in rubymain.cpp
	elsif opcode == TimerFired
		t = @timers.delete( data ) or raise UnknownTimerFired, "timer data: #{data}"
		t.call
	elsif opcode == ConnectionData
		c = @conns[conn_binding] or raise ConnectionNotBound, "received data #{data} for unknown signature: #{conn_binding}"
		c.receive_data data
	elsif opcode == LoopbreakSignalled
		run_deferred_callbacks
	elsif opcode == ConnectionNotifyReadable
		c = @conns[conn_binding] or raise ConnectionNotBound
		c.notify_readable
	elsif opcode == ConnectionNotifyWritable
		c = @conns[conn_binding] or raise ConnectionNotBound
		c.notify_writable
	end
end

.fork_reactor(&block) ⇒ Object

fork_reactor forks a new process and calls EM#run inside of it, passing your block. – This implementation is subject to change, especially if we clean up the relationship of EM#run to @reactor_running. Original patch by Aman Gupta.



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# File 'lib/eventmachine.rb', line 284

def EventMachine::fork_reactor &block
 Kernel.fork do
  if self.reactor_running?
   self.stop_event_loop
   self.release_machine
   self.instance_variable_set( '@reactor_running', false )
  end
  self.run block
 end
end

.get_max_timers ⇒ Object

Gets the current maximum number of allowed timers



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# File 'lib/eventmachine.rb', line 940

def self::get_max_timers
	get_max_timer_count
end

.get_outbound_data_size(sig) ⇒ Object

#get_outbound_data_size



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# File 'lib/pr_eventmachine.rb', line 181

def get_outbound_data_size sig
  r = Reactor.instance.get_selectable( sig ) or raise "unknown get_outbound_data_size target"
  r.get_outbound_data_size
end

.get_peername(sig) ⇒ Object

#get_peername



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# File 'lib/pr_eventmachine.rb', line 126

def get_peername sig
  selectable = Reactor.instance.get_selectable( sig ) or raise "unknown get_peername target"
  selectable.get_peername
end

.initialize_event_machine ⇒ Object

#initialize_event_machine



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# File 'lib/pr_eventmachine.rb', line 50

def self.initialize_event_machine
	@em = JEM.new
end

.invoke_popen(cmd) ⇒ Object 



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# File 'lib/jeventmachine.rb', line 116

def self.invoke_popen cmd
	# TEMPORARILY unsupported until someone figures out how to do it.
	raise "unsupported on this platform"
end

.library_type ⇒ Object

This is mostly useful for automated tests. Return a distinctive symbol so the caller knows whether he’s dealing with an extension or with a pure-Ruby library.



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# File 'lib/jeventmachine.rb', line 127

def self.library_type
	:java
end

.next_tick(pr = nil, &block) ⇒ Object

core. An advanced technique, this can be useful for improving memory management and/or application responsiveness, especially when scheduling large amounts of data for writing to a network connection. TODO, we need a FAQ entry on this subject.

#next_tick takes either a single argument (which must be a Proc) or a block. And I’m taking suggestions for a better name for this method. – This works by adding to the @resultqueue that’s used for #defer. The general idea is that next_tick is used when we want to give the reactor a chance to let other operations run, either to balance the load out more evenly, or to let outbound network buffers drain, or both. So we probably do NOT want to block, and we probably do NOT want to be spinning any threads. A program that uses next_tick but not #defer shouldn’t suffer the penalty of having Ruby threads running. They’re extremely expensive even if they’re just sleeping.



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# File 'lib/eventmachine.rb', line 1090

def self::next_tick pr=nil, &block
	raise "no argument or block given" unless ((pr && pr.respond_to?(:call)) or block)
	(@next_tick_queue ||= []) << ( pr || block )
	signal_loopbreak if reactor_running?
=begin
	(@next_tick_procs ||= []) << (pr || block)
	if @next_tick_procs.length == 1
		add_timer(0) {
			@next_tick_procs.each {|t| t.call}
			@next_tick_procs.clear
		}
	end
=end
end

.open_datagram_socket(address, port, handler = nil, *args) ⇒ Object

EventMachine#open_datagram_socket is for support of UDP-based protocols. Its usage is similar to that of EventMachine#start_server. It takes three parameters: an IP address (which must be valid on the machine which executes the method), a port number, and an optional Module name which will handle the data. This method will create a new UDP (datagram) socket and bind it to the address and port that you specify. The normal callbacks (see EventMachine#start_server) will be called as events of interest occur on the newly-created socket, but there are some differences in how they behave.

Connection#receive_data will be called when a datagram packet is received on the socket, but unlike TCP sockets, the message boundaries of the received data will be respected. In other words, if the remote peer sent you a datagram of a particular size, you may rely on Connection#receive_data to give you the exact data in the packet, with the original data length. Also observe that Connection#receive_data may be called with a zero-length data payload, since empty datagrams are permitted in UDP.

Connection#send_data is available with UDP packets as with TCP, but there is an important difference. Because UDP communications are connectionless, there is no implicit recipient for the packets you send. Ordinarily you must specify the recipient for each packet you send. However, EventMachine provides for the typical pattern of receiving a UDP datagram from a remote peer, performing some operation, and then sending one or more packets in response to the same remote peer. To support this model easily, just use Connection#send_data in the code that you supply for Connection:receive_data. EventMachine will provide an implicit return address for any messages sent to Connection#send_data within the context of a Connection#receive_data callback, and your response will automatically go to the correct remote peer. (TODO: Example-code needed!)

Observe that the port number that you supply to EventMachine#open_datagram_socket may be zero. In this case, EventMachine will create a UDP socket that is bound to an ephemeral (not well-known) port. This is not appropriate for servers that must publish a well-known port to which remote peers may send datagrams. But it can be useful for clients that send datagrams to other servers. If you do this, you will receive any responses from the remote servers through the normal Connection#receive_data callback. Observe that you will probably have issues with firewalls blocking the ephemeral port numbers, so this technique is most appropriate for LANs. (TODO: Need an example!)

If you wish to send datagrams to arbitrary remote peers (not necessarily ones that have sent data to which you are responding), then see Connection#send_datagram.

DO NOT call send_data from a datagram socket outside of a #receive_data method. Use #send_datagram. If you do use #send_data outside of a #receive_data method, you’ll get a confusing error because there is no “peer,” as #send_data requires. (Inside of #receive_data, #send_data “fakes” the peer as described above.)

– Replaced the implementation on 01Oct06. Thanks to Tobias Gustafsson for pointing out that this originally did not take a class but only a module.



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# File 'lib/eventmachine.rb', line 891

def self::open_datagram_socket address, port, handler=nil, *args
	klass = if (handler and handler.is_a?(Class))
	  raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
		handler
	else
		Class.new( Connection ) {handler and include handler}
	end

   arity = klass.instance_method(:initialize).arity
   expected = arity >= 0 ? arity : -(arity + 1)
   if (arity >= 0 and args.size != expected) or (arity < 0 and args.size < expected)
     raise ArgumentError, "wrong number of arguments for #{klass}#initialize (#{args.size} for #{expected})"
   end

	s = open_udp_socket address, port
	c = klass.new s, *args
	@conns[s] = c
	block_given? and yield c
	c
end

.open_keyboard(handler = nil, *args) ⇒ Object

(Experimental)



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# File 'lib/eventmachine.rb', line 1202

def EventMachine::open_keyboard handler=nil, *args
	klass = if (handler and handler.is_a?(Class))
	  raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
		handler
	else
		Class.new( Connection ) {handler and include handler}
	end

	arity = klass.instance_method(:initialize).arity
	expected = arity >= 0 ? arity : -(arity + 1)
	if (arity >= 0 and args.size != expected) or (arity < 0 and args.size < expected)
		raise ArgumentError, "wrong number of arguments for #{klass}#initialize (#{args.size} for #{expected})"
	end

	s = read_keyboard
	c = klass.new s, *args
	@conns[s] = c
	block_given? and yield c
	c
end

.open_udp_socket(host, port) ⇒ Object

#open_udp_socket



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# File 'lib/jeventmachine.rb', line 113

def self.open_udp_socket server, port
	@em.openUdpSocket server, port
end

.popen(cmd, handler = nil, *args) {|c| ... } ⇒ Object

Run an external process. This does not currently work on Windows.

module RubyCounter
  def post_init
    # count up to 5
    send_data "5\n"
  end
  def receive_data data
    puts "ruby sent me: #{data}"
  end
  def unbind
    puts "ruby died with exit status: #{get_status.exitstatus}"
  end
end

EM.run{
  EM.popen("ruby -e' $stdout.sync = true; gets.to_i.times{ |i| puts i+1; sleep 1 } '", RubyCounter)
}

Also see EM::DeferrableChildProcess and EM::system – At this moment, it’s only available on Unix. Perhaps misnamed since the underlying function uses socketpair and is full-duplex.

Yields:

  • (c) 


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# File 'lib/eventmachine.rb', line 1166

def self::popen cmd, handler=nil, *args
	klass = if (handler and handler.is_a?(Class))
	  raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
		handler
	else
		Class.new( Connection ) {handler and include handler}
	end

	w = Shellwords::shellwords( cmd )
	w.unshift( w.first ) if w.first
	s = invoke_popen( w )
	c = klass.new s, *args
	@conns[s] = c
	yield(c) if block_given?
	c
end

.reactor_running? ⇒ Boolean

Tells you whether the EventMachine reactor loop is currently running. Returns true or false. Useful when writing libraries that want to run event-driven code, but may be running in programs that are already event-driven. In such cases, if EventMachine#reactor_running? returns false, your code can invoke EventMachine#run and run your application code inside the block passed to that method. If EventMachine#reactor_running? returns true, just execute your event-aware code.

This method is necessary because calling EventMachine#run inside of another call to EventMachine#run generates a fatal error.

Returns:

  • (Boolean) 


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# File 'lib/eventmachine.rb', line 1194

def self::reactor_running?
	(@reactor_running || false)
end

.read_keyboard ⇒ Object

#read_keyboard



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# File 'lib/pr_eventmachine.rb', line 188

def self.read_keyboard
	# TEMPORARILY unsupported until someone figures out how to do it.
	raise "temporarily unsupported on this platform"
end

.reconnect(server, port, handler) ⇒ Object

– EXPERIMENTAL. DO NOT RELY ON THIS METHOD TO BE HERE IN THIS FORM, OR AT ALL. (03Nov06) Observe, the test for already-connected FAILS if we call a reconnect inside post_init, because we haven’t set up the connection in @conns by that point. RESIST THE TEMPTATION to “fix” this problem by redefining the behavior of post_init.

Changed 22Nov06: if called on an already-connected handler, just return the handler and do nothing more. Originally this condition raised an exception. We may want to change it yet again and call the block, if any.



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# File 'lib/eventmachine.rb', line 795

def EventMachine::reconnect server, port, handler
	raise "invalid handler" unless handler.respond_to?(:connection_completed)
	#raise "still connected" if @conns.has_key?(handler.signature)
	return handler if @conns.has_key?(handler.signature)
	s = connect_server server, port
	handler.signature = s
	@conns[s] = handler
	block_given? and yield handler
	handler
end

.release_machine ⇒ Object

release_machine. Probably a no-op.



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# File 'lib/pr_eventmachine.rb', line 68

def self.release_machine
	@em = nil
end

.run(blk = nil, tail = nil, &block) ⇒ Object

EventMachine::run initializes and runs an event loop. This method only returns if user-callback code calls stop_event_loop. Use the supplied block to define your clients and servers. The block is called by EventMachine::run immediately after initializing its internal event loop but before running the loop. Therefore this block is the right place to call start_server if you want to accept connections from remote clients.

For programs that are structured as servers, it’s usually appropriate to start an event loop by calling EventMachine::run, and let it run forever. It’s also possible to use EventMachine::run to make a single client-connection to a remote server, process the data flow from that single connection, and then call stop_event_loop to force EventMachine::run to return. Your program will then continue from the point immediately following the call to EventMachine::run.

You can of course do both client and servers simultaneously in the same program. One of the strengths of the event-driven programming model is that the handling of network events on many different connections will be interleaved, and scheduled according to the actual events themselves. This maximizes efficiency.

Server usage example

See the text at the top of this file for an example of an echo server.

Client usage example

See the description of stop_event_loop for an extremely simple client example.

– Obsoleted the use_threads mechanism. 25Nov06: Added the begin/ensure block. We need to be sure that release_machine gets called even if an exception gets thrown within any of the user code that the event loop runs. The best way to see this is to run a unit test with two functions, each of which calls EventMachine#run and each of which throws something inside of #run. Without the ensure, the second test will start without release_machine being called and will immediately throw a C++ runtime error.



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

def EventMachine::run blk=nil, tail=nil, &block
	@tails ||= []
	tail and @tails.unshift(tail)

	if reactor_running?
		(b = blk || block) and b.call # next_tick(b)
	else
		@conns = {}
		@acceptors = {}
		@timers = {}
		@wrapped_exception = nil
		begin
			@reactor_running = true
			initialize_event_machine
			(b = blk || block) and add_timer(0, b)
			if @next_tick_queue && !@next_tick_queue.empty?
				add_timer(0) { signal_loopbreak }
			end
			run_machine
		ensure
		  begin
			  release_machine
		  ensure
 				if @threadpool
 				  @threadpool.each { |t| t.exit }
 				  @threadpool.each { |t| t.kill! if t.alive? }
 				  @threadqueue = nil
 				  @resultqueue = nil				  
 			  end
 				@threadpool = nil
			end
			@reactor_running = false
		end

		until @tails.empty?
			@tails.pop.call
		end

		raise @wrapped_exception if @wrapped_exception
	end
end

.run_block(&block) ⇒ Object

Sugars a common use case. Will pass the given block to #run, but will terminate the reactor loop and exit the function as soon as the code in the block completes. (Normally, #run keeps running indefinitely, even after the block supplied to it finishes running, until user code calls #stop.)



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# File 'lib/eventmachine.rb', line 270

def EventMachine::run_block &block
 pr = proc {
  block.call
  EventMachine::stop
 }
 run(&pr)
end

.run_deferred_callbacks ⇒ Object

– The is the responder for the loopback-signalled event. It can be fired either by code running on a separate thread (EM#defer) or on the main thread (EM#next_tick). It will often happen that a next_tick handler will reschedule itself. We consume a copy of the tick queue so that tick events scheduled by tick events have to wait for the next pass through the reactor core.



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# File 'lib/eventmachine.rb', line 975

def self::run_deferred_callbacks # :nodoc:
	until (@resultqueue ||= []).empty?
		result,cback = @resultqueue.pop
		cback.call result if cback
	end

	@next_tick_queue ||= []
	if (l = @next_tick_queue.length) > 0
		l.times {|i| @next_tick_queue[i].call}
		@next_tick_queue.slice!( 0...l )
	end

=begin
	(@next_tick_queue ||= []).length.times {
		cback=@next_tick_queue.pop and cback.call
	}
=end
=begin
	if (@next_tick_queue ||= []) and @next_tick_queue.length > 0
		ary = @next_tick_queue.dup
		@next_tick_queue.clear
		until ary.empty?
			cback=ary.pop and cback.call
		end
	end
=end
end

.run_machine ⇒ Object

run_machine



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# File 'lib/pr_eventmachine.rb', line 63

def self.run_machine
	@em.run
end

.run_without_threads(&block) ⇒ Object

deprecated – EventMachine#run_without_threads is semantically identical to EventMachine#run, but it runs somewhat faster. However, it must not be used in applications that spin Ruby threads.



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# File 'lib/eventmachine.rb', line 302

def EventMachine::run_without_threads &block
  #EventMachine::run false, &block
  EventMachine::run(&block)
end

.send_data(target, data, datalength) ⇒ Object

#send_data



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# File 'lib/pr_eventmachine.rb', line 83

def self.send_data sig, data, length
	@em.sendData sig, data.to_java_bytes
end

.send_datagram(target, data, datalength, host, port) ⇒ Object

#send_datagram. This is currently only for UDP! We need to make it work with unix-domain sockets as well.



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# File 'lib/pr_eventmachine.rb', line 138

def self.send_datagram sig, data, length, address, port
	@em.sendDatagram sig, data, length, address, port
end

.send_file_data(sig, filename) ⇒ Object

#send_file_data



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# File 'lib/pr_eventmachine.rb', line 167

def send_file_data sig, filename
  sz = File.size(filename)
  raise "file too large" if sz > 32*1024
  data =
  begin
    File.read filename
  rescue
    ""
  end
  send_data sig, data, data.length
end

.set_comm_inactivity_timeout(sig, tm) ⇒ Object

#set_comm_inactivity_timeout



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# File 'lib/pr_eventmachine.rb', line 194

def self.set_comm_inactivity_timeout sig, interval
	@em.setCommInactivityTimeout sig, interval
end

.set_descriptor_table_size(n_descriptors = nil) ⇒ Object

Sets the maximum number of file or socket descriptors that your process may open. You can pass this method an integer specifying the new size of the descriptor table. Returns the new descriptor-table size, which may be less than the number you requested. If you call this method with no arguments, it will simply return the current size of the descriptor table without attempting to change it.

The new limit on open descriptors ONLY applies to sockets and other descriptors that belong to EventMachine. It has NO EFFECT on the number of descriptors you can create in ordinary Ruby code.

Not available on all platforms. Increasing the number of descriptors beyond its default limit usually requires superuser privileges. (See #set_effective_user for a way to drop superuser privileges while your program is running.)



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# File 'lib/eventmachine.rb', line 1136

def self::set_descriptor_table_size n_descriptors=nil
	EventMachine::set_rlimit_nofile n_descriptors
end

.set_effective_user(username) ⇒ Object

A wrapper over the setuid system call. Particularly useful when opening a network server on a privileged port because you can use this call to drop privileges after opening the port. Also very useful after a call to #set_descriptor_table_size, which generally requires that you start your process with root privileges.

This method has no effective implementation on Windows or in the pure-Ruby implementation of EventMachine. Call #set_effective_user by passing it a string containing the effective name of the user whose privilege-level your process should attain. This method is intended for use in enforcing security requirements, consequently it will throw a fatal error and end your program if it fails.



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# File 'lib/eventmachine.rb', line 1117

def self::set_effective_user username
	EventMachine::setuid_string username
end

.set_max_timer_count(n) ⇒ Object

#set_max_timer_count is a harmless no-op in pure Ruby, which doesn’t have a built-in limit on the number of available timers.



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# File 'lib/pr_eventmachine.rb', line 163

def self.set_max_timer_count num
	# harmless no-op in Java. There's no built-in timer limit.
end

.set_max_timers(ct) ⇒ Object

Sets the maximum number of timers and periodic timers that may be outstanding at any given time. You only need to call #set_max_timers if you need more than the default number of timers, which on most platforms is 1000. Call this method before calling EventMachine#run.



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# File 'lib/eventmachine.rb', line 934

def self::set_max_timers ct
	set_max_timer_count ct
end

.set_quantum(mills) ⇒ Object

For advanced users. This function sets the default timer granularity, which by default is slightly smaller than 100 milliseconds. Call this function to set a higher or lower granularity. The function affects the behavior of #add_timer and #add_periodic_timer. Most applications will not need to call this function.

The argument is a number of milliseconds. Avoid setting the quantum to very low values because that may reduce performance under some extreme conditions. We recommend that you not set a quantum lower than 10.

You may only call this function while an EventMachine loop is running (that is, after a call to EventMachine#run and before a subsequent call to EventMachine#stop).



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# File 'lib/eventmachine.rb', line 925

def self::set_quantum mills
	set_timer_quantum mills.to_i
end

.set_rlimit_nofile(n) ⇒ Object

#set_rlimit_nofile is a no-op in the pure-Ruby implementation. We simply return Ruby’s built-in per-process file-descriptor limit.



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# File 'lib/jeventmachine.rb', line 110

def self.set_rlimit_nofile n_descriptors
	# Currently a no-op for Java.
end

.set_timer_quantum(interval) ⇒ Object

#set_timer_quantum in milliseconds. The underlying Reactor function wants a (possibly fractional) number of seconds.



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

def self.set_timer_quantum q
	@em.setTimerQuantum q
end

.signal_loopbreak ⇒ Object

#signal_loopbreak



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# File 'lib/pr_eventmachine.rb', line 121

def self.signal_loopbreak
	@em.signalLoopbreak
end

.spawn(&block) ⇒ Object 



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# File 'lib/em/spawnable.rb', line 72

def EventMachine.spawn &block
	s = SpawnedProcess.new
	s.set_receiver block
	s
end

.spawn_threadpool ⇒ Object 



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# File 'lib/eventmachine.rb', line 1059

def self.spawn_threadpool
  until @threadpool.size == 20
		thread = Thread.new do
			while true
				op, cback = *@threadqueue.pop
				result = op.call
				@resultqueue << [result, cback]
				EventMachine.signal_loopbreak
			end
		end
		@threadpool << thread
	end
end

.start_server(server, port = nil, handler = nil, *args, &block) ⇒ Object

EventMachine::start_server initiates a TCP server (socket acceptor) on the specified IP address and port. The IP address must be valid on the machine where the program runs, and the process must be privileged enough to listen on the specified port (on Unix-like systems, superuser privileges are usually required to listen on any port lower than 1024). Only one listener may be running on any given address/port combination. start_server will fail if the given address and port are already listening on the machine, either because of a prior call to start_server or some unrelated process running on the machine. If start_server succeeds, the new network listener becomes active immediately and starts accepting connections from remote peers, and these connections generate callback events that are processed by the code specified in the handler parameter to start_server.

The optional handler which is passed to start_server is the key to EventMachine’s ability to handle particular network protocols. The handler parameter passed to start_server must be a Ruby Module that you must define. When the network server that is started by start_server accepts a new connection, it instantiates a new object of an anonymous class that is inherited from EventMachine::Connection, into which the methods from your handler have been mixed. Your handler module may redefine any of the methods in EventMachine::Connection in order to implement the specific behavior of the network protocol.

Callbacks invoked in response to network events always take place within the execution context of the object derived from EventMachine::Connection extended by your handler module. There is one object per connection, and all of the callbacks invoked for a particular connection take the form of instance methods called against the corresponding EventMachine::Connection object. Therefore, you are free to define whatever instance variables you wish, in order to contain the per-connection state required by the network protocol you are implementing.

start_server is often called inside the block passed to EventMachine::run, but it can be called from any EventMachine callback. start_server will fail unless the EventMachine event loop is currently running (which is why it’s often called in the block suppled to EventMachine::run).

You may call start_server any number of times to start up network listeners on different address/port combinations. The servers will all run simultaneously. More interestingly, each individual call to start_server can specify a different handler module and thus implement a different network protocol from all the others.

Usage example

Here is an example of a server that counts lines of input from the remote peer and sends back the total number of lines received, after each line. Try the example with more than one client connection opened via telnet, and you will see that the line count increments independently on each of the client connections. Also very important to note, is that the handler for the receive_data function, which our handler redefines, may not assume that the data it receives observes any kind of message boundaries. Also, to use this example, be sure to change the server and port parameters to the start_server call to values appropriate for your environment.

require 'rubygems'
require 'eventmachine'

module LineCounter

  MaxLinesPerConnection = 10

  def post_init
    puts "Received a new connection"
    @data_received = ""
    @line_count = 0
  end

  def receive_data data
    @data_received << data
    while @data_received.slice!( /^[^\n]*[\n]/m )
      @line_count += 1
      send_data "received #{@line_count} lines so far\r\n"
      @line_count == MaxLinesPerConnection and close_connection_after_writing
    end
  end

end # module LineCounter

EventMachine::run {
  host,port = "192.168.0.100", 8090
  EventMachine::start_server host, port, LineCounter
  puts "Now accepting connections on address #{host}, port #{port}..."
  EventMachine::add_periodic_timer( 10 ) { $stderr.write "*" }
}



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# File 'lib/eventmachine.rb', line 536

def EventMachine::start_server server, port=nil, handler=nil, *args, &block
  
  begin
    port = Integer(port)
  rescue ArgumentError, TypeError
    # there was no port, so server must be a unix domain socket
    # the port argument is actually the handler, and the handler is one of the args
    args.unshift handler if handler
    handler = port
    port = nil
  end if port
  
  klass = if (handler and handler.is_a?(Class))
    raise ArgumentError, 'must provide module or subclass of EventMachine::Connection' unless Connection > handler
    handler
  else
    Class.new( Connection ) {handler and include handler}
  end

  arity = klass.instance_method(:initialize).arity
  expected = arity >= 0 ? arity : -(arity + 1)
  if (arity >= 0 and args.size != expected) or (arity < 0 and args.size < expected)
    raise ArgumentError, "wrong number of arguments for #{klass}#initialize (#{args.size} for #{expected})" 
  end

  s = if port
        start_tcp_server server, port
      else
        start_unix_server server
      end
  @acceptors[s] = [klass,args,block]
  s
end

.start_tcp_server(host, port) ⇒ Object

#start_tcp_server



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

def self.start_tcp_server server, port
	@em.startTcpServer server, port
end

.start_tls(sig) ⇒ Object 



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# File 'lib/jeventmachine.rb', line 97

def self.start_tls sig
	@em.startTls sig
end

.start_unix_domain_server(filename, *args, &block) ⇒ Object 



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# File 'lib/eventmachine.rb', line 580

def EventMachine::start_unix_domain_server filename, *args, &block
  start_server filename, *args, &block
end

.start_unix_server(chain) ⇒ Object

#start_unix_server



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# File 'lib/pr_eventmachine.rb', line 110

def self.start_unix_server filename
	# TEMPORARILY unsupported until someone figures out how to do it.
	raise "unsupported on this platform"
end

.stop ⇒ Object

#stop



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

def self.stop
	@em.stop
end

.stop_event_loop ⇒ Object

stop_event_loop may called from within a callback method while EventMachine’s processing loop is running. It causes the processing loop to stop executing, which will cause all open connections and accepting servers to be run down and closed. Callbacks for connection-termination will be called as part of the processing of stop_event_loop. (There currently is no option to panic-stop the loop without closing connections.) When all of this processing is complete, the call to EventMachine::run which started the processing loop will return and program flow will resume from the statement following EventMachine::run call.

Usage example

require 'rubygems'
require 'eventmachine'

module Redmond

  def post_init
    puts "We're sending a dumb HTTP request to the remote peer."
    send_data "GET / HTTP/1.1\r\nHost: www.microsoft.com\r\n\r\n"
  end

  def receive_data data
    puts "We received #{data.length} bytes from the remote peer."
    puts "We're going to stop the event loop now."
    EventMachine::stop_event_loop
  end

  def unbind
    puts "A connection has terminated."
  end

end

puts "We're starting the event loop now."
EventMachine::run {
  EventMachine::connect "www.microsoft.com", 80, Redmond
}
puts "The event loop has stopped."

This program will produce approximately the following output:

We're starting the event loop now.
We're sending a dumb HTTP request to the remote peer.
We received 1440 bytes from the remote peer.
We're going to stop the event loop now.
A connection has terminated.
The event loop has stopped.



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# File 'lib/eventmachine.rb', line 444

def EventMachine::stop_event_loop
  EventMachine::stop
end

.stop_server(signature) ⇒ Object

Stop a TCP server socket that was started with EventMachine#start_server. – Requested by Kirk Haines. TODO, this isn’t OOP enough. We ought somehow to have #start_server return an object that has a close or a stop method on it.



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# File 'lib/eventmachine.rb', line 576

def EventMachine::stop_server signature
 EventMachine::stop_tcp_server signature
end

.stop_tcp_server(sig) ⇒ Object

#stop_tcp_server



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# File 'lib/pr_eventmachine.rb', line 104

def self.stop_tcp_server sig
	@em.stopTcpServer sig
end

.system(cmd, *args, &cb) ⇒ Object

EM::system is a simple wrapper for EM::popen. It is similar to Kernel::system, but requires a single string argument for the command and performs no shell expansion.

The block or proc passed to EM::system is called with two arguments: the output generated by the command, and a Process::Status that contains information about the command’s execution.

EM.run{
  EM.system('ls'){ |output,status| puts output if status.exitstatus == 0 }
}

You can also supply an additional proc to send some data to the process:

EM.run{
  EM.system('sh', proc{ |process|
    process.send_data("echo hello\n")
    process.send_data("exit\n")
  }, proc{ |out,status|
    puts(out)
  })
}

Like EM::popen, EM::system currently does not work on windows.



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# File 'lib/em/processes.rb', line 103

def EventMachine::system cmd, *args, &cb
  cb ||= args.pop if args.last.is_a? Proc
  init = args.pop if args.last.is_a? Proc

  EM.popen(cmd, SystemCmd, cb) do |c|
    init[c] if init
  end
end

.yield(&block) ⇒ Object 



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# File 'lib/em/spawnable.rb', line 78

def EventMachine.yield &block
	return YieldBlockFromSpawnedProcess.new( block, false )
end

.yield_and_notify(&block) ⇒ Object 



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# File 'lib/em/spawnable.rb', line 82

def EventMachine.yield_and_notify &block
	return YieldBlockFromSpawnedProcess.new( block, true )
end