perl/lib/Thrasher/EventLoop.pm

   1 package Thrasher::EventLoop;
   2 use strict;
   3 use warnings;
   4
   5 use Thrasher::Log qw(log debug);
   6
   7 =pod
   8
   9 =head1 NAME
  10
  11 Thrasher::EventLoop - the 'default' event loop for Thrasher Bird
  12
  13 =head1 DESCRIPTION
  14
  15 The trickiest part of Thrasher is that it needs to manage both
  16 connections to the protocols, and talking to the XMPP server
  17 itself. You can't use blocking connections on both.
  18
  19 This both specifies an interface, and a default event loop
  20 based on ignoring the transport entirely, which actually works
  21 if your "transport" is a pure perl module that never has long-
  22 running components.
  23
  24 The Event Loop is created by the main Thrasher routine while it is
  25 configuring all the pieces. Event loops are tied to protocols
  26 pretty intimately, so the Protocol you are using has responsibility
  27 for controlling what event loop you are using, so the Protocol
  28 can freely refer directly to advanced aspects of the
  29
  30 =cut
  31
  32 use Thrasher::Log qw(log);
  33
  34 use base 'Exporter';
  35
  36 our @EXPORT_OK = qw(IN OUT);
  37 our $IN = 1;
  38 our $OUT = 2;
  39
  40 sub new {
  41     my $class = shift;
  42     my $self = {};
  43
  44     $self->{protocol} = shift;
  45     $self->{socket} = shift;
  46     $self->{component} = shift;
  47
  48     bless $self, $class;
  49     return $self;
  50 }
  51
  52 sub go {
  53     my $self = shift;
  54
  55     # This test event loop just assumes the protocol is a
  56     # 'test' protocol and can be ignored, so despite the documentation
  57     # in this case we DO have exactly one socket to read, preventing
  58     # the need for fancy processing.
  59     while (defined(my $val = $self->{socket}->read)) {
  60         debug("IN: $val");
  61         $self->{component}->xml_in($val);
  62     }
  63
  64     $self->{socket}->close;
  65 }
  66
  67 # Returns some token that can be passed to 'cancel_schedule'
  68 # Timeout is in milliseconds
  69 # If the closure returns a true value, it should be rescheduled
  70 # again in the given timeout, otherwise it should stop.
  71 sub schedule {
  72     my $self = shift;
  73     my $closure = shift;
  74     my $timeout = shift;
  75
  76     log("Thrasher::EventLoop laughs in the face of your attempt to "
  77         ."schedule an event!");
  78     local $@;
  79     eval { $closure->(); };
  80     log("Error in scheduled callback: $@") if $@;
  81 }
  82
  83 # fd must be an actual file descriptor
  84 # Directions is a bit mask of $IN and $OUT
  85 # Return true to continue the watch, false to cancel it.
  86 sub add_fd_watch {
  87     my $self = shift;
  88     my $fd = shift;
  89     my $directions = shift;
  90     my $closure = shift;
  91
  92     die "Thrasher::EventLoop laughs in the face of your attempt "
  93         ."to watch a file descriptor! You need a real event loop.";
  94 }
  95
  96 sub remove_fd_watch {
  97     my $self = shift;
  98     my $opaque_token = shift;
  99
 100     die "Thrasher::EventLoop laughs in the face of your attempt "
 101         ."to cancel a file descriptor watch! Hey, you shouldn't "
 102         ."even be able to get here...";
 103 }
 104
 105 # Idle handler means "do a task after all other stuff in this
 106 # event loop run is done". The only thing Thrasher uses this for
 107 # is to properly shut the system down after a SIGINT or something.
 108 # Simpler event loops can implement this as simply immediately
 109 # executing the passed-in closure, but many event loops will become
 110 # offended if you do that.
 111 sub execute_on_idle {
 112     my $self = shift;
 113     my $closure = shift;
 114
 115     die "Thrasher::EventLoop laughs in the face of your attempt to "
 116         ."schedule something for idle execution!";
 117 }
 118
 119 # This should quit your event loop, preferably more politely than
 120 # with "exit()", since we may want to do more stuff later.
 121 sub quit {
 122     my $self = shift;
 123
 124     die "Thrasher::EventLoop laughs in the face of your quit!";
 125 }
 126
 127 1;