AnyEvent :: RabbitMQ问题与封闭渠道

Question

我正在编写一个用于将消息发布到消息队列（RabbitMQ）的主程序。该程序是用Perl 5编写的，并使用AnyEvent::RabbitMQ与RabbitMQ进行通信。

以下最小示例（针对我遇到的问题）将在第二个命令发送失败时通过相同的通道发送错误＆＃34;频道已关闭＆＃34;。

use strictures 2;

use AnyEvent::RabbitMQ;

main();

############################################################################
sub main {
  _log( debug => 'main' );
  my $condvar = AnyEvent->condvar;
  my $ar      = AnyEvent::RabbitMQ->new;
  $ar->load_xml_spec;
  _log( debug => 'Connecting to RabbitMQ...' );
  $ar->connect(
    host            => 'localhost',
    port            => 5672,
    user            => 'guest',
    pass            => 'guest',
    vhost           => '/',
    timeout         => 1,
    tls             => 0,
    on_success      => sub { _on_connect_success( $condvar, $ar, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure', @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return', @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close', @_ ) },
  );
  $condvar->recv;
  $ar->close;
  return;
}

############################################################################
sub _on_connect_success {
  my ( $condvar, $ar, $new_ar ) = @_;
  _log( debug => 'Connected to RabbitMQ.' );
  _open_channel( $condvar, $new_ar );
  return;
}

############################################################################
sub _open_channel {
  my ( $condvar, $ar ) = @_;
  _log( debug => 'Opening RabbitMQ channel...' );
  $ar->open_channel(
    on_success => sub { _on_open_channel_success( $condvar, $ar, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_open_channel_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Opened RabbitMQ channel.' );
  _declare_queue( $condvar, $ar, $channel );
  return;
}

############################################################################
sub _declare_queue {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declaring RabbitMQ queue...' );
  $channel->declare_queue(
    queue       => 'test',
    auto_delete => 1,
    passive     => 0,
    durable     => 0,
    exclusive   => 0,
    no_ack      => 1,
    ticket      => 0,
    on_success =>
      sub { _on_declare_queue_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_declare_queue_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declared RabbitMQ queue.' );
  _bind_queue( $condvar, $ar, $channel );
  return;
}

############################################################################
sub _bind_queue {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binding RabbitMQ queue...' );
  $channel->bind_queue(
    queue       => 'test',
    exchange    => '',
    routing_key => '',
    on_success => sub { _on_bind_queue_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_bind_queue_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binded RabbitMQ queue.' );
  _log( info  => 'Master ready to publish messages.' );
  _publish_message( $condvar, $ar, $channel, 'Hello, world!' );
  return;
}

############################################################################
sub _publish_message {
  my ( $condvar, $ar, $channel, $message ) = @_;
  _log( debug => "Publishing RabbitMQ message ($message)..." );
  $channel->publish(
    queue       => 'test',
    exchange    => '',
    routing_key => '',
    body        => $message,
    header      => {},
    mandatory   => 0,
    immediate   => 0,
    on_success =>
      sub { _on_publish_message_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
    on_ack          => sub { _error( $condvar, $ar, 'ack',          @_ ) },
    on_nack         => sub { _error( $condvar, $ar, 'nack',         @_ ) },
  );
  return;
}

############################################################################
sub _on_publish_message_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => "Published RabbitMQ message." );
  sleep 1;
  _publish_message( $condvar, $ar, $channel, 'Hello, world! Again ' . time );
  return;
}

############################################################################
sub _error {
  my ( $condvar, $ar, $type, @error ) = @_;
  _log( error => sprintf '%s - %s', $type, join ', ', @error );
  $condvar->send( $condvar, $ar, $type, @error );
  return;
}

############################################################################
sub _log {
  my ( $level, $message ) = @_;
  my @time = gmtime time;
  $time[5] += 1900;
  $time[4] += 1;
  my $time = sprintf '%04d-%02d-%02dT%02d:%02d:%02d+00:00', @time[ 5, 4, 3, 2, 1, 0 ];
  my @caller0    = caller(0);
  my @caller1    = caller(1);
  my $subroutine = $caller1[3];
  $subroutine =~ s/^$caller0[0]:://;
  print STDERR "$time [$level] $message at $caller0[1] line $caller0[2] ($subroutine; from $caller1[1] line $caller1[2])\n";
  return;
}

这个程序应该：

• 连接到RabbitMQ
• 打开RabbitMQ频道
• 声明一个simpe队列（名为＆＃34; test＆＃34;）
• 绑定到该队列（名为＆＃34; test＆＃34;）
• 发布消息（＆＃34; Hello，world！＆＃34;）
• 成功发布消息后等待一秒钟并发布另一条消息

此程序（主程序）应该不使用消息。还有其他程序可以完成这项工作。

最小的例子（见上文）将产生以下输出：

2015-08-12T13:02:07+00:00 [debug] main at minimal.pl line 9 (main; from minimal.pl line 5)
2015-08-12T13:02:07+00:00 [debug] Connecting to RabbitMQ... at minimal.pl line 13 (main; from minimal.pl line 5)
2015-08-12T13:02:07+00:00 [debug] Connected to RabbitMQ. at minimal.pl line 36 (_on_connect_success; from minimal.pl line 22)
2015-08-12T13:02:07+00:00 [debug] Opening RabbitMQ channel... at minimal.pl line 44 (_open_channel; from minimal.pl line 37)
2015-08-12T13:02:07+00:00 [debug] Opened RabbitMQ channel. at minimal.pl line 58 (_on_open_channel_success; from minimal.pl line 46)
2015-08-12T13:02:07+00:00 [debug] Declaring RabbitMQ queue... at minimal.pl line 66 (_declare_queue; from minimal.pl line 59)
2015-08-12T13:02:07+00:00 [debug] Declared RabbitMQ queue. at minimal.pl line 88 (_on_declare_queue_success; from minimal.pl line 76)
2015-08-12T13:02:07+00:00 [debug] Binding RabbitMQ queue... at minimal.pl line 96 (_bind_queue; from minimal.pl line 89)
2015-08-12T13:02:07+00:00 [error] failure - Channel closed at minimal.pl line 155 (_error; from minimal.pl line 102)
2015-08-12T13:02:07+00:00 [error] close - Net::AMQP::Frame::Method=HASH(0x38fe1c8) at minimal.pl line 155 (_error; from minimal.pl line 50)

为什么AnyEvent::RabbitMQ或RabbitMQ本身会关闭频道（不是连接或我错过了什么）？

Answer 1

如果您查看RabbitMQ服务器日志，您将看到如下内容：

  

{amqp_error，access_refused，＆＃34;默认交易所不允许进行操作＆＃34;，＆＃39; queue.bind＆＃39;}

显然，它不允许您在默认交换上绑定队列。所以你需要先声明并绑定自己的交换。

sub _declare_exchange {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declaring RabbitMQ exchange...' );
  $channel->declare_exchange(
    exchange        => 'testest',
    type            => 'fanout',
    on_success =>
      sub { _on_declare_exchange_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_declare_exchange_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declared RabbitMQ exchange.' );
  _bind_exchange( $condvar, $ar, $channel );
  return;
}

############################################################################
sub _bind_exchange {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binding RabbitMQ exchange...' );
  $channel->bind_exchange(
    source      => 'testest',
    destination => 'testest',
    routing_key => '',
    on_success => sub { _on_bind_exchange_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

一旦您设置了这些子设备，请告诉您的程序使用此自定义交换。

sub _on_open_channel_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Opened RabbitMQ channel.' );
  $channel->confirm;
  _declare_exchange( $condvar, $ar, $channel );
  return;
}

当您向队列发送消息时，$channel->confirm是必要的，以使RabbitMQ回答确认。如果你不这样做，成功处理程序将永远不会被调用，因为没有成功的响应回来。

然后在您的_bind_queue中，您需要将交换添加到bind_queue()来电。

  $channel->bind_queue(
    queue       => 'test',
    exchange    => 'testest', # <-- here
    routing_key => '',
    # ...
  );

_publish_message通过publish()调用需要完成同样的工作。在那里，您还应该用实际处理确认的内容替换on_ack处理程序。我认为你打算这样做，但有一个复制/粘贴错误 ¹ 。

$channel->publish(
  queue       => 'test',
  exchange    => 'testest', # <-- here
  routing_key => '',
  # ...
  on_ack          => sub { 
  _on_publish_message_success( $condvar, $ar, $channel, @_ );
  },
);

还有一件事是，当您使用AnyEvent时，sleep中的_on_publish_message_success调用不是一个好主意，因为这会停止整个程序。请改用Longest path in unweighted undirected graph。

my $t; 
$t = AE::timer(1,0,sub {
  _publish_message( $condvar, $ar, $channel, 'Hello, world! Again ' . time );
  undef $t;
});

以下是包含所有更改的完整代码。

use strictures 2;

use AnyEvent::RabbitMQ;

main();

############################################################################
sub main {
  _log( debug => 'main' );
  my $condvar = AnyEvent->condvar;
  my $ar      = AnyEvent::RabbitMQ->new;
  $ar->load_xml_spec;
  _log( debug => 'Connecting to RabbitMQ...' );
  $ar->connect(
    host            => 'localhost',
    port            => 5672,
    user            => 'guest',
    pass            => 'guest',
    vhost           => '/guest',
    timeout         => 1,
    tls             => 0,
    on_success      => sub { _on_connect_success( $condvar, $ar, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure', @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return', @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close', @_ ) },
  );
  $condvar->recv;
  $ar->close;
  return;
}

############################################################################
sub _on_connect_success {
  my ( $condvar, $ar, $new_ar ) = @_;
  _log( debug => 'Connected to RabbitMQ.' );
  _open_channel( $condvar, $new_ar );
  return;
}

############################################################################
sub _open_channel {
  my ( $condvar, $ar ) = @_;
  _log( debug => 'Opening RabbitMQ channel...' );
  $ar->open_channel(
    on_success => sub { _on_open_channel_success( $condvar, $ar, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_open_channel_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Opened RabbitMQ channel.' );
  $channel->confirm;
  _declare_exchange( $condvar, $ar, $channel );
  return;
}

############################################################################
sub _declare_exchange {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declaring RabbitMQ exchange...' );
  $channel->declare_exchange(
    exchange        => 'testest',
    type            => 'fanout',
    on_success =>
      sub { _on_declare_exchange_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_declare_exchange_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declared RabbitMQ exchange.' );
  _bind_exchange( $condvar, $ar, $channel );
  return;
}

############################################################################
sub _bind_exchange {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binding RabbitMQ exchange...' );
  $channel->bind_exchange(
    source      => 'testest',
    destination => 'testest',
    routing_key => '',
    on_success => sub { _on_bind_exchange_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_bind_exchange_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binded RabbitMQ exchange.' );
  _declare_queue( $condvar, $ar, $channel );
  return;
}


############################################################################
sub _declare_queue {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declaring RabbitMQ queue...' );
  $channel->declare_queue(
    queue       => 'test',
    auto_delete => 1,
    passive     => 0,
    durable     => 0,
    exclusive   => 0,
    no_ack      => 1,
    ticket      => 0,
    on_success =>
      sub { _on_declare_queue_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_declare_queue_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Declared RabbitMQ queue.' );
  _bind_queue( $condvar, $ar, $channel );
  return;
}

############################################################################
sub _bind_queue {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binding RabbitMQ queue...' );
  $channel->bind_queue(
    queue       => 'test',
    exchange    => 'testest',
    routing_key => '',
    on_success => sub { _on_bind_queue_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
  );
  return;
}

############################################################################
sub _on_bind_queue_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => 'Binded RabbitMQ queue.' );
  _log( info  => 'Master ready to publish messages.' );
  _publish_message( $condvar, $ar, $channel, 'Hello, world!' );
  return;
}

############################################################################
sub _publish_message {
  my ( $condvar, $ar, $channel, $message ) = @_;
  _log( debug => "Publishing RabbitMQ message ($message)..." );
  $channel->publish(
    queue       => 'test',
    exchange    => 'testest',
    routing_key => '',
    body        => $message,
    header      => {},
    mandatory   => 0,
    immediate   => 0,
    on_success =>
      sub { _on_publish_message_success( $condvar, $ar, $channel, @_ ) },
    on_failure      => sub { _error( $condvar, $ar, 'failure',      @_ ) },
    on_read_failure => sub { _error( $condvar, $ar, 'read_failure', @_ ) },
    on_return       => sub { _error( $condvar, $ar, 'return',       @_ ) },
    on_close        => sub { _error( $condvar, $ar, 'close',        @_ ) },
    on_ack          => sub { 
        _on_publish_message_success( $condvar, $ar, $channel, @_ );
#        _error( $condvar, $ar, 'ack',          @_ )    
    },
    on_nack         => sub { _error( $condvar, $ar, 'nack',         @_ ) },
  );
  return;
}

############################################################################
sub _on_publish_message_success {
  my ( $condvar, $ar, $channel ) = @_;
  _log( debug => "Published RabbitMQ message." );
  my $t; $t=AE::timer(1,0,sub {
      _publish_message( $condvar, $ar, $channel, 'Hello, world! Again ' . time );
      undef $t;
  });
  return;
}

############################################################################
sub _error {
  my ( $condvar, $ar, $type, @error ) = @_;
  _log( error => sprintf '%s - %s', $type, join ', ', @error );
  $condvar->send( $condvar, $ar, $type, @error );
  return;
}

############################################################################
sub _log {
  my ( $level, $message ) = @_;
  my @time = gmtime time;
  $time[5] += 1900;
  $time[4] += 1;
  my $time = sprintf '%04d-%02d-%02dT%02d:%02d:%02d+00:00', @time[ 5, 4, 3, 2, 1, 0 ];
  my @caller0    = caller(0);
  my @caller1    = caller(1);
  my $subroutine = $caller1[3];
  $subroutine =~ s/^$caller0[0]:://;
  print STDERR "$time [$level] $message at $caller0[1] line $caller0[2] ($subroutine; from $caller1[1] line $caller1[2])\n";
  return;
}

^{1）在某些地方，您需要为同事购买啤酒：）}