如何使用 Perl 的 AnyEvent::RabbitMQ 正确断开与 RabbitMQ 的连接？

Question

我想以正确的方式断开与 RabbitMQ 的连接。通过 reviewing the source code of Perl's AnyEvent::RabbitMQ（我正在使用），我找到了 close 方法，它似乎关闭了所有向 RabbitMQ 打开的通道。

所以我

连接到 RabbitMQ
打开了一个频道
宣布交换
绑定到该交易所
声明了一个队列
绑定到那个队列
在 AnyEvent::RabbitMQ 实例（不是 ::Channel 实例）上执行 close 方法

连接似乎已关闭，但 RabbitMQ 日志显示 "AMQP connection" 是 "connection_closed_abruptly"。

这是该连接的完整 RabbitMQ 日志：

=INFO REPORT==== 14-Jan-2016::10:02:15 ===
accepting AMQP connection <0.10868.0> (127.0.0.1:57764 -> 127.0.0.1:5672)

=WARNING REPORT==== 14-Jan-2016::10:02:16 ===
closing AMQP connection <0.10868.0> (127.0.0.1:57764 -> 127.0.0.1:5672):
connection_closed_abruptly

示例代码如下：

#!/usr/bin/perl
use strictures 1;

use AnyEvent::RabbitMQ;
use Data::Printer;

my ( $rabbitmq, $rabbitmq_channel );

my $condvar = AnyEvent->condvar;

$rabbitmq = AnyEvent::RabbitMQ->new->load_xml_spec()->connect(
  host       => '127.0.0.1',
  port       => 5672,
  user       => 'guest',
  pass       => 'guest',
  vhost      => '/',
  timeout    => 1,
  tls        => 0,
  tune       => { heartbeat => 1 },
  on_success => sub {
    ($rabbitmq) = @_;
    $rabbitmq->open_channel(
      on_success => sub {
        ($rabbitmq_channel) = @_;
        $rabbitmq_channel->confirm;
        $rabbitmq_channel->declare_exchange(
          exchange   => 'test_exchange',
          type       => 'fanout',
          on_success => sub {
            $rabbitmq_channel->bind_exchange(
              source      => 'test_exchange',
              destination => 'test_exchange',
              routing_key => '',
              on_success  => sub {
                $rabbitmq_channel->declare_queue(
                  queue      => 'test_queue',
                  on_success => sub {
                    $rabbitmq_channel->bind_queue(
                      queue       => 'test_queue',
                      exchange    => 'test_exchange',
                      routing_key => '',
                      on_success  => sub {
                        $rabbitmq->close;
                        undef $rabbitmq;
                      },
                      on_failure => sub { $condvar->send( __LINE__, @_ ) },
                    );
                  },
                  on_failure => sub { $condvar->send( __LINE__, @_ ) },
                );
              },
              on_failure => sub { $condvar->send( __LINE__, @_ ) },
            );
          },
          on_failure => sub { $condvar->send( __LINE__, @_ ) },
        );
      },
      on_failure => sub { $condvar->send( __LINE__, @_ ) },
      on_return  => sub { $condvar->send( __LINE__, @_ ) },
      on_close   => sub { $condvar->send( __LINE__, @_ ) },
    );
  },
  on_failure      => sub { $condvar->send( __LINE__, @_ ) },
  on_read_failure => sub { $condvar->send( __LINE__, @_ ) },
  on_return       => sub { $condvar->send( __LINE__, @_ ) },
  on_close        => sub { $condvar->send( __LINE__, @_ ) },
);

my $reason = [ $condvar->recv ];
p $reason;

如何使用 Perl AnyEvent::RabbitMQ 正确断开与 RabbitMQ 的连接？

Answer 1

有参考循环指标。这些可以防止结构被正确破坏。

"my $rabbitmq; $rabbitmq = ..." 大喊引用循环的可能性。
"my $rabbitmq_channel; $rabbitmq_channel = ..." 大喊引用循环的可能性。
$rabbitmq_channel 属于（存储在）$rabbitmq，但它也被 $rabbitmq_channel 的事件处理程序捕获。

标记为 <=== 的更改替换了不可接受的代码。

标记为 <--- 的更改可能是必要的。如果回调中未定义 $rabbitmq_channel，请删除此更改。

use Scalar::Util qw( weaken );

my $done_cv = AnyEvent->condvar;

my $rabbitmq = AnyEvent::RabbitMQ->new->load_xml_spec()->connect(  # <===
  host       => '127.0.0.1',
  port       => 5672,
  user       => 'guest',
  pass       => 'guest',
  vhost      => '/',
  timeout    => 1,
  tls        => 0,
  tune       => { heartbeat => 1 },
  on_success => sub {
    my ($rabbitmq) = @_;  # <===
    $rabbitmq->open_channel(
      on_success => sub {
        my ($rabbitmq_channel) = @_;  # <===
        {  # <---
          my $rabbitmq_channel = weaken($rabbitmq_channel);  # <---
          $rabbitmq_channel->confirm;
          $rabbitmq_channel->declare_exchange(
            exchange   => 'test_exchange',
            type       => 'fanout',
            on_success => sub {
              $rabbitmq_channel->bind_exchange(
                source      => 'test_exchange',
                destination => 'test_exchange',
                routing_key => '',
                on_success  => sub {
                  $rabbitmq_channel->declare_queue(
                    queue      => 'test_queue',
                    on_success => sub {
                      $rabbitmq_channel->bind_queue(
                        queue       => 'test_queue',
                        exchange    => 'test_exchange',
                        routing_key => '',
                        on_success  => sub { $done_cv->send( __LINE__, @_ ) },  # <===
                        on_failure => sub { $done_cv->send( __LINE__, @_ ) },
                      );
                    },
                    on_failure => sub { $done_cv->send( __LINE__, @_ ) },
                  );
                },
                on_failure => sub { $done_cv->send( __LINE__, @_ ) },
              );
            },
            on_failure => sub { $done_cv->send( __LINE__, @_ ) },
          );
        }  # <---
      },
      on_failure => sub { $done_cv->send( __LINE__, @_ ) },
      on_return  => sub { $done_cv->send( __LINE__, @_ ) },
      on_close   => sub { $done_cv->send( __LINE__, @_ ) },
    );
  },
  on_failure      => sub { $done_cv->send( __LINE__, @_ ) },
  on_read_failure => sub { $done_cv->send( __LINE__, @_ ) },
  on_return       => sub { $done_cv->send( __LINE__, @_ ) },
  on_close        => sub { $done_cv->send( __LINE__, @_ ) },
);

my $reason = [ $done_cv->recv ];
p $reason;

希望对您有所帮助。

Answer 2

这个问题是 AnyEvent::RabbitMQ.pm 库本身的错误。我不确定如何修复 sub close 本身，但关键部分是它从不执行在全局解构期间将 Connection::Close 和 Connection::CloseOk 方法发送到 RabbitMQ 服务器的代码。您可以在设置 AMQP 连接后通过执行以下操作来确认。

$rabbitmq->_push_write(Net::AMQP::Protocol::Connection::Close->new());
$rabbitmq->_push_write(Net::AMQP::Protocol::Connection::CloseOk->new());

这有点难，所以我正在研究正确的方法，希望维护者会接受拉取请求。

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