Class: Bunny::Channel

Inherits:
Object
  • Object
show all
Defined in:
lib/bunny/channel.rb

Overview

Channels in RabbitMQ

To quote AMQP 0.9.1 specification:

AMQP 0.9.1 is a multi-channelled protocol. Channels provide a way to multiplex a heavyweight TCP/IP connection into several light weight connections. This makes the protocol more “firewall friendly” since port usage is predictable. It also means that traffic shaping and other network QoS features can be easily employed. Channels are independent of each other and can perform different functions simultaneously with other channels, the available bandwidth being shared between the concurrent activities.

Opening Channels

Channels can be opened either via Bunny::Session#create_channel (sufficient in the majority of cases) or by instantiating Bunny::Channel directly:

This will automatically allocate a channel id.

Closing Channels

Channels are closed via #close. Channels that get a channel-level exception are closed, too. Closed channels can no longer be used. Attempts to use them will raise ChannelAlreadyClosed.

Higher-level API

Bunny offers two sets of methods on Channel: known as higher-level and lower-level APIs, respectively. Higher-level API mimics amqp gem API where exchanges and queues are objects (instance of Exchange and Queue, respectively). Lower-level API is built around AMQP 0.9.1 methods (commands), where queues and exchanges are passed as strings (à la RabbitMQ Java client, Langohr and Pika).

Queue Operations In Higher-level API

  • #queue is used to declare queues. The rest of the API is in Queue.

Exchange Operations In Higher-level API

Channel Qos (Prefetch Level)

It is possible to control how many messages at most a consumer will be given (before it acknowledges or rejects previously consumed ones). This setting is per channel and controlled via #prefetch.

Channel IDs

Channels are identified by their ids which are integers. Bunny takes care of allocating and releasing them as channels are opened and closed. It is almost never necessary to specify channel ids explicitly.

There is a limit on the maximum number of channels per connection, usually 65536. Note that allocating channels is very cheap on both client and server so having tens, hundreds or even thousands of channels is not a problem.

Channels and Error Handling

Channel-level exceptions are more common than connection-level ones and often indicate issues applications can recover from (such as consuming from or trying to delete a queue that does not exist).

With Bunny, channel-level exceptions are raised as Ruby exceptions, for example, NotFound, that provide access to the underlying channel.close method information.

Examples:

conn = Bunny.new
conn.start

ch   = conn.create_channel

ch  = conn.create_channel
ch.close

Handling 404 NOT_FOUND

begin
  ch.queue_delete("queue_that_should_not_exist#{rand}")
rescue Bunny::NotFound => e
  puts "Channel-level exception! Code: #{e.channel_close.reply_code}, message: #{e.channel_close.reply_text}"
end

Handling 406 PRECONDITION_FAILED

begin
  ch2 = conn.create_channel
  q   = "bunny.examples.recovery.q#{rand}"

  ch2.queue_declare(q, :durable => false)
  ch2.queue_declare(q, :durable => true)
rescue Bunny::PreconditionFailed => e
  puts "Channel-level exception! Code: #{e.channel_close.reply_code}, message: #{e.channel_close.reply_text}"
ensure
  conn.create_channel.queue_delete(q)
end

See Also:

Constant Summary

DEFAULT_CONTENT_TYPE =
"application/octet-stream".freeze
SHORTSTR_LIMIT =
255

Instance Attribute Summary (collapse)

Backwards compatibility with 0.8.0 (collapse)

Higher-level API for exchange operations (collapse)

Higher-level API for queue operations (collapse)

QoS and Flow Control (collapse)

Message acknowledgements (collapse)

Consumer and Message operations (basic.*) (collapse)

Queue operations (queue.*) (collapse)

Exchange operations (exchange.*) (collapse)

Flow control (channel.*) (collapse)

Transactions (tx.*) (collapse)

Publisher Confirms (confirm.*) (collapse)

Misc (collapse)

Network Failure Recovery (collapse)

Instance Method Summary (collapse)

Constructor Details

- (Channel) initialize(connection = nil, id = nil, work_pool = ConsumerWorkPool.new(1))



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# File 'lib/bunny/channel.rb', line 169

def initialize(connection = nil, id = nil, work_pool = ConsumerWorkPool.new(1))
  @connection = connection
  @logger     = connection.logger
  @id         = id || @connection.next_channel_id
  @status     = :opening

  @connection.register_channel(self)

  @queues     = Hash.new
  @exchanges  = Hash.new
  @consumers  = Hash.new
  @work_pool  = work_pool

  # synchronizes frameset delivery. MK.
  @publishing_mutex = @connection.mutex_impl.new
  @consumer_mutex   = @connection.mutex_impl.new

  @unconfirmed_set_mutex = @connection.mutex_impl.new

  self.reset_continuations

  # threads awaiting on continuations. Used to unblock
  # them when network connection goes down so that busy loops
  # that perform synchronous operations can work. MK.
  @threads_waiting_on_continuations           = Set.new
  @threads_waiting_on_confirms_continuations  = Set.new
  @threads_waiting_on_basic_get_continuations = Set.new

  @next_publish_seq_no = 0
  @delivery_tag_offset = 0

  @recoveries_counter = Bunny::Concurrent::AtomicFixnum.new(0)
  @uncaught_exception_handler = Proc.new do |e, consumer|
    @logger.error "Uncaught exception from consumer #{consumer.to_s}: #{e.message}"
  end
end

Instance Attribute Details

- (Bunny::Session) connection (readonly)



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# File 'lib/bunny/channel.rb', line 142

def connection
  @connection
end

- (Hash<String, Bunny::Consumer>) consumers (readonly)



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# File 'lib/bunny/channel.rb', line 158

def consumers
  @consumers
end

- (Hash<String, Bunny::Exchange>) exchanges (readonly)



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# File 'lib/bunny/channel.rb', line 152

def exchanges
  @exchanges
end

- (Integer) id



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# File 'lib/bunny/channel.rb', line 140

def id
  @id
end

- (Set<Integer>) nacked_set (readonly)



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# File 'lib/bunny/channel.rb', line 156

def nacked_set
  @nacked_set
end

- (Integer) next_publish_seq_no (readonly)



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# File 'lib/bunny/channel.rb', line 148

def next_publish_seq_no
  @next_publish_seq_no
end

- (Integer) prefetch_count (readonly)



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# File 'lib/bunny/channel.rb', line 161

def prefetch_count
  @prefetch_count
end

- (Hash<String, Bunny::Queue>) queues (readonly)



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# File 'lib/bunny/channel.rb', line 150

def queues
  @queues
end

- (Object) recoveries_counter (readonly)

Returns the value of attribute recoveries_counter



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# File 'lib/bunny/channel.rb', line 206

def recoveries_counter
  @recoveries_counter
end

- (Symbol) status (readonly)



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# File 'lib/bunny/channel.rb', line 144

def status
  @status
end

- (Set<Integer>) unconfirmed_set (readonly)



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# File 'lib/bunny/channel.rb', line 154

def unconfirmed_set
  @unconfirmed_set
end

- (Bunny::ConsumerWorkPool) work_pool (readonly)



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# File 'lib/bunny/channel.rb', line 146

def work_pool
  @work_pool
end

Instance Method Details

- (Object) ack(delivery_tag, multiple = false) Also known as: acknowledge

Acknowledges a message. Acknowledged messages are completely removed from the queue.



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# File 'lib/bunny/channel.rb', line 467

def ack(delivery_tag, multiple = false)
  guarding_against_stale_delivery_tags(delivery_tag) do
    basic_ack(delivery_tag.to_i, multiple)
  end
end

- (Boolean) active



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# File 'lib/bunny/channel.rb', line 262

def active
  open?
end

- (Boolean) any_consumers?

Returns true if there are consumers on this channel



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# File 'lib/bunny/channel.rb', line 936

def any_consumers?
  @consumer_mutex.synchronize { @consumers.any? }
end

- (NilClass) basic_ack(delivery_tag, multiple)

Acknowledges a delivery (message).

Examples:

Ack a message

conn  = Bunny.new
conn.start

ch    = conn.create_channel
q.subscribe do |delivery_info, properties, payload|
  # requeue the message
  ch.basic_ack(delivery_info.delivery_tag)
end

Ack a message fetched via basic.get

conn  = Bunny.new
conn.start

ch    = conn.create_channel
# we assume the queue exists and has messages
delivery_info, properties, payload = ch.basic_get("bunny.examples.queue3", :ack => true)
ch.basic_ack(delivery_info.delivery_tag)

Ack multiple messages fetched via basic.get

conn  = Bunny.new
conn.start

ch    = conn.create_channel
# we assume the queue exists and has messages
_, _, payload1 = ch.basic_get("bunny.examples.queue3", :ack => true)
_, _, payload2 = ch.basic_get("bunny.examples.queue3", :ack => true)
delivery_info, properties, payload3 = ch.basic_get("bunny.examples.queue3", :ack => true)
# ack all fetched messages up to payload3
ch.basic_ack(delivery_info.delivery_tag, true)

See Also:



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# File 'lib/bunny/channel.rb', line 731

def basic_ack(delivery_tag, multiple)
  raise_if_no_longer_open!
  @connection.send_frame(AMQ::Protocol::Basic::Ack.encode(@id, delivery_tag, multiple))

  nil
end

- (AMQ::Protocol::Basic::CancelOk) basic_cancel(consumer_tag)

Removes a consumer. Messages for this consumer will no longer be delivered. If the queue it was on is auto-deleted and this consumer was the last one, the queue will be deleted.



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# File 'lib/bunny/channel.rb', line 922

def basic_cancel(consumer_tag)
  @connection.send_frame(AMQ::Protocol::Basic::Cancel.encode(@id, consumer_tag, false))

  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_basic_cancel_ok = wait_on_continuations
  end

  maybe_kill_consumer_work_pool! unless any_consumers?

  @last_basic_cancel_ok
end

- (AMQ::Protocol::Basic::ConsumeOk) basic_consume(queue, consumer_tag = generate_consumer_tag, no_ack = false, exclusive = false, arguments = nil, &block) Also known as: consume

Registers a consumer for queue. Delivered messages will be handled with the block provided to this method.



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# File 'lib/bunny/channel.rb', line 814

def basic_consume(queue, consumer_tag = generate_consumer_tag, no_ack = false, exclusive = false, arguments = nil, &block)
  raise_if_no_longer_open!
  maybe_start_consumer_work_pool!

  queue_name = if queue.respond_to?(:name)
                 queue.name
               else
                 queue
               end

  # helps avoid race condition between basic.consume-ok and basic.deliver if there are messages
  # in the queue already. MK.
  if consumer_tag && consumer_tag.strip != AMQ::Protocol::EMPTY_STRING
    add_consumer(queue_name, consumer_tag, no_ack, exclusive, arguments, &block)
  end

  @connection.send_frame(AMQ::Protocol::Basic::Consume.encode(@id,
      queue_name,
      consumer_tag,
      false,
      no_ack,
      exclusive,
      false,
      arguments))

  begin
    Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
      @last_basic_consume_ok = wait_on_continuations
    end
  rescue Exception => e
    # if basic.consume-ok never arrives, unregister the proactively
    # registered consumer. MK.
    unregister_consumer(@last_basic_consume_ok.consumer_tag)

    raise e
  end

  # in case there is another exclusive consumer and we get a channel.close
  # response here. MK.
  raise_if_channel_close!(@last_basic_consume_ok)

  # covers server-generated consumer tags
  add_consumer(queue_name, @last_basic_consume_ok.consumer_tag, no_ack, exclusive, arguments, &block)

  @last_basic_consume_ok
end

- (AMQ::Protocol::Basic::ConsumeOk) basic_consume_with(consumer) Also known as: consume_with

Registers a consumer for queue as Bunny::Consumer instance.



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# File 'lib/bunny/channel.rb', line 870

def basic_consume_with(consumer)
  raise_if_no_longer_open!
  maybe_start_consumer_work_pool!

  # helps avoid race condition between basic.consume-ok and basic.deliver if there are messages
  # in the queue already. MK.
  if consumer.consumer_tag && consumer.consumer_tag.strip != AMQ::Protocol::EMPTY_STRING
    register_consumer(consumer.consumer_tag, consumer)
  end

  @connection.send_frame(AMQ::Protocol::Basic::Consume.encode(@id,
      consumer.queue_name,
      consumer.consumer_tag,
      false,
      consumer.no_ack,
      consumer.exclusive,
      false,
      consumer.arguments))

  begin
    Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
      @last_basic_consume_ok = wait_on_continuations
    end
  rescue Exception => e
    # if basic.consume-ok never arrives, unregister the proactively
    # registered consumer. MK.
    unregister_consumer(@last_basic_consume_ok.consumer_tag)

    raise e
  end

  # in case there is another exclusive consumer and we get a channel.close
  # response here. MK.
  raise_if_channel_close!(@last_basic_consume_ok)

  # covers server-generated consumer tags
  register_consumer(@last_basic_consume_ok.consumer_tag, consumer)

  raise_if_continuation_resulted_in_a_channel_error!

  @last_basic_consume_ok
end

- (Array) basic_get(queue, opts = {:ack => true})

Synchronously fetches a message from the queue, if there are any. This method is for cases when the convenience of synchronous operations is more important than throughput.

Examples:

Using Bunny::Channel#basic_get with manual acknowledgements

conn = Bunny.new
conn.start
ch   = conn.create_channel
# here we assume the queue already exists and has messages
delivery_info, properties, payload = ch.basic_get("bunny.examples.queue1", :ack => true)
ch.acknowledge(delivery_info.delivery_tag)

Options Hash (opts):

  • :ack (Boolean) — default: true

    Will this message be acknowledged manually?

See Also:



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# File 'lib/bunny/channel.rb', line 583

def basic_get(queue, opts = {:ack => true})
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Basic::Get.encode(@id, queue, !(opts[:ack])))
  # this is a workaround for the edge case when basic_get is called in a tight loop
  # and network goes down we need to perform recovery. The problem is, basic_get will
  # keep blocking the thread that calls it without clear way to constantly unblock it
  # from the network activity loop (where recovery happens) with the current continuations
  # implementation (and even more correct and convenient ones, such as wait/notify, should
  # we implement them). So we return a triple of nils immediately which apps should be
  # able to handle anyway as "got no message, no need to act". MK.
  @last_basic_get_response = if @connection.open?
                               wait_on_basic_get_continuations
                             else
                               [nil, nil, nil]
                             end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_basic_get_response
end

- (NilClass) basic_nack(delivery_tag, multiple = false, requeue = false)

Rejects or requeues messages just like #basic_reject but can do so with multiple messages at once.

Examples:

Requeue a message

conn  = Bunny.new
conn.start

ch    = conn.create_channel
q.subscribe do |delivery_info, properties, payload|
  # requeue the message
  ch.basic_nack(delivery_info.delivery_tag, false, true)
end

Reject a message

conn  = Bunny.new
conn.start

ch    = conn.create_channel
q.subscribe do |delivery_info, properties, payload|
  # requeue the message
  ch.basic_nack(delivery_info.delivery_tag)
end

Requeue a message fetched via basic.get

conn  = Bunny.new
conn.start

ch    = conn.create_channel
# we assume the queue exists and has messages
delivery_info, properties, payload = ch.basic_get("bunny.examples.queue3", :ack => true)
ch.basic_nack(delivery_info.delivery_tag, false, true)

Requeue multiple messages fetched via basic.get

conn  = Bunny.new
conn.start

ch    = conn.create_channel
# we assume the queue exists and has messages
_, _, payload1 = ch.basic_get("bunny.examples.queue3", :ack => true)
_, _, payload2 = ch.basic_get("bunny.examples.queue3", :ack => true)
delivery_info, properties, payload3 = ch.basic_get("bunny.examples.queue3", :ack => true)
# requeue all fetched messages up to payload3
ch.basic_nack(delivery_info.delivery_tag, true, true)

See Also:



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# File 'lib/bunny/channel.rb', line 791

def basic_nack(delivery_tag, multiple = false, requeue = false)
  raise_if_no_longer_open!
  @connection.send_frame(AMQ::Protocol::Basic::Nack.encode(@id,
      delivery_tag,
      multiple,
      requeue))

  nil
end

- (Bunny::Channel) basic_publish(payload, exchange, routing_key, opts = {})

Publishes a message using basic.publish AMQP 0.9.1 method.

Options Hash (opts):

  • :persistent (Boolean)

    Should the message be persisted to disk?

  • :mandatory (Boolean)

    Should the message be returned if it cannot be routed to any queue?

  • :timestamp (Integer)

    A timestamp associated with this message

  • :expiration (Integer)

    Expiration time after which the message will be deleted

  • :type (String)

    Message type, e.g. what type of event or command this message represents. Can be any string

  • :reply_to (String)

    Queue name other apps should send the response to

  • :content_type (String)

    Message content type (e.g. application/json)

  • :content_encoding (String)

    Message content encoding (e.g. gzip)

  • :correlation_id (String)

    Message correlated to this one, e.g. what request this message is a reply for

  • :priority (Integer)

    Message priority, 0 to 9. Not used by RabbitMQ, only applications

  • :message_id (String)

    Any message identifier

  • :user_id (String)

    Optional user ID. Verified by RabbitMQ against the actual connection username

  • :app_id (String)

    Optional application ID

Raises:

  • (ArgumentError)


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# File 'lib/bunny/channel.rb', line 522

def basic_publish(payload, exchange, routing_key, opts = {})
  raise_if_no_longer_open!
  raise ArgumentError, "routing key cannot be longer than #{SHORTSTR_LIMIT} characters" if routing_key && routing_key.size > SHORTSTR_LIMIT

  exchange_name = if exchange.respond_to?(:name)
                    exchange.name
                  else
                    exchange
                  end

  mode = if opts.fetch(:persistent, true)
           2
         else
           1
         end

  opts[:delivery_mode] ||= mode
  opts[:content_type]  ||= DEFAULT_CONTENT_TYPE
  opts[:priority]      ||= 0

  if @next_publish_seq_no > 0
    @unconfirmed_set_mutex.synchronize do
      @unconfirmed_set.add(@next_publish_seq_no)
      @next_publish_seq_no += 1
    end
  end

  frames = AMQ::Protocol::Basic::Publish.encode(@id,
    payload,
    opts,
    exchange_name,
    routing_key,
    opts[:mandatory],
    false,
    @connection.frame_max)
  @connection.send_frameset_without_timeout(frames, self)

  self
end

- (AMQ::Protocol::Basic::QosOk) basic_qos(count, global = false)

Controls message delivery rate using basic.qos AMQP 0.9.1 method.

Raises:

  • (ArgumentError)

See Also:



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# File 'lib/bunny/channel.rb', line 613

def basic_qos(count, global = false)
  raise ArgumentError.new("prefetch count must be a positive integer, given: #{prefetch_count}") if count < 0
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Basic::Qos.encode(@id, 0, count, global))

  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_basic_qos_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @prefetch_count = count

  @last_basic_qos_ok
end

- (AMQ::Protocol::Basic::RecoverOk) basic_recover(requeue)

Redeliver unacknowledged messages



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# File 'lib/bunny/channel.rb', line 634

def basic_recover(requeue)
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Basic::Recover.encode(@id, requeue))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_basic_recover_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @last_basic_recover_ok
end

- (NilClass) basic_reject(delivery_tag, requeue)

Rejects or requeues a message.

Examples:

Requeue a message

conn  = Bunny.new
conn.start

ch    = conn.create_channel
q.subscribe do |delivery_info, properties, payload|
  # requeue the message
  ch.basic_reject(delivery_info.delivery_tag, true)
end

Reject a message

conn  = Bunny.new
conn.start

ch    = conn.create_channel
q.subscribe do |delivery_info, properties, payload|
  # requeue the message
  ch.basic_reject(delivery_info.delivery_tag, false)
end

Requeue a message fetched via basic.get

conn  = Bunny.new
conn.start

ch    = conn.create_channel
# we assume the queue exists and has messages
delivery_info, properties, payload = ch.basic_get("bunny.examples.queue3", :ack => true)
ch.basic_reject(delivery_info.delivery_tag, true)

See Also:



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# File 'lib/bunny/channel.rb', line 684

def basic_reject(delivery_tag, requeue)
  raise_if_no_longer_open!
  @connection.send_frame(AMQ::Protocol::Basic::Reject.encode(@id, delivery_tag, requeue))

  nil
end

- (AMQ::Protocol::Channel::FlowOk) channel_flow(active)

Note:

Recent (e.g. 2.8.x., 3.x) RabbitMQ will employ TCP/IP-level back pressure on publishers if it detects that consumers do not keep up with them.

Enables or disables message flow for the channel. When message flow is disabled, no new messages will be delivered to consumers on this channel. This is typically used by consumers that cannot keep up with the influx of messages.



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# File 'lib/bunny/channel.rb', line 1266

def channel_flow(active)
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Channel::Flow.encode(@id, active))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_channel_flow_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @last_channel_flow_ok
end

- (Bunny::Session) client



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# File 'lib/bunny/channel.rb', line 267

def client
  @connection
end

- (Object) close

Closes the channel. Closed channels can no longer be used (this includes associated Queue, Exchange and Bunny::Consumer instances.



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# File 'lib/bunny/channel.rb', line 233

def close
  @connection.close_channel(self)
  closed!
  maybe_kill_consumer_work_pool!
end

- (Boolean) closed?

Returns true if this channel is closed (manually or because of an exception), false otherwise



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# File 'lib/bunny/channel.rb', line 247

def closed?
  @status == :closed
end

- (AMQ::Protocol::Confirm::SelectOk) confirm_select(callback = nil)

Enables publisher confirms for the channel.



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# File 'lib/bunny/channel.rb', line 1355

def confirm_select(callback=nil)
  raise_if_no_longer_open!

  if @next_publish_seq_no == 0
    @confirms_continuations = new_continuation
    @unconfirmed_set        = Set.new
    @nacked_set             = Set.new
    @next_publish_seq_no    = 1
    @only_acks_received = true
  end

  @confirms_callback = callback

  @connection.send_frame(AMQ::Protocol::Confirm::Select.encode(@id, false))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_confirm_select_ok = wait_on_continuations
  end
  @confirm_mode = true
  raise_if_continuation_resulted_in_a_channel_error!
  @last_confirm_select_ok
end

- (Object) default_exchange

Provides access to the default exchange



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# File 'lib/bunny/channel.rb', line 360

def default_exchange
  self.direct(AMQ::Protocol::EMPTY_STRING, :no_declare => true)
end

- (Bunny::Exchange) direct(name, opts = {})

Declares a direct exchange or looks it up in the cache of previously declared exchanges.

Options Hash (opts):

  • :durable (Boolean) — default: false

    Should the exchange be durable?

  • :auto_delete (Boolean) — default: false

    Should the exchange be automatically deleted when no longer in use?

  • :arguments (Hash) — default: {}

    Optional exchange arguments (used by RabbitMQ extensions)

See Also:



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# File 'lib/bunny/channel.rb', line 317

def direct(name, opts = {})
  Exchange.new(self, :direct, name, opts)
end

- (Bunny::Exchange) exchange(name, opts = {})

Declares a headers exchange or looks it up in the cache of previously declared exchanges.

Options Hash (opts):

  • :type (String, Symbol) — default: :direct

    Exchange type, e.g. :fanout or "x-consistent-hash"

  • :durable (Boolean) — default: false

    Should the exchange be durable?

  • :auto_delete (Boolean) — default: false

    Should the exchange be automatically deleted when no longer in use?

  • :arguments (Hash) — default: {}

    Optional exchange arguments

See Also:



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# File 'lib/bunny/channel.rb', line 378

def exchange(name, opts = {})
  Exchange.new(self, opts.fetch(:type, :direct), name, opts)
end

- (AMQ::Protocol::Exchange::BindOk) exchange_bind(source, destination, opts = {})

Binds an exchange to another exchange using exchange.bind AMQP 0.9.1 extension that RabbitMQ provides.

Options Hash (opts):

  • routing_key (String) — default: nil

    Routing key used for binding

  • arguments (Hash) — default: {}

    Optional arguments

See Also:



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# File 'lib/bunny/channel.rb', line 1177

def exchange_bind(source, destination, opts = {})
  raise_if_no_longer_open!

  source_name = if source.respond_to?(:name)
                  source.name
                else
                  source
                end

  destination_name = if destination.respond_to?(:name)
                       destination.name
                     else
                       destination
                     end

  @connection.send_frame(AMQ::Protocol::Exchange::Bind.encode(@id,
      destination_name,
      source_name,
      opts[:routing_key],
      false,
      opts[:arguments]))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_exchange_bind_ok = wait_on_continuations
  end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_exchange_bind_ok
end

- (AMQ::Protocol::Exchange::DeclareOk) exchange_declare(name, type, opts = {})

Declares a echange using echange.declare AMQP 0.9.1 method.

Options Hash (opts):

  • durable (Boolean) — default: false

    Should information about this echange be persisted to disk so that it can survive broker restarts? Typically set to true for long-lived exchanges.

  • auto_delete (Boolean) — default: false

    Should this echange be deleted when it is no longer used?

  • passive (Boolean) — default: false

    If true, exchange will be checked for existence. If it does not exist, NotFound will be raised.

See Also:



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# File 'lib/bunny/channel.rb', line 1117

def exchange_declare(name, type, opts = {})
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Exchange::Declare.encode(@id,
      name,
      type.to_s,
      opts.fetch(:passive, false),
      opts.fetch(:durable, false),
      opts.fetch(:auto_delete, false),
      opts.fetch(:internal, false),
      false, # nowait
      opts[:arguments]))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_exchange_declare_ok = wait_on_continuations
  end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_exchange_declare_ok
end

- (AMQ::Protocol::Exchange::DeleteOk) exchange_delete(name, opts = {})

Deletes a exchange using exchange.delete AMQP 0.9.1 method

Options Hash (opts):

  • if_unused (Boolean) — default: false

    Should this exchange be deleted only if it is no longer used

See Also:



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# File 'lib/bunny/channel.rb', line 1147

def exchange_delete(name, opts = {})
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Exchange::Delete.encode(@id,
      name,
      opts[:if_unused],
      false))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_exchange_delete_ok = wait_on_continuations
  end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_exchange_delete_ok
end

- (AMQ::Protocol::Exchange::UnbindOk) exchange_unbind(source, destination, opts = {})

Unbinds an exchange from another exchange using exchange.unbind AMQP 0.9.1 extension that RabbitMQ provides.

Options Hash (opts):

  • routing_key (String) — default: nil

    Routing key used for binding

  • arguments (Hash) — default: {}

    Optional arguments

See Also:



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# File 'lib/bunny/channel.rb', line 1221

def exchange_unbind(source, destination, opts = {})
  raise_if_no_longer_open!

  source_name = if source.respond_to?(:name)
                  source.name
                else
                  source
                end

  destination_name = if destination.respond_to?(:name)
                       destination.name
                     else
                       destination
                     end

  @connection.send_frame(AMQ::Protocol::Exchange::Unbind.encode(@id,
      destination_name,
      source_name,
      opts[:routing_key],
      false,
      opts[:arguments]))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_exchange_unbind_ok = wait_on_continuations
  end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_exchange_unbind_ok
end

- (Bunny::Exchange) fanout(name, opts = {})

Declares a fanout exchange or looks it up in the cache of previously declared exchanges.

Options Hash (opts):

  • :durable (Boolean) — default: false

    Should the exchange be durable?

  • :auto_delete (Boolean) — default: false

    Should the exchange be automatically deleted when no longer in use?

  • :arguments (Hash) — default: {}

    Optional exchange arguments (used by RabbitMQ extensions)

See Also:



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# File 'lib/bunny/channel.rb', line 299

def fanout(name, opts = {})
  Exchange.new(self, :fanout, name, opts)
end

- (Object) flow(active)

Flow control. When set to false, RabbitMQ will stop delivering messages on this channel.



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# File 'lib/bunny/channel.rb', line 428

def flow(active)
  channel_flow(active)
end

- (String) generate_consumer_tag(name = "bunny")

Unique string supposed to be used as a consumer tag.



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# File 'lib/bunny/channel.rb', line 1407

def generate_consumer_tag(name = "bunny")
  "#{name}-#{Time.now.to_i * 1000}-#{Kernel.rand(999_999_999_999)}"
end

- (Bunny::Exchange) headers(name, opts = {})

Declares a headers exchange or looks it up in the cache of previously declared exchanges.

Options Hash (opts):

  • :durable (Boolean) — default: false

    Should the exchange be durable?

  • :auto_delete (Boolean) — default: false

    Should the exchange be automatically deleted when no longer in use?

  • :arguments (Hash) — default: {}

    Optional exchange arguments

See Also:



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# File 'lib/bunny/channel.rb', line 353

def headers(name, opts = {})
  Exchange.new(self, :headers, name, opts)
end

- (Object) nack(delivery_tag, multiple = false, requeue = false)

Rejects a message. A rejected message can be requeued or dropped by RabbitMQ. This method is similar to #reject but supports rejecting multiple messages at once, and is usually preferred.



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# File 'lib/bunny/channel.rb', line 484

def nack(delivery_tag, multiple = false, requeue = false)
  guarding_against_stale_delivery_tags(delivery_tag) do
    basic_nack(delivery_tag.to_i, multiple, requeue)
  end
end

- (Integer) number



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# File 'lib/bunny/channel.rb', line 257

def number
  self.id
end

- (Object) on_error(&block)

Defines a handler for errors that are not responses to a particular operations (e.g. basic.ack, basic.reject, basic.nack).



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# File 'lib/bunny/channel.rb', line 1422

def on_error(&block)
  @on_error = block
end

- (Object) on_uncaught_exception(&block)

Defines a handler for uncaught exceptions in consumers (e.g. delivered message handlers).



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# File 'lib/bunny/channel.rb', line 1430

def on_uncaught_exception(&block)
  @uncaught_exception_handler = block
end

- (Bunny::Channel) open

Opens the channel and resets its internal state



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# File 'lib/bunny/channel.rb', line 216

def open
  @threads_waiting_on_continuations           = Set.new
  @threads_waiting_on_confirms_continuations  = Set.new
  @threads_waiting_on_basic_get_continuations = Set.new

  @connection.open_channel(self)
  # clear last channel error
  @last_channel_error = nil

  @status = :open

  self
end

- (Boolean) open?

Returns true if this channel is open, false otherwise



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# File 'lib/bunny/channel.rb', line 241

def open?
  @status == :open
end

- (Object) prefetch(count)

Sets how many messages will be given to consumers on this channel before they have to acknowledge or reject one of the previously consumed messages



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# File 'lib/bunny/channel.rb', line 419

def prefetch(count)
  self.basic_qos(count, false)
end

- (Bunny::Queue) queue(name = AMQ::Protocol::EMPTY_STRING, opts = {})

Declares a queue or looks it up in the per-channel cache.

Options Hash (opts):

  • :durable (Boolean) — default: false

    Should this queue be durable?

  • :auto-delete (Boolean) — default: false

    Should this queue be automatically deleted when the last consumer disconnects?

  • :exclusive (Boolean) — default: false

    Should this queue be exclusive (only can be used by this connection, removed when the connection is closed)?

  • :arguments (Boolean) — default: {}

    Additional optional arguments (typically used by RabbitMQ extensions and plugins)

See Also:



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# File 'lib/bunny/channel.rb', line 401

def queue(name = AMQ::Protocol::EMPTY_STRING, opts = {})
  q = find_queue(name) || Bunny::Queue.new(self, name, opts)

  register_queue(q)
end

- (AMQ::Protocol::Queue::BindOk) queue_bind(name, exchange, opts = {})

Binds a queue to an exchange using queue.bind AMQP 0.9.1 method

Options Hash (opts):

  • routing_key (String) — default: nil

    Routing key used for binding

  • arguments (Hash) — default: {}

    Optional arguments

See Also:



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# File 'lib/bunny/channel.rb', line 1040

def queue_bind(name, exchange, opts = {})
  raise_if_no_longer_open!

  exchange_name = if exchange.respond_to?(:name)
                    exchange.name
                  else
                    exchange
                  end

  @connection.send_frame(AMQ::Protocol::Queue::Bind.encode(@id,
      name,
      exchange_name,
      (opts[:routing_key] || opts[:key]),
      false,
      opts[:arguments]))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_queue_bind_ok = wait_on_continuations
  end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_queue_bind_ok
end

- (AMQ::Protocol::Queue::DeclareOk) queue_declare(name, opts = {})

Declares a queue using queue.declare AMQP 0.9.1 method.

Options Hash (opts):

  • durable (Boolean) — default: false

    Should information about this queue be persisted to disk so that it can survive broker restarts? Typically set to true for long-lived queues.

  • auto_delete (Boolean) — default: false

    Should this queue be deleted when the last consumer is cancelled?

  • exclusive (Boolean) — default: false

    Should only this connection be able to use this queue? If true, the queue will be automatically deleted when this connection is closed

  • passive (Boolean) — default: false

    If true, queue will be checked for existence. If it does not exist, NotFound will be raised.

See Also:



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# File 'lib/bunny/channel.rb', line 962

def queue_declare(name, opts = {})
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Queue::Declare.encode(@id,
      name,
      opts.fetch(:passive, false),
      opts.fetch(:durable, false),
      opts.fetch(:exclusive, false),
      opts.fetch(:auto_delete, false),
      false,
      opts[:arguments]))
  @last_queue_declare_ok = wait_on_continuations

  raise_if_continuation_resulted_in_a_channel_error!

  @last_queue_declare_ok
end

- (AMQ::Protocol::Queue::DeleteOk) queue_delete(name, opts = {})

Deletes a queue using queue.delete AMQP 0.9.1 method

Options Hash (opts):

  • if_unused (Boolean) — default: false

    Should this queue be deleted only if it has no consumers?

  • if_empty (Boolean) — default: false

    Should this queue be deleted only if it has no messages?

See Also:



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# File 'lib/bunny/channel.rb', line 991

def queue_delete(name, opts = {})
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Queue::Delete.encode(@id,
      name,
      opts[:if_unused],
      opts[:if_empty],
      false))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_queue_delete_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @last_queue_delete_ok
end

- (AMQ::Protocol::Queue::PurgeOk) queue_purge(name, opts = {})

Purges a queue (removes all messages from it) using queue.purge AMQP 0.9.1 method.



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# File 'lib/bunny/channel.rb', line 1014

def queue_purge(name, opts = {})
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Queue::Purge.encode(@id, name, false))

  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_queue_purge_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @last_queue_purge_ok
end

- (AMQ::Protocol::Queue::UnbindOk) queue_unbind(name, exchange, opts = {})

Unbinds a queue from an exchange using queue.unbind AMQP 0.9.1 method

Options Hash (opts):

  • routing_key (String) — default: nil

    Routing key used for binding

  • arguments (Hash) — default: {}

    Optional arguments

See Also:



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# File 'lib/bunny/channel.rb', line 1076

def queue_unbind(name, exchange, opts = {})
  raise_if_no_longer_open!

  exchange_name = if exchange.respond_to?(:name)
                    exchange.name
                  else
                    exchange
                  end

  @connection.send_frame(AMQ::Protocol::Queue::Unbind.encode(@id,
      name,
      exchange_name,
      opts[:routing_key],
      opts[:arguments]))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_queue_unbind_ok = wait_on_continuations
  end

  raise_if_continuation_resulted_in_a_channel_error!
  @last_queue_unbind_ok
end

- (Object) recover(ignored = true)

Tells RabbitMQ to redeliver unacknowledged messages



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# File 'lib/bunny/channel.rb', line 434

def recover(ignored = true)
  # RabbitMQ only supports basic.recover with requeue = true
  basic_recover(true)
end

- (Object) recover_cancelled_consumers!



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# File 'lib/bunny/channel.rb', line 1526

def recover_cancelled_consumers!
  @recover_cancelled_consumers = true
end

- (Object) recover_confirm_mode

Recovers publisher confirms mode. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1470

def recover_confirm_mode
  if using_publisher_confirmations?
    @delivery_tag_offset = @next_publish_seq_no - 1
    confirm_select(@confirms_callback)
  end
end

- (Object) recover_consumers

Recovers consumers. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1510

def recover_consumers
  unless @consumers.empty?
    @work_pool = ConsumerWorkPool.new(@work_pool.size)
    @work_pool.start
  end
  @consumers.values.dup.each do |c|
    c.recover_from_network_failure
  end
end

- (Object) recover_exchanges

Recovers exchanges. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1489

def recover_exchanges
  @exchanges.values.dup.each do |x|
    x.recover_from_network_failure
  end
end

- (Object) recover_from_network_failure

Recovers basic.qos setting, exchanges, queues and consumers. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1444

def recover_from_network_failure
  @logger.debug "Recovering channel #{@id} after network failure"
  release_all_continuations

  recover_prefetch_setting
  recover_confirm_mode
  recover_tx_mode
  recover_exchanges
  # this includes recovering bindings
  recover_queues
  recover_consumers
  increment_recoveries_counter
end

- (Object) recover_prefetch_setting

Recovers basic.qos setting. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1462

def recover_prefetch_setting
  basic_qos(@prefetch_count) if @prefetch_count
end

- (Object) recover_queues

Recovers queues and bindings. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1499

def recover_queues
  @queues.values.dup.each do |q|
    @logger.debug "Recovering queue #{q.name}"
    q.recover_from_network_failure
  end
end

- (Object) recover_tx_mode

Recovers transaction mode. Used by the Automatic Network Failure Recovery feature.



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# File 'lib/bunny/channel.rb', line 1481

def recover_tx_mode
  tx_select if @tx_mode
end

- (Boolean) recovers_cancelled_consumers?



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# File 'lib/bunny/channel.rb', line 1531

def recovers_cancelled_consumers?
  !!@recover_cancelled_consumers
end

- (Object) reject(delivery_tag, requeue = false)

Rejects a message. A rejected message can be requeued or dropped by RabbitMQ.



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# File 'lib/bunny/channel.rb', line 454

def reject(delivery_tag, requeue = false)
  guarding_against_stale_delivery_tags(delivery_tag) do
    basic_reject(delivery_tag.to_i, requeue)
  end
end

- (Object) synchronize(&block)

Synchronizes given block using this channel's mutex.



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# File 'lib/bunny/channel.rb', line 1399

def synchronize(&block)
  @publishing_mutex.synchronize(&block)
end

- (String) to_s



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# File 'lib/bunny/channel.rb', line 1539

def to_s
  "#<#{self.class.name}:#{object_id} @id=#{self.number} @connection=#{@connection.to_s}>"
end

- (Bunny::Exchange) topic(name, opts = {})

Declares a topic exchange or looks it up in the cache of previously declared exchanges.

Options Hash (opts):

  • :durable (Boolean) — default: false

    Should the exchange be durable?

  • :auto_delete (Boolean) — default: false

    Should the exchange be automatically deleted when no longer in use?

  • :arguments (Hash) — default: {}

    Optional exchange arguments (used by RabbitMQ extensions)

See Also:



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# File 'lib/bunny/channel.rb', line 335

def topic(name, opts = {})
  Exchange.new(self, :topic, name, opts)
end

- (AMQ::Protocol::Tx::CommitOk) tx_commit

Commits current transaction



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# File 'lib/bunny/channel.rb', line 1303

def tx_commit
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Tx::Commit.encode(@id))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_tx_commit_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @last_tx_commit_ok
end

- (AMQ::Protocol::Tx::RollbackOk) tx_rollback

Rolls back current transaction



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# File 'lib/bunny/channel.rb', line 1318

def tx_rollback
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Tx::Rollback.encode(@id))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_tx_rollback_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!

  @last_tx_rollback_ok
end

- (AMQ::Protocol::Tx::SelectOk) tx_select

Puts the channel into transaction mode (starts a transaction)



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# File 'lib/bunny/channel.rb', line 1287

def tx_select
  raise_if_no_longer_open!

  @connection.send_frame(AMQ::Protocol::Tx::Select.encode(@id))
  Bunny::Timeout.timeout(read_write_timeout, ClientTimeout) do
    @last_tx_select_ok = wait_on_continuations
  end
  raise_if_continuation_resulted_in_a_channel_error!
  @tx_mode = true

  @last_tx_select_ok
end

- (Boolean) using_publisher_confirmations? Also known as: using_publisher_confirms?

Returns true if this channel has Publisher Confirms enabled, false otherwise



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# File 'lib/bunny/channel.rb', line 1343

def using_publisher_confirmations?
  @next_publish_seq_no > 0
end

- (Boolean) using_tx?



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# File 'lib/bunny/channel.rb', line 1331

def using_tx?
  !!@tx_mode
end

- (Boolean) wait_for_confirms

Blocks calling thread until confirms are received for all currently unacknowledged published messages. Returns immediately if there are no outstanding confirms.



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# File 'lib/bunny/channel.rb', line 1387

def wait_for_confirms
  wait_on_confirms_continuations
  read_and_reset_only_acks_received
end