XDeath

XDeathMaxCountProcessor

XDeathMaxCountProcessor is a swarrot processor. Its goal is to execute a callback when x-death max count reached in order to kill poison message.

This is a very different approach than RetryProcessor because there is no software clone message republish. This processor use the native rabbitmq x-death functionnality.

Configuration

Key	Default	Description
x_death_max_count	300	The number of attempts before callback.
x_death_max_count_log_levels_map	[]	Map of classes to a log level when retry. (Warning by default)
x_death_max_count_fail_log_levels_map	[]	Map of classes to a log level when all retries failed. (Warning by default)

How it works

When your processor throw an exception (= failed to process a message), the XDeathMaxCount Processor will catch it and execute the callback if the message header x-death count exceed the x_death_max_count.

Your callback return a boolean or null:

• return true to continue to process messages
• return false to stop the consumer
• return null to throw an exception

Real example

Let's say you want to consume a queue named mail. You would like to have 3 retries if the mail is not sent correctly. Each retry was separate by 30 seconds.

First let's create the delaying exchange+queue

• Create an exchange waiting_30 (type: topic)
• Create an queue waiting_30 (x-dead-letter-exchange: , x-message-ttl: 30000)
• Bind the exchange waiting_30 to the queue waiting_30 with routing_key #

And then create the simple mail workflow.

• Create an exchange mail (type: direct)
• Create an queue queue_mail with (x-dead-letter-exchange: waiting_30, x-dead-letter-routing-key: queue_mail)
• Bind the exchange mail to the queue queue_mail with routing_key queue_mail

You must use the AckProcessor (or nack the message by yourself).

Once this configuration is done, when an exception is thrown, the AckProcessor will nack the message and rabbitmq will append or increase message header x-death count. This x-death header is the message trace when the message was reject or expired by a queue. So the message was reject to exchange waiting_30 and route to queue waiting_30. After 30 seconds the queue expire the message and move it to AMQP default exchange and route directly to queue queue_mail. If your consumer throw exception 3 times then the XDeathMaxCount will execute the configured callback and not rethrow the exception in order to let the Ack processor ack the message to stop retrying it.

XDeathMaxLifetimeProcessor

XDeathMaxLifetimeProcessor is a swarrot processor. Its goal is to execute a callback when x-death time exceed max lifetime in order to kill poison message.

This is a very different approach than RetryProcessor because there is no software clone message republish. This processor use the native rabbitmq x-death functionnality.

Configuration

Key	Default	Description
x_death_max_lifetime	3600	The number seconds before callback.
x_death_max_lifetime_log_levels_map	[]	Map of classes to a log level when retry. (Warning by default)
x_death_max_lifetime_fail_log_levels_map	[]	Map of classes to a log level when all retries failed. (Warning by default)

How it works

When your processor throw an exception (= failed to process a message), the XDeathMaxLifetime Processor will catch it and execute the callback if the message header x-death time exceed the x_death_max_lifetime.

Your callback return a boolean or null:

• return true to continue to process messages
• return false to stop the consumer
• return null to throw an exception

Real example

Let's say you want to consume a queue named mail. You would like to retry during 1 hour if the mail is not sent correctly. Each retry was separate by 30 seconds.

First let's create the delaying exchange+queue

• Create an exchange waiting_30 (type: topic)
• Create an queue waiting_30 (x-dead-letter-exchange: , x-message-ttl: 30000)

And then create the simple mail workflow.

• Create an exchange mail (type: direct)
• Create an queue queue_mail with (x-dead-letter-exchange: waiting_30, x-dead-letter-routing-key: queue_mail)
• Bind the exchange mail to the queue queue_mail with routing_key queue_mail

You must use the AckProcessor (or nack the message by yourself).

Once this configuration is done, when an exception is thrown, the AckProcessor will nack the message and rabbitmq will append x-death time header (with timestamp). This x-death header is the message trace when the message was reject or expired by a queue. So the message was reject to exchange waiting_30 and route to queue waiting_30. After 30 seconds the queue expire the message and move it to AMQP default exchange and route directly to queue queue_mail. After 1 hour if your consumer throw exception then the XDeathMaxLifetime will execute the configured callback and not rethrow the exception in order to let the Ack processor ack the message to stop retrying it.