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How to create a LIFO Queue Channel

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2

Currently I am using a Queue Channel in my Integration flow but it uses a FIFO way of extraction. Is there a way to change it to LIFO?

Also, is there a way to remove messages from the Queue based on a property?

I suspect I will need to use a PriorityChannel for switching from FIFO to LIFO but I can't figure out how it would be accomplished.

@Bean
 fun notificationChannel(): MessageChannel 
 return MessageChannels.queue().get()
 

For example, my QueueChannel will be filled with messages containing userId. Since I'm only interested in the latest state of the userId message I want to use LIFO and remove all messages with the same userId as the latest message.

java spring kotlin spring-integration

share|improve this question

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

add a comment
 | 

2

Currently I am using a Queue Channel in my Integration flow but it uses a FIFO way of extraction. Is there a way to change it to LIFO?

Also, is there a way to remove messages from the Queue based on a property?

I suspect I will need to use a PriorityChannel for switching from FIFO to LIFO but I can't figure out how it would be accomplished.

@Bean
 fun notificationChannel(): MessageChannel 
 return MessageChannels.queue().get()
 

For example, my QueueChannel will be filled with messages containing userId. Since I'm only interested in the latest state of the userId message I want to use LIFO and remove all messages with the same userId as the latest message.

java spring kotlin spring-integration

share|improve this question

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

add a comment
 | 

Currently I am using a Queue Channel in my Integration flow but it uses a FIFO way of extraction. Is there a way to change it to LIFO?

Also, is there a way to remove messages from the Queue based on a property?

I suspect I will need to use a PriorityChannel for switching from FIFO to LIFO but I can't figure out how it would be accomplished.

@Bean
 fun notificationChannel(): MessageChannel 
 return MessageChannels.queue().get()
 

For example, my QueueChannel will be filled with messages containing userId. Since I'm only interested in the latest state of the userId message I want to use LIFO and remove all messages with the same userId as the latest message.

java spring kotlin spring-integration

share|improve this question

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

@Bean
 fun notificationChannel(): MessageChannel 
 return MessageChannels.queue().get()
 

share|improve this question

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

share|improve this question

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

asked Mar 28 at 13:23

Radoslav HubenovRadoslav Hubenov

6911 silver badge66 bronze badges

2 Answers
2

active

oldest

votes

1

It sounds like you don't really want LIFO, you just want the latest for a given condition.

But, regardless, Queue is a pretty simple interface; it only has a handful of methods and the QueueChannel only uses poll(), offer() and size().

So it should be simple to create a custom queue, e.g. based on a thread-safe ConcurrentHashMap<String, Message<?>> with the key being your condition.

share|improve this answer

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How would I have to proceed so that the older messages with the same userId in the queue are discarded?
  
  – Radoslav Hubenov
  Mar 28 at 13:49
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If it's based on a Map, new entries with the same key will be replaced and it will only have the last one.
  
  – Gary Russell
  Mar 28 at 13:54
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If you want to retain order for different userIds, you can use a combination of a LinkedHashSet<String> for the userIds and Map<String, Message<?>> for the messages. The LinkedHashSet retains the original order when an element is replaced.
  
  – Gary Russell
  Mar 28 at 14:33
  

  
  
  
  

add a comment
 | 

1

Queue channel takes Queue as a constructor parameter public QueueChannel(Queue<Message<?>> queue) and spring-integration DSL provides public static QueueChannelSpec queue(Queue<Message<?>> queue). So you can use Collections.asLifoQueue(..) as an argument to the above factory method to get the behavior you want.

share|improve this answer

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges

add a comment
 | 

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1

It sounds like you don't really want LIFO, you just want the latest for a given condition.

But, regardless, Queue is a pretty simple interface; it only has a handful of methods and the QueueChannel only uses poll(), offer() and size().

So it should be simple to create a custom queue, e.g. based on a thread-safe ConcurrentHashMap<String, Message<?>> with the key being your condition.

share|improve this answer

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How would I have to proceed so that the older messages with the same userId in the queue are discarded?
  
  – Radoslav Hubenov
  Mar 28 at 13:49
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If it's based on a Map, new entries with the same key will be replaced and it will only have the last one.
  
  – Gary Russell
  Mar 28 at 13:54
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If you want to retain order for different userIds, you can use a combination of a LinkedHashSet<String> for the userIds and Map<String, Message<?>> for the messages. The LinkedHashSet retains the original order when an element is replaced.
  
  – Gary Russell
  Mar 28 at 14:33
  

  
  
  
  

add a comment
 | 

1

It sounds like you don't really want LIFO, you just want the latest for a given condition.

But, regardless, Queue is a pretty simple interface; it only has a handful of methods and the QueueChannel only uses poll(), offer() and size().

So it should be simple to create a custom queue, e.g. based on a thread-safe ConcurrentHashMap<String, Message<?>> with the key being your condition.

share|improve this answer

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  How would I have to proceed so that the older messages with the same userId in the queue are discarded?
  
  – Radoslav Hubenov
  Mar 28 at 13:49
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If it's based on a Map, new entries with the same key will be replaced and it will only have the last one.
  
  – Gary Russell
  Mar 28 at 13:54
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  If you want to retain order for different userIds, you can use a combination of a LinkedHashSet<String> for the userIds and Map<String, Message<?>> for the messages. The LinkedHashSet retains the original order when an element is replaced.
  
  – Gary Russell
  Mar 28 at 14:33
  

  
  
  
  

add a comment
 | 

It sounds like you don't really want LIFO, you just want the latest for a given condition.

But, regardless, Queue is a pretty simple interface; it only has a handful of methods and the QueueChannel only uses poll(), offer() and size().

So it should be simple to create a custom queue, e.g. based on a thread-safe ConcurrentHashMap<String, Message<?>> with the key being your condition.

share|improve this answer

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

share|improve this answer

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

answered Mar 28 at 13:40

Gary RussellGary Russell

94.5k99 gold badges5959 silver badges8686 bronze badges

1

Queue channel takes Queue as a constructor parameter public QueueChannel(Queue<Message<?>> queue) and spring-integration DSL provides public static QueueChannelSpec queue(Queue<Message<?>> queue). So you can use Collections.asLifoQueue(..) as an argument to the above factory method to get the behavior you want.

share|improve this answer

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges

add a comment
 | 

1

Queue channel takes Queue as a constructor parameter public QueueChannel(Queue<Message<?>> queue) and spring-integration DSL provides public static QueueChannelSpec queue(Queue<Message<?>> queue). So you can use Collections.asLifoQueue(..) as an argument to the above factory method to get the behavior you want.

share|improve this answer

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges

add a comment
 | 

Queue channel takes Queue as a constructor parameter public QueueChannel(Queue<Message<?>> queue) and spring-integration DSL provides public static QueueChannelSpec queue(Queue<Message<?>> queue). So you can use Collections.asLifoQueue(..) as an argument to the above factory method to get the behavior you want.

share|improve this answer

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges

share|improve this answer

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges

answered Mar 28 at 13:42

Oleg ZhurakouskyOleg Zhurakousky

2,39088 silver badges1010 bronze badges