fetchNextMessage: Returns the next unprocessed message from a message queue.

In ralmond/Proc4: Four Process Assessment Database and Dispatcher

Returns the next unprocessed message from a message queue.

Description

Searchers through the messages for the first unprocessed message. Return NULL if none is found.

Usage

fetchNextMessage(queue)
## S4 method for signature 'MessageQueue'
fetchNextMessage(queue)

Arguments

queue

The MessageQueue to search.

Details

The ListQueue message iterates through its internal collection until it finds an unprocessed message, or it runs out of messages. The MongoQueue message searches the collection.

Value

Either an object of class P4Message or NULL if there are no remaining unprocessed messages.

Note

The ListQueue method returns the current message if it has not been processed. Otherwise, it increments to pointer until if either finds an unprocessed messages or runs out of messages.

The MongoQueue method sorts the unprocessed messages by timestamp, and returns the one with the earliest message.

In both cases, markAsProcessed must be called on the processed message to advance the queue.

Author(s)

Russell Almond

See Also

MessageQueue, markAsProcessed, resetProcessedMessages

Examples

  messy <- list(
    P4Message("test","Test 1","Tester","Test Message"),
    P4Message("test","Test 2","Tester","Test Message",processed=TRUE),
    P4Message("test","Test 3","Tester","Test Message"))
  messq <- new("ListQueue","Qtest",messy)
  mess1 <- fetchNextMessage(messq)
  mess1
  fetchNextMessage(messq)
  markAsProcessed(messq,mess1)
  mess2 <- fetchNextMessage(messq)
  mess2
  markAsProcessed(messq,mess2)
  mess3 <- fetchNextMessage(messq)

ralmond/Proc4 documentation built on June 13, 2025, 7:13 a.m.