Module dev_dedup.erl

A device that deduplicates messages in an evaluation stream, returning status skip if the message has already been seen.

Description

This device is typically used to ensure that a message is only executed once, even if assigned multiple times, upon a ~process@1.0 evaluation. It can, however, be used in many other contexts.

This device honors the pass key if it is present in the message. If so, it will only run on the first pass. Additionally, the device supports a subject-key key that allows the caller to specify the key whose ID should be used for deduplication. If the subject-key key is not present, the device will use the body of the request as the subject. If the key is set to request, the device will use the entire request itself as the subject.

This device runs on the first pass of the compute key call if executed in a stack, and not in subsequent passes. Currently the device stores its list of already seen items in memory, but at some point it will likely make sense to drop them in the cache.

Function Index

dedup_test/0*
dedup_with_multipass_test/0*
handle/4*	Forward the keys and set functions to the message device, handle all others with deduplication.
info/1

Function Details

dedup_test/0 *

dedup_test() -> any()

dedup_with_multipass_test/0 *

dedup_with_multipass_test() -> any()

handle/4 *

handle(Key, M1, M2, Opts) -> any()

Forward the keys and set functions to the message device, handle all others with deduplication. This allows the device to be used in any context where a key is called. If the dedup-key

info/1

info(M1) -> any()