hasql-queue
A PostgreSQL backed queue
https://github.com/jfischoff/hasql-queue#readme
| Version on this page: | 1.0.1.1 |
| LTS Haskell 21.25: | 1.2.0.2 |
| Stackage Nightly 2023-06-21: | 1.2.0.2 |
| Latest on Hackage: | 1.2.0.2 |
Maintained by [email protected]
This version can be pinned in stack with:
hasql-queue-1.0.1.1@sha256:44168c7e38e01c856430f90739d4c41ac13855df66300fe095aa8fae7be3dd36,3364Module documentation for 1.0.1.1
- Hasql
Depends on 20 packages(full list with versions):
Used by 1 package in nightly-2020-06-15(full list with versions):
hasql-queue
This module utilizes PostgreSQL to implement a durable queue for efficently processing payloads.
Typically a producer would enqueue a new payload as part of larger database transaction
createAccount userRecord = transaction Serializable Write $ do
createUser userRecord
enqueueNotification "queue_channel" emailEncoder [makeVerificationEmail userRecord]
In another thread or process the consumer would drain the queue.
-- Wait for a single new record and try to send the email 5 times for giving
-- up and marking the payload as failed.
forever $ withDequeue "queue_channel" conn emailDecoder 5 1 $
mapM_ sendEmail
In the example above we used the Session API for enqueuing and the IO for
dequeuing.
The Session API is useful for composing larger transactions and the IO utilizes PostgreSQL notifications to avoid polling.
Installation
stack install hasql-queue