postgresql-simple-queue: A PostgreSQL backed queue

[ bsd3, library, web ] [ Propose Tags ]

This module utilize PostgreSQL to implement a durable queue for efficently processing arbitrary payloads which can be represented as JSON.

Typically a producer would enqueue a new payload as part of larger database transaction

 createAccount userRecord = do
    'runDBTSerializable' $ do
       createUserDB userRecord
       'enqueueDB' "queue_schema" $ makeVerificationEmail userRecord

In another thread or process, the consumer would drain the queue.

  forever $ do
    -- Attempt get a payload or block until one is available
    payload <- lock "queue" conn

    -- Perform application specifc parsing of the payload value
    case fromJSON $ pValue payload of
      Success x -> sendEmail x -- Perform application specific processing
      Error err -> logErr err

    -- Remove the payload from future processing
    dequeue "queue" conn $ pId payload

To support multiple queues in the same database, the API expects a table name string
to determine which queue tables to use.

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Versions 0.1.0.0, 0.1.0.1, 0.2.0.0, 0.2.1.0, 0.3.0.0, 0.4.0.0, 0.5.0.0, 0.5.0.1, 0.5.1.0, 0.5.1.1, 1.0.0, 1.0.1
Dependencies aeson, base (>=4.7 && <5), bytestring, exceptions, monad-control, pg-transact, postgresql-simple, random, stm, text, time, transformers [details]
License BSD-3-Clause
Copyright 2017 Jonathan Fischoff
Author Jonathan Fischoff
Maintainer jonathangfischoff@gmail.com
Category Web
Home page https://github.com/jfischoff/postgresql-queue#readme
Bug tracker https://github.com/jfischoff/postgresql-queue/issues
Source repo head: git clone https://github.com/jfischoff/postgresql-queue
Uploaded by JonathanFischoff at Thu Dec 21 03:26:39 UTC 2017
Distributions LTSHaskell:1.0.1, NixOS:1.0.1, Stackage:1.0.1
Downloads 2359 total (25 in the last 30 days)
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Status Docs available [build log]
Last success reported on 2017-12-21 [all 1 reports]
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Readme for postgresql-simple-queue-1.0.1

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postgresql-simple-queue

This module utilizes PostgreSQL to implement a durable queue for efficently processing arbitrary payloads which can be represented as JSON.

Typically a producer would enqueue a new payload as part of larger database transaction

createAccount userRecord = do
  runDBTSerializable $ do
    createUserDB userRecord
    enqueueDB $ makeVerificationEmail userRecord

In another thread or process, the consumer would drain the queue.

  forever $ do
    -- Attempt get a payload or block until one is available
    payload <- lock conn

    -- Perform application specifc parsing of the payload value
    case fromJSON $ pValue payload of
      Success x -> sendEmail x -- Perform application specific processing
      Error err -> logErr err

    -- Remove the payload from future processing
    dequeue conn $ pId payload

Installation

stack install postgresql-simple-queue

Blog

This package was discussed in the blog Testing PostgreSQL for Fun