maildir-queue

A wrapper for the maildir library with a queue-like interface (push and shift).

Also, a simple HTTP/JSON interface.

Install

gem install maildir-queue

Usage

Create a queue in /home/aaron/queue

require 'maildir/queue'
queue = Maildir::Queue.new("/home/aaron/queue")

Push a new message onto the queue.

message = queue.push("Hello World!")

List new messages

queue.list(:new) # => [message]

List messages that are being processed

queue.list(:cur) # => []

Move the first new message to ‘cur’ for processing

message = queue.shift # Returns nil if no new messages
message.data # => 'Hello World!'

queue.list(:new) # => []
queue.list(:cur) # => [message]

Delete a message after it’s processed

message.destroy

queue.list(:cur) # => []

Dealing with stalled messages

An exepected (but rare) behavior is for a client to fail while processing a message. Such messages will stay in ‘cur’ until retried.

Get a list of messages in cur that have not been modified in 5 minutes

messages = queue.stalled_messages(Time.now - 300)

Requeue them

count = queue.requeue_stalled_messages(Time.now - 300)

Clients can update a message’s timestamps to indicate it’s still being processed. Then the retry interval can be shorter than the time it takes to process a message.

message.utime(Time.now, Time.now)

Maildir::WebQueue, the HTTP/JSON interface

maildir-queue includes a simple Sinatra app providing an HTTP/JSON interface to a queue.

Configure it like so:

require 'maildir/web_queue'
app = Maildir::WebQueue
app.path = '/home/aaron/queue'

Push a message

POST /message?data=Hello World!

Shift a message

GET /message

Response:
{"key": "cur/message_id", "data": "Hello world!"}
Or 404 Not Found if no new messages

Delete a message

DELETE /message/key

Update a message’s timestamps

POST /touch/key

Show count of messages in new and cur

GET /status
Response:
{"new": 2, "cur": 10}

Note on Patches/Pull Requests