solzimer / fileq Goto Github PK

Hi, I'm trying to have more that one reader on the same queue and when I start the second reader, it fail:

reader.js code:

const FileQueue = require("fileq");

var queue = FileQueue.from("queue", {"path": __dirname });
var i=0;

setInterval(()=>{
	queue.peek((err,entry)=>{
		console.log(entry);
	});
},100);

Then try to run this code in 2 separated terminals as "node reader.js" ...
The first one run ok, but the second response with the below

Error:

/node_modules/levelup/lib/levelup.js:119
      return callback(new OpenError(err))
                      ^
Error [OpenError]: IO error: lock //queue/LOCK: Resource temporarily unavailable
    at //node_modules/levelup/lib/levelup.js:119:23
    at //node_modules/abstract-leveldown/abstract-leveldown.js:38:14
    at //node_modules/deferred-leveldown/deferred-leveldown.js:31:21
    at //node_modules/abstract-leveldown/abstract-leveldown.js:38:14
Emitted 'error' event on LevelUP instance at:
    at //node_modules/levelup/lib/levelup.js:60:19
    at //node_modules/levelup/lib/levelup.js:119:14
    at //node_modules/abstract-leveldown/abstract-leveldown.js:38:14
    at //node_modules/deferred-leveldown/deferred-leveldown.js:31:21
    at //node_modules/abstract-leveldown/abstract-leveldown.js:38:14

Unless I'm missing something, the path argument to FileQueue.from() has to be a name, and if you want to specify the location for your queue, you need to put it in the second argument, options.

Hi there,

I was looking around for a simple file backed FIFO message queue and found this library.
"peek" usually allows you to look at the head item on the queue without removing it.
"pop" usually is for removing an item from the queue.

I'm actually looking for the "peek" feature where I can process the head item on the queue first without removing it; and then after confirming it has successfully processed; remove it.

One interesting and seemingly useful approach I saw on 'file-queue' was a "Transactional Pop".
The way it worked is you executed "tpop" and were given a "commit" and "rollback" callback functions.
You'd process the message, then call the appropriate callback when it was sorted out what to do.

A feature that would be really nice is a queue flag to indicate that a transaction is currently in progress. I was iterating over several queues in a loop and found that I needed to introduce a queue_lock to prevent from processing multiple items from the queue simultaneously.

Hope that's useful!

Thanks for the library!