Moderate

A Node.js module to manage concurrency of I/O intensive tasks.

What is it

This module aims to help Node.js applications untilize their full non blocking potential when dealing with I/O intensive tasks. In applications with a large number of such tasks, management of the callback event handlers queue is required in order to prevent overloading. 'Moderate' helps adding callbacks to the queue at a non blocking pace, but with moderation to prevent overflows.

Install

npp install moderate

Use

See the documented test/example.js.

add

moderate.add({
    mem: /* task member key */,
    ex: /* task estimated expiry time in msecs */
});

add receives a param object with two keys:

1. mem: Task member key which is used to identify the task.
2. ex: an estimate for the maximum time (in msecs) required to perform this task.
   Usefull for cases in which there is some I/O error, and the associated task event handler is never called. Then the task is automatically discarded, eventhough we did not properly inform 'Moderate' of its completion with del.

active

moderate.active(function(NumOfActiveTasks) {
    // decide if to continue with your task
    // based on the current number of active
    // tasks.
});

active receives a callback function as a parameter, and sends it the number of currently active tasks. The callback function then should decide, based upon that number, if to continue with the task.

del

moderate.del(mem);

del signals 'Moderate' that the task member mem is no longer active.