Halt NPM | npm.io

Halt

Halt is a node addon that makes it possible for the user to stop the execution of a V8 instance without kill the current loop. Timeouts are managed by creating a parallel event loop who's sole objective is to manage the timer. When a program is bottlenecked by the CPU, you may want to kill this event and that is the reason why we throw a nice CPU bound Exception on timeout.

Installation

npm install halt

Compatibility

From node 0.12 - node 9 included iojs 3

Timer

When an engine is busy, a program needs more time to end but consumes the same amount of cpu ticks. In this case we would like to give more time to this program to end his execution while he doesn't consume too many cpu ticks. That's why the timer will be restarted until the maximum amount of cpu ticks is reached or the program ends his execution. This maximum is determined by the value send to halt.start/run() and the cpu ticks per millisecond which is configurable and has 1000 as default value.

Usage

You can either kill the javascript executing thread by

starting a timer on a function with halt.run()
manually calling start, protect and clear on the halt module

var halt = require('halt')
halt.ticksPerMsec = 1010;

function goFetchSomeMilk () { /* ... */; return milk; }

// In this case, max cpu ticks = 1000 * 60 * 10 * 1010;
// If max cpu ticks is reached, stop waiting

// Automatic managing
halt.run(goFetchSomeMilk, 1000 * 60 * 10)
 
// Manually managing
halt.start(1000 * 60 * 10);
halt.protect(goFetchSomeMilk);
halt.clear();

Exception

When execution is forcefully terminated using TerminateExecution(), a catchable exception is generated. In case you have sensible code and you want to recover the exception and catch it, you can use:

var halt = require('halt')

function goFetchSomeMilk () { /* ... */; return milk; }

try{
    halt.start(50);
    try{
        halt.protect(goFetchSomeMilk);
    }
    catch(){
        /* What ever you want */
    }
    halt.clear();
}