abbr

deasync

  nodeV = /[0-9]+\.[0-9]+/.exec(process.versions.node)[0],

  nodeVM = /[0-9]+/.exec(process.versions.node)[0];

var args = process.argv.slice(2).filter(function (arg) {

  } else if (arg.substring(0, 13) === '--target_arch') {

  console.error('Unsupported (?) architecture: `' + arch + '`');

var modPath = platform + '-' + arch + '-node-' + nodeV;

      fs.statSync(path.join(__dirname, 'bin', modPath, 'deasync.node'));

      modPath = platform + '-' + arch + '-node-' + nodeVM;

    console.log('`' + modPath + '` exists; testing');

          console.log('Problem with the binary; manual build incoming');

          console.log('stdout=' + stdout);

          console.log('Binary is fine; exiting');

    process.platform === 'win32' ? 'node-gyp.cmd' : 'node-gyp',

          'node-gyp not found! Please upgrade your install of npm! You need at least 1.1.5 (I think) ' +

  var installPath = path.join(__dirname, 'bin', modPath, 'deasync.node');

    fs.mkdirSync(path.join(__dirname, 'bin'));

    fs.mkdirSync(path.join(__dirname, 'bin', modPath));

    console.error('Build succeeded but target not found');

  fs.renameSync(targetPath, installPath);

  console.log('Installed in `' + installPath + '`');

  "description": "Turns async function into sync via JavaScript wrapper of Node event loop",

  "author": "Vladimir Kurchatkin <vladimir.kurchatkin@gmail.com>",

    "Fred Wen <wenfred@gmail.com> (https://github.com/abbr)"

    "url": "https://github.com/abbr/deasync.git"

  "homepage": "https://github.com/abbr/deasync",

[![NPM version](http://img.shields.io/npm/v/deasync.svg)](https://www.npmjs.org/package/deasync)

DeAsync turns async function into sync, implemented with a blocking mechanism by calling Node.js event loop at JavaScript layer. The core of deasync is written in C++.

Suppose you maintain a library that exposes a function <code>getData</code>. Your users call it to get actual data:   

Under the hood data is saved in a file so you implemented <code>getData</code> using Node.js built-in <code>fs.readFileSync</code>. It's obvious both <code>getData</code> and <code>fs.readFileSync</code> are sync functions. One day you were told to switch the underlying data source to a repo such as MongoDB which can only be accessed asynchronously. You were also told for backward compatibility, <code>getData</code> API cannot be changed to return merely a promise or demand a callback parameter. How do you meet both requirements?

You may tempted to use [node-fibers](https://github.com/laverdet/node-fibers) or a module derived from it, but node fibers can only wrap async function call into a sync function inside a fiber. In the case above you cannot assume all  callers are inside fibers. On the other hand, if you start a fiber in `getData` then `getData` itself will still return immediately without waiting for the async call result. For similar reason ES6 generators introduced in Node v0.11 won't work either. 

What really needed is a way to block subsequent JavaScript from running without blocking entire thread by yielding to allow other events in the event loop to be handled. Ideally the blockage is removed as soon as the result of async function is available. A less ideal but often acceptable alternative is a `sleep` function which you can use to implement the blockage like ```while(!done) sleep(100);```. It is less ideal because sleep duration has to be guessed. It is important the `sleep` function not only shouldn't block entire thread, but also shouldn't incur busy wait that pegs the CPU to 100%. 

* Generic wrapper of async function with conventional API signature `function(p1,...pn,function cb(error,result){})`. Returns `result` and throws `error` as exception if not null:

// done is printed last, as supposed, with cp.exec wrapped in deasync; first without.

* For async function with unconventional API, for instance `function asyncFunction(p1,function cb(res){})`, use `loopWhile(predicateFunc)` where `predicateFunc` is a function that returns boolean loop condition

require('deasync').loopWhile(function(){return !done;});

  // returns hello with sleep; undefined without

Except on a few [ platforms + Node version combinations](https://github.com/abbr/deasync-bin) where binary distribution is included, DeAsync uses node-gyp to compile C++ source code so you may need the compilers listed in [node-gyp](https://github.com/TooTallNate/node-gyp). You may also need to [update npm's bundled node-gyp](https://github.com/TooTallNate/node-gyp/wiki/Updating-npm's-bundled-node-gyp).

Unlike other (a)sync js packages that mostly have only syntactic impact, DeAsync also changes code execution sequence. As such, it is intended to solve niche cases like the above one. If all you are facing is syntactic problem such as callback hell, using a less drastic package implemented in pure js is recommended.

Pull requests and issue reporting are welcome. For issues to be considered by maintainer

  2. there must be evidence the issue is related to DeAsync

To that end, the issue should contain platform information, error message relevant to DeAsync, and preferably code snippet. If code snippet is supplied, it must be self-contained, i.e. independent from your runtime environment or other modules not explicitly specified via `require` in the code snippet.

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

		@@ -35,3 +35,3 @@ #!/usr/bin/env node
		mips64el: true,
		loongarch64: true,
		loong64: true,
		}.hasOwnProperty(arch)
		@@ -38,0 +38,0 @@ ) {

		{
		"name": "deasync",
		"version": "0.1.26",
		"version": "0.1.27",
		"description": "Turns async function into sync via JavaScript wrapper of Node event loop",
		@@ -5,0 +5,0 @@ "main": "index.js",

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