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@creationix creationix/cls.js Secret
Last active Dec 22, 2015

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module.exports = require('./multi-cls.js')();
if (!process.addAsyncListener) require('./polyfill.js');
module.exports = function () {
// Mini CLS library that consumes the new hook API
var ctx = Object.create(null);
var stack = [ctx];
process.addAsyncListener(function () {
return ctx;
}, {
before: add,
after: remove
});
return {
get: function (key) { return ctx[key]; },
set: function (key, value) { return ctx[key] = value; },
scope: scope
};
function add(newContext) {
ctx = newContext || Object.create(ctx);
stack.push(ctx);
}
function remove(oldContext) {
while (stack.length > 1) {
if (stack.pop() === oldContext) break;
}
ctx = stack[stack.length - 1];
}
function scope(fn) {
var context = add();
try { fn(); }
finally { remove(context); }
}
};
process.addAsyncListener = addAsyncListener;
var listeners = [];
// Wrap some easy event sources to test things out
setTimeout = wrapFirst(setTimeout);
setImmediate = wrapFirst(setImmediate);
setInterval = wrapFirst(setInterval);
process.nextTick = wrapFirst(process.nextTick);
process.nextTick = wrapFirst(process.nextTick);
var fs = require('fs');
fs.stat = wrapLast(fs.stat);
function addAsyncListener(onAsync, callbackObject) {
listeners.push({
onAsync: onAsync,
callbackObject: callbackObject
});
}
function wrapFirst(fn) {
return function () {
if (typeof arguments[0] === "function") {
arguments[0] = wrapCallback(arguments[0]);
}
return fn.apply(this, arguments);
};
}
function wrapLast(fn) {
return function () {
var index = arguments.length - 1;
if (typeof arguments[index] === "function") {
arguments[index] = wrapCallback(arguments[index]);
}
return fn.apply(this, arguments);
}
}
function wrapCallback(original) {
var list = Array.prototype.slice.call(listeners);
var length = list.length;
var hasAny = false, hasErr = false;
for (var i = 0; i < length; ++i) {
var obj = list[i].callbackObject;
if (obj) {
hasAny = true;
if (obj.error) hasErr = true;
}
}
return hasAny ? hasErr ? catchyWrap(original, list, length)
: normalWrap(original, list, length)
: noWrap(original, list, length);
}
function catchyWrap(original, list, length) {
var data = new Array(length);
for (var i = 0; i < length; ++i) {
var listener = list[i];
data[i] = listener.onAsync();
}
return function () {
var i, obj;
for (var i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.before) obj.before(data[i]);
}
try {
return original.apply(this, arguments);
}
catch (err) {
for (i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.after) obj.after(data[i]);
}
}
finally {
for (i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.after) obj.after(data[i]);
}
for (i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.done) obj.done(data[i]);
}
}
}
}
function normalWrap(original, list, length) {
var data = new Array(length);
for (var i = 0; i < length; ++i) {
var listener = list[i];
data[i] = listener.onAsync();
}
return function () {
var i, obj;
for (var i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.before) obj.before(data[i]);
}
try {
return original.apply(this, arguments);
}
finally {
for (i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.after) obj.after(data[i]);
}
for (i = 0; i < length; ++i) {
obj = list[i].callbackObject;
if (obj && obj.done) obj.done(data[i]);
}
}
}
}
function noWrap(original, list, length) {
for (var i = 0; i < length; ++i) {
list[i].onAsync();
}
return original;
}
var cls = require('./cls.js');
// Mini test that uses the mini CLS library
var fs = require('fs');
var assert = require('assert');
cls.set("value", 0);
console.log("before", cls.get("value"))
cls.scope(function () {
var left = 0;
cls.set("value", 42);
console.log("inside before", cls.get("value"))
setTimeout(after("setTimeout"), 100);
setImmediate(after("setImmediate"), 100);
process.nextTick(after("process.nextTick"));
fs.stat(__filename, after("fs.stat"));
console.log("inside after", cls.get("value"))
process.on('exit', function () {
if (left) throw new Error(left + " callbacks failed to fire");
});
function after(name) {
left++;
return function () {
left--;
console.log("after " + name + " tick", cls.get("value"));
assert.equal(cls.get("value"), 42);
}
}
});
console.log("afterfn", cls.get("value"))
cls.set("value", 1);
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