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perf(Scope): change Scope#id to be a simple number

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In apps that create lots of scopes (apps with large tables) the uid generation
shows up in the profiler and adds a few milliseconds. Using simple counter
doesn't have this overhead.

I think the initial fear of overflowing and thus using string alphanum sequence
is unjustified because even if an app was to create lots of scopes non-stop,
you could create about 28.6 million scopes per seconds for 10 years before
you would reach a number that can't be accurately represented in JS

BREAKING CHANGE: Scope#$id is now of time number rather than string. Since the
id is primarily being used for debugging purposes this change should not affect
anyone.
This commit is contained in:
Igor Minar
2014-06-04 06:38:31 -07:00
committed by rodyhaddad
parent 9971fbb3e0
commit 8c6a8171f9
5 changed files with 34 additions and 50 deletions
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34
src/Angular.js
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@@ -167,7 +167,7 @@ var /** holds major version number for IE or NaN for real browsers */
angular = window.angular || (window.angular = {}),
angularModule,
nodeName_,
uid = ['0', '0', '0'];
uid = 0;
/**
* IE 11 changed the format of the UserAgent string.
@@ -285,33 +285,17 @@ function reverseParams(iteratorFn) {
}
/**
* A consistent way of creating unique IDs in angular. The ID is a sequence of alpha numeric
* characters such as '012ABC'. The reason why we are not using simply a number counter is that
* the number string gets longer over time, and it can also overflow, where as the nextId
* will grow much slower, it is a string, and it will never overflow.
* A consistent way of creating unique IDs in angular.
*
* @returns {string} an unique alpha-numeric string
* Using simple numbers allows us to generate 28.6 million unique ids per second for 10 years before
* we hit number precision issues in JavaScript.
*
* Math.pow(2,53) / 60 / 60 / 24 / 365 / 10 = 28.6M
*
* @returns {number} an unique alpha-numeric string
*/
function nextUid() {
var index = uid.length;
var digit;
while(index) {
index--;
digit = uid[index].charCodeAt(0);
if (digit == 57 /*'9'*/) {
uid[index] = 'A';
return uid.join('');
}
if (digit == 90 /*'Z'*/) {
uid[index] = '0';
} else {
uid[index] = String.fromCharCode(digit + 1);
return uid.join('');
}
}
uid.unshift('0');
return uid.join('');
return ++uid;
}