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lib: freelist: use .pop() for allocation
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Array#pop() is known to be faster than Array#shift().
To be exact, it's O(1) vs. O(n). In this case there's no difference
from which side of the "pool" array the object is retrieved,
so .pop() should be preferred.

PR-URL: #2174
Reviewed-By: mscdex - Brian White <[email protected]>
Reviewed-By: jasnell - James M Snell <[email protected]>
Reviewed-By: ofrobots - Ali Ijaz Sheikh <[email protected]>
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subzey authored and Fishrock123 committed Mar 2, 2016
1 parent 51bc062 commit e3421ac
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Showing 3 changed files with 41 additions and 3 deletions.
38 changes: 38 additions & 0 deletions benchmark/misc/freelist.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
'use strict';

var common = require('../common.js');
var FreeList = require('internal/freelist').FreeList;

var bench = common.createBenchmark(main, {
n: [100000]
});

function main(conf) {
var n = conf.n;
var poolSize = 1000;
var list = new FreeList('test', poolSize, Object);
var i;
var j;
var used = [];

// First, alloc `poolSize` items
for (j = 0; j < poolSize; j++) {
used.push(list.alloc());
}

bench.start();

for (i = 0; i < n; i++){
// Return all the items to the pool
for (j = 0; j < poolSize; j++) {
list.free(used[j]);
}

// Re-alloc from pool
for (j = 0; j < poolSize; j++) {
list.alloc();
}
}

bench.end(n);
}
2 changes: 1 addition & 1 deletion lib/internal/freelist.js
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ exports.FreeList = function(name, max, constructor) {


exports.FreeList.prototype.alloc = function() {
return this.list.length ? this.list.shift() :
return this.list.length ? this.list.pop() :
this.constructor.apply(this, arguments);
};

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4 changes: 2 additions & 2 deletions test/parallel/test-freelist.js
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,6 @@ assert.strictEqual(flist1.free('test4'), false);
assert.strictEqual(flist1.free('test5'), false);

// At this point 'alloc' should just return the stored values
assert.strictEqual(flist1.alloc(), 'test1');
assert.strictEqual(flist1.alloc(), 'test2');
assert.strictEqual(flist1.alloc(), 'test3');
assert.strictEqual(flist1.alloc(), 'test2');
assert.strictEqual(flist1.alloc(), 'test1');

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