make a quick benchmark script

Dominic Tarr 9 years ago
parent 9af95d37bc
commit 76ce046de9

@ -0,0 +1,57 @@
var N = 1e7
var M = 10
benchmark encoding and decoding N random integers.
A number is encoded into a buffer, (the buffer is reused so
that allocation does not affect the benchmark)
to test the effect on performance of invalid records
(i.e. too short, with the Most Significant Byte missing)
every M items, attempt to decode from a shorter slice of the buffer.
This will probably be produce an invalid result. We do not
need to write into that buffer - because it refurs to the same memory as
the full size buffer.
run with INVALID=1 to include N/M invalid decodes.
with no invalid decodes, I get about 2428 decodes/ms
with invalid decodes:
old code that overruns buffer: 1122 decodes/ms
check length & return undefined: 2439 decodecs/ms
check length & return NaN: 2434 d/ms
check length & return -1: 2400 d/ms
conclusion, it doesn't make a significant difference whether
what is returned to show an invalid read,
but if you overrun the buffer the cost is considerable.
recomendation: return undefined
var buffer = new Buffer(8)
var _buffer = buffer.slice(0, 4)
var varint = require('./')
var l = N
var invalid = 0
includeInvalid = !!process.env.INVALID
var start =
while (l--) {
var int = Math.floor(Math.random()*0x01fffffffffffff)
varint.encode(int, buffer, 0)
//console.log(int, varint.decode(buffer, 0))
//every 1000 varints, do one that will be too short,
if(includeInvalid && !(l%M)) {
if(undefined == varint.decode(_buffer, 0))
invalid ++
} else
if(int !== varint.decode(buffer, 0))
throw new Error('decode was incorrect')
console.log('decode&encode/ms, invalidDecodes')
console.log(N/( - start) + ',', invalid)