Simple performance comparison for copying binary data to array and to buffer

[oleksiyk]

This is not a pull request to be merged, its a performance test for https://github.com/nlf/protobuf.js/issues/11

This is a dead simple performance comparison for copying large binary data:

1. by concatenating buffer with data to array
2. by copying buffer with data to preallocated buffer

On my machine the results are:

$ node perf/test.js
testWithBuffer: 1063.8297872340427 op/s
testWithArray: 19.76284584980237 op/s

Yes, we need to calculate the size of the buffer before copying but that shouldn't change results dramatically.

[oleksiyk]

Added Array.prototype.slice.call(value) as in original code and also slight emulation of calculating varInt byte size for 50 fields. Results are:

$ node perf/test.js
testWithBuffer: 1204.8192771084339 op/s
testWithArray: 8.505571149102662 op/s

[nlf]

See the "performance" branch

I made a first pass at this, not really any noticeable performance increase.

[oleksiyk]

You have to test performance with large data for bytes field to see the real difference. Its huge.

[oleksiyk]

I've updated this pull request to benchmark real encode of bytes field with a 1.7MB image. Its based on master branch so initially it will test original (array based) performance:

$ node perf/test.js
8.97827258035554 op/s

Then merge your "performance" branch and try again:

$ git pull upstream performance
From https://github.com/nlf/protobuf.js
 * branch            performance -> FETCH_HEAD
Merge made by the 'recursive' strategy.
 index.js           | 203 +++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------
 lib/varint.js      |  76 +++++++++++++++-------------
 package.json       |   2 +-
 test/basic.js      | 108 ++++++++++++++++++++++++++++++++-------
 test/conversion.js |   2 +-
 5 files changed, 278 insertions(+), 113 deletions(-)
$ node perf/test.js
1265.8227848101264 op/s

Its 158x times faster!

[nlf]

Closing since we merged performance to master