join-buffers-speed-test.js

(function() {
  const url = require('url');
  const http = require('http');
  const fs = require('fs');

  const DOWNLOAD_URI = process.argv[process.argv.length-1];

  function main() {
    var options = url.parse(DOWNLOAD_URI);
    options.method = 'GET';
    var req = http.request(options, function(res) {
      var buffers = [];
      var length = 0;
      res.on('data', function(chunk) {
        buffers.push(chunk);
        length += chunk.length;
      });
      res.on('end', function() {
        console.log('length: ' + length + ' bytes.');
        test(buffers, length);
      });
    });
    req.end();
  }

  function test(buffers, length) {
    [test1, test2].forEach(function(func) {
      var time = new Date();
      for (var i=10000; i>=0; i--) {
        func(buffers, length);
      }
      console.log(func.name + ': ' + (new Date() - time) + ' msec.');
    });
  }

  function test1(buffers, length) {
    var buffer = buffers.reduce(function(previousBuffer, currentBuffer) {
      var buffer = new Buffer(previousBuffer.length + currentBuffer.length);
      previousBuffer.copy(buffer);
      currentBuffer.copy(buffer, previousBuffer.length);
      return buffer;
    });
  }

  function test2(buffers, length) {
    var buffer = buffers.reduceRight(function(previousBuffer, currentBuffer) {
      length -= currentBuffer.length;
      currentBuffer.copy(previousBuffer, length);
      return previousBuffer;
    }, new Buffer(length));
  }

  if (require.main === module) {
    main();
  }
})();