benchmark: refactor buffer benchmarks

Add configuration object createBenchmark object for buffer size &
iteration in buffer-base64-encode & buffer-base64-decode.js.
PR-URL: #10175
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>

Author: troy0820

benchmark/buffers/buffer-base64-decode.js

@@ -2,15 +2,18 @@
 constassert=require('assert');
 constcommon=require('../common.js');
 
-constbench=common.createBenchmark(main,{});
+constbench=common.createBenchmark(main,{
+n: [32],
+});
 
 functionmain(conf){
+constn=+conf.n;
 consts='abcd'.repeat(8<<20);
 s.match(/./);// Flatten string.
 assert.strictEqual(s.length%4,0);
 constb=Buffer.allocUnsafe(s.length/4*3);
 b.write(s,0,s.length,'base64');
 bench.start();
-for(vari=0;i<32;i+=1)b.base64Write(s,0,s.length);
-bench.end(32);
+for(vari=0;i<n;i+=1)b.base64Write(s,0,s.length);
+bench.end(n);
 }

benchmark/buffers/buffer-base64-encode.js

@@ -1,16 +1,20 @@
 'use strict';
 varcommon=require('../common.js');
 
-varbench=common.createBenchmark(main,{});
+constbench=common.createBenchmark(main,{
+len: [64*1024*1024],
+n: [32]
+});
 
 functionmain(conf){
-varN=64*1024*1024;
-varb=Buffer.allocUnsafe(N);
-vars='';
-vari;
+constn=+conf.n;
+constlen=+conf.len;
+constb=Buffer.allocUnsafe(len);
+lets='';
+leti;
 for(i=0;i<256;++i)s+=String.fromCharCode(i);
-for(i=0;i<N;i+=256)b.write(s,i,256,'ascii');
+for(i=0;i<len;i+=256)b.write(s,i,256,'ascii');
 bench.start();
-for(i=0;i<32;++i)b.toString('base64');
-bench.end(64);
+for(i=0;i<n;++i)b.toString('base64');
+bench.end(n);
 }