Add a bench mark script to help measure performance impact of changes

This add a bench mark script that measures running cmds multiple
times and writes the results so we can know how a change impacts
performance.

Gemfile

@@ -4,3 +4,4 @@ gemspec
 
 gem 'rake'
 gem 'pry'
+gem "whysoslow"

bench/results.txt

@@ -0,0 +1,80 @@
+echo hi: 1 times
+----------------
+whysoslow? ..
+
+mem @ start             38 MB                   ??
+mem @ finish            38 MB                   +   0 MB,   0%
+
+         user     system   total    real
+time     0.0 ms   0.0 ms   0.0 ms   62.42 ms
+
+echo hi: 10 times
+-----------------
+whysoslow? ..
+
+mem @ start             38 MB                   ??
+mem @ finish            38 MB                   -   0 MB,   0%
+
+          user      system    total     real
+time      10.0 ms   10.0 ms   40.0 ms   619.93 ms
+
+echo hi: 100 times
+------------------
+whysoslow? ..
+
+mem @ start             38 MB                   ??
+mem @ finish            38 MB                   -   0 MB,   0%
+
+            user        system      total       real
+time        50.0 ms     50.0 ms     330.0 ms    6176.346 ms
+
+echo hi: 1000 times
+-------------------
+whysoslow? ..
+
+mem @ start             38 MB                   ??
+mem @ finish            42 MB                   +   4 MB,  10%
+
+             user         system       total        real
+time         500.0 ms     540.0 ms     3280.0 ms    61703.161 ms
+
+cat test/support/bigger-than-64k.txt: 1 times
+---------------------------------------------
+whysoslow? ..
+
+mem @ start             42 MB                   ??
+mem @ finish            42 MB                   -   0 MB,   0%
+
+          user      system    total     real
+time      0.0 ms    0.0 ms    0.0 ms    62.127 ms
+
+cat test/support/bigger-than-64k.txt: 10 times
+----------------------------------------------
+whysoslow? ..
+
+mem @ start             42 MB                   ??
+mem @ finish            44 MB                   +   2 MB,   6%
+
+           user       system     total      real
+time       10.0 ms    10.0 ms    50.0 ms    620.075 ms
+
+cat test/support/bigger-than-64k.txt: 100 times
+-----------------------------------------------
+whysoslow? ..
+
+mem @ start             44 MB                   ??
+mem @ finish            93 MB                   +  49 MB, 110%
+
+            user        system      total       real
+time        80.0 ms     100.0 ms    520.0 ms    6185.163 ms
+
+cat test/support/bigger-than-64k.txt: 1000 times
+------------------------------------------------
+whysoslow? ..
+
+mem @ start             93 MB                   ??
+mem @ finish            585 MB                  + 492 MB, 527%
+
+             user         system       total        real
+time         770.0 ms     900.0 ms     5290.0 ms    61803.114 ms
+

bench/runner.rb

@@ -0,0 +1,29 @@
+require 'whysoslow'
+require 'scmd'
+
+class ScmdBenchRunner
+
+  attr_reader :result
+
+  def self.run(*args)
+    self.new(*args).run
+  end
+
+  def initialize(printer_io, cmd, num_times = 10)
+    @cmd = cmd
+    @proc = proc do
+      num_times.times{ cmd.run! }
+    end
+
+    @printer = Whysoslow::DefaultPrinter.new(printer_io, {
+      :title => "#{@cmd.cmd_str}: #{num_times} times",
+      :verbose => true
+    })
+    @runner = Whysoslow::Runner.new(@printer)
+  end
+
+  def run
+    @runner.run &@proc
+  end
+
+end

script/bench.rb

@@ -0,0 +1,47 @@
+# $ bundle exec ruby script/bench.rb
+
+require 'bench/runner'
+
+class ScmdBenchLogger
+
+  def initialize(file_path)
+    @file = File.open(file_path, 'w')
+    @ios = [@file, $stdout]
+    yield self
+    @file.close
+  end
+
+  def method_missing(meth, *args, &block)
+    @ios.each do |io|
+      io.respond_to?(meth.to_s) ? io.send(meth.to_s, *args, &block) : super
+    end
+  end
+
+  def respond_to?(*args)
+    @ios.first.respond_to?(args.first.to_s) ? true : super
+  end
+
+end
+
+def run_cmd(logger, *args)
+  GC.disable
+
+  ScmdBenchRunner.run(logger, *args)
+  logger.puts
+
+  GC.enable
+  GC.start
+end
+
+ScmdBenchLogger.new('bench/results.txt') do |logger|
+  run_cmd(logger, Scmd.new("echo hi"), 1)
+  run_cmd(logger, Scmd.new("echo hi"), 10)
+  run_cmd(logger, Scmd.new("echo hi"), 100)
+  run_cmd(logger, Scmd.new("echo hi"), 1000)
+
+  run_cmd(logger, Scmd.new("cat test/support/bigger-than-64k.txt"), 1)
+  run_cmd(logger, Scmd.new("cat test/support/bigger-than-64k.txt"), 10)
+  run_cmd(logger, Scmd.new("cat test/support/bigger-than-64k.txt"), 100)
+  run_cmd(logger, Scmd.new("cat test/support/bigger-than-64k.txt"), 1000)
+end
+