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-rw-r--r--lib/profiler.rb59
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diff --git a/lib/profiler.rb b/lib/profiler.rb
index a4b8889093..0dd02687af 100644
--- a/lib/profiler.rb
+++ b/lib/profiler.rb
@@ -1,3 +1,62 @@
+# Profile provides a way to Profile your Ruby application.
+#
+# Profiling your program is a way of determining which methods are called and
+# how long each method takes to complete. This way you can detect which
+# methods are possible bottlenecks.
+#
+# Profiling your program will slow down your execution time considerably,
+# so activate it only when you need it. Don't confuse benchmarking with
+# profiling.
+#
+# There are two ways to activate Profiling:
+#
+# == Command line
+#
+# Run your Ruby script with <code>-rprofile</code>:
+#
+# ruby -rprofile example.rb
+#
+# If you're profiling an executable in your <code>$PATH</code> you can use
+# <code>ruby -S</code>:
+#
+# ruby -rprofile -S some_executable
+#
+# == From code
+#
+# Just require 'profile':
+#
+# require 'profile'
+#
+# def slow_method
+# 5000.times do
+# 9999999999999999*999999999
+# end
+# end
+#
+# def fast_method
+# 5000.times do
+# 9999999999999999+999999999
+# end
+# end
+#
+# slow_method
+# fast_method
+#
+# The output in both cases is a report when the execution is over:
+#
+# ruby -rprofile example.rb
+#
+# % cumulative self self total
+# time seconds seconds calls ms/call ms/call name
+# 68.42 0.13 0.13 2 65.00 95.00 Integer#times
+# 15.79 0.16 0.03 5000 0.01 0.01 Fixnum#*
+# 15.79 0.19 0.03 5000 0.01 0.01 Fixnum#+
+# 0.00 0.19 0.00 2 0.00 0.00 IO#set_encoding
+# 0.00 0.19 0.00 1 0.00 100.00 Object#slow_method
+# 0.00 0.19 0.00 2 0.00 0.00 Module#method_added
+# 0.00 0.19 0.00 1 0.00 90.00 Object#fast_method
+# 0.00 0.19 0.00 1 0.00 190.00 #toplevel
+
module Profiler__
# internal values
@@start = @@stack = @@map = nil