GLOBAL_MONOTONIC_CLOCK is now defined on all platforms.

Author: jdantonio

lib/concurrent/utility/monotonic_time.rb

@@ -1,43 +1,133 @@
 module Concurrent
 
-  if defined?(Process::CLOCK_MONOTONIC)
-    def monotonic_time
-      Process.clock_gettime(Process::CLOCK_MONOTONIC)
-    end
-  elsif RUBY_PLATFORM == 'java'
-    def monotonic_time
-      java.lang.System.nanoTime() / 1_000_000_000.0
-    end
-  else
+  GLOBAL_MONOTONIC_CLOCK = Class.new {
+
+    if defined?(Process::CLOCK_MONOTONIC)
+      def get_time(other = 0.0)
+        Process.clock_gettime(Process::CLOCK_MONOTONIC) - other.to_f
+      end
+    elsif RUBY_PLATFORM == 'java'
+      def get_time(other = 0.0)
+        (java.lang.System.nanoTime() / 1_000_000_000.0) - other.to_f
+      end
+    else
 
-    require 'thread'
+      require 'thread'
 
-    # @!visibility private
-    GLOBAL_MONOTONIC_CLOCK = Class.new {
+      # @!visibility private
       def initialize
         @mutex = Mutex.new
         @correction = 0
         @last_time = Time.now.to_f
       end
-      def get_time
-        @mutex.synchronize do
+
+      def get_time(other = 0.0)
+        @mutex.synchronize {
           @correction ||= 0 # compensating any back time shifts
           now = Time.now.to_f
           corrected_now = now + @correction
           if @last_time < corrected_now
-            return @last_time = corrected_now 
+            @last_time = corrected_now 
           else
             @correction += @last_time - corrected_now + 0.000_001
-            return @last_time = @correction + now
+            @last_time = @correction + now
           end
-        end
+        } - other.to_f
       end
-    }.new
+    end
+  }.new
+
+  def monotonic_time(other = 0.0)
+    GLOBAL_MONOTONIC_CLOCK.get_time(other)
+  end
+  module_function :monotonic_time
+end
+
+__END__
+
+#!/usr/bin/env ruby
+
+# $ ./time_test.rb
+# Native: 1735.94062338, Ruby: 1425391307.2322402
+#        user     system      total        real
+# Native time...
+#    0.310000   0.000000   0.310000 (  0.306102)
+# Ruby time...
+#    1.750000   0.000000   1.750000 (  1.757991)
+# Native interval...
+#    0.360000   0.010000   0.370000 (  0.358779)
+# Ruby interval...
+#    1.850000   0.000000   1.850000 (  1.857620)
+# Native: 1740.221591108, Ruby: 1425391312.2985182
+
+$: << File.expand_path('./lib', __FILE__)
+
+require 'benchmark'
+require 'thread'
+
+class MonotonicClock
+  def initialize
+    @mutex = Mutex.new
+    @correction = 0
+    @last_time = Time.now.to_f
+  end
+
+  def get_time_native
+    Process.clock_gettime(Process::CLOCK_MONOTONIC)
+  end
 
-    def monotonic_time
-      GLOBAL_MONOTONIC_CLOCK.get_time
+  def get_interval_native(other)
+    Process.clock_gettime(Process::CLOCK_MONOTONIC) - other.to_f
+  end
+
+  def get_time_ruby
+    @mutex.synchronize do
+      @correction ||= 0 # compensating any back time shifts
+      now = Time.now.to_f
+      corrected_now = now + @correction
+      if @last_time < corrected_now
+        return @last_time = corrected_now 
+      else
+        @correction += @last_time - corrected_now + 0.000_001
+        return @last_time = @correction + now
+      end
     end
   end
 
-  module_function :monotonic_time
+  def get_interval_ruby(other)
+    get_time_ruby - other.to_f
+  end
 end
+
+COUNT = 2_000_000
+CLOCK = MonotonicClock.new
+
+native_now = CLOCK.get_time_native
+ruby_now = CLOCK.get_time_ruby
+
+puts "Native: #{native_now}, Ruby: #{ruby_now}"
+
+Benchmark.bm do |bm|
+
+  puts "Native time..."
+  bm.report do
+    COUNT.times{ CLOCK.get_time_native }
+  end
+
+  puts "Ruby time..."
+  bm.report do
+    COUNT.times{ CLOCK.get_time_ruby }
+  end
+
+  puts "Native interval..."
+  bm.report do
+    COUNT.times{ CLOCK.get_interval_native(native_now) }
+  end
+
+  puts "Ruby interval..."
+  bm.report do
+    COUNT.times{ CLOCK.get_interval_ruby(ruby_now) }
+  end
+end
+
+puts "Native: #{CLOCK.get_time_native}, Ruby: #{CLOCK.get_time_ruby}"