[PATCH 2/2] pure: use monotonic clock if possible

[Eric Wong <e@80x24.org>]

Ruby 2.1.0 and later exposes Process.clock_gettime, resulting
in less garbage and access to the monotonic clock if it is
available.  Try to use it to achieve feature parity with the
C extension (which has always used the monotonic clock if possible).
---
 lib/clogger/pure.rb | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/clogger/pure.rb b/lib/clogger/pure.rb
index 9efb00c..5e7ccfe 100644
--- a/lib/clogger/pure.rb
+++ b/lib/clogger/pure.rb
@@ -28,7 +28,7 @@ def initialize(app, opts = {})
   end
 
   def call(env)
-    start = Time.now
+    start = mono_now
     resp = @app.call(env)
     unless resp.instance_of?(Array) && resp.size == 3
       log(env, 500, {}, start)
@@ -165,7 +165,7 @@ def log(env, status, headers, start = @start)
       when OP_TIME_LOCAL; Time.now.strftime(op[1])
       when OP_TIME_UTC; Time.now.utc.strftime(op[1])
       when OP_REQUEST_TIME
-        t = Time.now - start
+        t = mono_now - start
         time_format(t.to_i, (t - t.to_i) * 1000000, op[1], op[2])
       when OP_TIME
         t = Time.now
@@ -185,4 +185,14 @@ def log(env, status, headers, start = @start)
     end
     nil
   end
+
+  # favor monotonic clock if possible, and try to use clock_gettime in
+  # more recent Rubies since it generates less garbage
+  if defined?(Process::CLOCK_MONOTONIC)
+    def mono_now; Process.clock_gettime(Process::CLOCK_MONOTONIC); end
+  elsif defined?(Process::CLOCK_REALTIME)
+    def mono_now; Process.clock_gettime(Process::CLOCK_REALTIME); end
+  else
+    def mono_now; Time.now.to_f; end
+  end
 end
-- 
EW