[PATCH] use monotonic clock for timing

[PATCH] use monotonic clock for timing

[Eric Wong]

This makes us immune to system clock changes and has a nice
side effect of reducing runtime garbage.  The downside is
the additional cache overhead for extra constant lookups.

This requires Ruby 2.1 or later, but this is an unimportant
project and we can get away without caring for 2.0 and earlier.
---
 README                            | 1 -
 http_spew.gemspec                 | 1 +
 lib/http_spew/class_methods.rb    | 8 ++++----
 lib/http_spew/request.rb          | 8 ++++----
 test/test_input_spray_with_md5.rb | 4 ++--
 5 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/README b/README
index c8c2828..74aadd5 100644
--- a/README
+++ b/README
@@ -11,7 +11,6 @@ Use HTTP Spew if you wish you could kinda multicast with HTTP...
 * No support for DNS resolution (WONTFIX, ever)
 * No support for HTTPS
 * No support for keepalive (yet?)
-* No support for Ruby 1.8, this is Ruby 1.9-only
 * Not remotely RFC-compliant
 * Messes up analytics/reporting on servers
 * Resets server connections
diff --git a/http_spew.gemspec b/http_spew.gemspec
index 4aafc26..4bede9b 100644
--- a/http_spew.gemspec
+++ b/http_spew.gemspec
@@ -18,5 +18,6 @@ Gem::Specification.new do |s|
   s.add_dependency(%q<kcar>, [ "~> 0.3", ">= 0.3.1"])
   s.add_dependency(%q<kgio>, "~> 2.6")
   s.add_development_dependency(%q<olddoc>, "~> 1.0")
+  s.required_ruby_version = '>= 2.1'
   s.licenses = %w(GPL-2.0+)
 end
diff --git a/lib/http_spew/class_methods.rb b/lib/http_spew/class_methods.rb
index 938b55c..f068f6b 100644
--- a/lib/http_spew/class_methods.rb
+++ b/lib/http_spew/class_methods.rb
@@ -41,11 +41,11 @@ module HTTP_Spew::ClassMethods
   end
 
   def with_timeout(t)
-    t0 = Time.now
+    t0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
     yield
-    ensure
-      t[0] -= Time.now - t0
-      t[0] = 0.0 if t[0] < 0
+  ensure
+    t[0] -= Process.clock_gettime(Process::CLOCK_MONOTONIC) - t0
+    t[0] = 0.0 if t[0] < 0
   end
 
   # Returns an array of requests that are complete, including those
diff --git a/lib/http_spew/request.rb b/lib/http_spew/request.rb
index 16db39d..63bac64 100644
--- a/lib/http_spew/request.rb
+++ b/lib/http_spew/request.rb
@@ -55,17 +55,17 @@ class HTTP_Spew::Request
   # returns a 3-element Rack response array on successful completion
   # returns an Exception if one was raised
   def run(timeout)
-    t0 = Time.now
+    t0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
     buf, @buf = @buf, nil # make inspect nicer
     @to_io.write(buf)
     if @input
       @to_io.write(buf) while @input.read(0x4000, buf)
     end
-    timeout -= (Time.now - t0)
+    timeout -= (Process.clock_gettime(Process::CLOCK_MONOTONIC) - t0)
     while :wait_readable == (rv = read_response) && timeout >= 0.0
-      t0 = Time.now
+      t0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
       @to_io.kgio_wait_readable(timeout) if timeout > 0.0
-      timeout -= (Time.now - t0)
+      timeout -= (Process.clock_gettime(Process::CLOCK_MONOTONIC) - t0)
     end
     rv
     rescue => e
diff --git a/test/test_input_spray_with_md5.rb b/test/test_input_spray_with_md5.rb
index 1e030e0..37819e9 100644
--- a/test/test_input_spray_with_md5.rb
+++ b/test/test_input_spray_with_md5.rb
@@ -60,9 +60,9 @@ class TestInputSprayWithMD5 < Test::Unit::TestCase
       HTTP_Spew::Request.new(@env, md5_input, @sockaddr)
     end
     assert_equal @nr, reqs.size
-    t0 = Time.now
+    t0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
     rv = HTTP_Spew.wait_mt reqs.size, reqs, 3600
-    elapsed = Time.now - t0
+    elapsed = Process.clock_gettime(Process::CLOCK_MONOTONIC) - t0
     assert(elapsed <= 30, "took too long: #{elapsed}s")
     assert_equal @nr, rv.size
     rv.each { |r|
-- 
EW