Fix quietly_try_to_purge on Ruby 2.0

The tests of quietly_try_to_purge were failing on Ruby 2.0 due to the
net-http-local gem not working with that Ruby version.  When
Net::HTTP::bind is called, it temporarily replaces the open method of
TCPSocket with a version of open that only takes two parameters. The
Ruby 1.9 version of net/http.rb calls TCPSocket.open with two
parameters, but the Ruby 2.0 version calls it with 4, and so fails with
a mismatched number of arguments error.

In fact, net-http-local doesn't seem to be necessary with Ruby 2.0,
where one can supply a :local_port argument to Net::HTTP.start, so this
commit patches lib/quiet_opener.rb to use that approach with Ruby
>= 2.0, and net-http-local on earlier versions.

2 files changed, 30 insertions, 9 deletions

diff --git a/Gemfile b/Gemfile
index 6f5043710..9545f1ae1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,7 +20,7 @@ gem 'fastercsv', '>=1.5.5'
 gem 'jquery-rails', '~> 2.1'
 gem 'json'
 gem 'mahoro'
-gem 'net-http-local'
+gem 'net-http-local', :platforms => [:ruby_18, :ruby_19]
 gem 'net-purge'
 gem 'newrelic_rpm'
 gem 'rack'
diff --git a/lib/quiet_opener.rb b/lib/quiet_opener.rb
index ae6605c43..16ea27b8e 100644
--- a/lib/quiet_opener.rb
+++ b/lib/quiet_opener.rb
@@ -1,6 +1,8 @@
 require 'open-uri'
 require 'net-purge'
-require 'net/http/local'
+if RUBY_VERSION.to_f < 2.0
+    require 'net/http/local'
+end
 
 def quietly_try_to_open(url)
     begin
@@ -12,17 +14,36 @@ def quietly_try_to_open(url)
     return result
 end
 
+# On Ruby versions before 2.0, we need to use the net-http-local gem
+# to force the use of 127.0.0.1 as the local interface for the
+# connection.  However, at the time of writing this gem doesn't work
+# on Ruby 2.0 and it's not necessary with that Ruby version - one can
+# supply a :local_host option to Net::HTTP:start.  So, this helper
+# function is to abstract away that difference, and can be used as you
+# would Net::HTTP.start(host) when passed a block.
+def http_from_localhost(host)
+    if RUBY_VERSION.to_f >= 2.0
+        Net::HTTP.start(host, :local_host => '127.0.0.1') do |http|
+            yield http
+        end
+    else
+        Net::HTTP.bind '127.0.0.1' do
+            Net::HTTP.start(host) do |http|
+                yield http
+            end
+        end
+    end
+end
+
 def quietly_try_to_purge(host, url)
     begin
         result = ""
         result_body = ""
-        Net::HTTP.bind '127.0.0.1' do
-            Net::HTTP.start(host) {|http|
-                request = Net::HTTP::Purge.new(url)
-                response = http.request(request)
-                result = response.code
-                result_body = response.body
-            }
+        http_from_localhost(host) do |http|
+            request = Net::HTTP::Purge.new(url)
+            response = http.request(request)
+            result = response.code
+            result_body = response.body
         end
     rescue OpenURI::HTTPError, SocketError, Errno::ETIMEDOUT, Errno::ECONNREFUSED, Errno::EHOSTUNREACH, Errno::ECONNRESET, Errno::ENETUNREACH
         Rails.logger.warn("PURGE: Unable to reach host #{host}")