Introduce ActiveResource::Base.timeout. This allows a timeout to be set on the internal Net::HTTP instance ARes uses (default is 60 seconds). Setting a low timeout allows ARes clients to fail-fast in the event of a unresponsive/crashed server, rather than cause cascading failures in your application.

Signed-off-by: Michael Koziarski <michael@koziarski.com>

4 files changed, 117 insertions, 4 deletions

diff --git a/activeresource/lib/active_resource/base.rb b/activeresource/lib/active_resource/base.rb
index cd53c5d771..4072b9494d 100644
--- a/activeresource/lib/active_resource/base.rb
+++ b/activeresource/lib/active_resource/base.rb
@@ -166,6 +166,26 @@ module ActiveResource
   # 
   # Learn more about Active Resource's validation features in the ActiveResource::Validations documentation.
   #
+  # === Timeouts
+  #
+  # Active Resource relies on HTTP to access RESTful APIs and as such is inherently susceptible to slow or
+  # unresponsive servers. In such cases, your Active Resource method calls could timeout. You can control the
+  # amount of time before Active Resource times out with the +timeout+ variable.
+  #
+  #   class Person < ActiveResource::Base
+  #     self.site = "http://api.people.com:3000/"
+  #     self.timeout = 5
+  #   end
+  #
+  # This sets the +timeout+ to 5 seconds. You can adjust the timeout to a value suitable for the RESTful API
+  # you are accessing. It is recommended to set this to a reasonably low value to allow your Active Resource
+  # clients (especially if you are using Active Resource in a Rails application) to fail-fast (see
+  # http://en.wikipedia.org/wiki/Fail-fast) rather than cause cascading failures that could incapacitate your
+  # server.
+  #
+  # Internally, Active Resource relies on Ruby's Net::HTTP library to make HTTP requests. Setting +timeout+
+  # sets the <tt>read_timeout</tt> of the internal Net::HTTP instance to the same value. The default
+  # <tt>read_timeout</tt> is 60 seconds on most Ruby implementations.
   class Base
     # The logger for diagnosing and tracing Active Resource calls.
     cattr_accessor :logger
@@ -257,12 +277,27 @@ module ActiveResource
         write_inheritable_attribute("format", format)
         connection.format = format if site
       end
-      
+
       # Returns the current format, default is ActiveResource::Formats::XmlFormat
       def format # :nodoc:
         read_inheritable_attribute("format") || ActiveResource::Formats[:xml]
       end
 
+      # Sets the number of seconds after which requests to the REST API should time out.
+      def timeout=(timeout)
+        @connection = nil
+        @timeout = timeout
+      end
+
+      # Gets tthe number of seconds after which requests to the REST API should time out.
+      def timeout
+        if defined?(@timeout)
+          @timeout
+        elsif superclass != Object && superclass.timeout
+          superclass.timeout
+        end
+      end
+
       # An instance of ActiveResource::Connection that is the base connection to the remote service.
       # The +refresh+ parameter toggles whether or not the connection is refreshed at every request
       # or not (defaults to <tt>false</tt>).
@@ -271,6 +306,7 @@ module ActiveResource
           @connection = Connection.new(site, format) if refresh || @connection.nil?
           @connection.user = user if user
           @connection.password = password if password
+          @connection.timeout = timeout if timeout
           @connection
         else
           superclass.connection
diff --git a/activeresource/lib/active_resource/connection.rb b/activeresource/lib/active_resource/connection.rb
index c8cee7aaa3..3b61009f43 100644
--- a/activeresource/lib/active_resource/connection.rb
+++ b/activeresource/lib/active_resource/connection.rb
@@ -55,7 +55,7 @@ module ActiveResource
   # This class is used by ActiveResource::Base to interface with REST
   # services.
   class Connection
-    attr_reader :site, :user, :password
+    attr_reader :site, :user, :password, :timeout
     attr_accessor :format
 
     class << self
@@ -90,6 +90,11 @@ module ActiveResource
       @password = password
     end
 
+    # Set the number of seconds after which HTTP requests to the remote service should time out.
+    def timeout=(timeout)
+      @timeout = timeout
+    end
+
     # Execute a GET request.
     # Used to get (find) resources.
     def get(path, headers = {})
@@ -167,18 +172,19 @@ module ActiveResource
         http             = Net::HTTP.new(@site.host, @site.port)
         http.use_ssl     = @site.is_a?(URI::HTTPS)
         http.verify_mode = OpenSSL::SSL::VERIFY_NONE if http.use_ssl
+        http.read_timeout = @timeout if @timeout # If timeout is not set, the default Net::HTTP timeout (60s) is used.
         http
       end
 
       def default_header
         @default_header ||= { 'Content-Type' => format.mime_type }
       end
-      
+
       # Builds headers for request to remote service.
       def build_request_headers(headers)
         authorization_header.update(default_header).update(headers)
       end
-      
+
       # Sets authorization header
       def authorization_header
         (@user || @password ? { 'Authorization' => 'Basic ' + ["#{@user}:#{ @password}"].pack('m').delete("\r\n") } : {})
diff --git a/activeresource/test/base_test.rb b/activeresource/test/base_test.rb
index 9caca803b7..9e2f6c1831 100644
--- a/activeresource/test/base_test.rb
+++ b/activeresource/test/base_test.rb
@@ -88,6 +88,12 @@ class BaseTest < Test::Unit::TestCase
     assert_equal('test123', Forum.connection.password)
   end
 
+  def test_should_accept_setting_timeout
+    Forum.timeout = 5
+    assert_equal(5, Forum.timeout)
+    assert_equal(5, Forum.connection.timeout)
+  end
+
   def test_user_variable_can_be_reset
     actor = Class.new(ActiveResource::Base)
     actor.site = 'http://cinema'
@@ -108,6 +114,16 @@ class BaseTest < Test::Unit::TestCase
     assert_nil actor.connection.password
   end
 
+  def test_timeout_variable_can_be_reset
+    actor = Class.new(ActiveResource::Base)
+    actor.site = 'http://cinema'
+    assert_nil actor.timeout
+    actor.timeout = 5
+    actor.timeout = nil
+    assert_nil actor.timeout
+    assert_nil actor.connection.timeout
+  end
+
   def test_credentials_from_site_are_decoded
     actor = Class.new(ActiveResource::Base)
     actor.site = 'http://my%40email.com:%31%32%33@cinema'
@@ -232,6 +248,40 @@ class BaseTest < Test::Unit::TestCase
     assert_equal fruit.password, apple.password, 'subclass did not adopt changes from parent class'
   end
 
+  def test_timeout_reader_uses_superclass_timeout_until_written
+    # Superclass is Object so returns nil.
+    assert_nil ActiveResource::Base.timeout
+    assert_nil Class.new(ActiveResource::Base).timeout
+    Person.timeout = 5
+
+    # Subclass uses superclass timeout.
+    actor = Class.new(Person)
+    assert_equal Person.timeout, actor.timeout
+
+    # Changing subclass timeout doesn't change superclass timeout.
+    actor.timeout = 10
+    assert_not_equal Person.timeout, actor.timeout
+
+    # Changing superclass timeout doesn't overwrite subclass timeout.
+    Person.timeout = 15
+    assert_not_equal Person.timeout, actor.timeout
+
+    # Changing superclass timeout after subclassing changes subclass timeout.
+    jester = Class.new(actor)
+    actor.timeout = 20
+    assert_equal actor.timeout, jester.timeout
+
+    # Subclasses are always equal to superclass timeout when not overridden.
+    fruit = Class.new(ActiveResource::Base)
+    apple = Class.new(fruit)
+
+    fruit.timeout = 25
+    assert_equal fruit.timeout, apple.timeout, 'subclass did not adopt changes from parent class'
+
+    fruit.timeout = 30
+    assert_equal fruit.timeout, apple.timeout, 'subclass did not adopt changes from parent class'
+  end
+
   def test_updating_baseclass_site_object_wipes_descendent_cached_connection_objects
     # Subclasses are always equal to superclass site when not overridden    
     fruit = Class.new(ActiveResource::Base)
@@ -279,6 +329,22 @@ class BaseTest < Test::Unit::TestCase
     assert_not_equal(first_connection, second_connection, 'Connection should be re-created')
   end
 
+  def test_updating_baseclass_timeout_wipes_descendent_cached_connection_objects
+    # Subclasses are always equal to superclass timeout when not overridden
+    fruit = Class.new(ActiveResource::Base)
+    apple = Class.new(fruit)
+    fruit.site = 'http://market'
+
+    fruit.timeout = 5
+    assert_equal fruit.connection.timeout, apple.connection.timeout
+    first_connection = apple.connection.object_id
+
+    fruit.timeout = 10
+    assert_equal fruit.connection.timeout, apple.connection.timeout
+    second_connection = apple.connection.object_id
+    assert_not_equal(first_connection, second_connection, 'Connection should be re-created')
+  end
+
   def test_collection_name
     assert_equal "people", Person.collection_name
   end
diff --git a/activeresource/test/connection_test.rb b/activeresource/test/connection_test.rb
index 38fdbd3b2f..6c907614e7 100644
--- a/activeresource/test/connection_test.rb
+++ b/activeresource/test/connection_test.rb
@@ -101,6 +101,11 @@ class ConnectionTest < Test::Unit::TestCase
     assert_equal site, @conn.site
   end
 
+  def test_timeout_accessor
+    @conn.timeout = 5
+    assert_equal 5, @conn.timeout
+  end
+
   def test_get
     matz = @conn.get("/people/1.xml")
     assert_equal "Matz", matz["name"]