supporting the retry-after header for redirections as well

lib/httpx.rb

@@ -5,6 +5,7 @@ require "httpx/version"
 require "httpx/extensions"
 
 require "httpx/errors"
+require "httpx/utils"
 require "httpx/altsvc"
 require "httpx/callbacks"
 require "httpx/loggable"

lib/httpx/plugins/follow_redirects.rb

@@ -59,8 +59,26 @@ module HTTPX
             return ErrorResponse.new(request, error, options)
           end
 
-          connection = find_connection(retry_request, connections, options)
-          connection.send(retry_request)
+          retry_after = response.headers["retry-after"]
+
+          if retry_after
+            # Servers send the "Retry-After" header field to indicate how long the
+            # user agent ought to wait before making a follow-up request.
+            # When sent with any 3xx (Redirection) response, Retry-After indicates
+            # the minimum time that the user agent is asked to wait before issuing
+            # the redirected request.
+            #
+            retry_after = Utils.parse_retry_after(retry_after)
+
+            log { "redirecting after #{retry_after} secs..." }
+            pool.after(retry_after) do
+              connection = find_connection(retry_request, connections, options)
+              connection.send(retry_request)
+            end
+          else
+            connection = find_connection(retry_request, connections, options)
+            connection.send(retry_request)
+          end
           nil
         end
 

lib/httpx/plugins/rate_limiter.rb

@@ -35,21 +35,12 @@ module HTTPX
         # the minimum time that the user agent is asked to wait before issuing
         # the redirected request.
         #
-        # The value of this field can be either an HTTP-date or a number of
-        # seconds to delay after the response is received.
-        def retry_after_rate_limit(_request, response)
+        def retry_after_rate_limit(_, response)
           retry_after = response.headers["retry-after"]
 
           return unless retry_after
 
-          begin
-            # first: bet on it being an integer
-            Integer(retry_after)
-          rescue ArgumentError
-            # Then it's a datetime
-            time = Time.httpdate(retry_after)
-            time - Time.now
-          end
+          Utils.parse_retry_after(retry_after)
         end
       end
     end

lib/httpx/utils.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module HTTPX
+  module Utils
+    module_function
+
+    # The value of this field can be either an HTTP-date or a number of
+    # seconds to delay after the response is received.
+    def parse_retry_after(retry_after)
+      # first: bet on it being an integer
+      Integer(retry_after)
+    rescue ArgumentError
+      # Then it's a datetime
+      time = Time.httpdate(retry_after)
+      time - Time.now
+    end
+  end
+end

test/support/requests/plugins/follow_redirects.rb

@@ -36,6 +36,19 @@ module Requests
         verify_status(response, 302)
       end
 
+      def test_plugin_follow_redirects_retry_after
+        session = HTTPX.plugin(SessionWithMockResponse[302, "retry-after" => "2"]).plugin(:follow_redirects)
+
+        before_time = Process.clock_gettime(Process::CLOCK_MONOTONIC, :second)
+        response = session.get(max_redirect_uri(1))
+        after_time = Process.clock_gettime(Process::CLOCK_MONOTONIC, :second)
+
+        verify_status(response, 200)
+
+        total_time = after_time - before_time
+        assert total_time >= 2, "request didn't take as expected to redirect (#{total_time} secs)"
+      end
+
       def test_plugin_follow_insecure_no_insecure_downgrade
         return unless origin.start_with?("https")
 

test/support/requests/plugins/rate_limiter.rb

@@ -41,7 +41,7 @@ module Requests
         verify_rated_responses(rate_limiter_session, 429)
 
         total_time = after_time - before_time
-        assert_in_delta 2, total_time, 1, "request didn't take as expected to retry (#{total_time} secs)"
+        assert total_time >= 2, "request didn't take as expected to retry (#{total_time} secs)"
       end
 
       def test_plugin_rate_limiter_retry_after_date
@@ -57,7 +57,7 @@ module Requests
 
         verify_rated_responses(rate_limiter_session, 429)
         total_time = after_time - before_time
-        assert_in_delta 3, total_time, 1, "request didn't take as expected to retry (#{total_time} secs)"
+        assert total_time >= 2, "request didn't take as expected to retry (#{total_time} secs)"
       end
 
       private

test/support/session_with_mock_response.rb

@@ -7,6 +7,10 @@ module SessionWithMockResponse
     self
   end
 
+  module ResponseMethods
+    attr_writer :status
+  end
+
   module InstanceMethods
     def initialize(*)
       super
@@ -19,11 +23,9 @@ module SessionWithMockResponse
       response.close
       @mock_responses_counter -= 1
 
-      mock_response = @options.response_class.new(request,
-                                                  Thread.current[:httpx_mock_response_status],
-                                                  "2.0",
-                                                  Thread.current[:httpx_mock_response_headers])
-      super(request, mock_response)
+      response.status = Thread.current[:httpx_mock_response_status]
+      response.merge_headers(Thread.current[:httpx_mock_response_headers])
+      super(request, response)
     end
   end
 end