1 files changed, 52 insertions, 8 deletions
diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
index 4c0554d27b..7590fb6843 100644
--- a/actionpack/lib/action_controller/metal/live.rb
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -102,17 +102,30 @@ module ActionController
             end
           end
 
-          message = json.gsub("\n", "\ndata: ")
+          message = json.gsub(/\n/, "\ndata: ")
           @stream.write "data: #{message}\n\n"
         end
     end
 
+    class ClientDisconnected < RuntimeError
+    end
+
     class Buffer < ActionDispatch::Response::Buffer #:nodoc:
       include MonitorMixin
 
+      # Ignore that the client has disconnected.
+      #
+      # If this value is `true`, calling `write` after the client
+      # disconnects will result in the written content being silently
+      # discarded. If this value is `false` (the default), a
+      # ClientDisconnected exception will be raised.
+      attr_accessor :ignore_disconnect
+
       def initialize(response)
         @error_callback = lambda { true }
         @cv = new_cond
+        @aborted = false
+        @ignore_disconnect = false
         super(response, SizedQueue.new(10))
       end
 
@@ -123,6 +136,17 @@ module ActionController
         end
 
         super
+
+        unless connected?
+          @buf.clear
+
+          unless @ignore_disconnect
+            # Raise ClientDisconnected, which is a RuntimeError (not an
+            # IOError), because that's more appropriate for something beyond
+            # the developer's control.
+            raise ClientDisconnected, "client disconnected"
+          end
+        end
       end
 
       def each
@@ -133,6 +157,10 @@ module ActionController
         @response.sent!
       end
 
+      # Write a 'close' event to the buffer; the producer/writing thread
+      # uses this to notify us that it's finished supplying content.
+      #
+      # See also #abort.
       def close
         synchronize do
           super
@@ -141,12 +169,26 @@ module ActionController
         end
       end
 
-      def await_close
+      # Inform the producer/writing thread that the client has
+      # disconnected; the reading thread is no longer interested in
+      # anything that's being written.
+      #
+      # See also #close.
+      def abort
         synchronize do
-          @cv.wait_until { @closed }
+          @aborted = true
+          @buf.clear
         end
       end
 
+      # Is the client still connected and waiting for content?
+      #
+      # The result of calling `write` when this is `false` is determined
+      # by `ignore_disconnect`.
+      def connected?
+        !@aborted
+      end
+
       def on_error(&block)
         @error_callback = block
       end
@@ -157,7 +199,7 @@ module ActionController
     end
 
     class Response < ActionDispatch::Response #:nodoc: all
-      class Header < DelegateClass(Hash)
+      class Header < DelegateClass(Hash) # :nodoc:
         def initialize(response, header)
           @response = response
           super(header)
@@ -255,10 +297,12 @@ module ActionController
       logger = ActionController::Base.logger
       return unless logger
 
-      message = "\n#{exception.class} (#{exception.message}):\n"
-      message << exception.annoted_source_code.to_s if exception.respond_to?(:annoted_source_code)
-      message << "  " << exception.backtrace.join("\n  ")
-      logger.fatal("#{message}\n\n")
+      logger.fatal do
+        message = "\n#{exception.class} (#{exception.message}):\n"
+        message << exception.annoted_source_code.to_s if exception.respond_to?(:annoted_source_code)
+        message << "  " << exception.backtrace.join("\n  ")
+        "#{message}\n\n"
+      end
     end
 
     def response_body=(body)