* lib/drb/drb.rb: Support graceful shutdown.

  (DRbTCPSocket#initialize): Create a pipe for shutdown notification.
  (DRbTCPSocket#close): Invoke close_shutdown_pipe.
  (DRbTCPSocket#close_shutdown_pipe): New private method.
  (DRbTCPSocket#accept): Use accept_or_shutdown.
  (DRbTCPSocket#accept_or_shutdown): New private method which returns
  nil on shutdown.
  (DRbServer#stop_service): Use shutdown instead of Thread#kill.
  (DRbServer#run): Break infinite loop when main_loop returns nil.
  (DRbServer#main_loop): @protocol.accept may return nil.

* lib/drb/ssl.rb: Follow above change.

* lib/drb/unix.rb: Ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47678 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 45 insertions, 7 deletions

diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
index 26f39b789f..ab352afa1d 100644
--- a/lib/drb/drb.rb
+++ b/lib/drb/drb.rb
@@ -905,6 +905,7 @@ module DRb
       @acl = config[:tcp_acl]
       @msg = DRbMessage.new(config)
       set_sockopt(@socket)
+      @shutdown_pipe_r, @shutdown_pipe_w = IO.pipe
     end
 
     # Get the URI that we are connected to.
@@ -952,14 +953,28 @@ module DRb
         @socket.close
         @socket = nil
       end
+      close_shutdown_pipe
     end
 
+    def close_shutdown_pipe
+      if @shutdown_pipe_r && !@shutdown_pipe_r.closed?
+        @shutdown_pipe_r.close
+        @shutdown_pipe_r = nil
+      end
+      if @shutdown_pipe_w && !@shutdown_pipe_w.closed?
+        @shutdown_pipe_w.close
+        @shutdown_pipe_w = nil
+      end
+    end
+    private :close_shutdown_pipe
+
     # On the server side, for an instance returned by #open_server,
     # accept a client connection and return a new instance to handle
     # the server's side of this client-server session.
     def accept
       while true
-        s = @socket.accept
+        s = accept_or_shutdown
+        return nil unless s
         break if (@acl ? @acl.allow_socket?(s) : true)
         s.close
       end
@@ -971,6 +986,20 @@ module DRb
       self.class.new(uri, s, @config)
     end
 
+    def accept_or_shutdown
+      readables, = IO.select([@socket, @shutdown_pipe_r])
+      if readables.include? @shutdown_pipe_r
+        return nil
+      end
+      @socket.accept
+    end
+    private :accept_or_shutdown
+
+    # Graceful shutdown
+    def shutdown
+      @shutdown_pipe_w.close if @shutdown_pipe_w && !@shutdown_pipe_w.closed?
+    end
+
     # Check to see if this connection is alive.
     def alive?
       return false unless @socket
@@ -1438,7 +1467,12 @@ module DRb
       if  Thread.current['DRb'] && Thread.current['DRb']['server'] == self
         Thread.current['DRb']['stop_service'] = true
       else
-        @thread.kill.join
+        if @protocol.respond_to? :shutdown
+          @protocol.shutdown
+        else
+          @thread.kill # xxx: Thread#kill
+        end
+        @thread.join
       end
     end
 
@@ -1463,8 +1497,7 @@ module DRb
     def run
       Thread.start do
         begin
-          while true
-            main_loop
+          while main_loop
           end
         ensure
           @protocol.close if @protocol
@@ -1607,7 +1640,9 @@ module DRb
     # returning responses, until the client closes the connection
     # or a local method call fails.
     def main_loop
-      Thread.start(@protocol.accept) do |client|
+      client0 = @protocol.accept
+      return nil if !client0
+      Thread.start(client0) do |client|
         @grp.add Thread.current
         Thread.current['DRb'] = { 'client' => client ,
                                   'server' => self }
diff --git a/lib/drb/ssl.rb b/lib/drb/ssl.rb
index dd4df4e129..efd8271a78 100644
--- a/lib/drb/ssl.rb
+++ b/lib/drb/ssl.rb
@@ -322,7 +322,8 @@ module DRb
     def accept # :nodoc:
       begin
       while true
-        soc = @socket.accept
+        soc = accept_or_shutdown
+        return nil unless soc
         break if (@acl ? @acl.allow_socket?(soc) : true)
         soc.close
       end
diff --git a/lib/drb/unix.rb b/lib/drb/unix.rb
index 4d245780a5..3fb8d0ecce 100644
--- a/lib/drb/unix.rb
+++ b/lib/drb/unix.rb
@@ -98,10 +98,12 @@ module DRb
       @socket.close
       File.unlink(path) if @server_mode
       @socket = nil
+      close_shutdown_pipe
     end
 
     def accept
-      s = @socket.accept
+      s = accept_or_shutdown
+      return nil unless s
       self.class.new(nil, s, @config)
     end