Merge pull request elastic#657 from logstash/tcp-output-client-close-fix

Tcp output client remote-has-closed fix

lib/logstash/outputs/tcp.rb

@@ -2,7 +2,6 @@
 require "logstash/namespace"
 require "thread"
 
-
 # Write events over a TCP socket.
 #
 # Each event json is separated by a newline.
@@ -68,6 +67,7 @@ def write(msg)
 
   public
   def register
+    require "stud/try"
     if server?
       @logger.info("Starting tcp output listener", :address => "#{@host}:#{@port}")
       @server_socket = TCPServer.new(@host, @port)
@@ -91,16 +91,24 @@ def register
         @client_threads.reject! {|t| !t.alive? }
       end
     else
-      @client_socket = nil
+      client_socket = nil
       @codec.on_event do |payload|
         begin
-          connect unless @client_socket
-          @client_socket.write(payload)
+          client_socket = connect unless client_socket
+          r,w,e = IO.select([client_socket], [client_socket], [client_socket], nil)
+          # don't expect any reads, but a readable socket might
+          # mean the remote end closed, so read it and throw it away.
+          # we'll get an EOFError if it happens.
+          client_socket.sysread(16384) if r.any?
+
+          # Now send the payload
+          client_socket.syswrite(payload) if w.any?
         rescue => e
           @logger.warn("tcp output exception", :host => @host, :port => @port,
                        :exception => e, :backtrace => e.backtrace)
+          client_socket.close rescue nil
+          client_socket = nil
           sleep @reconnect_interval
-          @client_socket = nil
           retry
         end
       end
@@ -109,7 +117,9 @@ def register
 
   private
   def connect
-    @client_socket = TCPSocket.new(@host, @port)
+    Stud::try do
+      return TCPSocket.new(@host, @port)
+    end
   end # def connect
 
   private