Merge pull request #4189 from etehtsea/tcpserver-sysaccept

Implement TCPServer#sysaccept

core/src/main/java/org/jruby/ext/socket/RubyTCPServer.java

@@ -52,6 +52,7 @@
 import org.jruby.runtime.Visibility;
 import org.jruby.runtime.builtin.IRubyObject;
 
+import org.jruby.util.io.FilenoUtil;
 import org.jruby.util.io.SelectorFactory;
 import java.nio.channels.spi.SelectorProvider;
 
@@ -236,6 +237,35 @@ public IRubyObject accept_nonblock(ThreadContext context, Ruby runtime, boolean
         }
     }
 
+    @JRubyMethod(name = "sysaccept")
+    public IRubyObject sysaccept(ThreadContext context) {
+        Ruby runtime = context.runtime;
+
+        try {
+            RubyThread thread = context.getThread();
+
+            while (true) {
+                boolean ready = thread.select(this, SelectionKey.OP_ACCEPT);
+
+                if (!ready) {
+                    // we were woken up without being selected...poll for thread events and go back to sleep
+                    context.pollThreadEvents();
+
+                } else {
+                    SocketChannel connected = getServerSocketChannel().accept();
+                    if (connected == null) continue;
+
+                    connected.finishConnect();
+
+                    return runtime.newFixnum(FilenoUtil.filenoFrom(connected));
+                }
+            }
+
+        } catch(IOException e) {
+            throw runtime.newIOErrorFromException(e);
+        }
+    }
+
     @JRubyMethod(name = "listen", required = 1)
     public IRubyObject listen(ThreadContext context, IRubyObject backlog) {
         return RubyFixnum.zero(context.runtime);