Fix ConcurrentCloseTest flakiness.

We were running the risk that the server's end of a client socket would get
closed by the finalizer thread, resulting in read(2) returning 0 to the client,
and the test failing like this:

  junit.framework.AssertionFailedError: read returned -1
      at libcore.java.net.ConcurrentCloseTest.test_read(ConcurrentCloseTest.java:121)
      at java.lang.reflect.Method.invokeNative(Native Method)

(cherry-pick of 4bbcd7e5aee1e984a4fcf46385667f9ad03dbc16.)

Bug: 7206024
Change-Id: I0dae214a7ee609655f4f4781abf4457863bcfd5f

1 files changed, 38 insertions, 35 deletions

diff --git a/luni/src/test/java/libcore/java/net/ConcurrentCloseTest.java b/luni/src/test/java/libcore/java/net/ConcurrentCloseTest.java
index d33c5f3..06a546a 100644
--- a/luni/src/test/java/libcore/java/net/ConcurrentCloseTest.java
+++ b/luni/src/test/java/libcore/java/net/ConcurrentCloseTest.java
@@ -16,11 +16,13 @@
 
 package libcore.java.net;
 
+import java.io.IOException;
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
 import java.net.InetSocketAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
+import java.net.SocketAddress;
 import java.net.SocketException;
 import java.nio.channels.AsynchronousCloseException;
 import java.nio.channels.ClosedChannelException;
@@ -102,16 +104,7 @@ public class ConcurrentCloseTest extends junit.framework.TestCase {
     }
 
     public void test_read() throws Exception {
-        final ServerSocket ss = new ServerSocket(0);
-        new Thread(new Runnable() {
-            public void run() {
-                try {
-                    ss.accept();
-                } catch (Exception ex) {
-                    ex.printStackTrace();
-                }
-            }
-        }).start();
+        SilentServer ss = new SilentServer();
         Socket s = new Socket();
         s.connect(ss.getLocalSocketAddress());
         new Killer(s).start();
@@ -126,16 +119,7 @@ public class ConcurrentCloseTest extends junit.framework.TestCase {
     }
 
     public void test_read_multiple() throws Throwable {
-        final ServerSocket ss = new ServerSocket(0);
-        new Thread(new Runnable() {
-            public void run() {
-                try {
-                    ss.accept();
-                } catch (Exception ex) {
-                    ex.printStackTrace();
-                }
-            }
-        }).start();
+        SilentServer ss = new SilentServer();
         final Socket s = new Socket();
         s.connect(ss.getLocalSocketAddress());
 
@@ -173,6 +157,8 @@ public class ConcurrentCloseTest extends junit.framework.TestCase {
         for (Throwable exception : thrownExceptions) {
             throw exception;
         }
+
+        ss.close();
     }
 
     public void test_recv() throws Exception {
@@ -190,21 +176,7 @@ public class ConcurrentCloseTest extends junit.framework.TestCase {
     }
 
     public void test_write() throws Exception {
-        final ServerSocket ss = new ServerSocket(0);
-        new Thread(new Runnable() {
-            public void run() {
-                try {
-                    System.err.println("accepting...");
-
-                    Socket client = ss.accept();
-                    System.err.println("accepted...");
-                    Thread.sleep(30 * 1000);
-                    System.err.println("server exiting...");
-                } catch (Exception ex) {
-                    ex.printStackTrace();
-                }
-            }
-        }).start();
+        final SilentServer ss = new SilentServer();
         Socket s = new Socket();
         s.connect(ss.getLocalSocketAddress());
         new Killer(s).start();
@@ -224,6 +196,37 @@ public class ConcurrentCloseTest extends junit.framework.TestCase {
         ss.close();
     }
 
+    // This server accepts connections, but doesn't read or write anything.
+    // It holds on to the Socket connecting to the client so it won't be GCed.
+    // Call "close" to close both the server socket and its client connection.
+    static class SilentServer {
+        private final ServerSocket ss;
+        private Socket client;
+
+        public SilentServer() throws IOException {
+            ss = new ServerSocket(0);
+            new Thread(new Runnable() {
+                public void run() {
+                    try {
+                        client = ss.accept();
+                    } catch (Exception ex) {
+                        ex.printStackTrace();
+                    }
+                }
+            }).start();
+        }
+
+        public SocketAddress getLocalSocketAddress() {
+            return ss.getLocalSocketAddress();
+        }
+
+        public void close() throws IOException {
+            client.close();
+            ss.close();
+        }
+    }
+
+    // This thread calls the "close" method on the supplied T after 2s.
     static class Killer<T> extends Thread {
         private final T s;