clear buffers before returning to pool

Author: andrewang-canva

src/main/java/com/timgroup/statsd/StatsDSender.java

@@ -81,6 +81,7 @@ void sendLoop() {
             try {
 
                 if (buffer != null) {
+                    buffer.clear();
                     pool.put(buffer);
                 }
 
@@ -94,7 +95,6 @@ void sendLoop() {
                 buffer.flip();
                 final int sentBytes = clientChannel.send(buffer, address);
 
-                buffer.clear();
                 if (sizeOfBuffer != sentBytes) {
                     throw new IOException(
                             String.format("Could not send stat %s entirely to %s. Only sent %d out of %d bytes",

src/test/java/com/timgroup/statsd/NonBlockingStatsDClientTest.java

@@ -16,6 +16,9 @@
 import java.util.Random;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.BlockingQueue;
 import java.util.logging.Logger;
 
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -1337,4 +1340,59 @@ public SlowStatsDNonBlockingStatsDClient build() throws StatsDClientException {
             }
         }
     }
+
+    @Test(timeout = 5000L)
+    public void failed_write_buffer() throws Exception {
+        final BlockingQueue sync = new ArrayBlockingQueue(1);
+        final IOException marker = new IOException();
+        NonBlockingStatsDClientBuilder builder = new NonBlockingStatsDClientBuilder() {
+                @Override
+                public NonBlockingStatsDClient build() {
+                    this.originDetectionEnabled(false);
+                    this.bufferPoolSize(1);
+                    return new NonBlockingStatsDClient(resolve()) {
+                        @Override
+                        ClientChannel createByteChannel(Callable<SocketAddress> addressLookup, int timeout, int bufferSize) throws Exception {
+                            return new DatagramClientChannel(addressLookup.call()) {
+                                @Override
+                                public int write(ByteBuffer data) throws IOException {
+                                    try {
+                                        sync.put(new Object());
+                                    } catch (InterruptedException e) {
+                                    }
+                                    throw marker;
+                                }
+                            };
+                        }
+                    };
+                }
+            };
+
+        final BlockingQueue errors = new LinkedBlockingQueue();
+        NonBlockingStatsDClient client = builder
+            .hostname("localhost")
+            .blocking(true)
+            .errorHandler(new StatsDClientErrorHandler() {
+                    @Override
+                    public void handle(Exception ex) {
+                        if (ex == marker) {
+                            return;
+                        }
+                        System.out.println(ex.toString());
+                        try {
+                            errors.put(ex);
+                        } catch (InterruptedException e) {
+                        }
+                    }
+
+                })
+            .build();
+
+        client.gauge("test", 1);
+        sync.take();
+        client.gauge("test", 1);
+        client.stop();
+
+        assertEquals(0, errors.size());
+    }
 }