Add retry to GraphiteSender

- Add single retry to DGraphiteSender
- Remove the unused Writer field from DGraphiteSender
- Adjust down the log level to WARN when failing to report metrics

Author: rbygrave

metrics-graphite/pom.xml

@@ -8,6 +8,7 @@
   </parent>
 
   <artifactId>avaje-metrics-graphite</artifactId>
+  <version>9.4-RC2</version>
 
   <properties>
     <surefire.useModulePath>false</surefire.useModulePath>

metrics-graphite/src/main/java/io/avaje/metrics/graphite/DGraphiteReporter.java

@@ -5,8 +5,7 @@
 import java.io.IOException;
 import java.util.List;
 
-import static java.lang.System.Logger.Level.DEBUG;
-import static java.lang.System.Logger.Level.ERROR;
+import static java.lang.System.Logger.Level.*;
 
 final class DGraphiteReporter implements GraphiteReporter {
 
@@ -30,7 +29,7 @@ public void report() {
       }
       sender.flush();
     } catch (IOException e) {
-      log.log(ERROR, "Error reporting metrics", e);
+      log.log(WARNING, "Error reporting metrics", e);
     } finally {
       try {
         sender.close();

metrics-graphite/src/main/java/io/avaje/metrics/graphite/DGraphiteSender.java

@@ -1,5 +1,6 @@
 package io.avaje.metrics.graphite;
 
+import io.avaje.applog.AppLog;
 import io.avaje.metrics.*;
 
 import javax.net.SocketFactory;
@@ -11,13 +12,17 @@
 import java.util.List;
 import java.util.regex.Pattern;
 
+import static java.lang.System.Logger.Level.INFO;
+import static java.lang.System.Logger.Level.WARNING;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 /**
  * A client to a Carbon server that sends all metrics after they have been pickled in configurable sized batches
  */
 final class DGraphiteSender implements GraphiteSender {
 
+  private static final System.Logger log = AppLog.getLogger(GraphiteReporter.class);
+
   /**
    * Minimally necessary pickle opcodes.
    */
@@ -40,7 +45,6 @@ final class DGraphiteSender implements GraphiteSender {
   private final String prefix;
   private final long timedThreshold;
   private Socket socket;
-  private Writer writer;
 
   DGraphiteSender(InetSocketAddress address, SocketFactory socketFactory, int batchSize, String prefix, long timedThreshold) {
     this.address = address;
@@ -56,7 +60,6 @@ public void connect() throws IOException {
       throw new IllegalStateException("Already connected");
     }
     this.socket = socketFactory.createSocket(address.getAddress(), address.getPort());
-    this.writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream(), UTF_8));
   }
 
   @Override
@@ -138,25 +141,27 @@ public void visit(GaugeLong.Stats gauge) {
   @Override
   public void flush() throws IOException {
     writeMetrics();
-    if (writer != null) {
-      writer.flush();
-    }
   }
 
   @Override
-  public void close() throws IOException {
+  public void close() {
     try {
       flush();
-      if (writer != null) {
-        writer.close();
-      }
-    } catch (IOException ex) {
-      if (socket != null) {
+    } catch (IOException e) {
+      log.log(INFO, "Exception flushing metrics {0}", e);
+    } finally {
+      closeSocket();
+    }
+  }
+
+  private void closeSocket() {
+    if (socket != null) {
+      try {
         socket.close();
+      } catch (IOException e) {
+        log.log(INFO, "Exception trying to close socket {0}", e);
       }
-    } finally {
-      this.socket = null;
-      this.writer = null;
+      socket = null;
     }
   }
 
@@ -168,13 +173,9 @@ public void close() throws IOException {
   private void writeMetrics() throws IOException {
     if (!metrics.isEmpty()) {
       try {
-        byte[] payload = pickleMetrics(metrics);
-        byte[] header = ByteBuffer.allocate(4).putInt(payload.length).array();
-
-        OutputStream outputStream = socket.getOutputStream();
-        outputStream.write(header);
-        outputStream.write(payload);
-        outputStream.flush();
+        final byte[] payload = pickleMetrics(metrics);
+        final byte[] header = ByteBuffer.allocate(4).putInt(payload.length).array();
+        send(header, payload);
       } finally {
         // if there was an error, we might miss some data. for now, drop those on the floor and
         // try to keep going.
@@ -183,6 +184,24 @@ private void writeMetrics() throws IOException {
     }
   }
 
+  private void send(byte[] header, byte[] payload) throws IOException {
+    try {
+      sendPayload(header, payload);
+    } catch (IOException e) {
+      log.log(WARNING, "Retry sending metrics due to {0}", e);
+      closeSocket();
+      this.socket = socketFactory.createSocket(address.getAddress(), address.getPort());
+      sendPayload(header, payload);
+    }
+  }
+
+  private void sendPayload(byte[] header, byte[] payload) throws IOException {
+    OutputStream outputStream = socket.getOutputStream();
+    outputStream.write(header);
+    outputStream.write(payload);
+    outputStream.flush();
+  }
+
   /**
    * See: <a href="http://readthedocs.org/docs/graphite/en/1.0/feeding-carbon.html">feeding-carbon</a>
    */
@@ -247,10 +266,11 @@ public String sanitize(String string) {
     return WHITESPACE.matcher(string.trim()).replaceAll(DASH);
   }
 
-  static class MetricTuple {
-    long timestamp;
-    String value;
-    String[] names;
+  static final class MetricTuple {
+
+    final long timestamp;
+    final String value;
+    final String[] names;
 
     MetricTuple(long timestamp, String value, String... names) {
       this.timestamp = timestamp;