Adding retry logic to Loggly appenders

.gitignore

@@ -12,3 +12,4 @@ target
 out
 build
 local.properties
+/.nb-gradle/

loggly/src/main/java/ch/qos/logback/ext/loggly/AbstractLogglyAppender.java

@@ -35,6 +35,7 @@
  * @author <a href="mailto:cleclerc@xebia.fr">Cyrille Le Clerc</a>
  */
 public abstract class AbstractLogglyAppender<E> extends UnsynchronizedAppenderBase<E> {
+
     public static final String DEFAULT_ENDPOINT_PREFIX = "https://logs-01.loggly.com/";
     public static final String DEFAULT_LAYOUT_PATTERN = "%d{\"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'\",UTC} %-5level [%thread] %logger: %m%n";
     protected static final Charset UTF_8 = Charset.forName("UTF-8");
@@ -48,6 +49,7 @@ public abstract class AbstractLogglyAppender<E> extends UnsynchronizedAppenderBa
     private String proxyHost;
     protected Proxy proxy;
     private int httpReadTimeoutInMillis = 1000;
+    private int httpMaxNumberOfRetries = 3;
 
     @Override
     public void start() {
@@ -90,7 +92,7 @@ protected byte[] toBytes(final InputStream is) throws IOException {
         int count;
         byte[] buf = new byte[512];
 
-        while((count = is.read(buf, 0, buf.length)) != -1) {
+        while ((count = is.read(buf, 0, buf.length)) != -1) {
             baos.write(buf, 0, count);
         }
         baos.flush();
@@ -135,14 +137,13 @@ protected String buildEndpointUrl(String inputKey) {
         return new StringBuilder(DEFAULT_ENDPOINT_PREFIX).append(getEndpointPrefix())
                 .append(inputKey).toString();
     }
-    
+
     /**
-     * Returns the URL path prefix for the Loggly endpoint to which the 
-     * implementing class will send log events. This path prefix varies
-     * for the different Loggly services. The final endpoint URL is built
-     * by concatenating the {@link #DEFAULT_ENDPOINT_PREFIX} with the
-     * endpoint prefix from {@link #getEndpointPrefix()} and the 
-     * {@link #inputKey}.
+     * Returns the URL path prefix for the Loggly endpoint to which the
+     * implementing class will send log events. This path prefix varies for the
+     * different Loggly services. The final endpoint URL is built by
+     * concatenating the {@link #DEFAULT_ENDPOINT_PREFIX} with the endpoint
+     * prefix from {@link #getEndpointPrefix()} and the {@link #inputKey}.
      *
      * @return the URL path prefix for the Loggly endpoint
      */
@@ -194,8 +195,9 @@ public int getProxyPort() {
     public void setProxyPort(int proxyPort) {
         this.proxyPort = proxyPort;
     }
+
     public void setProxyPort(String proxyPort) {
-        if(proxyPort == null || proxyPort.trim().isEmpty()) {
+        if (proxyPort == null || proxyPort.trim().isEmpty()) {
             // handle logback configuration default value like "<proxyPort>${logback.loggly.proxy.port:-}</proxyPort>"
             proxyPort = "0";
         }
@@ -207,7 +209,7 @@ public String getProxyHost() {
     }
 
     public void setProxyHost(String proxyHost) {
-        if(proxyHost == null || proxyHost.trim().isEmpty()) {
+        if (proxyHost == null || proxyHost.trim().isEmpty()) {
             // handle logback configuration default value like "<proxyHost>${logback.loggly.proxy.host:-}</proxyHost>"
             proxyHost = null;
         }
@@ -221,4 +223,20 @@ public int getHttpReadTimeoutInMillis() {
     public void setHttpReadTimeoutInMillis(int httpReadTimeoutInMillis) {
         this.httpReadTimeoutInMillis = httpReadTimeoutInMillis;
     }
+
+    public int getHttpMaxNumberOfRetries() {
+        return httpMaxNumberOfRetries;
+    }
+
+    public void setHttpMaxNumberOfRetries(int httpMaxNumberOfRetries) {
+        if (httpMaxNumberOfRetries <= 0) {
+            this.httpMaxNumberOfRetries = 0;
+        } else {
+            this.httpMaxNumberOfRetries = httpMaxNumberOfRetries;
+        }
+    }
+
+    protected boolean canRetry(int currentRetryCount) {
+        return currentRetryCount <= getHttpMaxNumberOfRetries();
+    }
 }

loggly/src/main/java/ch/qos/logback/ext/loggly/LogglyAppender.java

@@ -21,7 +21,8 @@
 import java.net.URL;
 
 /**
- * An Appender that posts logging messages to <a href="http://www.loggly.com">Loggly</a>, a cloud logging service.
+ * An Appender that posts logging messages to
+ * <a href="http://www.loggly.com">Loggly</a>, a cloud logging service.
  *
  * @author Mårten Gustafson
  * @author Les Hazlewood
@@ -30,7 +31,7 @@
 public class LogglyAppender<E> extends AbstractLogglyAppender<E> {
 
     public static final String ENDPOINT_URL_PATH = "inputs/";
-    
+
     public LogglyAppender() {
     }
 
@@ -41,28 +42,37 @@ protected void append(E eventObject) {
     }
 
     private void postToLoggly(final String event) {
-        try {
-            assert endpointUrl != null;
-            URL endpoint = new URL(endpointUrl);
-            final HttpURLConnection connection;
-            if (proxy == null) {
-                connection = (HttpURLConnection) endpoint.openConnection();
-            } else {
-                connection = (HttpURLConnection) endpoint.openConnection(proxy);
+        int currentRetryCount = 0;
+        boolean success = false;
+        while (!success && canRetry(currentRetryCount)) {
+            try {
+                assert endpointUrl != null;
+                URL endpoint = new URL(endpointUrl);
+                final HttpURLConnection connection;
+                if (proxy == null) {
+                    connection = (HttpURLConnection) endpoint.openConnection();
+                } else {
+                    connection = (HttpURLConnection) endpoint.openConnection(proxy);
+                }
+                connection.setRequestMethod("POST");
+                connection.setDoOutput(true);
+                connection.addRequestProperty("Content-Type", this.layout.getContentType());
+                connection.connect();
+                sendAndClose(event, connection.getOutputStream());
+                connection.disconnect();
+                final int responseCode = connection.getResponseCode();
+                if (responseCode == 200) {
+                    success = true;
+                } else if (!canRetry(currentRetryCount)) {
+                    final String message = readResponseBody(connection.getInputStream());
+                    addError("Loggly post failed (HTTP " + responseCode + ").  Response body:\n" + message);
+                } 
+            } catch (final IOException e) {
+                if (!canRetry(currentRetryCount)) {
+                    addError("IOException while attempting to communicate with Loggly", e);
+                }
             }
-            connection.setRequestMethod("POST");
-            connection.setDoOutput(true);
-            connection.addRequestProperty("Content-Type", this.layout.getContentType());
-            connection.connect();
-            sendAndClose(event, connection.getOutputStream());
-            connection.disconnect();
-            final int responseCode = connection.getResponseCode();
-            if (responseCode != 200) {
-                final String message = readResponseBody(connection.getInputStream());
-                addError("Loggly post failed (HTTP " + responseCode + ").  Response body:\n" + message);
-            }
-        } catch (final IOException e) {
-            addError("IOException while attempting to communicate with Loggly", e);
+            currentRetryCount++;
         }
     }
 
@@ -79,4 +89,3 @@ protected String getEndpointPrefix() {
         return ENDPOINT_URL_PATH;
     }
 }
-