Limit time waiting for the "retry lock" + stop retrying if the thread…

… is interrupted

src/main/java/net/logstash/logback/appender/AsyncDisruptorAppender.java

@@ -530,7 +530,7 @@ protected void append(Event event) {
                 if ((consecutiveDropped % this.droppedWarnFrequency) == 1) {
                     addWarn("Dropped " + consecutiveDropped + " events (and counting...) due to ring buffer at max capacity [" + this.ringBufferSize + "]");
                 }
-
+                
                 // Notify listeners
                 //
                 fireEventAppendFailed(event, RING_BUFFER_FULL_EXCEPTION);
@@ -539,6 +539,10 @@ protected void append(Event event) {
         } catch (ShutdownInProgressException e) {
             // Same message as if Appender#append is called after the appender is stopped...
             addWarn("Attempted to append to non started appender [" + this.getName() + "].");
+
+        } catch (InterruptedException e) {
+            // be silent but re-interrupt the thread
+            Thread.currentThread().interrupt();
         }
     }
 
@@ -551,8 +555,9 @@ protected void append(Event event) {
      *         could not be added to the ring buffer.
      * @throws ShutdownInProgressException thrown when the appender is shutdown while retrying
      *         to enqueue the event
+     * @throws InterruptedException thrown when the logging thread is interrupted while retrying
      */
-    private boolean enqueue(Event event) throws ShutdownInProgressException {
+    private boolean enqueue(Event event) throws ShutdownInProgressException, InterruptedException {
         // Try enqueue the "normal" way
         //
         if (this.disruptor.getRingBuffer().tryPublishEvent(this.eventTranslator, event)) {
@@ -567,31 +572,39 @@ private boolean enqueue(Event event) throws ShutdownInProgressException {
 
         // Determine how long we can retry
         //
-        long deadline = this.appendTimeout.getMilliseconds() < 0
+        final long waitTime = this.appendTimeout.getMilliseconds() < 0
                 ? Long.MAX_VALUE
-                : System.currentTimeMillis() + this.appendTimeout.getMilliseconds();
+                : this.appendTimeout.getMilliseconds();
+        final long deadline = System.currentTimeMillis() + waitTime;
 
         long backoff = 1L;
         long backoffLimit = TimeUnit.MILLISECONDS.toNanos(this.appendRetryFrequency.getMilliseconds());
-
+        
 
         // Limit retries to a single thread at once to avoid burning CPU cycles "for nothing"
         // in CPU constraint environments.
         //
-        lock.lock();
+        if (!lock.tryLock(waitTime, TimeUnit.MILLISECONDS)) {
+            return false;
+        }
+
         try {
             do {
+                if (!isStarted()) {
+                    throw new ShutdownInProgressException();
+                }
+
                 if (deadline <= System.currentTimeMillis()) {
                     return false;
                 }
 
-                if (!isStarted()) {
-                    throw new ShutdownInProgressException();
+                if (Thread.currentThread().isInterrupted()) {
+                    throw new InterruptedException();
                 }
-
+                
                 LockSupport.parkNanos(backoff);
                 backoff = Math.min(backoff * 2, backoffLimit);
-
+                
             } while (!this.disruptor.getRingBuffer().tryPublishEvent(this.eventTranslator, event));
 
             return true;