Expose disruptor discard count in AsyncLoggerContext

Author: adamthom-amzn

log4j-core/src/main/java/org/apache/logging/log4j/core/async/AsyncLoggerContext.java

@@ -124,4 +124,14 @@ public RingBufferAdmin createRingBufferAdmin() {
     public void setUseThreadLocals(final boolean useThreadLocals) {
         loggerDisruptor.setUseThreadLocals(useThreadLocals);
     }
+
+    /**
+     * Returns the number of logging events discarded by the disruptor's queue full policy, or 0 if the disruptor
+     * does not use a discarding policy or has not discarded.
+     *
+     * @return 0 if the disruptor is not configured to discard or has not discarded, otherwise a positive long
+     */
+    public long getDiscardCount() {
+        return DiscardingAsyncQueueFullPolicy.getDiscardCount(loggerDisruptor.getAsyncQueueFullPolicy());
+    }
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/async/AsyncLoggerDisruptor.java

@@ -69,6 +69,10 @@ WaitStrategy getWaitStrategy() {
         return waitStrategy;
     }
 
+    AsyncQueueFullPolicy getAsyncQueueFullPolicy() {
+        return asyncQueueFullPolicy;
+    }
+
     public String getContextName() {
         return contextName;
     }

log4j-core/src/main/java/org/apache/logging/log4j/core/async/package-info.java

@@ -18,7 +18,7 @@
  * Provides Asynchronous Logger classes and interfaces for low-latency logging.
  */
 @Export
-@Version("2.21.0")
+@Version("2.22.0")
 package org.apache.logging.log4j.core.async;
 
 import org.osgi.annotation.bundle.Export;