Logger: Log context of DruidExceptions. (apache#17316)

* Logger: Log context of DruidExceptions.

There is often interesting and unique information available in the
"context" of a DruidException. This information is additive to both
the message and the cause, and was missed when we log. This patch adds
the DruidException context to log messages whenever stack traces are
enabled.

* Only log nonempty contexts.

processing/src/main/java/org/apache/druid/java/util/common/logger/Logger.java

@@ -21,6 +21,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
+import org.apache.druid.error.DruidException;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.SegmentId;
@@ -103,8 +104,9 @@ public String toString()
   }
 
   /**
-   * Returns a copy of this Logger that does not log exception stack traces, unless the log level is DEBUG or lower.
-   * Useful for writing code like: {@code log.noStackTrace().warn(e, "Something happened.");}
+   * Returns a copy of this Logger that does not log exception stack traces or {@link DruidException#getContext()},
+   * unless the log level is DEBUG or lower. Useful for writing code like:
+   * {@code log.noStackTrace().warn(e, "Something happened.");}
    */
   public Logger noStackTrace()
   {
@@ -270,7 +272,14 @@ public boolean isInfoEnabled()
 
   private void logException(BiConsumer<String, Throwable> fn, Throwable t, String message)
   {
-    if (stackTraces || log.isDebugEnabled()) {
+    final boolean logStackTrace = stackTraces || log.isDebugEnabled();
+
+    if (logStackTrace) {
+      // If logging stack traces, *also* log extra context information about DruidExceptions.
+      if (t instanceof DruidException && !((DruidException) t).getContext().isEmpty()) {
+        message = (message == null ? "" : message + "\nDruidException context: " + ((DruidException) t).getContext());
+      }
+
       fn.accept(message, t);
     } else {
       if (message.isEmpty()) {