zuozhiw commented on a change in pull request #1484: [CALCITE-3386]
CyclicMetadataException singleton instance causes confusion when debugging
URL: https://github.com/apache/calcite/pull/1484#discussion_r331727687
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File path:
core/src/main/java/org/apache/calcite/rel/metadata/CyclicMetadataException.java
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@@ -21,15 +21,12 @@
* computing metadata.
*/
public class CyclicMetadataException extends RuntimeException {
- /** Singleton instance. Since this exception is thrown for signaling
purposes,
- * rather than on an actual error, re-using a singleton instance saves the
- * effort of constructing an exception instance. */
- @SuppressWarnings("ThrowableInstanceNeverThrown")
- public static final CyclicMetadataException INSTANCE =
- new CyclicMetadataException();
-
- /** Creates a CyclicMetadataException. */
- private CyclicMetadataException() {
+ /**
+ * Creates a CyclicMetadataException.
+ * Reusing a singleton instance is a bad idea because of wrong stack trace.
+ * See https://stackoverflow.com/questions/15090664
Review comment:
this is removed from the code and moved to commit message
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