Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/574#discussion_r78168984
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/DrillFunctionRegistry.java
---
@@ -218,4 +302,141 @@ private void
registerOperatorsWithoutInference(DrillOperatorTable operatorTable)
}
}
}
+
+ /**
+ * Function registry holder. Stores function implementations by jar
name, function name.
+ */
+ private class GenericRegistryHolder<T, U> {
+ private final ReadWriteLock readWriteLock = new
ReentrantReadWriteLock();
+ private final AutoCloseableLock readLock = new
AutoCloseableLock(readWriteLock.readLock());
+ private final AutoCloseableLock writeLock = new
AutoCloseableLock(readWriteLock.writeLock());
+
--- End diff --
I use ReentrantReadWriteLock to perform locking, and then wrap its read /
write locks into AutoCloseableLock. It should work as documented [1]: allow
multiple reads at the same time, restrict to one write at a time, disallow
reads and writes at the same time.
[1]
https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/locks/ReentrantReadWriteLock.html
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