Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/574#discussion_r77698675
--- 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());
+
+ // jar name, Map<function name, List<signature>
+ private final Map<T, Map<T, List<T>>> jars;
+
+ // function name, Map<signature, function holder>
--- End diff --
T appears to be a String. functions is a map of signature to map of Strings
to FuncHolders. This is crying out for an explanation. How is the signature
represented? Classic Java encoding? Something else? What does the Map hold?
What is the key in the inner map? Function name? Jar name? Meaning will become
clear by studying the code, but much time could be saved by explaining the
structure in a comment.
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