Github user jcmcote commented on a diff in the pull request:
https://github.com/apache/drill/pull/512#discussion_r66370984
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/CharSequenceWrapper.java
---
@@ -17,13 +17,52 @@
*/
package org.apache.drill.exec.expr.fn.impl;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.CharacterCodingException;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
+import java.nio.charset.CoderResult;
+import java.util.regex.Matcher;
+
import io.netty.buffer.DrillBuf;
+/**
+ * A CharSequence is a readable sequence of char values. This interface
provides
+ * uniform, read-only access to many different kinds of char sequences. A
char
+ * value represents a character in the Basic Multilingual Plane (BMP) or a
+ * surrogate. Refer to Unicode Character Representation for details.<br>
+ * Specifically this implementation of the CharSequence adapts a Drill
+ * {@link DrillBuf} to the CharSequence. The implementation is meant to be
+ * re-used that is allocated once and then passed DrillBuf to adapt. This
can be
+ * handy to exploit API that consume CharSequence avoiding the need to
create
+ * string objects.
+ *
+ */
public class CharSequenceWrapper implements CharSequence {
+ // The adapted drill buffer (in the case of US-ASCII)
+ private DrillBuf buffer;
+ // The converted bytes in the case of non ASCII
+ private CharBuffer charBuffer;
--- End diff --
The CharSequenceWrapper does the same work as the Java String. That is
convert the utf-8 bytes to a sequence of chars.
However it re-uses the CharBuffer instead of constantly allocating new
arrays and letting them garbage collect. This will eliminate lots of churn in
the GC.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
