Github user chunhui-shi commented on a diff in the pull request:
https://github.com/apache/drill/pull/430#discussion_r57202442
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/HashHelper.java
---
@@ -17,47 +17,77 @@
*/
package org.apache.drill.exec.expr.fn.impl;
+import io.netty.buffer.DrillBuf;
+import org.apache.drill.common.config.DrillConfig;
+import org.apache.drill.common.exceptions.DrillConfigurationException;
+
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
-public class HashHelper {
+public abstract class HashHelper {
static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(HashHelper.class);
+ public static final String defaultHashClassName = new
String("org.apache.drill.exec.expr.fn.impl.MurmurHash3");
+ static final String HASH_CLASS_PROP = "drill.exec.hash.class";
+ static String actualHashClassName = defaultHashClassName;
+ static DrillHash hashCall = new MurmurHash3();
+ static {
- /** taken from mahout **/
- public static int hash(ByteBuffer buf, int seed) {
- // save byte order for later restoration
-
- int m = 0x5bd1e995;
- int r = 24;
+ try {
+ DrillConfig config = DrillConfig.create();
+ String configuredClassName = config.getString(HASH_CLASS_PROP);
+ if(configuredClassName != null && configuredClassName != "") {
+ actualHashClassName = configuredClassName;
+ hashCall = config.getInstanceOf(HASH_CLASS_PROP, DrillHash.class);
+ }
+ logger.debug("HashHelper initializes with " + actualHashClassName);
+ }
+ catch(Exception ex){
+ logger.error("Could not initialize Hash %s", ex.getMessage());
+ }
+ }
- int h = seed ^ buf.remaining();
+ public static String getHashClassName(){
+ return actualHashClassName;
+ }
- while (buf.remaining() >= 4) {
- int k = buf.getInt();
+ public static int hash32(int val, long seed) {
+ double converted = val;
+ return hash32(converted, seed);
+ }
+ public static int hash32(long val, long seed) {
+ double converted = val;
+ return hash32(converted, seed);
+ }
+ public static int hash32(float val, long seed){
+ double converted = val;
+ return hash32(converted, seed);
+ }
- k *= m;
- k ^= k >>> r;
- k *= m;
+ public static int hash32(double val, long seed){
+ return hashCall.hash32(val, seed);
+ }
- h *= m;
- h ^= k;
- }
+ public static int hash32(int start, int end, DrillBuf buffer, int seed){
+ return hashCall.hash32(start, end, buffer, seed);
--- End diff --
I looked at the JIT optimized result (C2) at runtime, you are right that
this 'hashCall' did not get optimized, the optimization effort seems adding an
extra comparing logic of 3 instructions (checking if it is hashCall) before the
inline optimization as shown below:
0x00007f8bb75f38ac: mov $0x7c5f3b438,%r10 ; {oop(a
'java/lang/Class' = 'org/apache/drill/exec/expr/fn/impl/HashHelper')}
0x00007f8bb75f38b6: cmp 0x68(%r10),%r12d
0x00007f8bb75f38ba: je 0x00007f8bb75f38d6 ;*invokevirtual hash32
; -
org.apache.drill.exec.expr.fn.impl.HashHelper::hash32@7 (line 80)
So I will be removing the indirection. Thanks.
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