[
https://issues.apache.org/jira/browse/KAFKA-3768?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Satendra Kumar updated KAFKA-3768:
----------------------------------
Description:
Scala recommend use if/else block instead of pattern match on boolean values.
For example:
{code:title=Comparasion.scala|borderStyle=solid}
class Comparasion {
def method1(flag: Boolean): String = {
flag match {
case true => "TRUE"
case false => "FALSE"
}
}
def method2(flag: Boolean): String = {
if(flag) {
"TRUE"
}else {
"FALSE"
}
}
}
{code}
Byte code comparison between method1 and method2:
scala>javap -cp Comparasion
{code:title=Comparasion.class|borderStyle=solid}
Compiled from "<console>"
public class Comparasion {
public java.lang.String method1(boolean);
Code:
0: iload_1
1: istore_2
2: iconst_1
3: iload_2
4: if_icmpne 13
7: ldc #9 // String TRUE
9: astore_3
10: goto 21
13: iconst_0
14: iload_2
15: if_icmpne 23
18: ldc #11 // String FALSE
20: astore_3
21: aload_3
22: areturn
23: new #13 // class scala/MatchError
26: dup
27: iload_2
28: invokestatic #19 // Method
scala/runtime/BoxesRunTime.boxToBoolean:(Z)Ljava/lang/Boolean;
31: invokespecial #23 // Method
scala/MatchError."<init>":(Ljava/lang/Object;)V
34: athrow
public java.lang.String method2(boolean);
Code:
0: iload_1
1: ifeq 9
4: ldc #9 // String TRUE
6: goto 11
9: ldc #11 // String FALSE
11: areturn
public Comparasion();
Code:
0: aload_0
1: invokespecial #33 // Method
java/lang/Object."<init>":()V
4: return
}
{code}
method1 have 23 line of byte code and method2 have only 6 line byte code.
Pattern match are more expensive comparison to if/else block.
was:
Scala recommend use if/else clock instead of pattern match on boolean values.
For example:
class Comparasion {
def method1(flag: Boolean): String = {
flag match {
case true => "TRUE"
case false => "FALSE"
}
}
def method2(flag: Boolean): String = {
if(flag) {
"TRUE"
}else {
"FALSE"
}
}
}
Byte code comparison between method1 and method2:
scala>javap -cp Comparasion
Compiled from "<console>"
public class Comparasion {
public java.lang.String method1(boolean);
Code:
0: iload_1
1: istore_2
2: iconst_1
3: iload_2
4: if_icmpne 13
7: ldc #9 // String TRUE
9: astore_3
10: goto 21
13: iconst_0
14: iload_2
15: if_icmpne 23
18: ldc #11 // String FALSE
20: astore_3
21: aload_3
22: areturn
23: new #13 // class scala/MatchError
26: dup
27: iload_2
28: invokestatic #19 // Method
scala/runtime/BoxesRunTime.boxToBoolean:(Z)Ljava/lang/Boolean;
31: invokespecial #23 // Method
scala/MatchError."<init>":(Ljava/lang/Object;)V
34: athrow
public java.lang.String method2(boolean);
Code:
0: iload_1
1: ifeq 9
4: ldc #9 // String TRUE
6: goto 11
9: ldc #11 // String FALSE
11: areturn
public Comparasion();
Code:
0: aload_0
1: invokespecial #33 // Method
java/lang/Object."<init>":()V
4: return
}
method1 have 23 line of byte code and 6 line byte code. Pattern match are more
expensive comparison to if/else block.
> Replace all pattern match on boolean value by if/elase block.
> -------------------------------------------------------------
>
> Key: KAFKA-3768
> URL: https://issues.apache.org/jira/browse/KAFKA-3768
> Project: Kafka
> Issue Type: Improvement
> Reporter: Satendra Kumar
> Priority: Minor
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> Scala recommend use if/else block instead of pattern match on boolean
> values.
> For example:
> {code:title=Comparasion.scala|borderStyle=solid}
> class Comparasion {
> def method1(flag: Boolean): String = {
> flag match {
> case true => "TRUE"
> case false => "FALSE"
> }
> }
> def method2(flag: Boolean): String = {
> if(flag) {
> "TRUE"
> }else {
> "FALSE"
> }
> }
> }
> {code}
> Byte code comparison between method1 and method2:
> scala>javap -cp Comparasion
> {code:title=Comparasion.class|borderStyle=solid}
> Compiled from "<console>"
> public class Comparasion {
> public java.lang.String method1(boolean);
> Code:
> 0: iload_1
> 1: istore_2
> 2: iconst_1
> 3: iload_2
> 4: if_icmpne 13
> 7: ldc #9 // String TRUE
> 9: astore_3
> 10: goto 21
> 13: iconst_0
> 14: iload_2
> 15: if_icmpne 23
> 18: ldc #11 // String FALSE
> 20: astore_3
> 21: aload_3
> 22: areturn
> 23: new #13 // class scala/MatchError
> 26: dup
> 27: iload_2
> 28: invokestatic #19 // Method
> scala/runtime/BoxesRunTime.boxToBoolean:(Z)Ljava/lang/Boolean;
> 31: invokespecial #23 // Method
> scala/MatchError."<init>":(Ljava/lang/Object;)V
> 34: athrow
> public java.lang.String method2(boolean);
> Code:
> 0: iload_1
> 1: ifeq 9
> 4: ldc #9 // String TRUE
> 6: goto 11
> 9: ldc #11 // String FALSE
> 11: areturn
> public Comparasion();
> Code:
> 0: aload_0
> 1: invokespecial #33 // Method
> java/lang/Object."<init>":()V
> 4: return
> }
> {code}
> method1 have 23 line of byte code and method2 have only 6 line byte code.
> Pattern match are more expensive comparison to if/else block.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
