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8332249: Micro-optimize Method.hashCode #19433

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8332249: Micro-optimize Method.hashCode #19433

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de10484
Micro-optimize Method.hashCode
sgwizdak-aws May 28, 2024
fcab4f2
Fix whitespace issues pointed by the bot
sgwizdak-aws May 28, 2024
2e4c0c9
Remove changes to JavaDoc per guidance.
sgwizdak-aws May 28, 2024
0893009
Merge branch 'master' into method-hashcode-JDK-8332249
sgwizdak-aws Jun 3, 2024
ab5bc86
Move hashCode benchmark into the newly created MethodBenchmark file
sgwizdak-aws Jun 3, 2024
4364d99
Remove trailing whitespace.
sgwizdak-aws Jun 3, 2024
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10 changes: 9 additions & 1 deletion src/java.base/share/classes/java/lang/reflect/Method.java
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,8 @@ public final class Method extends Executable {
// If this branching structure would ever contain cycles, deadlocks can
// occur in annotation code.
private Method root;
// Hash code of this object
private int hash;

// Generics infrastructure
private String getGenericSignature() {return signature;}
Expand Down Expand Up @@ -381,7 +383,13 @@ public boolean equals(Object obj) {
* method's declaring class name and the method's name.
*/
public int hashCode() {
return getDeclaringClass().getName().hashCode() ^ getName().hashCode();
int hc = hash;

if (hc == 0) {
hc = hash = getDeclaringClass().getName().hashCode() ^ getName()
.hashCode();
}
return hc;
}

/**
Expand Down
13 changes: 11 additions & 2 deletions test/micro/org/openjdk/bench/java/lang/reflect/MethodBenchmark.java
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Expand Up @@ -36,8 +36,9 @@
import org.openjdk.jmh.annotations.Warmup;

/**
* Benchmark measuring the speed of Method/Method.getExceptionTypes() and
* getParameterTypes(), in cases where the result array is length zero.
* Benchmark measuring the speed of Method/Method.getExceptionTypes(),
* getParameterTypes() in cases where the result array is length zero,
* and hashCode().
*/
@BenchmarkMode(Mode.AverageTime)
@State(Scope.Benchmark)
Expand All @@ -50,6 +51,7 @@ public class MethodBenchmark {
Method emptyParametersMethod;
Method oneExceptionMethod;
Method oneParameterMethod;
Method hashCodeMethod;

public MethodBenchmark() {
try {
Expand All @@ -58,6 +60,8 @@ public MethodBenchmark() {

emptyExceptionsMethod = emptyParametersMethod;
oneExceptionMethod = oneParameterMethod;

hashCodeMethod = String.class.getDeclaredMethod("toString");
} catch (Exception e) {
throw new RuntimeException(e);
}
Expand All @@ -82,4 +86,9 @@ public Object[] getParameterTypes() throws Exception {
public Object[] getParameterTypesEmpty() throws Exception {
return emptyParametersMethod.getParameterTypes();
}

@Benchmark
public int getMethodHashCode() {
return hashCodeMethod.hashCode();
}
}