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use MethodHandles instead of reflect.Method #4329

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use MethodHandles instead of reflect.Method #4329

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1001b52
use MethodHandles instead of reflect.Method
pjfanning Jan 18, 2024
ef5a7c0
Merge branch '2.17' into method-handle
cowtowncoder Jun 8, 2024
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53 changes: 33 additions & 20 deletions src/main/java/com/fasterxml/jackson/databind/jdk14/JDK14Util.java
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
package com.fasterxml.jackson.databind.jdk14;

import java.lang.reflect.Method;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.util.Collections;
import java.util.List;

Expand Down Expand Up @@ -41,9 +43,9 @@ public static AnnotatedConstructor findRecordConstructor(AnnotatedClass recordCl
}

static class RecordAccessor {
private final Method RECORD_GET_RECORD_COMPONENTS;
private final Method RECORD_COMPONENT_GET_NAME;
private final Method RECORD_COMPONENT_GET_TYPE;
private final MethodHandle RECORD_GET_RECORD_COMPONENTS;
private final MethodHandle RECORD_COMPONENT_GET_NAME;
private final MethodHandle RECORD_COMPONENT_GET_TYPE;

private final static RecordAccessor INSTANCE;
private final static RuntimeException PROBLEM;
Expand All @@ -62,14 +64,25 @@ static class RecordAccessor {

private RecordAccessor() throws RuntimeException {
try {
RECORD_GET_RECORD_COMPONENTS = Class.class.getMethod("getRecordComponents");
Class<?> c = Class.forName("java.lang.reflect.RecordComponent");
RECORD_COMPONENT_GET_NAME = c.getMethod("getName");
RECORD_COMPONENT_GET_TYPE = c.getMethod("getType");
} catch (Exception e) {
final Class<?> recordComponentClass = Class.forName("java.lang.reflect.RecordComponent");
final MethodHandles.Lookup lookup = MethodHandles.lookup();
final MethodType classReturnMethodType = MethodType.methodType(Class.class);
final MethodType stringReturnMethodType = MethodType.methodType(String.class);
final MethodHandle arrayTypeMethodHandle =
lookup.findVirtual(Class.class, "arrayType", classReturnMethodType);
final Class<?> recordComponentArrayClass = (Class<?>)
arrayTypeMethodHandle.invokeExact(recordComponentClass);
final MethodType recordComponentArrayMethodType = MethodType.methodType(recordComponentArrayClass);
RECORD_GET_RECORD_COMPONENTS = lookup.findVirtual(
Class.class, "getRecordComponents", recordComponentArrayMethodType);
RECORD_COMPONENT_GET_NAME = lookup.findVirtual(
recordComponentClass, "getName", stringReturnMethodType);
RECORD_COMPONENT_GET_TYPE = lookup.findVirtual(
recordComponentClass, "getType", classReturnMethodType);
} catch (Throwable t) {
throw new RuntimeException(String.format(
"Failed to access Methods needed to support `java.lang.Record`: (%s) %s",
e.getClass().getName(), e.getMessage()), e);
"Failed to access Methods needed to support `java.lang.Record`: (%s) %s",
t.getClass().getName(), t.getMessage()), t);
}
}

Expand All @@ -91,10 +104,10 @@ public String[] getRecordFieldNames(Class<?> recordType) throws IllegalArgumentE
for (int i = 0; i < components.length; i++) {
try {
names[i] = (String) RECORD_COMPONENT_GET_NAME.invoke(components[i]);
} catch (Exception e) {
} catch (Throwable t) {
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What would be the reason to catch Errors too?

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it's a required change unfortunately because invoke throws Throwable. this method shouldnt throw at all though

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Ok. Odd, not sure why it does that... never understood why method signature would do that (given Errors need not be declared anyway so why not just throws Exception). Oh well. At least this is for a reason then.

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Did you know that Java reflection API is now implemented using MethodHandle(s)? So by using Java reflection, you are already using MethodHandle(s) under the hood.

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Is this what you mean?
https://openjdk.org/jeps/416

I'll close this PR anyway because of the animal sniffer issues.

throw new IllegalArgumentException(String.format(
"Failed to access name of field #%d (of %d) of Record type %s",
i, components.length, ClassUtil.nameOf(recordType)), e);
i, components.length, ClassUtil.nameOf(recordType)), t);
}
}
return names;
Expand All @@ -112,18 +125,18 @@ public RawTypeName[] getRecordFields(Class<?> recordType) throws IllegalArgument
String name;
try {
name = (String) RECORD_COMPONENT_GET_NAME.invoke(components[i]);
} catch (Exception e) {
} catch (Throwable t) {
throw new IllegalArgumentException(String.format(
"Failed to access name of field #%d (of %d) of Record type %s",
i, components.length, ClassUtil.nameOf(recordType)), e);
i, components.length, ClassUtil.nameOf(recordType)), t);
}
Class<?> type;
try {
type = (Class<?>) RECORD_COMPONENT_GET_TYPE.invoke(components[i]);
} catch (Exception e) {
} catch (Throwable t) {
throw new IllegalArgumentException(String.format(
"Failed to access type of field #%d (of %d) of Record type %s",
i, components.length, ClassUtil.nameOf(recordType)), e);
i, components.length, ClassUtil.nameOf(recordType)), t);
}
results[i] = new RawTypeName(type, name);
}
Expand All @@ -134,12 +147,12 @@ protected Object[] recordComponents(Class<?> recordType) throws IllegalArgumentE
{
try {
return (Object[]) RECORD_GET_RECORD_COMPONENTS.invoke(recordType);
} catch (Exception e) {
if (NativeImageUtil.isUnsupportedFeatureError(e)) {
} catch (Throwable t) {
if (NativeImageUtil.isUnsupportedFeatureError(t)) {
return null;
}
throw new IllegalArgumentException("Failed to access RecordComponents of type "
+ClassUtil.nameOf(recordType));
+ ClassUtil.nameOf(recordType));
}
}

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