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Extract a helper class for constructing lambdas from TemplateCompiler
This will soon be reused in a few different places. Add a tiny optimization for lambdas with zero bound parameters by compiling them to an `ldc` instruction. This special case happens to satisfy all of our current usecases and will satisfy a subset of the upcoming ones. This should be a tiny bootstraping and codesize improvement. PiperOrigin-RevId: 575868161
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java/src/com/google/template/soy/jbcsrc/restricted/LambdaFactory.java
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| /* | ||
| * Copyright 2023 Google Inc. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| package com.google.template.soy.jbcsrc.restricted; | ||
|
|
||
| import static com.google.common.base.Preconditions.checkArgument; | ||
| import static com.google.common.base.Preconditions.checkState; | ||
| import static java.util.Arrays.asList; | ||
|
|
||
| import com.google.common.collect.ImmutableList; | ||
| import com.google.template.soy.jbcsrc.restricted.Expression.Feature; | ||
| import com.google.template.soy.jbcsrc.restricted.Expression.Features; | ||
| import com.google.template.soy.jbcsrc.shared.ExtraConstantBootstraps; | ||
| import java.lang.invoke.LambdaMetafactory; | ||
| import java.lang.invoke.MethodHandle; | ||
| import java.lang.invoke.MethodHandles; | ||
| import java.lang.invoke.MethodType; | ||
| import org.objectweb.asm.ConstantDynamic; | ||
| import org.objectweb.asm.Handle; | ||
| import org.objectweb.asm.Type; | ||
|
|
||
| /** | ||
| * A helper for generating lambda callsites. Allows for some extra compile time checking and | ||
| * encapsulation. | ||
| */ | ||
| public final class LambdaFactory { | ||
|
|
||
| private static final Handle METAFACTORY_HANDLE = | ||
| MethodRef.createPure( | ||
| LambdaMetafactory.class, | ||
| "metafactory", | ||
| MethodHandles.Lookup.class, | ||
| String.class, | ||
| MethodType.class, | ||
| MethodType.class, | ||
| MethodHandle.class, | ||
| MethodType.class) | ||
| .asHandle(); | ||
| private static final Handle CONDY_METAFACTORY = | ||
| MethodRef.createPure( | ||
| ExtraConstantBootstraps.class, | ||
| "constantMetafactory", | ||
| MethodHandles.Lookup.class, | ||
| String.class, | ||
| Class.class, | ||
| MethodType.class, | ||
| MethodHandle.class, | ||
| MethodType.class) | ||
| .asHandle(); | ||
|
|
||
| /** | ||
| * Create a {@code LambdaFactory} that can create instances of an interface that implements {@code | ||
| * interfaceMethod} by delegating to {@code implMethod}. | ||
| */ | ||
| public static LambdaFactory create(MethodRef interfaceMethod, MethodRef implMethod) { | ||
| checkState(interfaceMethod.isInterfaceMethod(), "Only interfaces are supported"); | ||
| return new LambdaFactory(interfaceMethod.owner(), interfaceMethod, implMethod); | ||
| } | ||
|
|
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| private final TypeInfo interfaceType; | ||
| private final String interfaceMethodName; | ||
| private final Type interfaceMethodType; | ||
| private final MethodRef implMethod; | ||
| private final String callSiteDescriptor; | ||
| private final ImmutableList<Type> boundParams; | ||
|
|
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| private LambdaFactory(TypeInfo interfaceType, MethodRef interfaceMethod, MethodRef implMethod) { | ||
| this.interfaceType = interfaceType; | ||
| this.interfaceMethodName = interfaceMethod.method().getName(); | ||
| this.implMethod = implMethod; | ||
| // Skip the first param as it is the receiver type. MethodRef models 'receivers' as an argument | ||
| // but the jdk models them separately so from the perspective of the lambda-metafactory it isn't | ||
| // part of the interface method signature. | ||
| var interfaceMethodParams = | ||
| interfaceMethod.argTypes().subList(1, interfaceMethod.argTypes().size()); | ||
| this.interfaceMethodType = | ||
| Type.getMethodType( | ||
| interfaceMethod.returnType(), interfaceMethodParams.toArray(new Type[0])); | ||
| // Lambdas are essentially an inner classes | ||
| // class Impl extends Interface { | ||
| // Impl(...boundParams) {...} | ||
| // method(..freeParams) { return target(..boundParams, ...freeParams);} | ||
| // } | ||
| // So all 'free' params must be in trailing argument position of the target method and exactly | ||
| // match the interface method parameter types. | ||
| // The JDK does allow for there to be some mismatch, as long as the mismatches are resolvable | ||
| // with simple type coercion rules (aka if the java cast operator could handle it, so could the | ||
| // lambda factory). However, for now we require an exact match. | ||
| var trailingImplParams = | ||
| implMethod | ||
| .argTypes() | ||
| .subList( | ||
| implMethod.argTypes().size() - interfaceMethodParams.size(), | ||
| implMethod.argTypes().size()); | ||
| checkArgument( | ||
| interfaceMethodParams.equals(trailingImplParams), | ||
| "trailing parameters of %s must match the free parameters of %s", | ||
| implMethod, | ||
| interfaceMethod); | ||
| this.boundParams = | ||
| implMethod | ||
| .argTypes() | ||
| .subList(0, implMethod.argTypes().size() - interfaceMethodParams.size()); | ||
| this.callSiteDescriptor = | ||
| Type.getMethodDescriptor(interfaceType.type(), boundParams.toArray(new Type[0])); | ||
| } | ||
|
|
||
| public Expression invoke(Expression... args) { | ||
| return invoke(asList(args)); | ||
| } | ||
|
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| public Expression invoke(Iterable<Expression> args) { | ||
| Expression.checkTypes(boundParams, args); | ||
| var features = Features.of(Feature.NON_JAVA_NULLABLE, Feature.NON_SOY_NULLISH); | ||
| if (Expression.areAllCheap(args)) { | ||
| features = features.plus(Feature.CHEAP); | ||
| } | ||
| return new Expression(interfaceType.type(), features) { | ||
| @Override | ||
| protected void doGen(CodeBuilder cb) { | ||
| // When there are no bound parameters we can link this with condy instead of indy. | ||
| // According to Brian Goetz this should be faster to link even if the impls are identical | ||
| // See https://mail.openjdk.org/pipermail/amber-dev/2023-October/008327.html | ||
| if (boundParams.isEmpty()) { | ||
| cb.visitLdcInsn( | ||
| new ConstantDynamic( | ||
| interfaceMethodName, | ||
| interfaceType.type().getDescriptor(), | ||
| CONDY_METAFACTORY, | ||
| interfaceMethodType, | ||
| implMethod.asHandle(), | ||
| interfaceMethodType)); | ||
|
|
||
| } else { | ||
| for (Expression arg : args) { | ||
| arg.gen(cb); | ||
| } | ||
| cb.visitInvokeDynamicInsn( | ||
| interfaceMethodName, | ||
| callSiteDescriptor, | ||
| METAFACTORY_HANDLE, | ||
| interfaceMethodType, | ||
| implMethod.asHandle(), | ||
| interfaceMethodType); | ||
| } | ||
| } | ||
| }; | ||
| } | ||
| } |
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109 changes: 109 additions & 0 deletions
109
java/tests/com/google/template/soy/jbcsrc/restricted/LambdaFactoryTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,109 @@ | ||
| /* | ||
| * Copyright 2023 Google Inc. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package com.google.template.soy.jbcsrc.restricted; | ||
|
|
||
| import static com.google.common.truth.Truth.assertThat; | ||
| import static com.google.template.soy.jbcsrc.restricted.BytecodeUtils.constant; | ||
|
|
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| import com.google.template.soy.jbcsrc.restricted.testing.ExpressionEvaluator; | ||
| import java.util.function.BiFunction; | ||
| import java.util.function.Function; | ||
| import java.util.function.Supplier; | ||
| import org.junit.Test; | ||
| import org.junit.runner.RunWith; | ||
| import org.junit.runners.JUnit4; | ||
|
|
||
| @RunWith(JUnit4.class) | ||
| public final class LambdaFactoryTest { | ||
| // Interface methods to implement with a lambda | ||
| private static final MethodRef SUPPLIER_GET = MethodRef.createPure(Supplier.class, "get"); | ||
| private static final MethodRef FUNCTION_APPLY = | ||
| MethodRef.createPure(Function.class, "apply", Object.class); | ||
| private static final MethodRef BIFUNCTION_APPLY = | ||
| MethodRef.createPure(BiFunction.class, "apply", Object.class, Object.class); | ||
|
|
||
| // Implementation referecences | ||
| private static final MethodRef IDENTITY_FUNCTION = | ||
| MethodRef.createPure(LambdaFactoryTest.class, "identity", Object.class); | ||
| private static final MethodRef RETURNS_HELLO_FUNCTION = | ||
| MethodRef.createPure(LambdaFactoryTest.class, "returnsHello"); | ||
| private static final MethodRef CONCAT_FUNCTION = | ||
| MethodRef.createPure(LambdaFactoryTest.class, "concat", Object.class, Object.class); | ||
|
|
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| // Actual implementations | ||
| public static Object identity(Object o) { | ||
| return o; | ||
| } | ||
|
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| public static Object concat(Object o, Object o2) { | ||
| return o + ", " + o2; | ||
| } | ||
|
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| public static Object returnsHello() { | ||
| return "hello"; | ||
| } | ||
|
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| @Test | ||
| public void testNoBoundParameters() throws ReflectiveOperationException { | ||
| @SuppressWarnings("unchecked") | ||
| Supplier<Object> supplier = | ||
| (Supplier) | ||
| ExpressionEvaluator.evaluate( | ||
| LambdaFactory.create(SUPPLIER_GET, RETURNS_HELLO_FUNCTION).invoke()); | ||
|
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| assertThat(supplier.get()).isEqualTo("hello"); | ||
| } | ||
|
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| @Test | ||
| public void testOneBundParameter() throws ReflectiveOperationException { | ||
| @SuppressWarnings("unchecked") | ||
| Supplier<Object> supplier = | ||
| (Supplier) | ||
| ExpressionEvaluator.evaluate( | ||
| LambdaFactory.create(SUPPLIER_GET, IDENTITY_FUNCTION).invoke(constant("bound"))); | ||
| assertThat(supplier.get()).isEqualTo("bound"); | ||
| } | ||
|
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| @Test | ||
| public void testOneFreeParameter() throws ReflectiveOperationException { | ||
| @SuppressWarnings("unchecked") | ||
| Function<Object, Object> fn = | ||
| (Function) | ||
| ExpressionEvaluator.evaluate( | ||
| LambdaFactory.create(FUNCTION_APPLY, IDENTITY_FUNCTION).invoke()); | ||
| assertThat(fn.apply("free")).isEqualTo("free"); | ||
| } | ||
|
|
||
| @Test | ||
| public void testOneFreeAndOneBoundParameter() throws ReflectiveOperationException { | ||
| @SuppressWarnings("unchecked") | ||
| Function<Object, Object> fn = | ||
| (Function) | ||
| ExpressionEvaluator.evaluate( | ||
| LambdaFactory.create(FUNCTION_APPLY, CONCAT_FUNCTION).invoke(constant("first"))); | ||
| assertThat(fn.apply("second")).isEqualTo("first, second"); | ||
| } | ||
|
|
||
| @Test | ||
| public void testTwoFreeParameters() throws ReflectiveOperationException { | ||
| @SuppressWarnings("unchecked") | ||
| BiFunction<Object, Object, Object> fn = | ||
| (BiFunction) | ||
| ExpressionEvaluator.evaluate( | ||
| LambdaFactory.create(BIFUNCTION_APPLY, CONCAT_FUNCTION).invoke()); | ||
| assertThat(fn.apply("first", "second")).isEqualTo("first, second"); | ||
| } | ||
| } |