| // Copyright 2023 The Bazel Authors. All rights reserved. |
| // |
| // 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.devtools.build.lib.skyframe.serialization.autocodec; |
| |
| import com.google.devtools.build.lib.skyframe.serialization.ObjectCodec; |
| import com.google.devtools.build.lib.unsafe.UnsafeProvider; |
| import com.squareup.javapoet.ClassName; |
| import com.squareup.javapoet.MethodSpec; |
| import com.squareup.javapoet.TypeSpec; |
| import javax.lang.model.element.Modifier; |
| import javax.lang.model.element.Name; |
| import javax.lang.model.element.TypeElement; |
| import javax.lang.model.element.VariableElement; |
| |
| /** |
| * Generates code for a specific field. |
| * |
| * <p>Always stores the offset of the field in a variable named {@link #getOffsetName}. |
| */ |
| abstract class FieldGenerator { |
| /** |
| * A string that should never occur in user code identifiers. |
| * |
| * <p>This is used to create unique identifiers that won't collide. |
| */ |
| private static final String GENERATED_TAG = "$AutoCodec$"; |
| |
| private static final String OFFSET_SUFFIX = "_offset"; |
| |
| private final VariableElement variable; |
| private final ClassName parentName; |
| private final String namePrefix; |
| |
| /** |
| * Constructor. |
| * |
| * @param variable the field being serialized. Note that {@link VariableElement} contains a |
| * reference to the enclosing class. |
| * @param hierarchyLevel a variable could occur in either the class being serialized or in one of |
| * its ancestor classes. This is 0 for the class itself, 1 for its superclass, and so on. It |
| * is used to avoid naming collisions, particularly in the case of shadowed variables. |
| */ |
| FieldGenerator(VariableElement variable, int hierarchyLevel) { |
| this.variable = variable; |
| this.parentName = ClassName.get((TypeElement) variable.getEnclosingElement()); |
| this.namePrefix = variable.getSimpleName() + GENERATED_TAG + hierarchyLevel; |
| } |
| |
| /** Any created member variables should start with this prefix. */ |
| final String getNamePrefix() { |
| return namePrefix; |
| } |
| |
| /** The name of the enclosing class, used in generated code. */ |
| final ClassName getParentName() { |
| return parentName; |
| } |
| |
| /** |
| * Generated codecs store the offset of every field of the serialized class in a member variable. |
| * |
| * @return name of the offset member variable |
| */ |
| final String getOffsetName() { |
| return namePrefix + OFFSET_SUFFIX; |
| } |
| |
| /** |
| * Name of the field being serialized. |
| * |
| * <p>Implementations may refer to this for reflection. |
| */ |
| final Name getParameterName() { |
| return variable.getSimpleName(); |
| } |
| |
| final void generateOffsetMember(TypeSpec.Builder classBuilder, MethodSpec.Builder constructor) { |
| classBuilder.addField(long.class, getOffsetName(), Modifier.PRIVATE, Modifier.FINAL); |
| constructor.addStatement( |
| "this.$L = $T.unsafe().objectFieldOffset($T.class.getDeclaredField(\"$L\"))", |
| getOffsetName(), |
| UnsafeProvider.class, |
| getParentName(), |
| variable.getSimpleName()); |
| } |
| |
| /** |
| * Generates any additional member variables needed for this field. |
| * |
| * <p>To avoid collisions, field specific field names should be prefixed with {@link #namePrefix}. |
| * |
| * <p>The *offset* field is already generated by {@link #generateOffsetMember}. |
| */ |
| void generateAdditionalMemberVariables(TypeSpec.Builder classBuilder) {} |
| |
| /** |
| * Adds field specific code to the constructor. |
| * |
| * <p>Many implementations don't need to do anything here given that the offset is already |
| * initialized by {@link #generateOffsetMember}. |
| */ |
| void generateConstructorCode(MethodSpec.Builder constructor) {} |
| |
| /** |
| * Adds {@link ObjectCodec#serialize} code to serialize this field. |
| * |
| * <p>Implementations may assume that the parameters of {@link ObjectCodec#serialize} are present |
| * in the generated method's scope and may be referenced. |
| */ |
| abstract void generateSerializeCode(MethodSpec.Builder serialize); |
| |
| /** |
| * Adds field specific deserialize code. |
| * |
| * <p>Implementations may assume the presence of parameters of {@link |
| * AsyncObjectCodec#deserializeAsync}. |
| */ |
| abstract void generateDeserializeCode(MethodSpec.Builder deserialize); |
| } |