| // 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; |
| |
| import com.google.protobuf.CodedInputStream; |
| import java.io.IOException; |
| import java.util.concurrent.Callable; |
| |
| /** |
| * {@link ObjectCodec} that returns a continuation when deserializing. |
| * |
| * <p>The {@link AsyncDeserializationContext} can defer invoking of the continuation until all |
| * asynchronous dependencies are resolved. |
| */ |
| public abstract class DeferredObjectCodec<T> implements ObjectCodec<T> { |
| /** |
| * A supplier-like object returned when deserializing with this codec. |
| * |
| * <p>Does not include any synchronization. The caller must ensure that {@link #call} is not |
| * called until after all requested sub-values are available. |
| * |
| * <p>This interface should only be used by codec implementations and serialization code. |
| */ |
| public interface DeferredValue<T> extends Callable<T> { |
| @Override // to remove the checked exception |
| T call(); |
| } |
| |
| @Override |
| public final MemoizationStrategy getStrategy() { |
| return MemoizationStrategy.MEMOIZE_AFTER; |
| } |
| |
| /** Implementation that adapts this codec for synchronous use. */ |
| @Override |
| public final T deserialize(DeserializationContext context, CodedInputStream codedIn) |
| throws SerializationException, IOException { |
| return deserializeDeferred(context, codedIn).call(); |
| } |
| |
| /** |
| * This differs from {@link #deserialize} by using the narrower {@link |
| * AsyncDeserializationContext} and returning a {@link DeferredValue}. |
| * |
| * <p>This is used in cases where the deserialized object cannot even be constructed before the |
| * children become available, which is common for immutable types. |
| * |
| * <p>Note that {@link DeferredValue} is invoked when all child instances have been provided, but |
| * that may include partially formed child-instances. Use {@link |
| * FlatDeserializationContext#deserializeFully} if the child-instances must be fully formed. |
| */ |
| public abstract DeferredValue<T> deserializeDeferred( |
| AsyncDeserializationContext context, CodedInputStream codedIn) |
| throws SerializationException, IOException; |
| } |