| // Copyright 2014 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.skyframe; |
| |
| import com.google.common.base.Throwables; |
| import javax.annotation.Nullable; |
| |
| /** |
| * Wrapper for a value or the untyped exception thrown when trying to compute it. |
| * |
| * <p>Sky functions should generally prefer using exception-typed subclasses such as {@link |
| * ValueOrException}, {@link ValueOrException2}, etc. Occasionally, it may be useful to work with |
| * {@link ValueOrUntypedException} instead, for example to share logic for processing Skyframe |
| * requests that use different exception types or arity. |
| */ |
| public abstract class ValueOrUntypedException { |
| |
| /** |
| * Returns the stored value, or {@code null} if it has not yet been computed. If an exception is |
| * stored, it is wrapped in {@link IllegalStateException} and thrown. |
| * |
| * <p>This method is useful when a value is not expected to store an exception but was requested |
| * in the same batch as values which may store an exception. |
| */ |
| @Nullable |
| public final SkyValue getUnchecked() { |
| Exception e = getException(); |
| if (e != null) { |
| throw new IllegalStateException(e); |
| } |
| return getValue(); |
| } |
| |
| /** |
| * Returns the stored value, or {@code null} if it has not yet been computed. If an exception is |
| * stored, it is thrown as-is if it is an instance of {@code exceptionClass} and wrapped in {@link |
| * IllegalStateException} otherwise. |
| * |
| * <p>This method is useful when a value is only expected to store {@code exceptionClass} but was |
| * requested in the same batch as values which may store other types of exceptions. |
| */ |
| @Nullable |
| public final <E extends Exception> SkyValue getOrThrow(Class<E> exceptionClass) throws E { |
| Exception e = getException(); |
| if (e != null) { |
| Throwables.throwIfInstanceOf(e, exceptionClass); |
| throw new IllegalStateException(e); |
| } |
| return getValue(); |
| } |
| |
| /** Returns the stored value, if there was one. */ |
| @Nullable |
| abstract SkyValue getValue(); |
| |
| /** Returns the stored exception, if there was one. */ |
| @Nullable |
| abstract Exception getException(); |
| |
| public static ValueOrUntypedException ofValueUntyped(SkyValue value) { |
| return new ValueOrUntypedExceptionImpl(value); |
| } |
| |
| public static ValueOrUntypedException ofNull() { |
| return ValueOrUntypedExceptionImpl.NULL; |
| } |
| |
| public static ValueOrUntypedException ofExn(Exception e) { |
| return new ValueOrUntypedExceptionExnImpl(e); |
| } |
| |
| private static final class ValueOrUntypedExceptionImpl extends ValueOrUntypedException { |
| static final ValueOrUntypedExceptionImpl NULL = new ValueOrUntypedExceptionImpl(null); |
| @Nullable private final SkyValue value; |
| |
| ValueOrUntypedExceptionImpl(@Nullable SkyValue value) { |
| this.value = value; |
| } |
| |
| @Override |
| @Nullable |
| public SkyValue getValue() { |
| return value; |
| } |
| |
| @Override |
| public Exception getException() { |
| return null; |
| } |
| } |
| |
| private static final class ValueOrUntypedExceptionExnImpl extends ValueOrUntypedException { |
| private final Exception exception; |
| |
| ValueOrUntypedExceptionExnImpl(Exception exception) { |
| this.exception = exception; |
| } |
| |
| @Override |
| @Nullable |
| public SkyValue getValue() { |
| return null; |
| } |
| |
| @Override |
| public Exception getException() { |
| return exception; |
| } |
| } |
| } |