| // Copyright 2015 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.Preconditions; |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe; |
| import javax.annotation.Nullable; |
| |
| /** |
| * A node in the graph without the means to access its value. All operations on this class are |
| * thread-safe. Note, however, the warning on the return value of {@link #markDirty}. |
| * |
| * <p>This interface is public only for the benefit of alternative graph implementations outside of |
| * the package. |
| */ |
| public interface ThinNodeEntry { |
| |
| /** Returns whether the entry has been built and is finished evaluating. */ |
| @ThreadSafe |
| boolean isDone(); |
| |
| /** |
| * Returns true if the entry is marked dirty, meaning that at least one of its transitive |
| * dependencies is marked changed. |
| */ |
| @ThreadSafe |
| boolean isDirty(); |
| |
| /** |
| * Returns true if the entry is marked changed, meaning that it must be re-evaluated even if its |
| * dependencies' values have not changed. |
| */ |
| @ThreadSafe |
| boolean isChanged(); |
| |
| /** |
| * Marks this node dirty, or changed if {@code isChanged} is true. The node is put in the |
| * just-created state. It will be re-evaluated if necessary during the evaluation phase, but if it |
| * has not changed, it will not force a re-evaluation of its parents. |
| * |
| * <p>{@code markDirty(b)} must not be called on an undone node if {@code isChanged() == b}. It is |
| * the caller's responsibility to ensure that this does not happen. Calling {@code |
| * markDirty(false)} when {@code isChanged() == true} has no effect. The idea here is that the |
| * caller will only ever want to call {@code markDirty()} a second time if a transition from a |
| * dirty-unchanged state to a dirty-changed state is required. |
| * |
| * @return A {@link ThinNodeEntry.MarkedDirtyResult} if the node was previously clean, and {@code |
| * null} if it was already dirty. If it was already dirty, the caller should abort its |
| * handling of this node, since another thread is already dealing with it. Note the warning on |
| * {@link ThinNodeEntry.MarkedDirtyResult} regarding the collection it provides. |
| */ |
| @Nullable |
| @ThreadSafe |
| MarkedDirtyResult markDirty(boolean isChanged) throws InterruptedException; |
| |
| /** |
| * Returned by {@link #markDirty} if that call changed the node from clean to dirty. Contains an |
| * iterable of the node's reverse deps for efficiency, because the single use case for {@link |
| * #markDirty} is during invalidation, and if such an invalidation call wins, the invalidator |
| * must immediately afterwards schedule the invalidation of the node's reverse deps. |
| * |
| * <p>Warning: {@link #getReverseDepsUnsafe()} may return a live view of the reverse deps |
| * collection of the marked-dirty node. The consumer of this data must be careful only to |
| * iterate over and consume its values while that collection is guaranteed not to change. This |
| * is true during invalidation, because reverse deps don't change during invalidation. |
| */ |
| class MarkedDirtyResult { |
| private final Iterable<SkyKey> reverseDepsUnsafe; |
| |
| public MarkedDirtyResult(Iterable<SkyKey> reverseDepsUnsafe) { |
| this.reverseDepsUnsafe = Preconditions.checkNotNull(reverseDepsUnsafe); |
| } |
| |
| public Iterable<SkyKey> getReverseDepsUnsafe() { |
| return reverseDepsUnsafe; |
| } |
| } |
| } |