| // Copyright 2015 Google Inc. 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.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. |
| * |
| * <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 an immutable iterable of the direct deps of this node. This method may only be called |
| * after the evaluation of this node is complete. |
| * |
| * <p>This method is not very efficient, but is only be called in limited circumstances -- |
| * when the node is about to be deleted, or when the node is expected to have no direct deps (in |
| * which case the overhead is not so bad). It should not be called repeatedly for the same node, |
| * since each call takes time proportional to the number of direct deps of the node. |
| */ |
| @ThreadSafe |
| Iterable<SkyKey> getDirectDeps(); |
| |
| /** |
| * Removes a reverse dependency. |
| */ |
| @ThreadSafe |
| void removeReverseDep(SkyKey reverseDep); |
| |
| /** |
| * Removes a reverse dependency. |
| * |
| * <p>May only be called if this entry is not done (i.e. {@link #isDone} is false) and |
| * {@param reverseDep} is present in {@link #getReverseDeps} |
| */ |
| @ThreadSafe |
| void removeInProgressReverseDep(SkyKey reverseDep); |
| |
| /** |
| * Returns a copy of the set of reverse dependencies. Note that this introduces a potential |
| * check-then-act race; {@link #removeReverseDep} may fail for a key that is returned here. |
| */ |
| @ThreadSafe |
| Iterable<SkyKey> getReverseDeps(); |
| |
| /** |
| * 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 true if the node was previously clean, and false 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. |
| */ |
| @Nullable |
| @ThreadSafe |
| boolean markDirty(boolean isChanged); |
| } |