// Copyright 2016 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.MoreObjects;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.util.GroupedList;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.skyframe.NodeEntry.DirtyState;
import java.util.Collection;
import java.util.Set;
/**
* State for a node that has been dirtied, and will be checked to see if it needs re-evaluation, and
* either marked clean or re-evaluated.
*
* <p>This class is public only for the benefit of alternative graph implementations outside of the
* package.
*/
public abstract class DirtyBuildingState {
/**
* The state of a dirty node. A node is marked dirty in the DirtyBuildingState constructor, and
* goes into either the state {@link DirtyState#CHECK_DEPENDENCIES} or {@link
* DirtyState#NEEDS_REBUILDING}, depending on whether the caller specified that the node was
* itself changed or not. Never null.
*/
private DirtyState dirtyState;
/**
* The dependencies requested (with group markers) last time the node was built (and below, the
* value last time the node was built). They will be compared to dependencies requested on this
* build to check whether this node has changed in {@link NodeEntry#setValue}. If they are null,
* it means that this node is being built for the first time. See {@link
* InMemoryNodeEntry#directDeps} for more on dependency group storage.
*/
protected abstract GroupedList<SkyKey> getLastBuildDirectDeps() throws InterruptedException;
/**
* The number of groups of the dependencies requested last time when the node was built.
*
* <p>Getting the number of last-built dependencies should not throw {@link InterruptedException}.
*/
protected abstract int getNumOfGroupsInLastBuildDirectDeps();
/** The value of the node the last time it was built. */
protected abstract SkyValue getLastBuildValue() throws InterruptedException;
/**
* Group of children to be checked next in the process of determining if this entry needs to be
* re-evaluated. Used by {@link DirtyBuildingState#getNextDirtyDirectDeps} and {@link
* #signalDepInternal}.
*/
protected int dirtyDirectDepIndex;
protected DirtyBuildingState(boolean isChanged) {
dirtyState = isChanged ? DirtyState.NEEDS_REBUILDING : DirtyState.CHECK_DEPENDENCIES;
// We need to iterate through the deps to see if they have changed, or to remove them if one
// has. Initialize the iterating index.
dirtyDirectDepIndex = 0;
}
static DirtyBuildingState create(
boolean isChanged, GroupedList<SkyKey> lastBuildDirectDeps, SkyValue lastBuildValue) {
return new FullDirtyBuildingState(isChanged, lastBuildDirectDeps, lastBuildValue);
}
final void markChanged() {
Preconditions.checkState(dirtyState == DirtyState.CHECK_DEPENDENCIES, this);
Preconditions.checkState(dirtyDirectDepIndex == 0, "Unexpected evaluation: %s", this);
dirtyState = DirtyState.NEEDS_REBUILDING;
}
final void forceChanged() {
Preconditions.checkState(dirtyState == DirtyState.CHECK_DEPENDENCIES, this);
Preconditions.checkState(getNumOfGroupsInLastBuildDirectDeps() == dirtyDirectDepIndex, this);
dirtyState = DirtyState.REBUILDING;
}
final boolean isChanged() {
return dirtyState == DirtyState.NEEDS_REBUILDING || dirtyState == DirtyState.REBUILDING;
}
private void checkFinishedBuildingWhenAboutToSetValue() {
Preconditions.checkState(
dirtyState == DirtyState.VERIFIED_CLEAN || dirtyState == DirtyState.REBUILDING,
"not done building %s",
this);
}
/**
* If this node is not yet known to need rebuilding, sets {@link #dirtyState} to {@link
* DirtyState#NEEDS_REBUILDING} if the child has changed, and {@link DirtyState#VERIFIED_CLEAN} if
* the child has not changed and this was the last child to be checked (as determined by {@code
* isReady} and comparing {@link #dirtyDirectDepIndex} and {@link
* DirtyBuildingState#getNumOfGroupsInLastBuildDirectDeps()}.
*/
final void signalDepInternal(boolean childChanged, boolean isReady) {
Preconditions.checkState(
isChanged() || (dirtyState == DirtyState.CHECK_DEPENDENCIES && dirtyDirectDepIndex > 0),
"Unexpected not evaluating: %s",
this);
if (!isChanged()) {
// Synchronization isn't needed here because the only caller is NodeEntry, which does it
// through the synchronized method signalDep(Version).
if (childChanged) {
dirtyState = DirtyState.NEEDS_REBUILDING;
} else if (dirtyState == DirtyState.CHECK_DEPENDENCIES
&& isReady
&& getNumOfGroupsInLastBuildDirectDeps() == dirtyDirectDepIndex) {
// No other dep already marked this as NEEDS_REBUILDING, no deps outstanding, and this was
// the last block of deps to be checked.
dirtyState = DirtyState.VERIFIED_CLEAN;
}
}
}
/**
* Returns true if {@code newValue}.equals the value from the last time this node was built.
* Should only be used by {@link NodeEntry#setValue}.
*
* <p>Changes in direct deps do <i>not</i> force this to return false. Only the value is
* considered.
*/
final boolean unchangedFromLastBuild(SkyValue newValue) throws InterruptedException {
checkFinishedBuildingWhenAboutToSetValue();
return !(newValue instanceof NotComparableSkyValue) && getLastBuildValue().equals(newValue);
}
/**
* Returns true if the deps requested during this evaluation ({@code directDeps}) are exactly
* those requested the last time this node was built, in the same order.
*/
final boolean depsUnchangedFromLastBuild(GroupedList<SkyKey> directDeps)
throws InterruptedException {
checkFinishedBuildingWhenAboutToSetValue();
return getLastBuildDirectDeps().equals(directDeps);
}
final boolean noDepsLastBuild() {
return getNumOfGroupsInLastBuildDirectDeps() == 0;
}
/** @see NodeEntry#getDirtyState() */
final DirtyState getDirtyState() {
return dirtyState;
}
/**
* Gets the next children to be re-evaluated to see if this dirty node needs to be re-evaluated.
*
* <p>See {@link NodeEntry#getNextDirtyDirectDeps}.
*/
final Collection<SkyKey> getNextDirtyDirectDeps() throws InterruptedException {
Preconditions.checkState(dirtyState == DirtyState.CHECK_DEPENDENCIES, this);
Preconditions.checkState(dirtyDirectDepIndex < getNumOfGroupsInLastBuildDirectDeps(), this);
return getLastBuildDirectDeps().get(dirtyDirectDepIndex++);
}
/**
* Returns the remaining direct deps that have not been checked. If {@code preservePosition} is
* true, this method is non-mutating. If {@code preservePosition} is false, the caller must
* process the returned set, and so subsequent calls to this method will return the empty set.
*/
Set<SkyKey> getAllRemainingDirtyDirectDeps(boolean preservePosition) throws InterruptedException {
ImmutableSet.Builder<SkyKey> result = ImmutableSet.builder();
for (int ind = dirtyDirectDepIndex; ind < getNumOfGroupsInLastBuildDirectDeps(); ind++) {
result.addAll(getLastBuildDirectDeps().get(ind));
}
if (!preservePosition) {
dirtyDirectDepIndex = getNumOfGroupsInLastBuildDirectDeps();
}
return result.build();
}
protected void markRebuilding() {
Preconditions.checkState(dirtyState == DirtyState.NEEDS_REBUILDING, this);
dirtyState = DirtyState.REBUILDING;
}
protected MoreObjects.ToStringHelper getStringHelper() {
return MoreObjects.toStringHelper(this)
.add("dirtyState", dirtyState)
.add("dirtyDirectDepIndex", dirtyDirectDepIndex);
}
@Override
public String toString() {
return getStringHelper().toString();
}
private static class FullDirtyBuildingState extends DirtyBuildingState {
private final GroupedList<SkyKey> lastBuildDirectDeps;
private final SkyValue lastBuildValue;
private FullDirtyBuildingState(
boolean isChanged, GroupedList<SkyKey> lastBuildDirectDeps, SkyValue lastBuildValue) {
super(isChanged);
this.lastBuildDirectDeps = lastBuildDirectDeps;
Preconditions.checkState(
isChanged || getNumOfGroupsInLastBuildDirectDeps() > 0,
"%s is being marked dirty, not changed, but has no children that could have dirtied it",
this);
this.lastBuildValue = lastBuildValue;
}
@Override
protected SkyValue getLastBuildValue() {
return lastBuildValue;
}
@Override
protected GroupedList<SkyKey> getLastBuildDirectDeps() throws InterruptedException {
return lastBuildDirectDeps;
}
@Override
protected int getNumOfGroupsInLastBuildDirectDeps() {
return lastBuildDirectDeps.listSize();
}
@Override
protected MoreObjects.ToStringHelper getStringHelper() {
return super.getStringHelper()
.add("lastBuildDirectDeps", lastBuildDirectDeps)
.add("lastBuildValue", lastBuildValue);
}
}
}