Refactor InMemoryNodeEntry into an interface.

Right now its only direct implementation is `IncrementalInMemoryNodeEntry`, but soon `EdglessInMemoryNodeEntry` will get its own dedicated implementation instead of inheriting from incremental.

PiperOrigin-RevId: 553809945
Change-Id: I9abcc5d503ce7890903b5cd852b2637d63fc7bf9

src/main/java/com/google/devtools/build/skyframe/DelegatingNodeEntry.java

@@ -14,6 +14,7 @@
 package com.google.devtools.build.skyframe;
 
 import com.google.common.collect.ImmutableSet;
+import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -198,7 +199,7 @@ public void removeInProgressReverseDep(SkyKey reverseDep) {
   }
 
   @Override
-  public Iterable<SkyKey> getReverseDepsForDoneEntry() throws InterruptedException {
+  public Collection<SkyKey> getReverseDepsForDoneEntry() throws InterruptedException {
     return getDelegate().getReverseDepsForDoneEntry();
   }
 

src/main/java/com/google/devtools/build/skyframe/DirtyBuildingState.java

@@ -71,11 +71,11 @@ static DirtyBuildingState createNew(boolean hasLowFanout) {
    * needs to be re-scheduled, and ensures that only one thread gets a true return value.
    *
    * <p>The second problem is solved by first adding the newly discovered deps to a node's {@link
-   * InMemoryNodeEntry#directDeps}, and then looping through the direct deps and registering this
-   * node as a reverse dependency. This ensures that the signaledDeps counter can only reach {@link
-   * GroupedDeps#numElements} on the very last iteration of the loop, i.e., the thread is not
-   * working on the node anymore. Note that this requires that there is no code after the loop in
-   * {@link ParallelEvaluator.Evaluate#run}.
+   * IncrementalInMemoryNodeEntry#directDeps}, and then looping through the direct deps and
+   * registering this node as a reverse dependency. This ensures that the signaledDeps counter can
+   * only reach {@link GroupedDeps#numElements} on the very last iteration of the loop, i.e., the
+   * thread is not working on the node anymore. Note that this requires that there is no code after
+   * the loop in {@link ParallelEvaluator.Evaluate#run}.
    */
   private int signaledDeps = NOT_EVALUATING_SENTINEL;
 
@@ -114,7 +114,7 @@ static DirtyBuildingState createNew(boolean hasLowFanout) {
    * 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.
+   * IncrementalInMemoryNodeEntry#directDeps} for more on dependency group storage.
    *
    * <p>Public only for the use of alternative graph implementations.
    */
@@ -216,7 +216,9 @@ private void checkFinishedBuildingWhenAboutToSetValue() {
    * DirtyBuildingState#getNumOfGroupsInLastBuildDirectDeps()}.
    */
   final void signalDep(
-      InMemoryNodeEntry entry, Version childVersion, @Nullable SkyKey childForDebugging) {
+      IncrementalInMemoryNodeEntry entry,
+      Version childVersion,
+      @Nullable SkyKey childForDebugging) {
     // Synchronization isn't needed here because the only caller is InMemoryNodeEntry, which does it
     // through the synchronized method signalDep.
     checkState(isEvaluating(), "%s %s", entry, childForDebugging);

src/main/java/com/google/devtools/build/skyframe/EdgelessInMemoryNodeEntry.java

@@ -23,7 +23,8 @@
  * while the node is being built, but will not be stored once the node is done and written to the
  * graph. Any attempt to access the edges once the node is done will fail the build fast.
  */
-public class EdgelessInMemoryNodeEntry extends InMemoryNodeEntry {
+// TODO(b/262871730): Do not extend IncrementalInMemoryNodeEntry.
+public class EdgelessInMemoryNodeEntry extends IncrementalInMemoryNodeEntry {
 
   public EdgelessInMemoryNodeEntry(SkyKey key) {
     super(key);

src/main/java/com/google/devtools/build/skyframe/InMemoryGraphImpl.java

@@ -164,7 +164,7 @@ public Map<SkyKey, NodeEntry> getBatchMap(
 
   @ForOverride
   protected InMemoryNodeEntry newNodeEntry(SkyKey key) {
-    return new InMemoryNodeEntry(key);
+    return new IncrementalInMemoryNodeEntry(key);
   }
 
   @Override