Use concrete collections, not lazy set difference/intersection/filter…

… views, on hot codepaths in the Skyframe engine code, when we'll be iterating more than once.

PiperOrigin-RevId: 519045507
Change-Id: Iaf0b2c6cfb90b9fbe1bd8c0bd3867b3985baa5b9

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

@@ -20,6 +20,7 @@
 import com.github.benmanes.caffeine.cache.Cache;
 import com.github.benmanes.caffeine.cache.Caffeine;
 import com.google.common.base.Throwables;
+import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -761,15 +762,17 @@ public void run() {
         // "newDeps" refers to newly discovered this time around after a SkyFunction#compute call
         // and not to be confused with the oldDeps variable which refers to the last evaluation,
         // i.e. a prior call to ParallelEvaluator#eval.
-        Set<SkyKey> newDepsThatWerentInTheLastEvaluation;
-        Set<SkyKey> newDepsThatWereInTheLastEvaluation;
+        Collection<SkyKey> newDepsThatWerentInTheLastEvaluation;
+        ImmutableList<SkyKey> newDepsThatWereInTheLastEvaluation;
         if (oldDeps.isEmpty()) {
           // When there are no old deps (clean evaluations), avoid set views which have O(n) size.
           newDepsThatWerentInTheLastEvaluation = newDeps;
-          newDepsThatWereInTheLastEvaluation = ImmutableSet.of();
+          newDepsThatWereInTheLastEvaluation = ImmutableList.of();
         } else {
-          newDepsThatWerentInTheLastEvaluation = Sets.difference(newDeps, oldDeps);
-          newDepsThatWereInTheLastEvaluation = Sets.intersection(newDeps, oldDeps);
+          newDepsThatWerentInTheLastEvaluation =
+              ImmutableList.copyOf(Sets.difference(newDeps, oldDeps));
+          newDepsThatWereInTheLastEvaluation =
+              ImmutableList.copyOf(Sets.intersection(newDeps, oldDeps));
         }
 
         InterruptibleSupplier<NodeBatch> newDepsThatWerentInTheLastEvaluationNodes =
@@ -1026,15 +1029,14 @@ private boolean maybeHandleRegisteringNewlyDiscoveredDepsForDoneEntry(
     }
 
     env.addTemporaryDirectDepsTo(entry);
-    Set<SkyKey> newlyAddedNewDeps;
-    Set<SkyKey> previouslyRegisteredNewDeps;
+    Collection<SkyKey> newlyAddedNewDeps;
+    ImmutableCollection<SkyKey> previouslyRegisteredNewDeps;
     if (oldDeps.isEmpty()) {
-      // When there are no old deps (clean evaluations), avoid set views which have O(n) size.
       newlyAddedNewDeps = newDeps;
       previouslyRegisteredNewDeps = ImmutableSet.of();
     } else {
-      newlyAddedNewDeps = Sets.difference(newDeps, oldDeps);
-      previouslyRegisteredNewDeps = Sets.intersection(newDeps, oldDeps);
+      newlyAddedNewDeps = ImmutableList.copyOf(Sets.difference(newDeps, oldDeps));
+      previouslyRegisteredNewDeps = ImmutableList.copyOf(Sets.intersection(newDeps, oldDeps));
     }
 
     InterruptibleSupplier<NodeBatch> newlyAddedNewDepNodes =

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

@@ -885,7 +885,8 @@ Set<SkyKey> commitAndGetParents(NodeEntry primaryEntry) throws InterruptedExcept
     GroupedDeps temporaryDirectDeps = primaryEntry.getTemporaryDirectDeps();
     if (!oldDeps.isEmpty()) {
       // Remove the rdep on this entry for each of its old deps that is no longer a direct dep.
-      Set<SkyKey> depsToRemove = Sets.difference(oldDeps, temporaryDirectDeps.toSet());
+      ImmutableList<SkyKey> depsToRemove =
+          ImmutableList.copyOf(Sets.difference(oldDeps, temporaryDirectDeps.toSet()));
       NodeBatch oldDepEntries =
           evaluatorContext.getGraph().getBatch(skyKey, Reason.RDEP_REMOVAL, depsToRemove);
       for (SkyKey key : depsToRemove) {