Attempt to tolerate missing keys a bit more gracefully: reset the cur…

…rent node to restart from scratch, rather than continuing on an almost certainly doomed path, where we'll crash later.

This is explicitly abusing the action rewinding framework to mitigate a different bug.

PiperOrigin-RevId: 243119106

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

@@ -40,7 +40,7 @@
 import com.google.devtools.build.skyframe.ParallelEvaluatorContext.EnqueueParentBehavior;
 import com.google.devtools.build.skyframe.QueryableGraph.Reason;
 import com.google.devtools.build.skyframe.SkyFunction.Restart;
-import com.google.devtools.build.skyframe.SkyFunctionEnvironment.UndonePreviouslyRequestedDep;
+import com.google.devtools.build.skyframe.SkyFunctionEnvironment.UndonePreviouslyRequestedDeps;
 import com.google.devtools.build.skyframe.SkyFunctionException.ReifiedSkyFunctionException;
 import com.google.devtools.build.skyframe.ThinNodeEntry.DirtyType;
 import java.math.BigInteger;
@@ -425,7 +425,7 @@ public void run() {
           env =
               new SkyFunctionEnvironment(
                   skyKey, state.getTemporaryDirectDeps(), oldDeps, evaluatorContext);
-        } catch (UndonePreviouslyRequestedDep undonePreviouslyRequestedDep) {
+        } catch (UndonePreviouslyRequestedDeps undonePreviouslyRequestedDeps) {
           // If a previously requested dep is no longer done, restart this node from scratch.
           restart(skyKey, state);
           // Top priority since this node has already been evaluating, so get it off our plate.

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

@@ -26,7 +26,7 @@
 import com.google.devtools.build.lib.util.GroupedList;
 import com.google.devtools.build.skyframe.ParallelEvaluatorContext.EnqueueParentBehavior;
 import com.google.devtools.build.skyframe.QueryableGraph.Reason;
-import com.google.devtools.build.skyframe.SkyFunctionEnvironment.UndonePreviouslyRequestedDep;
+import com.google.devtools.build.skyframe.SkyFunctionEnvironment.UndonePreviouslyRequestedDeps;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Deque;
@@ -156,12 +156,12 @@ private static ErrorInfo checkForCycles(SkyKey root, ParallelEvaluatorContext ev
                   directDeps,
                   Sets.difference(entry.getAllRemainingDirtyDirectDeps(), removedDeps),
                   evaluatorContext);
-        } catch (UndonePreviouslyRequestedDep undoneDep) {
+        } catch (UndonePreviouslyRequestedDeps undoneDep) {
           // All children were finished according to the CHILDREN_FINISHED sentinel, and cycle
           // detection does not do normal SkyFunction evaluation, so no restarting nor child
           // dirtying was possible.
           throw new IllegalStateException(
-              "Previously requested dep not done: " + undoneDep.getDepKey(), undoneDep);
+              "Previously requested dep not done: " + undoneDep.getDepKeys(), undoneDep);
         }
         env.setError(entry, ErrorInfo.fromChildErrors(key, errorDeps));
         env.commit(entry, EnqueueParentBehavior.SIGNAL);

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

@@ -162,7 +162,7 @@ public void post(ExtendedEventHandler.Postable e) {
       GroupedList<SkyKey> directDeps,
       Set<SkyKey> oldDeps,
       ParallelEvaluatorContext evaluatorContext)
-      throws InterruptedException, UndonePreviouslyRequestedDep {
+      throws InterruptedException, UndonePreviouslyRequestedDeps {
     super(directDeps);
     this.skyKey = skyKey;
     this.oldDeps = oldDeps;
@@ -193,10 +193,10 @@ public void post(ExtendedEventHandler.Postable e) {
     try {
       this.previouslyRequestedDepsValues =
           batchPrefetch(skyKey, directDeps, oldDeps, /*assertDone=*/ false);
-    } catch (UndonePreviouslyRequestedDep undonePreviouslyRequestedDep) {
+    } catch (UndonePreviouslyRequestedDeps undonePreviouslyRequestedDeps) {
       throw new IllegalStateException(
-          "batchPrefetch can't throw UndonePreviouslyRequestedDep unless assertDone is true",
-          undonePreviouslyRequestedDep);
+          "batchPrefetch can't throw UndonePreviouslyRequestedDeps unless assertDone is true",
+          undonePreviouslyRequestedDeps);
     }
     Preconditions.checkState(
         !this.previouslyRequestedDepsValues.containsKey(ErrorTransienceValue.KEY),
@@ -206,7 +206,7 @@ public void post(ExtendedEventHandler.Postable e) {
 
   private Map<SkyKey, SkyValue> batchPrefetch(
       SkyKey requestor, GroupedList<SkyKey> depKeys, Set<SkyKey> oldDeps, boolean assertDone)
-      throws InterruptedException, UndonePreviouslyRequestedDep {
+      throws InterruptedException, UndonePreviouslyRequestedDeps {
     QueryableGraph.PrefetchDepsRequest request = null;
     if (PREFETCH_OLD_DEPS) {
       request = new QueryableGraph.PrefetchDepsRequest(requestor, oldDeps, depKeys);
@@ -235,6 +235,7 @@ private Map<SkyKey, SkyValue> batchPrefetch(
           .getGraphInconsistencyReceiver()
           .noteInconsistencyAndMaybeThrow(
               requestor, difference, Inconsistency.ALREADY_DECLARED_CHILD_MISSING);
+      throw new UndonePreviouslyRequestedDeps(ImmutableList.copyOf(difference));
     }
     ImmutableMap.Builder<SkyKey, SkyValue> depValuesBuilder =
         ImmutableMap.builderWithExpectedSize(batchMap.size());
@@ -251,7 +252,7 @@ private Map<SkyKey, SkyValue> batchPrefetch(
                 skyKey,
                 ImmutableList.of(entry.getKey()),
                 Inconsistency.BUILDING_PARENT_FOUND_UNDONE_CHILD);
-        throw new UndonePreviouslyRequestedDep(entry.getKey());
+        throw new UndonePreviouslyRequestedDeps(ImmutableList.of(entry.getKey()));
       }
       depValuesBuilder.put(entry.getKey(), !depDone ? NULL_MARKER : valueMaybeWithMetadata);
       if (depDone) {
@@ -902,16 +903,16 @@ public String toString() {
         .toString();
   }
 
-  /** Thrown during environment construction if a previously requested dep is no longer done. */
-  static class UndonePreviouslyRequestedDep extends Exception {
-    private final SkyKey depKey;
+  /** Thrown during environment construction if previously requested deps are no longer done. */
+  static class UndonePreviouslyRequestedDeps extends Exception {
+    private final ImmutableList<SkyKey> depKeys;
 
-    UndonePreviouslyRequestedDep(SkyKey depKey) {
-      this.depKey = depKey;
+    UndonePreviouslyRequestedDeps(ImmutableList<SkyKey> depKeys) {
+      this.depKeys = depKeys;
     }
 
-    SkyKey getDepKey() {
-      return depKey;
+    ImmutableList<SkyKey> getDepKeys() {
+      return depKeys;
     }
   }
 }