Create a flag to toggle tracking of lost discovered inputs.

It is expected that this behavior is not necessary. The flag will allow for thorough vetting before removing it.

While here, update the help string for `--rewind_lost_inputs` to remove outdated prerequisites.

PiperOrigin-RevId: 588409077
Change-Id: I87dbbac0b910a3d90fc4fbf4b722f0d90edbe8c3

src/main/java/com/google/devtools/build/lib/buildtool/BuildRequestOptions.java

@@ -343,11 +343,19 @@ public String getSymlinkPrefix(String productName) {
       defaultValue = "false",
       documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
       effectTags = {OptionEffectTag.EXECUTION},
-      help =
-          "Whether to use action rewinding to recover from lost inputs. Ignored unless"
-              + " prerequisites for rewinding are met (no incrementality, no action cache).")
+      help = "Whether to use action rewinding to recover from lost inputs.")
   public boolean rewindLostInputs;
 
+  @Option(
+      name = "track_lost_discovered_inputs",
+      defaultValue = "true",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {OptionEffectTag.EXECUTION},
+      help =
+          "Whether to track lost discovered inputs and proactively request them after rewinding."
+              + " This option is a rollout mechanism for removing this behavior, see b/315059768.")
+  public boolean trackLostDiscoveredInputs;
+
   @Option(
       name = "incompatible_skip_genfiles_symlink",
       defaultValue = "true",

src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java

@@ -222,6 +222,7 @@ public void injectTree(SpecialArtifact output, TreeArtifactValue tree) {
   private OutputService outputService;
   private boolean finalizeActions;
   private boolean rewindingEnabled;
+  private boolean trackLostDiscoveredInputs;
   private final Supplier<ImmutableList<Root>> sourceRootSupplier;
 
   private DiscoveredModulesPruner discoveredModulesPruner;
@@ -304,6 +305,7 @@ void prepareForExecution(
     // Cache some option values for performance, since we consult them on every action.
     this.finalizeActions = buildRequestOptions.finalizeActions;
     this.rewindingEnabled = buildRequestOptions.rewindLostInputs;
+    this.trackLostDiscoveredInputs = buildRequestOptions.trackLostDiscoveredInputs;
     this.outputService = outputService;
     this.outputDirectoryHelper = outputDirectoryHelper;
 
@@ -451,7 +453,7 @@ void prepareForRewinding(
       // obsolete.
       state.obsolete(failedKey, buildActionMap, ownerlessArtifactWrapper);
     }
-    if (!lostDiscoveredInputs.isEmpty()) {
+    if (trackLostDiscoveredInputs && !lostDiscoveredInputs.isEmpty()) {
       lostDiscoveredInputsMap.put(ownerlessArtifactWrapper, lostDiscoveredInputs);
     }
     if (!actionFileSystemType().inMemoryFileSystem()) {