[8.1.0] Distinguish between input and output prefetching in request m…

src/main/java/com/google/devtools/build/lib/actions/ActionInputPrefetcher.java

@@ -37,7 +37,8 @@ public ListenableFuture<Void> prefetchFiles(
             ActionExecutionMetadata action,
             Iterable<? extends ActionInput> inputs,
             MetadataSupplier metadataSupplier,
-            Priority priority) {
+            Priority priority,
+            Reason reason) {
           // Do nothing.
           return immediateVoidFuture();
         }
@@ -72,6 +73,15 @@ public enum Priority {
     LOW,
   }
 
+  /** The reason for prefetching. */
+  enum Reason {
+    /** The requested files are needed as inputs to the given action. */
+    INPUTS,
+
+    /** The requested files are requested as outputs of the given action. */
+    OUTPUTS,
+  }
+
   /**
    * Initiates best-effort prefetching of all given inputs.
    *
@@ -83,7 +93,8 @@ ListenableFuture<Void> prefetchFiles(
       ActionExecutionMetadata action,
       Iterable<? extends ActionInput> inputs,
       MetadataSupplier metadataSupplier,
-      Priority priority);
+      Priority priority,
+      Reason reason);
 
   /**
    * Whether the prefetcher requires the metadata for a tree artifact to be available whenever one

src/main/java/com/google/devtools/build/lib/exec/AbstractSpawnStrategy.java

@@ -29,6 +29,7 @@
 import com.google.devtools.build.lib.actions.ActionExecutionMetadata;
 import com.google.devtools.build.lib.actions.ActionInput;
 import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Priority;
+import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Reason;
 import com.google.devtools.build.lib.actions.ArtifactExpander;
 import com.google.devtools.build.lib.actions.ArtifactPathResolver;
 import com.google.devtools.build.lib.actions.EnvironmentalExecException;
@@ -290,7 +291,8 @@ public ListenableFuture<Void> prefetchInputs() throws ForbiddenActionInputExcept
                     getInputMapping(PathFragment.EMPTY_FRAGMENT, /* willAccessRepeatedly= */ true)
                         .values(),
                     getInputMetadataProvider()::getInputMetadata,
-                    Priority.MEDIUM),
+                    Priority.MEDIUM,
+                    Reason.INPUTS),
             BulkTransferException.class,
             (BulkTransferException e) -> {
               if (executionOptions.useNewExitCodeForLostInputs

src/main/java/com/google/devtools/build/lib/remote/AbstractActionInputPrefetcher.java

@@ -242,14 +242,14 @@ protected abstract ListenableFuture<Void> doDownloadFile(
       Path tempPath,
       PathFragment execPath,
       FileArtifactValue metadata,
-      Priority priority)
+      Priority priority,
+      Reason reason)
       throws IOException;
 
   protected void prefetchVirtualActionInput(VirtualActionInput input) throws IOException {}
 
   /**
-   * Fetches remotely stored action outputs, that are inputs to this spawn, and stores them under
-   * their path in the output base.
+   * Fetches remotely stored action outputs and stores them under their path in the output base.
    *
    * <p>The {@code inputs} may not contain any unexpanded directories.
    *
@@ -263,7 +263,8 @@ public ListenableFuture<Void> prefetchFiles(
       ActionExecutionMetadata action,
       Iterable<? extends ActionInput> inputs,
       MetadataSupplier metadataSupplier,
-      Priority priority) {
+      Priority priority,
+      Reason reason) {
     List<ActionInput> files = new ArrayList<>();
 
     for (ActionInput input : inputs) {
@@ -297,7 +298,8 @@ public ListenableFuture<Void> prefetchFiles(
     try (var s = Profiler.instance().profile("compose prefetches")) {
       for (var file : files) {
         transfers.add(
-            prefetchFile(action, dirsWithOutputPermissions, metadataSupplier, file, priority));
+            prefetchFile(
+                action, dirsWithOutputPermissions, metadataSupplier, file, priority, reason));
       }
     }
 
@@ -328,7 +330,8 @@ private ListenableFuture<Void> prefetchFile(
       Set<Path> dirsWithOutputPermissions,
       MetadataSupplier metadataSupplier,
       ActionInput input,
-      Priority priority) {
+      Priority priority,
+      Reason reason) {
     try {
       if (input instanceof VirtualActionInput virtualActionInput) {
         prefetchVirtualActionInput(virtualActionInput);
@@ -360,7 +363,8 @@ private ListenableFuture<Void> prefetchFile(
               dirsWithOutputPermissions,
               input,
               metadata,
-              priority);
+              priority,
+              reason);
 
       if (symlink != null) {
         result = result.andThen(plantSymlink(symlink));
@@ -479,7 +483,8 @@ private Completable downloadFileNoCheckRx(
       Set<Path> dirsWithOutputPermissions,
       ActionInput actionInput,
       FileArtifactValue metadata,
-      Priority priority) {
+      Priority priority,
+      Reason reason) {
     // If the path to be prefetched is a non-dangling symlink, prefetch its target path instead.
     // Note that this only applies to symlinks created by spawns (or, currently, with the internal
     // version of BwoB); symlinks created in-process through an ActionFileSystem should have already
@@ -524,7 +529,8 @@ private Completable downloadFileNoCheckRx(
                                 tempPath,
                                 finalPath.relativeTo(execRoot),
                                 metadata,
-                                priority),
+                                priority,
+                                reason),
                         directExecutor())
                     .doOnComplete(
                         () -> {
@@ -686,7 +692,11 @@ public void finalizeAction(Action action, OutputMetadataStore outputMetadataStor
       try (var s = Profiler.instance().profile(ProfilerTask.REMOTE_DOWNLOAD, "Download outputs")) {
         getFromFuture(
             prefetchFiles(
-                action, outputsToDownload, outputMetadataStore::getOutputMetadata, Priority.HIGH));
+                action,
+                outputsToDownload,
+                outputMetadataStore::getOutputMetadata,
+                Priority.HIGH,
+                Reason.OUTPUTS));
       }
     }
   }

src/main/java/com/google/devtools/build/lib/remote/RemoteActionFileSystem.java

@@ -31,6 +31,7 @@
 import com.google.devtools.build.lib.actions.ActionInputHelper;
 import com.google.devtools.build.lib.actions.ActionInputMap;
 import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Priority;
+import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Reason;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.Artifact.SpecialArtifact;
 import com.google.devtools.build.lib.actions.Artifact.TreeFileArtifact;
@@ -753,7 +754,11 @@ private void downloadFileIfRemote(PathFragment path) throws IOException {
       }
       getFromFuture(
           inputFetcher.prefetchFiles(
-              action, ImmutableList.of(input), this::getInputMetadata, Priority.CRITICAL));
+              action,
+              ImmutableList.of(input),
+              this::getInputMetadata,
+              Priority.CRITICAL,
+              Reason.INPUTS));
     } catch (InterruptedException e) {
       Thread.currentThread().interrupt();
       throw new IOException(String.format("Received interrupt while fetching file '%s'", path), e);

src/main/java/com/google/devtools/build/lib/remote/RemoteActionInputFetcher.java

@@ -89,11 +89,19 @@ protected ListenableFuture<Void> doDownloadFile(
       Path tempPath,
       PathFragment execPath,
       FileArtifactValue metadata,
-      Priority priority)
+      Priority priority,
+      Reason reason)
       throws IOException {
     checkArgument(metadata.isRemote(), "Cannot download file that is not a remote file.");
     RequestMetadata requestMetadata =
-        TracingMetadataUtils.buildMetadata(buildRequestId, commandId, "prefetcher", action);
+        TracingMetadataUtils.buildMetadata(
+            buildRequestId,
+            commandId,
+            switch (reason) {
+              case INPUTS -> "input";
+              case OUTPUTS -> "output";
+            },
+            action);
     RemoteActionExecutionContext context = RemoteActionExecutionContext.create(requestMetadata);
 
     Digest digest = DigestUtil.buildDigest(metadata.getDigest(), metadata.getSize());

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

@@ -29,6 +29,7 @@
 import com.google.devtools.build.lib.actions.ActionInputMap;
 import com.google.devtools.build.lib.actions.ActionInputPrefetcher;
 import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Priority;
+import com.google.devtools.build.lib.actions.ActionInputPrefetcher.Reason;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.Artifact.DerivedArtifact;
 import com.google.devtools.build.lib.actions.CompletionContext;
@@ -469,7 +470,7 @@ private void downloadArtifact(
             ActionUtils.getActionForLookupData(env, derivedArtifact.getGeneratingActionKey());
         var future =
             actionInputPrefetcher.prefetchFiles(
-                action, filesToDownload, inputMap::getInputMetadata, Priority.LOW);
+                action, filesToDownload, inputMap::getInputMetadata, Priority.LOW, Reason.OUTPUTS);
         futures.add(future);
       }
     } else {
@@ -485,7 +486,7 @@ private void downloadArtifact(
             ActionUtils.getActionForLookupData(env, derivedArtifact.getGeneratingActionKey());
         var future =
             actionInputPrefetcher.prefetchFiles(
-                action, ImmutableList.of(artifact), inputMap::getInputMetadata, Priority.LOW);
+                action, ImmutableList.of(artifact), inputMap::getInputMetadata, Priority.LOW, Reason.OUTPUTS);
         futures.add(future);
       }
     }