Create output directories with remote execution

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

@@ -62,6 +62,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSortedMap;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Maps;
 import com.google.common.eventbus.Subscribe;
@@ -139,6 +140,7 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.SortedMap;
+import java.util.TreeMap;
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.Executor;
@@ -305,8 +307,25 @@ public boolean mayBeExecutedRemotely(Spawn spawn) {
         && Spawns.mayBeExecutedRemotely(spawn);
   }
 
+  private SortedMap<PathFragment, ActionInput> buildOutputDirMap(Spawn spawn) {
+    TreeMap<PathFragment, ActionInput> outputDirMap = new TreeMap<>();
+    for (ActionInput output : spawn.getOutputFiles()) {
+      if (output instanceof Artifact && ((Artifact) output).isTreeArtifact()) {
+        outputDirMap.put(
+            PathFragment.create(remotePathResolver.getWorkingDirectory())
+                .getRelative(output.getExecPath()),
+            output);
+      }
+    }
+    return outputDirMap;
+  }
+
   private MerkleTree buildInputMerkleTree(Spawn spawn, SpawnExecutionContext context)
       throws IOException, ForbiddenActionInputException {
+    // Add output directories to inputs so that they are created as empty directories by the
+    // executor. The spec only requires the executor to create the parent directory of an output
+    // directory, which differs from the behavior of both local and sandboxed execution.
+    SortedMap<PathFragment, ActionInput> outputDirMap = buildOutputDirMap(spawn);
     if (remoteOptions.remoteMerkleTreeCache) {
       MetadataProvider metadataProvider = context.getMetadataProvider();
       ConcurrentLinkedQueue<MerkleTree> subMerkleTrees = new ConcurrentLinkedQueue<>();
@@ -316,9 +335,18 @@ private MerkleTree buildInputMerkleTree(Spawn spawn, SpawnExecutionContext conte
           (Object nodeKey, InputWalker walker) -> {
             subMerkleTrees.add(buildMerkleTreeVisitor(nodeKey, walker, metadataProvider));
           });
+      if (!outputDirMap.isEmpty()) {
+        subMerkleTrees.add(MerkleTree.build(outputDirMap, metadataProvider, execRoot, digestUtil));
+      }
       return MerkleTree.merge(subMerkleTrees, digestUtil);
     } else {
       SortedMap<PathFragment, ActionInput> inputMap = remotePathResolver.getInputMapping(context);
+      if (!outputDirMap.isEmpty()) {
+        SortedMap<PathFragment, ActionInput> newInputMap = new TreeMap<>();
+        newInputMap.putAll(inputMap);
+        newInputMap.putAll(outputDirMap);
+        inputMap = newInputMap;
+      }
       return MerkleTree.build(inputMap, context.getMetadataProvider(), execRoot, digestUtil);
     }
   }

src/test/shell/bazel/remote/remote_execution_test.sh

@@ -3119,6 +3119,48 @@ EOF
     //pkg:a &>$TEST_log || fail "expected build to succeed with sibling repository layout"
 }
 
+function test_create_tree_artifact_outputs() {
+  touch WORKSPACE
+  mkdir -p pkg
+
+  cat > pkg/def.bzl <<'EOF'
+def _r(ctx):
+    d = ctx.actions.declare_directory("%s/empty_dir" % ctx.label.name)
+    ctx.actions.run_shell(
+        outputs = [d],
+        command = "cd %s && pwd" % d.path,
+    )
+    return [DefaultInfo(files = depset([d]))]
+
+r = rule(implementation = _r)
+EOF
+
+cat > pkg/BUILD <<'EOF'
+load(":def.bzl", "r")
+
+r(name = "a")
+EOF
+
+  bazel build \
+    --spawn_strategy=remote \
+    --remote_executor=grpc://localhost:${worker_port} \
+    //pkg:a &>$TEST_log || fail "expected build to succeed"
+
+  bazel clean --expunge
+  bazel build \
+    --spawn_strategy=remote \
+    --remote_executor=grpc://localhost:${worker_port} \
+    --experimental_remote_merkle_tree_cache \
+    //pkg:a &>>$TEST_log || fail "expected build to succeed with Merkle tree cache"
+
+  bazel clean --expunge
+  bazel build \
+    --spawn_strategy=remote \
+    --remote_executor=grpc://localhost:${worker_port} \
+    --experimental_sibling_repository_layout \
+    //pkg:a &>>$TEST_log || fail "expected build to succeed with sibling repository layout"
+}
+
 # Runs coverage with `cc_test` and RE then checks the coverage file is returned.
 # Older versions of gcov are not supported with bazel coverage and so will be skipped.
 # See the above `test_java_rbe_coverage_produces_report` for more information.

src/tools/remote/src/main/java/com/google/devtools/build/remote/worker/ExecutionServer.java

@@ -283,8 +283,8 @@ private ActionResult execute(
     }
     for (String output : command.getOutputDirectoriesList()) {
       Path file = workingDirectory.getRelative(output);
-      if (file.exists()) {
-        throw new FileAlreadyExistsException("Output directory/file already exists: " + file);
+      if (file.isFile()) {
+        throw new FileAlreadyExistsException("Existing file at output directory path: " + file);
       }
       file.getParentDirectory().createDirectoryAndParents();
       outputs.add(file);