feat(rollup): add worker support to rollup_bundle

Adds rollup_bundle(supports_workers), disabled by default. This enables
rollup to be run in a worker process to perform incremental builds when
notified of file changes from bazel.

Worker mode currently supports only a very small subset of the standard
rollup CLI arguments.

e2e/webapp/BUILD.bazel

@@ -7,6 +7,8 @@ rollup_bundle(
     srcs = ["strings.js"],
     entry_point = "app.js",
     output_dir = True,
+    # Enable experimental faster builds with Bazel workers
+    supports_workers = True,
 )
 
 terser_minified(

internal/pkg_npm/test/BUILD.bazel

@@ -1,6 +1,6 @@
 load("@build_bazel_rules_nodejs//:index.bzl", "pkg_npm")
 load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
-load("@npm_bazel_rollup//:index.from_src.bzl", "rollup_bundle")
+load("@npm_bazel_rollup//:index.bzl", "rollup_bundle")
 load("@npm_bazel_typescript//:index.from_src.bzl", "ts_library")
 load("//internal/node:context.bzl", "node_context_data")
 load("//third_party/github.com/bazelbuild/bazel-skylib:rules/write_file.bzl", "write_file")

internal/pkg_web/test/BUILD.bazel

@@ -1,7 +1,7 @@
 load("@build_bazel_rules_nodejs//:index.bzl", "pkg_web")
 load("@npm//@babel/cli:index.bzl", "babel")
 load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
-load("@npm_bazel_rollup//:index.from_src.bzl", "rollup_bundle")
+load("@npm_bazel_rollup//:index.bzl", "rollup_bundle")
 load("@npm_bazel_terser//:index.from_src.bzl", "terser_minified")
 load("@npm_bazel_typescript//:index.from_src.bzl", "ts_library")
 

internal/pkg_web/test2/BUILD.bazel

@@ -1,7 +1,7 @@
 load("@build_bazel_rules_nodejs//:index.bzl", "pkg_web")
 load("@npm//@babel/cli:index.bzl", "babel")
 load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
-load("@npm_bazel_rollup//:index.from_src.bzl", "rollup_bundle")
+load("@npm_bazel_rollup//:index.bzl", "rollup_bundle")
 load("@npm_bazel_terser//:index.from_src.bzl", "terser_minified")
 
 rollup_bundle(

packages/labs/test/grpc_web/BUILD.bazel

@@ -1,6 +1,6 @@
 load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
 load("@npm_bazel_karma//:index.from_src.bzl", "karma_web_test_suite")
-load("@npm_bazel_rollup//:index.from_src.bzl", "rollup_bundle")
+load("@npm_bazel_rollup//:index.bzl", "rollup_bundle")
 load("@npm_bazel_typescript//:index.from_src.bzl", "ts_library")
 
 # This test checks that the protos can be resolved in a nodejs environment

packages/protractor/test/protractor-2/BUILD.bazel

@@ -1,6 +1,6 @@
 load("@npm//http-server:index.bzl", "http_server")
 load("@npm_bazel_protractor//:index.from_src.bzl", "protractor_web_test_suite")
-load("@npm_bazel_rollup//:index.from_src.bzl", "rollup_bundle")
+load("@npm_bazel_rollup//:index.bzl", "rollup_bundle")
 load("@npm_bazel_terser//:index.from_src.bzl", "terser_minified")
 load("@npm_bazel_typescript//:index.bzl", "ts_config")
 load("@npm_bazel_typescript//:index.from_src.bzl", "ts_devserver", "ts_library")

packages/rollup/BUILD.bazel

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 load("@build_bazel_rules_nodejs//:tools/defaults.bzl", "codeowners", "pkg_npm")
+load("//third_party/github.com/bazelbuild/bazel-skylib:rules/copy_file.bzl", "copy_file")
 
 codeowners(
     teams = ["@jbedard"],
@@ -33,12 +34,34 @@ genrule(
     visibility = ["//docs:__pkg__"],
 )
 
+# Copy the proto file to a matching third_party/... nested directory
+# so the runtime require() statements still work
+_worker_proto_dir = "third_party/github.com/bazelbuild/bazel/src/main/protobuf"
+
+genrule(
+    name = "copy_worker_js",
+    srcs = ["//packages/worker:npm_package"],
+    outs = ["worker.js"],
+    cmd = "cp $(execpath //packages/worker:npm_package)/index.js $@",
+    visibility = ["//visibility:public"],
+)
+
+copy_file(
+    name = "copy_worker_proto",
+    src = "@build_bazel_rules_typescript//%s:worker_protocol.proto" % _worker_proto_dir,
+    out = "%s/worker_protocol.proto" % _worker_proto_dir,
+    visibility = ["//visibility:public"],
+)
+
 pkg_npm(
     name = "npm_package",
     srcs = [
         "@npm_bazel_rollup//:package_contents",
     ],
     build_file_content = """exports_files(["rollup.config.js"])""",
+    substitutions = {
+        "//:rollup-worker-local": "@npm//@bazel/rollup/bin:rollup-worker",
+    },
     vendor_external = [
         "npm_bazel_rollup",
     ],
@@ -48,5 +71,8 @@ pkg_npm(
         #   external/npm_bazel_rollup/docs.raw: Generating proto for Starlark doc for docs failed (Exit 1)
         "@bazel_tools//src/conditions:windows": [],
         "//conditions:default": [":generate_README"],
-    }),
+    }) + [
+        ":copy_worker_proto",
+        ":worker.js",
+    ],
 )

packages/rollup/src/BUILD.bazel

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+load("@build_bazel_rules_nodejs//:index.bzl", "nodejs_binary")
 load("@build_bazel_rules_nodejs//tools/stardoc:index.bzl", "stardoc")
 
 package(default_visibility = ["//visibility:public"])
@@ -42,8 +43,22 @@ filegroup(
     name = "package_contents",
     srcs = [
         "index.bzl",
+        "index.js",
         "package.json",
         "rollup.config.js",
         "rollup_bundle.bzl",
     ],
 )
+
+nodejs_binary(
+    name = "rollup-worker-local",
+    data = [
+        # NOTE: we ought to link to the original location instead of copying
+        # "@build_bazel_rules_nodejs//packages/worker:npm_package",
+        "@build_bazel_rules_nodejs//packages/rollup:worker.js",
+        "@build_bazel_rules_nodejs//packages/rollup:copy_worker_proto",
+        "@npm//protobufjs",
+        "@npm//rollup",
+    ],
+    entry_point = "index.js",
+)