fix(builtin): improve execution requirements for copy file operations

internal/pkg_web/pkg_web.bzl

@@ -15,6 +15,7 @@
 """Contains the pkg_web rule.
 """
 
+load("//third_party/github.com/bazelbuild/bazel-skylib:rules/copy_common.bzl", "COPY_EXECUTION_REQUIREMENTS")
 load("@rules_nodejs//nodejs:providers.bzl", "STAMP_ATTR", "StampSettingInfo")
 
 _DOC = """Assembles a web application from source files."""
@@ -42,13 +43,6 @@ See the section on stamping in the README.""",
     ),
 }
 
-# Hints for Bazel spawn strategy
-_execution_requirements = {
-    # Copying files is entirely IO-bound and there is no point doing this work
-    # remotely.
-    "no-remote-exec": "1",
-}
-
 def _move_files(ctx, root_paths):
     """Moves files into an output directory
 
@@ -81,7 +75,7 @@ def _move_files(ctx, root_paths):
         outputs = [www_dir],
         executable = ctx.executable._assembler,
         arguments = [args],
-        execution_requirements = _execution_requirements,
+        execution_requirements = COPY_EXECUTION_REQUIREMENTS,
         env = {"COMPILATION_MODE": ctx.var["COMPILATION_MODE"]},
     )
     return depset([www_dir])

third_party/github.com/bazelbuild/bazel-skylib/rules/copy_common.bzl

@@ -0,0 +1,22 @@
+# Copyright 2019 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Exposes common helpers to help on copying files rules"""
+
+load(
+    "//third_party/github.com/bazelbuild/bazel-skylib:rules/private/copy_common_private.bzl",
+    _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS",
+)
+
+COPY_EXECUTION_REQUIREMENTS = _COPY_EXECUTION_REQUIREMENTS

third_party/github.com/bazelbuild/bazel-skylib/rules/private/copy_common_private.bzl

@@ -0,0 +1,73 @@
+# Copyright 2019 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"Helpers for copy rules"
+
+# Hints for Bazel spawn strategy
+COPY_EXECUTION_REQUIREMENTS = {
+    # ----------------+-----------------------------------------------------------------------------
+    # no-remote       | Prevents the action or test from being executed remotely or cached remotely.
+    #                 | This is equivalent to using both `no-remote-cache` and `no-remote-exec`.
+    # ----------------+-----------------------------------------------------------------------------
+    # no-remote-cache | Results in the action or test never being cached remotely (but it may
+    #                 | be cached locally; it may also be executed remotely). Note: for the purposes
+    #                 | of this tag, the disk-cache is considered a local cache, whereas the http
+    #                 | and gRPC caches are considered remote. If a combined cache is specified
+    #                 | (i.e. a cache with local and remote components), it's treated as a remote
+    #                 | cache and disabled entirely unless --incompatible_remote_results_ignore_disk
+    #                 | is set in which case the local components will be used.
+    # ----------------+-----------------------------------------------------------------------------
+    # no-remote-exec  | Results in the action or test never being executed remotely (but it may be
+    #                 | cached remotely).
+    # ----------------+-----------------------------------------------------------------------------
+    # no-cache        | Results in the action or test never being cached (remotely or locally)
+    # ----------------+-----------------------------------------------------------------------------
+    # no-sandbox      | Results in the action or test never being sandboxed; it can still be cached
+    #                 | or run remotely - use no-cache or no-remote to prevent either or both of
+    #                 | those.
+    # ----------------+-----------------------------------------------------------------------------
+    # local           | Precludes the action or test from being remotely cached, remotely executed,
+    #                 | or run inside the sandbox. For genrules and tests, marking the rule with the
+    #                 | local = True attribute has the same effect.
+    # ----------------+-----------------------------------------------------------------------------
+    # See https://bazel.google.cn/reference/be/common-definitions?hl=en&authuser=0#common-attributes
+    #
+    # Copying file & directories is entirely IO-bound and there is no point doing this work
+    # remotely.
+    #
+    # Also, remote-execution does not allow source directory inputs, see
+    # https://github.com/bazelbuild/bazel/commit/c64421bc35214f0414e4f4226cc953e8c55fa0d2 So we must
+    # not attempt to execute remotely in that case.
+    #
+    # There is also no point pulling the output file or directory from the remote cache since the
+    # bytes to copy are already available locally. Conversely, no point in writing to the cache if
+    # no one has any reason to check it for this action.
+    #
+    # Read and writing to disk cache is disabled as well primarily to reduce disk usage on the local
+    # machine. A disk cache hit of a directory copy could be slghtly faster than a copy since the
+    # disk cache stores the directory artifact as a single entry, but the slight performance bump
+    # comes at the cost of heavy disk cache usage, which is an unmanaged directory that grow beyond
+    # the bounds of the physical disk.
+    # TODO: run benchmarks to measure the impact on copy_directory
+    #
+    # Sandboxing for this action is wasteful as well since there is a 1:1 mapping of input
+    # file/directory to output file/directory and no room for non-hermetic inputs to sneak in to the
+    # input.
+    "no-remote": "1",
+    "no-remote-cache": "1",
+    "no-remote-exec": "1",
+    "no-cache": "1",
+    "no-sandbox": "1",
+    "local": "1",
+}

third_party/github.com/bazelbuild/bazel-skylib/rules/private/copy_file_private.bzl

@@ -24,16 +24,7 @@ cmd.exe (on Windows). `_copy_xfile` marks the resulting file executable,
 `_copy_file` does not.
 """
 
-# Hints for Bazel spawn strategy
-_execution_requirements = {
-    # Copying files is entirely IO-bound and there is no point doing this work remotely.
-    # Also, remote-execution does not allow source directory inputs, see
-    # https://github.com/bazelbuild/bazel/commit/c64421bc35214f0414e4f4226cc953e8c55fa0d2
-    # So we must not attempt to execute remotely in that case.
-    # no-remote | Prevents the action or test from being executed remotely or cached remotely.
-    #           | This is equivalent to using both `no-remote-cache` and `no-remote-exec`.
-    "no-remote": "1",
-}
+load(":rules/private/copy_common_private.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
 
 def _hash_file(file):
     return str(hash(file.path))
@@ -81,7 +72,7 @@ def copy_cmd(ctx, src, dst):
         mnemonic = mnemonic,
         progress_message = progress_message,
         use_default_shell_env = True,
-        execution_requirements = _execution_requirements,
+        execution_requirements = _COPY_EXECUTION_REQUIREMENTS,
     )
 
 # buildifier: disable=function-docstring
@@ -103,7 +94,7 @@ def copy_bash(ctx, src, dst):
         mnemonic = mnemonic,
         progress_message = progress_message,
         use_default_shell_env = True,
-        execution_requirements = _execution_requirements,
+        execution_requirements = _COPY_EXECUTION_REQUIREMENTS,
     )
 
 def _copy_file_impl(ctx):