fix: improve execution requirements of all copy files/directory rules for better perf (#79)

lib/private/BUILD.bazel

@@ -5,17 +5,27 @@ exports_files(
     visibility = ["//docs:__pkg__"],
 )
 
+bzl_library(
+    name = "copy_common",
+    srcs = ["copy_common.bzl"],
+    visibility = ["//lib:__subpackages__"],
+)
+
 bzl_library(
     name = "copy_file",
     srcs = ["copy_file.bzl"],
     visibility = ["//lib:__subpackages__"],
-    deps = [":directory_path"],
+    deps = [
+        ":copy_common",
+        ":directory_path",
+    ],
 )
 
 bzl_library(
     name = "copy_directory",
     srcs = ["copy_directory.bzl"],
     visibility = ["//lib:__subpackages__"],
+    deps = [":copy_common"],
 )
 
 bzl_library(
@@ -23,6 +33,7 @@ bzl_library(
     srcs = ["copy_to_directory.bzl"],
     visibility = ["//lib:__subpackages__"],
     deps = [
+        ":copy_common",
         ":directory_path",
         ":output_files",
         ":paths",

lib/private/copy_common.bzl

@@ -0,0 +1,59 @@
+"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",
+}

lib/private/copy_directory.bzl

@@ -4,14 +4,7 @@ This rule copies a directory to another location using Bash (on Linux/macOS) or
 cmd.exe (on Windows).
 """
 
-# 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-exec": "1",
-}
+load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
 
 def _copy_cmd(ctx, src, dst):
     # Most Windows binaries built with MSVC use a certain argument quoting
@@ -49,7 +42,7 @@ 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,
     )
 
 def _copy_bash(ctx, src, dst):
@@ -65,7 +58,7 @@ 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_directory_action(ctx, src, dst, is_windows = False):

lib/private/copy_file.bzl

@@ -24,17 +24,9 @@ cmd.exe (on Windows). `_copy_xfile` marks the resulting file executable,
 `_copy_file` does not.
 """
 
+load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
 load(":directory_path.bzl", "DirectoryPathInfo")
 
-# 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-exec": "1",
-}
-
 def _copy_cmd(ctx, src, src_path, dst):
     # Most Windows binaries built with MSVC use a certain argument quoting
     # scheme. Bazel uses that scheme too to quote arguments. However,
@@ -70,7 +62,7 @@ def _copy_cmd(ctx, src, src_path, dst):
         mnemonic = mnemonic,
         progress_message = progress_message,
         use_default_shell_env = True,
-        execution_requirements = _execution_requirements,
+        execution_requirements = _COPY_EXECUTION_REQUIREMENTS,
     )
 
 def _copy_bash(ctx, src, src_path, dst):
@@ -86,7 +78,7 @@ def _copy_bash(ctx, src, src_path, dst):
         mnemonic = mnemonic,
         progress_message = progress_message,
         use_default_shell_env = True,
-        execution_requirements = _execution_requirements,
+        execution_requirements = _COPY_EXECUTION_REQUIREMENTS,
     )
 
 def copy_file_action(ctx, src, dst, dir_path = None, is_windows = False):

lib/private/copy_to_directory.bzl

@@ -1,6 +1,7 @@
 "copy_to_directory implementation"
 
 load("@bazel_skylib//lib:paths.bzl", skylib_paths = "paths")
+load(":copy_common.bzl", _COPY_EXECUTION_REQUIREMENTS = "COPY_EXECUTION_REQUIREMENTS")
 load(":paths.bzl", "paths")
 load(":directory_path.bzl", "DirectoryPathInfo")
 
@@ -13,16 +14,6 @@ _copy_to_directory_attr = {
     "is_windows": attr.bool(mandatory = True),
 }
 
-# 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-exec": "1",
-}
-
 def _longest_match(subject, tests, allow_partial = False):
     match = None
     high_score = 0
@@ -101,7 +92,7 @@ fi
         mnemonic = "CopyToDirectory",
         progress_message = "Copying files to directory",
         use_default_shell_env = True,
-        execution_requirements = _execution_requirements,
+        execution_requirements = _COPY_EXECUTION_REQUIREMENTS,
     )
 
 def _copy_to_dir_cmd(ctx, copy_paths, dst_dir):