support non-worker invocation when rules try to use a worker invocation

Author: rickeylev

sphinxdocs/private/sphinx.bzl

@@ -269,6 +269,12 @@ def _run_sphinx(ctx, format, source_path, inputs, output_prefix, use_persistent_
     run_args = []  # Copy of the args to forward along to debug runner
     args = ctx.actions.args()  # Args passed to the action
 
+    # An args file is required for persistent workers, but we don't know if
+    # the action will use worker mode or not (settings we can't see may
+    # force non-worker mode). For consistency, always use a params file.
+    args.use_param_file("@%s", use_always = True)
+    args.set_param_file_format("multiline")
+
     # NOTE: sphinx_build.py relies on the first two args being the srcdir and
     # outputdir, in that order.
     args.add(source_path)
@@ -289,7 +295,8 @@ def _run_sphinx(ctx, format, source_path, inputs, output_prefix, use_persistent_
 
     if use_persistent_workers:
         # * Normally Sphinx puts doctrees in the output dir. We can't do that
-        #   because Bazel will clear the output directory every invocation.
+        #   because Bazel will clear the output directory every invocation. To
+        #   work around that, create it as a sibling directory.
         # * Use a non-dot prefixed name so it shows up more visibly.
         args.add(paths.join(output_dir.path + "_doctrees"), format = "--doctree-dir=%s")
 
@@ -318,10 +325,11 @@ def _run_sphinx(ctx, format, source_path, inputs, output_prefix, use_persistent_
     for tool in ctx.attr.tools:
         tools.append(tool[DefaultInfo].files_to_run)
 
+    # NOTE: Command line flags or RBE capabilities may override the execution
+    # requirements and disable workers. Thus, we can't assume that these
+    # exec requirements will actually be respected.
     execution_requirements = {}
     if use_persistent_workers:
-        args.use_param_file("@%s", use_always = True)
-        args.set_param_file_format("multiline")
         execution_requirements["supports-workers"] = "1"
         execution_requirements["requires-worker-protocol"] = "json"
 

sphinxdocs/private/sphinx_build.py

@@ -201,14 +201,29 @@ def _handle_env_get_outdated(self, app, env, added, changed, removed):
             env.path2doc(p)
             for p in self.changed_paths
         }
+
         logger.info("changed docs: %s", changed)
         return changed
 
+def _worker_main(stdin, stdout, exec_root):
+    with Worker(stdin, stdout, exec_root) as worker:
+        return worker.run()
+
+
+def _non_worker_main(argv):
+    args = []
+    for arg in sys.argv:
+        if arg.startswith("@"):
+            with open(arg.removeprefix("@")) as fp:
+                lines = [line.strip() for line in fp if line.strip()]
+            args.extend(lines)
+        else:
+            args.append(arg)
+    sys.argv[:] = args
+    return main()
 
 if __name__ == "__main__":
     if "--persistent_worker" in sys.argv:
-        with Worker(sys.stdin, sys.stdout, os.getcwd()) as worker:
-            sys.exit(worker.run())
+        sys.exit(_worker_main(sys.stdin, sys.stdout, os.getcwd()))
     else:
-        raise Exception("non-worker path taken")
-        sys.exit(main())
+        sys.exit(_non_worker_main())