[siso] add autosiso wrappers

Developers will be able to use `autosiso` command to invoke siso builds.
This CL extracts reclient management logic from `ninja_reclient` to be  reused in both Ninja and Siso builds.

Bug: b/278675516
Change-Id: I3e64a3188db184f4d3f851063a0feef7d3a73d6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4445366
Auto-Submit: Junji Watanabe <jwata@google.com>
Reviewed-by: Philipp Wollermann <philwo@google.com>
Commit-Queue: Joanna Wang <jojwang@chromium.org>
Reviewed-by: Fumitoshi Ukai <ukai@google.com>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Joanna Wang <jojwang@chromium.org>
diff --git a/reclient_helper.py b/reclient_helper.py
new file mode 100644
index 0000000..54f258d
--- /dev/null
+++ b/reclient_helper.py
@@ -0,0 +1,143 @@
+# Copyright 2023 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""This helper provides a build context that handles
+the reclient lifecycle safely. It will automatically start
+reproxy before running ninja and stop reproxy when build stops
+for any reason e.g. build completion, keyboard interrupt etc."""
+
+import contextlib
+import hashlib
+import os
+import subprocess
+import sys
+
+import gclient_paths
+
+
+def find_reclient_bin_dir():
+  tools_path = gclient_paths.GetBuildtoolsPath()
+  if not tools_path:
+    return None
+
+  reclient_bin_dir = os.path.join(tools_path, 'reclient')
+  if os.path.isdir(reclient_bin_dir):
+    return reclient_bin_dir
+  return None
+
+
+def find_reclient_cfg():
+  tools_path = gclient_paths.GetBuildtoolsPath()
+  if not tools_path:
+    return None
+
+  reclient_cfg = os.path.join(tools_path, 'reclient_cfgs', 'reproxy.cfg')
+  if os.path.isfile(reclient_cfg):
+    return reclient_cfg
+  return None
+
+
+def run(cmd_args):
+  if os.environ.get('NINJA_SUMMARIZE_BUILD') == '1':
+    print(' '.join(cmd_args))
+  return subprocess.call(cmd_args)
+
+
+def start_reproxy(reclient_cfg, reclient_bin_dir):
+  return run([
+      os.path.join(reclient_bin_dir, 'bootstrap'),
+      '--re_proxy=' + os.path.join(reclient_bin_dir, 'reproxy'),
+      '--cfg=' + reclient_cfg
+  ])
+
+
+def stop_reproxy(reclient_cfg, reclient_bin_dir):
+  return run([
+      os.path.join(reclient_bin_dir, 'bootstrap'), '--shutdown',
+      '--cfg=' + reclient_cfg
+  ])
+
+
+def find_ninja_out_dir(args):
+  # Ninja uses getopt_long, which allows to intermix non-option arguments.
+  # To leave non supported parameters untouched, we do not use getopt.
+  for index, arg in enumerate(args[1:]):
+    if arg == '-C':
+      # + 1 to get the next argument and +1 because we trimmed off args[0]
+      return args[index + 2]
+    if arg.startswith('-C'):
+      # Support -Cout/Default
+      return arg[2:]
+  return '.'
+
+
+def set_reproxy_path_flags(out_dir, make_dirs=True):
+  """Helper to setup the logs and cache directories for reclient.
+
+  Creates the following directory structure if make_dirs is true:
+  out_dir/
+    .reproxy_tmp/
+      logs/
+      cache/
+
+  The following env vars are set if not already set:
+    RBE_output_dir=out_dir/.reproxy_tmp/logs
+    RBE_proxy_log_dir=out_dir/.reproxy_tmp/logs
+    RBE_log_dir=out_dir/.reproxy_tmp/logs
+    RBE_cache_dir=out_dir/.reproxy_tmp/cache
+  *Nix Only:
+    RBE_server_address=unix://out_dir/.reproxy_tmp/reproxy.sock
+  Windows Only:
+    RBE_server_address=pipe://md5(out_dir/.reproxy_tmp)/reproxy.pipe
+  """
+  tmp_dir = os.path.abspath(os.path.join(out_dir, '.reproxy_tmp'))
+  log_dir = os.path.join(tmp_dir, 'logs')
+  cache_dir = os.path.join(tmp_dir, 'cache')
+  if make_dirs:
+    os.makedirs(tmp_dir, exist_ok=True)
+    os.makedirs(log_dir, exist_ok=True)
+    os.makedirs(cache_dir, exist_ok=True)
+  os.environ.setdefault("RBE_output_dir", log_dir)
+  os.environ.setdefault("RBE_proxy_log_dir", log_dir)
+  os.environ.setdefault("RBE_log_dir", log_dir)
+  os.environ.setdefault("RBE_cache_dir", cache_dir)
+  if sys.platform.startswith('win'):
+    pipe_dir = hashlib.md5(tmp_dir.encode()).hexdigest()
+    os.environ.setdefault("RBE_server_address",
+                          "pipe://%s/reproxy.pipe" % pipe_dir)
+  else:
+    os.environ.setdefault("RBE_server_address",
+                          "unix://%s/reproxy.sock" % tmp_dir)
+
+
+@contextlib.contextmanager
+def build_context(argv):
+  # If use_remoteexec is set, but the reclient binaries or configs don't
+  # exist, display an error message and stop.  Otherwise, the build will
+  # attempt to run with rewrapper wrapping actions, but will fail with
+  # possible non-obvious problems.
+  reclient_bin_dir = find_reclient_bin_dir()
+  reclient_cfg = find_reclient_cfg()
+  if reclient_bin_dir is None or reclient_cfg is None:
+    print(("Build is configured to use reclient but necessary binaries "
+           "or config files can't be found.  Developer builds with "
+           "reclient are not yet supported.  Try regenerating your "
+           "build with use_goma in place of use_remoteexec for now."),
+          file=sys.stderr)
+    yield 1
+    return
+  try:
+    set_reproxy_path_flags(find_ninja_out_dir(argv))
+  except OSError:
+    print("Error creating reproxy_tmp in output dir", file=sys.stderr)
+    yield 1
+    return
+  reproxy_ret_code = start_reproxy(reclient_cfg, reclient_bin_dir)
+  if reproxy_ret_code != 0:
+    yield reproxy_ret_code
+    return
+  try:
+    yield
+  finally:
+    print("Shutting down reproxy...", file=sys.stderr)
+    stop_reproxy(reclient_cfg, reclient_bin_dir)