autoninja: cache negative result of gcloud account check

This is to remove 1~3 seconds from no-op build using autoninja.

Bug: b/309720176
Change-Id: I2c15a43517d5a99eae794015c18c884a3f3fdef4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5092847
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Philipp Wollermann <philwo@chromium.org>
Reviewed-by: Scott Lee <ddoman@chromium.org>

.gitignore

@@ -101,3 +101,6 @@ testing_support/google_appengine
 
 # Ignore the file that logs Python 2 scripts run during presubmits.
 /python2_usage.txt
+
+# Ignore the internal data used by autoninja.
+/.autoninja*

autoninja.py

@@ -19,10 +19,12 @@ import multiprocessing
 import os
 import platform
 import re
+import shelve
 import shlex
 import shutil
 import subprocess
 import sys
+import time
 import warnings
 
 import google.auth
@@ -103,16 +105,29 @@ def _is_google_corp_machine_using_external_account():
     if not _is_google_corp_machine():
         return False
 
-    account = _adc_account()
-    if account and not account.endswith("@google.com"):
-        return True
+    with shelve.open(os.path.join(SCRIPT_DIR, ".autoninja")) as db:
+        last_false = db.get("last_false")
+        now = time.time()
+        if last_false is not None and now < last_false + 12 * 60 * 60:
+            # Do not check account if it is checked in last 12 hours.
+            return False
 
-    account = _gcloud_auth_account()
-    if not account:
+        account = _adc_account()
+        if account and not account.endswith("@google.com"):
+            return True
+
+        account = _gcloud_auth_account()
+        if not account:
+            db["last_false"] = now
+            return False
+
+        # Handle service account and google account as internal account.
+        if not (account.endswith("@google.com")
+                or account.endswith("gserviceaccount.com")):
+            return True
+
+        db["last_false"] = now
         return False
-    # Handle service account and google account as internal account.
-    return not (account.endswith("@google.com")
-                or account.endswith("gserviceaccount.com"))
 
 
 def _quote_for_cmd(arg):

tests/autoninja_test.py

@@ -3,6 +3,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import glob
 import multiprocessing
 import os
 import os.path
@@ -165,6 +166,11 @@ class AutoninjaTest(trial_dir.TestCase):
                                                     adc_account,
                                                     gcloud_auth_account,
                                                     expected):
+        for shelve_file in glob.glob(
+                os.path.join(autoninja.SCRIPT_DIR, ".autoninja*")):
+            # Clear cache.
+            os.remove(shelve_file)
+
         with mock.patch('autoninja._is_google_corp_machine',
                         return_value=is_corp), mock.patch(
                             'autoninja._adc_account',