Support autoninja -o/--offline to disable goma

It is sometimes helpful to do a full build of Chrome using goma while
online and then do incremental builds without goma while offline or with
poor network bandwidth. Turning off goma in gn args triggers a full
rebuild but the GOMA_DISABLED environment variable can be used to
disable goma without triggering a rebuild.

In order to make this feature easier to discover and use this change
adds support for -o/--offline to autoninja. autoninja -h will mention
this flag and autoninja.bat/autoninja.py handle it appropriately. This
means setting the environment variable in autoninja.bat, and using it
to adjust the -j value and stripping it out in autoninja.py.

The bash script that wraps autoninja.py on Linux and OSX did not need
updating because the Python script can emit 'GOMA_DISABLED=1 ninja ...'
and this is executed by bash.

This was produced during pair programming with jessemckenna@

Bug: b/172039612
Change-Id: Ifcfbc598ac20f23e5fe013e02979b5b8c2851b01
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2510818
Auto-Submit: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>

autoninja.bat

@@ -14,19 +14,30 @@ REM to see how quickly process creation is happening - often a critical clue on
 REM Windows. The trailing space is intentional.
 if "%NINJA_SUMMARIZE_BUILD%" == "1" set NINJA_STATUS=[%%r processes, %%f/%%t @ %%o/s : %%es ] 
 
+set scriptdir=%~dp0
+
+:loop
+IF NOT "%1"=="" (
+    @rem Tell goma to not do network compiles.
+    IF "%1"=="--offline" SET GOMA_DISABLED=1
+    IF "%1"=="-o" SET GOMA_DISABLED=1
+    SHIFT
+    GOTO :loop
+)
+
 REM Execute whatever is printed by autoninja.py.
 REM Also print it to reassure that the right settings are being used.
-FOR /f "usebackq tokens=*" %%a in (`vpython %~dp0autoninja.py "%*"`) do echo %%a & %%a
+FOR /f "usebackq tokens=*" %%a in (`vpython %scriptdir%autoninja.py "%*"`) do echo %%a & %%a
 @if errorlevel 1 goto buildfailure
 
 REM Use call to invoke vpython script here, because we use vpython via vpython.bat.
-@if "%NINJA_SUMMARIZE_BUILD%" == "1" call vpython.bat %~dp0post_build_ninja_summary.py %*
-@call vpython.bat %~dp0ninjalog_uploader_wrapper.py --cmdline %*
+@if "%NINJA_SUMMARIZE_BUILD%" == "1" call vpython.bat %scriptdir%post_build_ninja_summary.py %*
+@call vpython.bat %scriptdir%ninjalog_uploader_wrapper.py --cmdline %*
 
 exit /b
 :buildfailure
 
-@call vpython.bat %~dp0ninjalog_uploader_wrapper.py --cmdline %*
+@call vpython.bat %scriptdir%ninjalog_uploader_wrapper.py --cmdline %*
 
 REM Return an error code of 1 so that if a developer types:
 REM "autoninja chrome && chrome" then chrome won't run if the build fails.

autoninja.py

@@ -30,6 +30,7 @@ SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
 # The -t tools are incompatible with -j
 t_specified = False
 j_specified = False
+offline = False
 output_dir = '.'
 input_args = sys.argv
 # On Windows the autoninja.bat script passes along the arguments enclosed in
@@ -56,6 +57,15 @@ for index, arg in enumerate(input_args[1:]):
   elif arg.startswith('-C'):
     # Support -Cout/Default
     output_dir = arg[2:]
+  elif arg == '-o' or arg == '--offline':
+    offline = True
+  elif arg == '-h':
+    print('autoninja: Use -o/--offline to temporary disable goma.',
+          file=sys.stderr)
+    print(file=sys.stderr)
+
+# Strip -o/--offline so ninja doesn't see them.
+input_args = [ arg for arg in input_args if arg != '-o' and arg != '--offline']
 
 use_remote_build = False
 
@@ -92,7 +102,7 @@ elif os.path.exists(os.path.join(output_dir, 'rules.ninja')):
 # for each compile step. Checking this environment variable ensures that
 # autoninja uses an appropriate -j value in this situation.
 goma_disabled_env = os.environ.get('GOMA_DISABLED', '0').lower()
-if goma_disabled_env in ['true', 't', 'yes', 'y', '1']:
+if offline or goma_disabled_env in ['true', 't', 'yes', 'y', '1']:
   use_remote_build = False
 
 # Specify ninja.exe on Windows so that ninja.bat can call autoninja and not
@@ -150,4 +160,10 @@ for i in range(len(args)):
 if os.environ.get('NINJA_SUMMARIZE_BUILD', '0') == '1':
   args += ['-d', 'stats']
 
-print(' '.join(args))
+if offline and not sys.platform.startswith('win'):
+  # Tell goma to do local compiles. On Windows this environment variable is set
+  # by the wrapper batch file.
+  print('GOMA_DISABLED=1 ' + ' '.join(args))
+else:
+  print(' '.join(args))
+