Optimize reboots with Android emulator initialization

src/clusterfuzz/_internal/platforms/android/adb.py

@@ -880,8 +880,16 @@ def write_command_line_file(command_line, app_path):
   write_data_to_file(command_line_file_contents, command_line_path)
 
 
-def write_data_to_file(contents, file_path):
-  """Writes content to file."""
+def write_data_to_file(contents, file_path, should_reboot=True):
+  """Writes content to file.
+
+  Args:
+    contents: The string content to write.
+    file_path: The path to the file on the Android device.
+    should_reboot: Whether to reboot the device after writing the file.
+        Only applies if `file_path` is under `/system`, since we need to
+        remount that partition as read-write first.
+  """
   # If this is a file in /system, we need to remount /system as read-write and
   # after file is written, revert it back to read-only.
   is_system_file = file_path.startswith('/system')
@@ -896,5 +904,9 @@ def write_data_to_file(contents, file_path):
   run_shell_command('chmod 0644 %s' % file_path, root=True)
 
   if is_system_file:
-    reboot()
-    wait_until_fully_booted()
+    if should_reboot:
+      reboot()
+      wait_until_fully_booted()
+    else:
+      # Manually revert /system to read-only since we aren't rebooting.
+      run_shell_command('mount -o ro,remount /system', root=True)

src/clusterfuzz/_internal/platforms/android/device.py

@@ -316,11 +316,12 @@ def initialize_device():
   add_test_accounts_if_needed()
 
   # Setup AddressSanitizer if needed.
-  sanitizer.setup_asan_if_needed()
+  asan_reboot_done = sanitizer.setup_asan_if_needed()
 
   # Reboot device as above steps would need it and also it brings device in a
   # good state.
-  reboot()
+  if not asan_reboot_done:
+    reboot()
 
   # Make sure we are running as root after restart.
   adb.run_as_root()

src/clusterfuzz/_internal/platforms/android/sanitizer.py

@@ -69,25 +69,31 @@ def set_options(sanitizer_tool_name, sanitizer_options):
   if not sanitizer_options_file_path:
     return
 
-  adb.write_data_to_file(sanitizer_options, sanitizer_options_file_path)
+  # Skip reboot as the app will pick up the options file on restart.
+  adb.write_data_to_file(
+      sanitizer_options, sanitizer_options_file_path, should_reboot=False)
 
 
-def setup_asan_if_needed():
-  """Set up asan on device."""
+def setup_asan_if_needed() -> bool:
+  """Set up asan on device.
+
+  Returns:
+    True if the device was rebooted or restarted during setup, False otherwise.
+  """
   if not environment.get_value('ASAN_DEVICE_SETUP'):
     # Only do this step if explicitly enabled in the job type. This cannot be
     # determined from libraries in application directory since they can go
     # missing in a bad build, so we want to catch that.
-    return
+    return False
 
   if settings.get_sanitizer_tool_name():
     # If this is a sanitizer build, no need to setup ASAN (incompatible).
-    return
+    return False
 
   app_directory = environment.get_value('APP_DIR')
   if not app_directory:
     # No app directory -> No ASAN runtime library. No work to do, bail out.
-    return
+    return False
 
   # Initialize variables.
   android_directory = environment.get_platform_resources_directory()
@@ -108,7 +114,7 @@ def setup_asan_if_needed():
   result = process.run_and_wait()
   if result.return_code:
     logs.error('Failed to setup ASan on device.', output=result.output)
-    return
+    return False
 
   logs.info(
       'ASan device setup script successfully finished, waiting for boot.',
@@ -117,3 +123,5 @@ def setup_asan_if_needed():
   # Wait until fully booted as otherwise shell restart followed by a quick
   # reboot can trigger data corruption in /data/data.
   adb.wait_until_fully_booted()
+
+  return True

src/clusterfuzz/_internal/tests/core/platforms/android/device_test.py

@@ -17,21 +17,60 @@
 
 from clusterfuzz._internal.platforms.android import device
 from clusterfuzz._internal.tests.test_libs import android_helpers
+from clusterfuzz._internal.tests.test_libs import helpers
 
 
 class InitializeEnvironmentTest(android_helpers.AndroidTest):
-  """Tests for """
+  """Tests for the device environment initialization process (`initialize_environment`)."""
 
   def test(self):
     """Ensure that initialize_environment throws no exceptions."""
     device.initialize_environment()
 
 
+class InitializeDeviceRebootLogicTest(unittest.TestCase):
+  """Tests the reboot batching logic in initialize_device."""
+
+  def setUp(self):
+    helpers.patch(self, [
+        'clusterfuzz._internal.system.environment.is_engine_fuzzer_job',
+        'clusterfuzz._internal.platforms.android.adb.setup_adb',
+        'clusterfuzz._internal.platforms.android.adb.run_as_root',
+        'clusterfuzz._internal.platforms.android.device.configure_system_build_properties',
+        'clusterfuzz._internal.platforms.android.device.configure_device_settings',
+        'clusterfuzz._internal.platforms.android.device.add_test_accounts_if_needed',
+        'clusterfuzz._internal.platforms.android.sanitizer.setup_asan_if_needed',
+        'clusterfuzz._internal.platforms.android.device.reboot',
+        'clusterfuzz._internal.platforms.android.wifi.configure',
+        'clusterfuzz._internal.platforms.android.device.setup_host_and_device_forwarder_if_needed',
+        'clusterfuzz._internal.platforms.android.settings.change_se_linux_to_permissive_mode',
+        'clusterfuzz._internal.platforms.android.app.wait_until_optimization_complete',
+        'clusterfuzz._internal.platforms.android.ui.clear_notifications',
+        'clusterfuzz._internal.platforms.android.ui.unlock_screen',
+    ])
+    self.mock.is_engine_fuzzer_job.return_value = False
+
+  def test_reboot_if_asan_did_not_run(self):
+    """Test that `initialize_device()` calls `reboot()` if the ASan setup
+    script did not."""
+    self.mock.setup_asan_if_needed.return_value = False
+
+    device.initialize_device()
+    self.mock.reboot.assert_called_once()
+
+  def test_no_reboot_if_asan_ran(self):
+    """Test that `initialize_device()` skips calling `reboot()` if the ASan
+    setup script did."""
+    self.mock.setup_asan_if_needed.return_value = True
+
+    device.initialize_device()
+    self.mock.reboot.assert_not_called()
+
+
 class AddTestAccountsIfNeededTest(unittest.TestCase):
   """Tests for add_test_accounts_if_needed."""
 
   def setUp(self):
-    from clusterfuzz._internal.tests.test_libs import helpers
     helpers.patch(self, [
         'clusterfuzz._internal.system.environment.is_uworker',
         'clusterfuzz._internal.base.persistent_cache.get_value',