Refactor test scripts for android to improve performance

build/android/pylib/device/device_utils.py

Index: build/android/pylib/device/device_utils.py
diff --git a/build/android/pylib/device/device_utils.py b/build/android/pylib/device/device_utils.py
index fe9d2c64324ecb378bf43b4c63aa8e1d13a94acc..54f9a5dd505581394b8e5bd85a366a742454bd5a 100644
--- a/build/android/pylib/device/device_utils.py
+++ b/build/android/pylib/device/device_utils.py
@@ -126,6 +126,7 @@ class DeviceUtils(object):
     self._default_timeout = default_timeout
     self._default_retries = default_retries
     self._cache = {}
+    self._cache['application_paths'] = {}
     assert hasattr(self, decorators.DEFAULT_TIMEOUT_ATTR)
     assert hasattr(self, decorators.DEFAULT_RETRIES_ATTR)
 
@@ -279,6 +280,10 @@ class DeviceUtils(object):
     # in Lollipop.
     # TODO(jbudorick): Check if this is fixed as new Android versions are
     # released to put an upper bound on this.
+    application_paths = self._cache['application_paths']

[jbudorick, 2015/01/21 22:54:09]

If we stay with the cache, please move this above the comment. It's explaining
the lines that follow.

+    if package in application_paths:
+      return application_paths[package]
+
     should_check_return = (self.build_version_sdk <

[jbudorick, 2015/01/21 22:54:09]

w.r.t. my tuning suggestion: we already have some version-dependent code here.

                            constants.ANDROID_SDK_VERSION_CODES.LOLLIPOP)
     output = self.RunShellCommand(['pm', 'path', package], single_line=True,
@@ -288,7 +293,8 @@ class DeviceUtils(object):
     if not output.startswith('package:'):
       raise device_errors.CommandFailedError('pm path returned: %r' % output,
                                              str(self))
-    return output[len('package:'):]
+    application_paths[package] = output[len('package:'):]
+    return application_paths[package]
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def WaitUntilFullyBooted(self, wifi=False, timeout=None, retries=None):
@@ -359,6 +365,7 @@ class DeviceUtils(object):
 
     self.adb.Reboot()
     self._cache = {}
+    self._cache['application_paths'] = {}
     timeout_retry.WaitFor(device_offline, wait_period=1)
     if block:
       self.WaitUntilFullyBooted()
@@ -396,6 +403,10 @@ class DeviceUtils(object):
     if should_install:
       self.adb.Install(apk_path, reinstall=reinstall)
 
+    application_paths = self._cache['application_paths']
+    if package_name in application_paths:
+      del application_paths[package_name]
+
   @decorators.WithTimeoutAndRetriesFromInstance()
   def RunShellCommand(self, cmd, check_return=False, cwd=None, env=None,
                       as_root=False, single_line=False,
@@ -421,6 +432,9 @@ class DeviceUtils(object):
     TODO(perezju) Change the default of |check_return| to True when callers
       have switched to the new behaviour.
 
+    TODO(jaekyun) Should clear some of non-RO cache items if this command
+      affects them.
+
     Args:
       cmd: A string with the full command to run on the device, or a sequence
         containing the command and its arguments.
@@ -456,6 +470,10 @@ class DeviceUtils(object):
 
     if not isinstance(cmd, basestring):
       cmd = ' '.join(cmd_helper.SingleQuote(s) for s in cmd)
+
+    if cmd.startswith('pm install') or cmd.startswith('pm uninstall'):

[jbudorick, 2015/01/21 22:54:09]

O_O

This looks _extremely_ dangerous / flaky / terrifying / high-maintenance / etc.

+      self._cache['application_paths'] = {}
+
     if env:
       env = ' '.join(env_quote(k, v) for k, v in env.iteritems())
       cmd = '%s %s' % (env, cmd)