Android Incremental Install Always use the same device cache

build/android/pylib/local/device/local_device_environment.py

 # Copyright 2014 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.
 
 import datetime
 import logging
 import os
 import threading
 
 from devil.android import device_blacklist
@@ skipping 43 matching lines @@
     else:
       self._devices = available_devices
 
     if self._enable_device_cache:
       for d in self._devices:
         cache_path = _DeviceCachePath(d)
         if os.path.exists(cache_path):
           logging.info('Using device cache: %s', cache_path)
           with open(cache_path) as f:
             d.LoadCacheData(f.read())
+          # Delete cached file so that any exceptions cause it to be cleared.
           os.unlink(cache_path)
     if self._logcat_output_dir:
       for d in self._devices:
         logcat_file = os.path.join(
             self._logcat_output_dir,
             '%s_%s' % (d.adb.GetDeviceSerial(),
                        datetime.datetime.utcnow().strftime('%Y%m%dT%H%M%S')))
         monitor = logcat_monitor.LogcatMonitor(
             d.adb, clear=True, output_file=logcat_file)
         self._logcat_monitors.append(monitor)
@@ skipping 39 matching lines @@
       m.Stop()
       m.Close()
 
   def BlacklistDevice(self, device, reason='local_device_failure'):
     device_serial = device.adb.GetDeviceSerial()
     if self._blacklist:
       self._blacklist.Extend([device_serial], reason=reason)
     with self._devices_lock:
       self._devices = [d for d in self._devices if str(d) != device_serial]