telemetry: Fix killing the perf profiler

build/android/pylib/device/device_utils.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.
 
 """Provides a variety of device interactions based on adb.
 
 Eventually, this will be based on adb_wrapper.
 """
 # pylint: disable=unused-argument
 
@@ skipping 718 matching lines @@
       retries: number of retries
 
     Returns:
       The number of processes attempted to kill.
 
     Raises:
       CommandFailedError if no process was killed and |quiet| is False.
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
-    pids = self.GetPids(process_name)
+    pids = [pid for (_, pid) in self._GetProcessPidPairs(process_name)]
     if not pids:
       if quiet:
         return 0
       else:
         raise device_errors.CommandFailedError(
             'No process "%s"' % process_name, str(self))
 
-    cmd = ['kill', '-%d' % signum] + pids.values()
+    cmd = ['kill', '-%d' % signum] + pids
     self.RunShellCommand(cmd, as_root=as_root, check_return=True)
 
     if blocking:
       # TODO(perezu): use timeout_retry.WaitFor
       wait_period = 0.1
-      while self.GetPids(process_name):
+      while self._GetProcessPidPairs(process_name):
         time.sleep(wait_period)
 
     return len(pids)
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def StartActivity(self, intent_obj, blocking=False, trace_file_name=None,
                     force_stop=False, timeout=None, retries=None):
     """Start package's activity on the device.
 
     Args:
@@ skipping 793 matching lines @@
       retries: number of retries
 
     Returns:
       The device's main ABI name.
 
     Raises:
       CommandTimeoutError on timeout.
     """
     return self.GetProp('ro.product.cpu.abi')
 
-  @decorators.WithTimeoutAndRetriesFromInstance()
-  def GetPids(self, process_name, timeout=None, retries=None):
-    """Returns the PIDs of processes with the given name.
+  def _GetProcessPidPairs(self, process_name):

[jbudorick, 2015/07/24 17:10:56]

I think I'd prefer making a breaking change to the GetPids interface by having
it return

{
  'process': [process_pid0, process_pid1, ...]
}

instead of adding a separate function. I imagine most clients of GetPids would
want to know all of the pids that a given process is using, not just an
arbitrary one.

+    """Returns a list of (process, pid) pairs for all matching processes.
 
     Note that the |process_name| is often the package name.
 
     Args:
       process_name: A string containing the process name to get the PIDs for.
-      timeout: timeout in seconds
-      retries: number of retries
 
     Returns:
-      A dict mapping process name to PID for each process that contained the
+      A list with (process, pid) pairs for all processes that contained the
       provided |process_name|.
 
     Raises:
       CommandTimeoutError on timeout.
       DeviceUnreachableError on missing device.
     """
-    procs_pids = {}
+    procs_pids = []
     try:
       ps_output = self._RunPipedShellCommand(
           'ps | grep -F %s' % cmd_helper.SingleQuote(process_name))
     except device_errors.AdbShellCommandFailedError as e:
       if e.status and isinstance(e.status, list) and not e.status[0]:
         # If ps succeeded but grep failed, there were no processes with the
         # given name.
         return procs_pids
       else:
         raise
 
     for line in ps_output:
       try:
         ps_data = line.split()
         if process_name in ps_data[-1]:
-          procs_pids[ps_data[-1]] = ps_data[1]
+          pid, process = ps_data[1], ps_data[-1]
+          procs_pids.append((process, pid))
       except IndexError:
         pass
     return procs_pids
 
   @decorators.WithTimeoutAndRetriesFromInstance()
+  def GetPids(self, process_name, timeout=None, retries=None):
+    """Returns the PIDs of processes with the given name.
+
+    Note that the |process_name| is often the package name.
+
+    If there are multiple instances of the same process, only one of the PIDs
+    will be returned.
+
+    Args:
+      process_name: A string containing the process name to get the PIDs for.
+      timeout: timeout in seconds
+      retries: number of retries
+
+    Returns:
+      A dict mapping process name to PID for each process that contained the
+      provided |process_name|.
+
+    Raises:
+      CommandTimeoutError on timeout.
+      DeviceUnreachableError on missing device.
+    """
+    return dict(self._GetProcessPidPairs(process_name))
+
+  @decorators.WithTimeoutAndRetriesFromInstance()
   def TakeScreenshot(self, host_path=None, timeout=None, retries=None):
     """Takes a screenshot of the device.
 
     Args:
       host_path: A string containing the path on the host to save the
                  screenshot to. If None, a file name in the current
                  directory will be generated.
       timeout: timeout in seconds
       retries: number of retries
 
@@ skipping 127 matching lines @@
   def HealthyDevices(cls):
     blacklist = device_blacklist.ReadBlacklist()
     def blacklisted(adb):
       if adb.GetDeviceSerial() in blacklist:
         logging.warning('Device %s is blacklisted.', adb.GetDeviceSerial())
         return True
       return False
 
     return [cls(adb) for adb in adb_wrapper.AdbWrapper.Devices()
             if not blacklisted(adb)]