processors: add uxperf

Add a simplified version of the uxperf processor. This version only
extracts and calculates durations of UX_PERF sections from logcat.
Currently, this does not correlate them agains frames/fps data.

wa/processors/uxperf.py

@@ -0,0 +1,48 @@
+import os
+
+from wa import ResultProcessor
+from wa.utils.android import LogcatParser
+
+
+class UxperfProcessor(ResultProcessor):
+
+    name = 'uxperf'
+
+    def process_job_output(self, output, target_info, job_output):
+        logcat = output.get_artifact('logcat')
+        if not logcat:
+            return
+
+        parser = LogcatParser()
+        start_times = {}
+
+        filepath = output.get_path(logcat.path)
+        for entry in parser.parse(filepath):
+            if not entry.tag == 'UX_PERF':
+                continue
+
+            parts = entry.message.split()
+            if len(parts) != 3:
+                message = 'Unexpected UX_PERF message @ {}: {}'
+                self.logger.warning(message.format(entry.timestamp, entry.message))
+                continue
+
+            action, state, when = parts
+            when = int(when)
+            if state == 'start':
+                if action in start_times:
+                    self.logger.warning('start before end @ {}'.format(entry.timestamp))
+                start_times[action] = when
+            elif state == 'end':
+                start_time = start_times.pop(action, None)
+                if start_time is None:
+                    self.logger.warning('end without start @ {}'.format(entry.timestamp))
+                    continue
+
+                duration = (when - start_time) / 1000
+                metric_name = '{}_duration'.format(action)
+                output.add_metric(metric_name, duration, 'microseconds',
+                                  lower_is_better=True)
+
+            else:
+                self.logger.warning('Unexpected state "{}" @ {}'.format(state, entry.timestamp))