trace: Add logcat trace collector

devlib/trace/logcat.py

@@ -0,0 +1,58 @@
+import os
+import re
+import shutil
+
+from devlib.trace import TraceCollector
+from devlib.utils.android import LogcatMonitor
+
+class LogcatCollector(TraceCollector):
+
+    def __init__(self, target, regexps=None):
+        super(LogcatCollector, self).__init__(target)
+        self.regexps = regexps
+        self._collecting = False
+        self._prev_log = None
+
+    def reset(self):
+        """
+        Clear Collector data but do not interrupt collection
+        """
+        if not self._monitor:
+            return
+
+        if self._collecting:
+            self._monitor.clear_log()
+        elif self._prev_log:
+            os.remove(self._prev_log)
+            self._prev_log = None
+
+    def start(self):
+        """
+        Start collecting logcat lines
+        """
+        self._monitor = LogcatMonitor(self.target, self.regexps)
+        if self._prev_log:
+            # Append new data collection to previous collection
+            self._monitor.start(self._prev_log)
+        else:
+            self._monitor.start()
+
+        self._collecting = True
+
+    def stop(self):
+        """
+        Stop collecting logcat lines
+        """
+        if not self._collecting:
+            raise RuntimeError('Logcat monitor not running, nothing to stop')
+
+        self._monitor.stop()
+        self._collecting = False
+        self._prev_log = self._monitor.logfile
+
+    def get_trace(self, outfile):
+        """
+        Output collected logcat lines to designated file
+        """
+        # copy self._monitor.logfile to outfile
+        shutil.copy(self._monitor.logfile, outfile)