Add new timing mechanism to ftrace.

systrace/systrace/tracing_agents/ftrace_agent.py

Index: systrace/systrace/tracing_agents/ftrace_agent.py
diff --git a/systrace/systrace/tracing_agents/ftrace_agent.py b/systrace/systrace/tracing_agents/ftrace_agent.py
index 89d3e1aefbc8277106cf72d2df72e3579cf7429f..fc69c74c633f989b33bbc6287856561172b608c2 100644
--- a/systrace/systrace/tracing_agents/ftrace_agent.py
+++ b/systrace/systrace/tracing_agents/ftrace_agent.py
@@ -4,7 +4,6 @@
 
 import os
 import sys
-import time
 
 from devil.utils import timeout_retry
 from systrace import tracing_agents
@@ -116,13 +115,6 @@ class FtraceAgent(tracing_agents.TracingAgent):
       buffer_size = self._options.trace_buf_size
     return buffer_size
 
-  def _get_trace_time(self):
-    wait_time = 5
-    if ((self._options.trace_time is not None)
-        and (self._options.trace_time > 0)):
-      wait_time = self._options.trace_time
-    return wait_time
-
   def _fix_categories(self, categories):
     """
     Applies the default category (sched) if there are no categories
@@ -168,23 +160,12 @@ class FtraceAgent(tracing_agents.TracingAgent):
                              args=[options, categories])
 
   def _StopAgentTracingImpl(self):
-    pass
-
-  def StopAgentTracing(self, timeout):
-    return timeout_retry.Run(self._StopAgentTracingImpl,
-                             timeout, 1)
-
-  def _GetResultsImpl(self):
     """Collect the result of tracing.
 
     This function will block while collecting the result. For sync mode, it
     reads the data, e.g., from stdout, until it finishes. For async mode, it
     blocks until the agent is stopped and the data is ready.
     """
-    try:
-      time.sleep(self._get_trace_time())
-    except KeyboardInterrupt:
-      pass
     self._fio.writeFile(FT_TRACE_ON, '0')
     for category in self._categories:
       self._category_disable(category)
@@ -195,6 +176,11 @@ class FtraceAgent(tracing_agents.TracingAgent):
     if self._options.fix_circular:
       print "WARN: circular buffer fixups are not yet supported."
 
+  def StopAgentTracing(self, timeout):
+    return timeout_retry.Run(self._StopAgentTracingImpl,
+                             timeout, 1)
+
+  def _GetResultsImpl(self):
     # get the output
     d = self._fio.readFile(FT_TRACE)
     self._fio.writeFile(FT_BUFFER_SIZE, "1")