[DO NOT COMMIT] Refactor systrace to support new clock sync design

systrace/systrace/agents/ftrace_agent.py

Index: systrace/systrace/agents/ftrace_agent.py
diff --git a/systrace/systrace/agents/ftrace_agent.py b/systrace/systrace/agents/ftrace_agent.py
index 758fc617e5e10dea6140501b7a7d678e6dbf49ce..3186f2beb5fa175a02f3cd352846d5c5ff711283 100644
--- a/systrace/systrace/agents/ftrace_agent.py
+++ b/systrace/systrace/agents/ftrace_agent.py
@@ -6,7 +6,7 @@ import os
 import sys
 import time
 
-from systrace import systrace_agent
+from systrace import tracing_agent
 
 
 class FtraceAgentIo(object):
@@ -90,7 +90,7 @@ def try_create_agent(options, categories):
   return FtraceAgent(options, categories, FtraceAgentIo)
 
 
-class FtraceAgent(systrace_agent.SystraceAgent):
+class FtraceAgent(tracing_agent.TracingAgent):
 
   def __init__(self, options, categories, fio=FtraceAgentIo):
     """Initialize a systrace agent.
@@ -99,13 +99,16 @@ class FtraceAgent(systrace_agent.SystraceAgent):
       options: The command-line options.
       categories: The trace categories to capture.
     """
-    super(FtraceAgent, self).__init__(options, categories)
-    if not self._categories:
+    super(FtraceAgent, self).__init__()
+    if not categories:
       self._categories = ["sched"]
+    else:
+      self._categories = categories
     self._fio = fio
+    self._options = options
     self._categories = [x for x in self._categories
                         if self._is_category_available(x)]
-    self._expect_trace = False
+    self._should_output_trace = False
 
   def _get_trace_buffer_size(self):
     buffer_size = 4096
@@ -121,13 +124,14 @@ class FtraceAgent(systrace_agent.SystraceAgent):
       wait_time = self._options.trace_time
     return wait_time
 
-  def start(self):
+  #override
+  def StartAgentTracing(self):
     """Start tracing.
     """
     if self._options.list_categories or len(self._categories) == 0:
-      self._expect_trace = False
+      self._should_output_trace = False
     else:
-      self._expect_trace = True
+      self._should_output_trace = True
 
       self._fio.writeFile(FT_BUFFER_SIZE, str(self._get_trace_buffer_size()))
 
@@ -148,8 +152,10 @@ class FtraceAgent(systrace_agent.SystraceAgent):
       sys.stdout.flush()
 
       self._fio.writeFile(FT_TRACE_ON, '1')
+    return True
 
-  def collect_result(self):
+  #override
+  def StopAgentTracing(self):
     """Collect the result of tracing.
 
     This function will block while collecting the result. For sync mode, it
@@ -172,17 +178,10 @@ class FtraceAgent(systrace_agent.SystraceAgent):
         print "WARN: tgid fixing is not yet supported."
       if self._options.fix_circular:
         print "WARN: circular buffer fixups are not yet supported."
+    return True
 
-  def expect_trace(self):
-    """Check if the agent is returning a trace or not.
-
-    This will be determined in collect_result().
-    Returns:
-      Whether the agent is expecting a trace or not.
-    """
-    return self._expect_trace
-
-  def get_trace_data(self):
+  #override
+  def GetResults(self):
     """Get the trace data.
 
     Returns:
@@ -190,10 +189,16 @@ class FtraceAgent(systrace_agent.SystraceAgent):
     """
     d = self._fio.readFile(FT_TRACE)
     self._fio.writeFile(FT_BUFFER_SIZE, "1")
-    return d
+    return tracing_agent.TraceResults('systemTraceEvents', d,
+                                      self._should_output_trace)
+
+  #override
+  def SupportsExplicitClockSync(self):
+    return False
 
-  def get_class_name(self):
-    return 'trace-data'
+  #override
+  def RecordClockSyncMarker(self, sync_id, callback):
+    raise NotImplementedError
 
   def _is_category_available(self, category):
     if category not in all_categories: