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

systrace/systrace/tracing_agents/ftrace_agent.py

Index: systrace/systrace/tracing_agents/ftrace_agent.py
diff --git a/systrace/systrace/agents/ftrace_agent.py b/systrace/systrace/tracing_agents/ftrace_agent.py
similarity index 74%
rename from systrace/systrace/agents/ftrace_agent.py
rename to systrace/systrace/tracing_agents/ftrace_agent.py
index 758fc617e5e10dea6140501b7a7d678e6dbf49ce..ecff8605750fb1f2f14ff42500accac4d239e362 100644
--- a/systrace/systrace/agents/ftrace_agent.py
+++ b/systrace/systrace/tracing_agents/ftrace_agent.py
@@ -6,8 +6,8 @@ import os
 import sys
 import time
 
-from systrace import systrace_agent
-
+from systrace.tracing_agents import TracingAgent
+from systrace.tracing_agents import TraceResults
 
 class FtraceAgentIo(object):
 
@@ -83,6 +83,9 @@ all_categories = {
     }
 }
 
+def list_categories(options):
+  agent = FtraceAgent(options, [], FtraceAgentIo)
+  agent._print_avail_categories()
 
 def try_create_agent(options, categories):
   if options.target != 'linux':
@@ -90,7 +93,7 @@ def try_create_agent(options, categories):
   return FtraceAgent(options, categories, FtraceAgentIo)
 
 
-class FtraceAgent(systrace_agent.SystraceAgent):
+class FtraceAgent(TracingAgent):
 
   def __init__(self, options, categories, fio=FtraceAgentIo):

[Zhen Wang, 2016/03/29 18:53:40]

Do not pass in options and categories. Pass them in StartAgentTracing()

[alexandermont, 2016/03/30 01:04:25]

Done

     """Initialize a systrace agent.
@@ -103,9 +106,9 @@ class FtraceAgent(systrace_agent.SystraceAgent):
     if not self._categories:
       self._categories = ["sched"]
     self._fio = fio
+    self._options = options
     self._categories = [x for x in self._categories
                         if self._is_category_available(x)]
-    self._expect_trace = False
 
   def _get_trace_buffer_size(self):
     buffer_size = 4096
@@ -121,68 +124,53 @@ class FtraceAgent(systrace_agent.SystraceAgent):
       wait_time = self._options.trace_time
     return wait_time
 
-  def start(self):
+  def _StartAgentTracing_func(self):
     """Start tracing.
     """

[Zhen Wang, 2016/03/29 18:53:40]

Run self._fio.haveWritePermissions before actually starting tracing. If the user
forgets sudo, we have a way to print some nice error message out early (and
return early). For example: "No write permission to ..., perhaps you need
sudo/root?"

[alexandermont, 2016/03/30 01:04:25]

Done

-    if self._options.list_categories or len(self._categories) == 0:
-      self._expect_trace = False
-    else:
-      self._expect_trace = True
-
-      self._fio.writeFile(FT_BUFFER_SIZE, str(self._get_trace_buffer_size()))
+    self._fio.writeFile(FT_BUFFER_SIZE, str(self._get_trace_buffer_size()))
 
-      self._fio.writeFile(FT_CLOCK, 'global')
-      self._fio.writeFile(FT_TRACER, 'nop')
-      self._fio.writeFile(FT_OVERWRITE, "0")
+    self._fio.writeFile(FT_CLOCK, 'global')
+    self._fio.writeFile(FT_TRACER, 'nop')
+    self._fio.writeFile(FT_OVERWRITE, "0")
 
-      # TODO: riandrews to push necessary patches for TGID option to upstream
-      # linux kernel
-      # self._fio.writeFile(FT_PRINT_TGID, '1')
+    # TODO: riandrews to push necessary patches for TGID option to upstream
+    # linux kernel
+    # self._fio.writeFile(FT_PRINT_TGID, '1')
 
-      for category in self._categories:
-        self._category_enable(category)
+    for category in self._categories:
+      self._category_enable(category)
 
-      self._fio.writeFile(FT_TRACE, '')
+    self._fio.writeFile(FT_TRACE, '')
 
-      print "starting tracing."
-      sys.stdout.flush()
+    print "starting tracing."
+    sys.stdout.flush()
 
-      self._fio.writeFile(FT_TRACE_ON, '1')
+    self._fio.writeFile(FT_TRACE_ON, '1')
+    return True
 
-  def collect_result(self):
+  def _StopAgentTracing_func(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.
     """
-    if self._options.list_categories or len(self._categories) == 0:
-      self._print_avail_categories()
-    else:
-      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)
-      if self._options.fix_threads:
-        print "WARN: thread name fixing is not yet supported."
-      if self._options.fix_tgids:
-        print "WARN: tgid fixing is not yet supported."
-      if self._options.fix_circular:
-        print "WARN: circular buffer fixups are not yet supported."
-
-  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
+    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)
+    if self._options.fix_threads:
+      print "WARN: thread name fixing is not yet supported."
+    if self._options.fix_tgids:
+      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 get_trace_data(self):
+  def _GetResults_func(self):
     """Get the trace data.
 
     Returns:
@@ -190,10 +178,13 @@ class FtraceAgent(systrace_agent.SystraceAgent):
     """
     d = self._fio.readFile(FT_TRACE)
     self._fio.writeFile(FT_BUFFER_SIZE, "1")
-    return d
+    return TraceResults('systemTraceEvents', d)
+
+  def SupportsExplicitClockSync(self):
+    return False
 
-  def get_class_name(self):
-    return 'trace-data'
+  def RecordClockSyncMarker(self, sync_id, callback):
+    raise NotImplementedError
 
   def _is_category_available(self, category):
     if category not in all_categories: