add model save tracer

Change-Id: Idf8e264a4328acdca0fa435f6d9b9b346a2152d4

scalpels/agents/base.py

@@ -66,6 +66,13 @@ def parse_rabbit(out):
                "data": out}
     return (rbt_ret, )
 
+def _parse_count_stream(out, name):
+    ret = {"name": name,
+           "unit": "count",
+           "rtype": "stream",
+           "data": out}
+    return (ret, )
+
 def parse_oslolock(out):
     """
     in:
@@ -77,8 +84,7 @@ def parse_oslolock(out):
         unit: Count
         data: [(ts, 0), ...)
     """
-    ret = {"name": "Oslo-Lock",
-           "unit": "count",
-           "rtype": "stream",
-           "data": out}
-    return (ret, )
+    return _parse_count_stream(out, "Oslo-Lock")
+
+def parse_modelsave(out):
+    return _parse_count_stream(out, "Model-Save")

scalpels/cli/actions/start.py

@@ -41,6 +41,7 @@ agents_map = {
     "rpc": "bash %s/port-input-traffic.sh 5672",
     "traffic": "bash %s/device-input-traffic.sh eth0",
     "oslolock": "stap %s/oslo-lock.stp", # with sudo, need add current user to stapdev group
+    "modelsave": "stap %s/model-save.stp", # with sudo, need add current user to stapdev group
 }
 
 def run(config):

scripts/model-save.stp

@@ -0,0 +1,14 @@
+#!/usr/bin/stap
+
+global count = 0;
+global old_count = 0;
+probe python.function.entry {
+	if ((funcname == "save") && isinstr(filename, "oslo_db/sqlalchemy/models.py") ) {
+		count = count + 1;
+	}
+}
+probe timer.ms(1000) {
+	new_count = count - old_count;
+	printf("%d\n", new_count);
+	old_count = count;
+}