[Qemu-devel] [PATCH 21/34] scripts/kvm/kvm_stat: Encapsulate filters variable

[Janosch Frank]

The variable was only used in one class but still was defined
globally. Additionaly the detect_platform routine which prepares the
data that goes into the variable was called on each start of the
script, no matter if the class was needed.

To make the variable local to the TracepointProvider class, a new
function that calls detect_platform and returns the filters was
introduced.
---
 scripts/kvm/kvm_stat | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/scripts/kvm/kvm_stat b/scripts/kvm/kvm_stat
index 20fc5c9..868c6a5 100755
--- a/scripts/kvm/kvm_stat
+++ b/scripts/kvm/kvm_stat
@@ -296,10 +296,14 @@ def get_online_cpus():
                                      int(cpu_range[1]) + 1))
     return cpulist
 
-filters = {}
-filters['kvm_userspace_exit'] = ('reason', USERSPACE_EXIT_REASONS)
-if EXIT_REASONS:
-    filters['kvm_exit'] = ('exit_reason', EXIT_REASONS)
+
+def get_filters():
+    detect_platform()
+    filters = {}
+    filters['kvm_userspace_exit'] = ('reason', USERSPACE_EXIT_REASONS)
+    if EXIT_REASONS:
+        filters['kvm_exit'] = ('exit_reason', EXIT_REASONS)
+    return filters
 
 libc = ctypes.CDLL('libc.so.6', use_errno=True)
 syscall = libc.syscall
@@ -379,6 +383,7 @@ class Event(object):
 class TracepointProvider(object):
     def __init__(self):
         self.group_leaders = []
+        self.filters = get_filters()
         self._fields = self.get_available_fields()
         self.setup_traces()
         self.fields = self._fields
@@ -388,8 +393,8 @@ class TracepointProvider(object):
         fields = walkdir(path)[1]
         extra = []
         for field in fields:
-            if field in filters:
-                filter_name_, filter_dicts = filters[field]
+            if field in self.filters:
+                filter_name_, filter_dicts = self.filters[field]
                 for name in filter_dicts:
                     extra.append(field + '(' + name + ')')
         fields += extra
@@ -414,8 +419,9 @@ class TracepointProvider(object):
                 match = re.match(r'(.*)\((.*)\)', name)
                 if match:
                     tracepoint, sub = match.groups()
-                    tracefilter = '%s==%d\0' % (filters[tracepoint][0],
-                                                filters[tracepoint][1][sub])
+                    tracefilter = ('%s==%d\0' %
+                                   (self.filters[tracepoint][0],
+                                    self.filters[tracepoint][1][sub]))
                 group.add_event(name, event_set='kvm',
                                 tracepoint=tracepoint,
                                 tracefilter=tracefilter)
@@ -646,7 +652,6 @@ def check_access():
 
 def main():
     check_access()
-    detect_platform()
     options = get_options()
     providers = get_providers(options)
     stats = Stats(providers, fields=options.fields)
-- 
2.3.0