Implement metrics on locmem cache (#72)

Author: geobeau

django_prometheus/cache/backends/locmem.py

@@ -0,0 +1,17 @@
+from django.core.cache.backends import locmem
+from django_prometheus.cache.metrics import (
+    django_cache_get_total, django_cache_hits_total, django_cache_misses_total)
+
+
+class LocMemCache(locmem.LocMemCache):
+    """Inherit filebased cache to add metrics about hit/miss ratio"""
+
+    def get(self, key, default=None, version=None):
+        django_cache_get_total.labels(backend='locmem').inc()
+        cached = super(LocMemCache, self).get(
+            key, default=None, version=None)
+        if cached is not None:
+            django_cache_hits_total.labels(backend='locmem').inc()
+        else:
+            django_cache_misses_total.labels(backend='locmem').inc()
+        return cached

django_prometheus/tests/end2end/testapp/settings.py

@@ -149,6 +149,10 @@ def GetMiddlewareClasses():
     'filebased': {
         'BACKEND': 'django_prometheus.cache.backends.filebased.FileBasedCache',
         'LOCATION': '/var/tmp/django_cache',
+    },
+    'locmem': {
+        'BACKEND': 'django_prometheus.cache.backends.locmem.LocMemCache',
+        'LOCATION': '/var/tmp/locmem_cache',
     }
 }
 

django_prometheus/tests/end2end/testapp/test_caches.py

@@ -9,30 +9,20 @@ class TestCachesMetrics(PrometheusTestCaseMixin, TestCase):
     """Test django_prometheus.caches metrics."""
 
     def testCounters(self):
-        cache_memcached = caches['memcached']
-        cache_filebased = caches['filebased']
-
-        cache_filebased.set('foo1', 'bar')
-        cache_filebased.get('foo1')
-        cache_filebased.get('foo1')
-        cache_filebased.get('foofoo')
-
-        self.assertMetricEquals(
-            3, 'django_cache_get_total', backend='filebased')
-        self.assertMetricEquals(
-            2, 'django_cache_get_hits_total', backend='filebased')
-        self.assertMetricEquals(
-            1, 'django_cache_get_misses_total', backend='filebased')
+        supported_caches = ['memcached', 'filebased', 'locmem']
 
         # Note: those tests require a memcached server running
-        cache_memcached.set('foo2', 'bar')
-        cache_memcached.get('foo2')
-        cache_memcached.get('foofoo')
-        cache_memcached.get('foofoo')
-
-        self.assertMetricEquals(
-            3, 'django_cache_get_total', backend='memcached')
-        self.assertMetricEquals(
-            1, 'django_cache_get_hits_total', backend='memcached')
-        self.assertMetricEquals(
-            2, 'django_cache_get_misses_total', backend='memcached')
+        for supported_cache in supported_caches:
+            tested_cache = caches[supported_cache]
+
+            tested_cache.set('foo1', 'bar')
+            tested_cache.get('foo1')
+            tested_cache.get('foo1')
+            tested_cache.get('foofoo')
+
+            self.assertMetricEquals(
+                3, 'django_cache_get_total', backend=supported_cache)
+            self.assertMetricEquals(
+                2, 'django_cache_get_hits_total', backend=supported_cache)
+            self.assertMetricEquals(
+                1, 'django_cache_get_misses_total', backend=supported_cache)