bitbake: toaster: Add an invalidate cache method on data update signal

Instead of relying on the cache expiring over an amount of time we can
listen to the changed notification on the models to invalidate the
cache. Also fixes overlapping cache names.

(Bitbake rev: eb0b1450e421cf65b407b1ac0336ac24ffc626e8)

Signed-off-by: Michael Wood <michael.g.wood@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/toaster/orm/models.py

@@ -26,6 +26,7 @@ from django.utils import timezone
 
 from django.core import validators
 from django.conf import settings
+import django.db.models.signals
 
 class GitURLValidator(validators.URLValidator):
     import re
@@ -1176,3 +1177,14 @@ class LogMessage(models.Model):
     message=models.CharField(max_length=240)
     pathname = models.FilePathField(max_length=255, blank=True)
     lineno = models.IntegerField(null=True)
+
+def invalidate_cache(**kwargs):
+    from django.core.cache import cache
+    try:
+      cache.clear()
+    except Exception as e:
+      print "Problem with cache backend: Failed to clear cache"
+      pass
+
+django.db.models.signals.post_save.connect(invalidate_cache)
+django.db.models.signals.post_delete.connect(invalidate_cache)