From 46ca31651187d542f69301485ef6440ee4566b4a Mon Sep 17 00:00:00 2001
From: elie <elie>
Date: Sun, 23 Jan 2011 09:04:39 +0000
Subject: cache MIB columnar objects instance ID <-> symbolic representation
 mapping for performance reasons

---
 pysnmp/cache.py | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 pysnmp/cache.py

(limited to 'pysnmp/cache.py')

diff --git a/pysnmp/cache.py b/pysnmp/cache.py
new file mode 100644
index 00000000..4023c460
--- /dev/null
+++ b/pysnmp/cache.py
@@ -0,0 +1,37 @@
+# Limited-size dictionary class to use for caches
+
+class Cache:
+    def __init__(self, maxSize=256):
+        self.__maxSize = maxSize
+        self.__size = 0
+        self.__chopSize = maxSize/10
+        self.__chopSize = self.__chopSize and self.__chopSize or 1
+        self.__cache = {}
+        self.__usage = {}
+
+    def __contains__(self, k): return k in self.__cache
+
+    def __getitem__(self, k):
+        self.__usage[k] = self.__usage[k] + 1
+        return self.__cache[k]
+
+    def __len__(self): return self.__size
+        
+    def __setitem__(self, k, v):
+        if self.__size >= self.__maxSize:
+            keys = self.__usage.keys()
+            keys.sort(lambda x,y,d=self.__usage: cmp(d[x],d[y]))
+            print keys[:self.__chopSize]
+            for _k in keys[:self.__chopSize]:
+                del self.__cache[_k]
+                del self.__usage[_k]
+            self.__size = self.__size - self.__chopSize
+        if k not in self.__cache:
+            self.__size = self.__size + 1
+            self.__usage[k] = 0L
+        self.__cache[k] = v
+
+    def __delitem__(self, k):
+        del self.__cache[k]
+        del self.__usage[k]
+        self.__size = self.__size - 1
-- 
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