added LRU caching of skiplist results

[p2pool.git] / p2pool / util / memoize.py

diff --git a/p2pool/util/memoize.py b/p2pool/util/memoize.py
index b5efab2..4199ccb 100644 (file)
--- a/p2pool/util/memoize.py
+++ b/p2pool/util/memoize.py
@@ -1,3 +1,21 @@
+import itertools
+
+class LRUDict(object):
+    def __init__(self, n):
+        self.n = n
+        self.inner = {}
+        self.counter = itertools.count()
+    def get(self, key, default=None):
+        if key in self.inner:
+            x, value = self.inner[key]
+            self.inner[key] = self.counter.next(), value
+            return value
+        return default
+    def __setitem__(self, key, value):
+        self.inner[key] = self.counter.next(), value
+        while len(self.inner) > self.n:
+            self.inner.pop(min(self.inner, key=lambda k: self.inner[k][0]))
+
 _nothing = object()
 
 def memoize_with_backing(backing, has_inverses=set()):