From c9357b241711321d4b1aeae3ba730e63364e7e22 Mon Sep 17 00:00:00 2001
From: melvinzhang <melvinzhang@gmail.com>
Date: Fri, 10 Feb 2017 20:49:40 +0800
Subject: [PATCH] add python script used to evaluation effect of cache size on
 number of cache misses

---
 scripts/tune-cache-size.py | 45 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 scripts/tune-cache-size.py

diff --git a/scripts/tune-cache-size.py b/scripts/tune-cache-size.py
new file mode 100644
index 0000000000..b65d9eff80
--- /dev/null
+++ b/scripts/tune-cache-size.py
@@ -0,0 +1,45 @@
+# reads lines from stdin representing requests
+# outputs percentage of cache misses for various cache sizes
+
+import collections
+
+class LRUCache:
+    def __init__(self, capacity):
+        self.capacity = capacity
+        self.cache = collections.OrderedDict()
+        self.misses = 0
+
+    def get(self, key):
+        try:
+            value = self.cache.pop(key)
+            self.cache[key] = value
+            return value
+        except KeyError:
+            self.misses += 1
+            return -1
+
+    def set(self, key, value):
+        try:
+            self.cache.pop(key)
+        except KeyError:
+            if len(self.cache) >= self.capacity:
+                self.cache.popitem(last=False)
+        self.cache[key] = value
+
+caches = [LRUCache(i*10) for i in range(1, 11)]
+
+import sys
+
+seen = set()
+
+cnt = 0
+for line in sys.stdin:
+    cnt += 1
+    for c in caches:
+        if line in seen:
+            c.get(line)
+        c.set(line, 0)
+    seen.add(line)
+
+for c in caches:
+    print c.capacity, c.misses * 100.0 / cnt