From: Simon J Mudd <sjmudd@pobox.com>
Date: Tue, 25 Nov 2014 22:25:10 +0000 (+0100)
Subject: Provide a simplistic key value cache to reduce regexp usage
X-Git-Url: http://git.iain.cx/?a=commitdiff_plain;h=79dc9f00908f1bc9d46d5c5eeadada11a02b08d1;p=pstop.git

Provide a simplistic key value cache to reduce regexp usage
---

diff --git a/key_value_cache/key_value_cache.go b/key_value_cache/key_value_cache.go
new file mode 100644
index 0000000..e5881b6
--- /dev/null
+++ b/key_value_cache/key_value_cache.go
@@ -0,0 +1,55 @@
+package key_value_cache
+
+import (
+	"errors"
+
+	"github.com/sjmudd/pstop/lib"
+)
+
+// provide a mapping from filename to table.schema etc
+type KeyValueCache struct {
+	cache                                            map[string]string
+	read_requests, served_from_cache, write_requests int
+}
+
+// create a new KeyValueCache entry
+func NewKeyValueCache() KeyValueCache {
+	lib.Logger.Println("KeyValueCache()")
+	var kvc KeyValueCache
+
+	return kvc
+}
+
+// return value if found
+func (kvc *KeyValueCache) Get(key string) (result string, err error) {
+	lib.Logger.Println("KeyValueCache.Get(", key, ")")
+	if kvc.cache == nil {
+		lib.Logger.Println("KeyValueCache.Get() kvc.cache is empty so enabling it")
+		kvc.cache = make(map[string]string)
+		kvc.read_requests = 0
+		kvc.served_from_cache = 0
+		kvc.write_requests = 0
+	}
+
+	kvc.read_requests++
+
+	if result, ok := kvc.cache[key]; ok {
+		kvc.served_from_cache++
+		lib.Logger.Println("Found: read_requests/servced_from_cache:", kvc.read_requests, kvc.served_from_cache)
+		return result, nil
+	} else {
+		lib.Logger.Println("Not found: read_requests/served_from_cache:", kvc.read_requests, kvc.served_from_cache)
+		return "", errors.New("Not found")
+	}
+}
+
+// write to cache and return value
+func (kvc *KeyValueCache) Put(key, value string) string {
+	lib.Logger.Println("KeyValueCache.Put(", key, ",", value, ")")
+	kvc.cache[key] = value
+	return value
+}
+
+func (kvc *KeyValueCache) Statistics() (int, int, int) {
+	return kvc.read_requests, kvc.served_from_cache, kvc.write_requests
+}