Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

plugins/processors/ifname/cache.go

@@ -0,0 +1,83 @@
+package ifname
+
+// See https://girai.dev/blog/lru-cache-implementation-in-go/
+
+import (
+	"container/list"
+)
+
+type LRUValType = TTLValType
+
+type hashType map[keyType]*list.Element
+
+type LRUCache struct {
+	cap uint       // capacity
+	l   *list.List // doubly linked list
+	m   hashType   // hash table for checking if list node exists
+}
+
+// Pair is the value of a list node.
+type Pair struct {
+	key   keyType
+	value LRUValType
+}
+
+// initializes a new LRUCache.
+func NewLRUCache(capacity uint) LRUCache {
+	return LRUCache{
+		cap: capacity,
+		l:   new(list.List),
+		m:   make(hashType, capacity),
+	}
+}
+
+// Get a list node from the hash map.
+func (c *LRUCache) Get(key keyType) (LRUValType, bool) {
+	// check if list node exists
+	if node, ok := c.m[key]; ok {
+		val := node.Value.(*list.Element).Value.(Pair).value
+		// move node to front
+		c.l.MoveToFront(node)
+		return val, true
+	}
+	return LRUValType{}, false
+}
+
+// Put key and value in the LRUCache
+func (c *LRUCache) Put(key keyType, value LRUValType) {
+	// check if list node exists
+	if node, ok := c.m[key]; ok {
+		// move the node to front
+		c.l.MoveToFront(node)
+		// update the value of a list node
+		node.Value.(*list.Element).Value = Pair{key: key, value: value}
+	} else {
+		// delete the last list node if the list is full
+		if uint(c.l.Len()) == c.cap {
+			// get the key that we want to delete
+			idx := c.l.Back().Value.(*list.Element).Value.(Pair).key
+			// delete the node pointer in the hash map by key
+			delete(c.m, idx)
+			// remove the last list node
+			c.l.Remove(c.l.Back())
+		}
+		// initialize a list node
+		node := &list.Element{
+			Value: Pair{
+				key:   key,
+				value: value,
+			},
+		}
+		// push the new list node into the list
+		ptr := c.l.PushFront(node)
+		// save the node pointer in the hash map
+		c.m[key] = ptr
+	}
+}
+
+func (c *LRUCache) Delete(key keyType) {
+	if node, ok := c.m[key]; ok {
+		c.l.Remove(node)
+		delete(c.m, key)
+	}
+}