review comments: added metrics docs, licence header and made cache st…

…ruct private

Signed-off-by: Ashish Naware <ashishnaware3@gmail.com>

pkg/observer/cache.go

@@ -1,3 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright Authors of Tetragon
+
 package observer
 
 import (
@@ -7,14 +10,14 @@ import (
 	lru "github.com/hashicorp/golang-lru/v2"
 )
 
-type Cache struct {
+type cache struct {
 	cache *lru.Cache[dataapi.DataEventId, []byte]
 	size  int
 }
 
-func NewCache(
+func newCache(
 	dataCacheSize int,
-) (*Cache, error) {
+) (*cache, error) {
 	lruCache, err := lru.NewWithEvict(
 		dataCacheSize,
 		func(_ dataapi.DataEventId, _ []byte) {
@@ -24,14 +27,14 @@ func NewCache(
 	if err != nil {
 		return nil, err
 	}
-	cache := &Cache{
+	cache := &cache{
 		cache: lruCache,
 		size:  dataCacheSize,
 	}
 	return cache, nil
 }
 
-func (c *Cache) get(dataEventId dataapi.DataEventId) ([]byte, error) {
+func (c *cache) get(dataEventId dataapi.DataEventId) ([]byte, error) {
 	data, ok := c.cache.Get(dataEventId)
 	if !ok {
 		dataCacheMisses.WithLabelValues("get").Inc()
@@ -40,15 +43,15 @@ func (c *Cache) get(dataEventId dataapi.DataEventId) ([]byte, error) {
 	return data, nil
 }
 
-func (c *Cache) add(id dataapi.DataEventId, msgData []byte) bool {
+func (c *cache) add(id dataapi.DataEventId, msgData []byte) bool {
 	evicted := c.cache.Add(id, msgData)
 	if !evicted {
 		dataCacheTotal.Inc()
 	}
 	return evicted
 }
 
-func (c *Cache) remove(desc dataapi.DataEventDesc) bool {
+func (c *cache) remove(desc dataapi.DataEventDesc) bool {
 	present := c.cache.Remove(desc.Id)
 	if present {
 		dataCacheTotal.Dec()

pkg/observer/data.go

@@ -19,12 +19,12 @@ func init() {
 }
 
 var (
-	dataCache *Cache
+	dataCache *cache
 )
 
 func InitDataCache(size int) error {
 	var err error
-	dataCache, err = NewCache(size)
+	dataCache, err = newCache(size)
 	return err
 }