Initial commitHEADmaster

2 files changed, 104 insertions, 0 deletions

diff --git a/cache.go b/cache.go
new file mode 100644
index 0000000..887f672
--- /dev/null
+++ b/cache.go
@@ -0,0 +1,101 @@
+package cache
+
+import (
+	"fmt"
+	"log/slog"
+	"time"
+)
+
+type Cache struct {
+	items map[string]*CacheItem
+}
+
+type CacheItem struct {
+	Value     interface{}
+	CreatedAt time.Time
+}
+
+// Create a new Cache object with no auto expiration.
+func New() *Cache {
+	slog.Debug("")
+
+	return &Cache{
+		items: make(map[string]*CacheItem),
+	}
+}
+
+// Get the age of a cached item.
+func (this *Cache) Age(key string) time.Duration {
+	item, ok := this.items[key]
+
+	if !ok {
+		return 0
+	}
+
+	return time.Since(item.CreatedAt)
+}
+
+// Delete an item from the cache.
+func (this *Cache) Delete(key string) {
+	delete(this.items, key)
+}
+
+// Delete all items older than the given duration.
+func (this *Cache) Expire(duration time.Duration) uint {
+	var counter uint = 0
+
+	for key, item := range this.items {
+		if time.Since(item.CreatedAt) < duration {
+			continue
+		}
+
+		slog.Debug(
+			"Expiring",
+			"package", "cache",
+			"type", "Cache",
+			"func", "GetSet",
+			"key", key,
+			"value", fmt.Sprintf("%+v", item.Value),
+			"age", this.Age(key),
+		)
+
+		this.Delete(key)
+		counter++
+	}
+
+	return counter
+}
+
+// Get the value of a cached item.
+func (this *Cache) Get(key string) interface{} {
+	item, ok := this.items[key]
+
+	if !ok {
+		return nil
+	}
+
+	return item.Value
+}
+
+// Get or set a cache item in a single statement.
+func (this *Cache) GetSet(key string, f func() interface{}) interface{} {
+	value := this.Get(key)
+
+	if value != nil {
+		slog.Debug("Cache hit", "package", "cache", "type", "Cache", "func", "GetSet", "age", this.Age(key), "value", fmt.Sprintf("%+v", value))
+		return value
+	}
+
+	slog.Debug("Cache miss", "package", "cache", "type", "Cache", "func", "GetSet")
+	this.Set(key, f())
+
+	return this.Get(key)
+}
+
+// Set a cached value.
+func (this *Cache) Set(key string, value interface{}) {
+	this.items[key] = &CacheItem{
+		Value:     value,
+		CreatedAt: time.Now(),
+	}
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..1136c4c
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.tyil.nl/go/cache.git
+
+go 1.22.6