format/pack/ingest: Init

1 files changed, 53 insertions, 0 deletions

diff --git a/format/pack/ingest/cache.go b/format/pack/ingest/cache.go
new file mode 100644
index 00000000..9c0b7a4f
--- /dev/null
+++ b/format/pack/ingest/cache.go
@@ -0,0 +1,53 @@
+package ingest
+
+import (
+	"codeberg.org/lindenii/furgit/internal/lru"
+	"codeberg.org/lindenii/furgit/objecttype"
+)
+
+// deltaBaseCacheKey identifies one resolved base by record index.
+type deltaBaseCacheKey struct {
+	recordIdx int
+}
+
+// deltaBaseCacheValue stores one resolved base object payload.
+type deltaBaseCacheValue struct {
+	realType objecttype.Type
+	content  []byte
+}
+
+// deltaBaseCache is a bounded LRU for resolved base payloads.
+type deltaBaseCache struct {
+	lru *lru.Cache[deltaBaseCacheKey, deltaBaseCacheValue]
+}
+
+// newDeltaBaseCache creates one bounded base cache.
+func newDeltaBaseCache(maxBytes int64) *deltaBaseCache {
+	return &deltaBaseCache{
+		lru: lru.New(
+			maxBytes,
+			func(_ deltaBaseCacheKey, value deltaBaseCacheValue) int64 {
+				return int64(len(value.content))
+			},
+			nil,
+		),
+	}
+}
+
+// get returns a cloned cache entry for recordIdx.
+func (cache *deltaBaseCache) get(recordIdx int) (objecttype.Type, []byte, bool) {
+	value, ok := cache.lru.Get(deltaBaseCacheKey{recordIdx: recordIdx})
+	if !ok {
+		return objecttype.TypeInvalid, nil, false
+	}
+
+	return value.realType, append([]byte(nil), value.content...), true
+}
+
+// add stores a cloned cache entry for recordIdx.
+func (cache *deltaBaseCache) add(recordIdx int, realType objecttype.Type, content []byte) {
+	cache.lru.Add(deltaBaseCacheKey{recordIdx: recordIdx}, deltaBaseCacheValue{
+		realType: realType,
+		content:  append([]byte(nil), content...),
+	})
+}