blossom: add an alternative BlobIndex implementation in memory.

khatru/blossom/blob.go

@@ -24,4 +24,7 @@ type BlobIndex interface {
 	Delete(ctx context.Context, sha256 string, pubkey nostr.PubKey) error
 }
 
-var _ BlobIndex = (*EventStoreBlobIndexWrapper)(nil)
+var (
+	_ BlobIndex = (*EventStoreBlobIndexWrapper)(nil)
+	_ BlobIndex = (*MemoryBlobIndex)(nil)
+)

khatru/blossom/memoryindex.go

@@ -0,0 +1,89 @@
+package blossom
+
+import (
+	"context"
+	"errors"
+	"iter"
+	"slices"
+
+	"fiatjaf.com/nostr"
+	"github.com/puzpuzpuz/xsync/v3"
+)
+
+type ownedBlob struct {
+	blob   BlobDescriptor
+	owners []nostr.PubKey
+}
+
+type MemoryBlobIndex struct {
+	m *xsync.MapOf[string, ownedBlob]
+}
+
+func NewMemoryBlobIndex() MemoryBlobIndex {
+	return MemoryBlobIndex{
+		m: xsync.NewMapOf[string, ownedBlob](),
+	}
+}
+
+func (x MemoryBlobIndex) Keep(ctx context.Context, blob BlobDescriptor, pubkey nostr.PubKey) error {
+	x.m.Compute(blob.SHA256, func(oldValue ownedBlob, loaded bool) (newValue ownedBlob, delete bool) {
+		if loaded {
+			newValue = oldValue
+			if !slices.Contains(newValue.owners, pubkey) {
+				newValue.owners = append(newValue.owners, pubkey)
+			}
+		} else {
+			newValue = ownedBlob{
+				blob:   blob,
+				owners: []nostr.PubKey{pubkey},
+			}
+		}
+
+		return newValue, false
+	})
+
+	return nil
+}
+
+func (x MemoryBlobIndex) List(ctx context.Context, pubkey nostr.PubKey) iter.Seq[BlobDescriptor] {
+	return func(yield func(BlobDescriptor) bool) {
+		x.m.Range(func(key string, value ownedBlob) bool {
+			if value.blob.Owner == value.owners[0] {
+				if !yield(value.blob) {
+					return false
+				}
+			}
+			return true
+		})
+	}
+}
+
+func (x MemoryBlobIndex) Get(ctx context.Context, sha256 string) (*BlobDescriptor, error) {
+	if val, ok := x.m.Load(sha256); ok {
+		val.blob.Owner = val.owners[0]
+		return &val.blob, nil
+	}
+	return nil, errors.New("not found")
+}
+
+func (x MemoryBlobIndex) Delete(ctx context.Context, sha256 string, pubkey nostr.PubKey) error {
+	x.m.Compute(sha256, func(oldValue ownedBlob, loaded bool) (newValue ownedBlob, delete bool) {
+		if loaded {
+			if idx := slices.Index(oldValue.owners, pubkey); idx != -1 {
+				if len(oldValue.owners) == 1 {
+					// this is the only owner, remove the blob
+					return oldValue, true
+				} else {
+					// remove this owner
+					oldValue.owners[idx] = oldValue.owners[len(oldValue.owners)-1]
+					oldValue.owners = oldValue.owners[0 : len(oldValue.owners)-1]
+					return oldValue, false
+				}
+			}
+		}
+
+		return oldValue, true
+	})
+
+	return nil
+}