make lmdb and badger backends use a binary encoding instead of nson.

badger/count.go

@@ -0,0 +1,83 @@
+package badger
+
+import (
+	"context"
+	"encoding/binary"
+
+	"github.com/dgraph-io/badger/v4"
+	"github.com/nbd-wtf/go-nostr"
+	nostr_binary "github.com/nbd-wtf/go-nostr/binary"
+)
+
+func (b BadgerBackend) CountEvents(ctx context.Context, filter nostr.Filter) (int64, error) {
+	var count int64 = 0
+
+	queries, extraFilter, since, prefixLen, idxOffset, err := prepareQueries(filter)
+	if err != nil {
+		return 0, err
+	}
+
+	err = b.View(func(txn *badger.Txn) error {
+		// iterate only through keys and in reverse order
+		opts := badger.DefaultIteratorOptions
+		opts.PrefetchValues = false
+		opts.Reverse = true
+
+		// actually iterate
+		for _, q := range queries {
+			it := txn.NewIterator(opts)
+			defer it.Close()
+
+			for it.Seek(q.startingPoint); it.ValidForPrefix(q.prefix); it.Next() {
+				item := it.Item()
+				key := item.Key()
+
+				if !q.skipTimestamp {
+					createdAt := binary.BigEndian.Uint32(key[prefixLen:idxOffset])
+					if createdAt < since {
+						break
+					}
+				}
+
+				idx := make([]byte, 5)
+				idx[0] = rawEventStorePrefix
+				copy(idx[1:], key[idxOffset:])
+
+				// fetch actual event
+				item, err := txn.Get(idx)
+				if err != nil {
+					if err == badger.ErrDiscardedTxn {
+						return err
+					}
+
+					panic(err)
+				}
+
+				if extraFilter == nil {
+					count++
+				} else {
+					err = item.Value(func(val []byte) error {
+						evt := &nostr.Event{}
+						if err := nostr_binary.Unmarshal(val, evt); err != nil {
+							return err
+						}
+
+						// check if this matches the other filters that were not part of the index
+						if extraFilter == nil || extraFilter.Matches(evt) {
+							count++
+						}
+
+						return nil
+					})
+					if err != nil {
+						panic(err)
+					}
+				}
+			}
+		}
+
+		return nil
+	})
+
+	return count, err
+}