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

lmdb/count.go

@@ -0,0 +1,91 @@
+package lmdb
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+
+	"github.com/bmatsuo/lmdb-go/lmdb"
+	"github.com/nbd-wtf/go-nostr"
+	nostr_binary "github.com/nbd-wtf/go-nostr/binary"
+)
+
+func (b *LMDBBackend) CountEvents(ctx context.Context, filter nostr.Filter) (int64, error) {
+	var count int64 = 0
+
+	dbi, queries, extraFilter, since, prefixLen, err := b.prepareQueries(filter)
+	if err != nil {
+		return 0, err
+	}
+
+	err = b.lmdbEnv.View(func(txn *lmdb.Txn) error {
+		// actually iterate
+		for _, q := range queries {
+			cursor, err := txn.OpenCursor(dbi)
+			if err != nil {
+				continue
+			}
+
+			var k []byte
+			var idx []byte
+			var iterr error
+
+			if _, _, errsr := cursor.Get(q.startingPoint, nil, lmdb.SetRange); errsr != nil {
+				if operr, ok := errsr.(*lmdb.OpError); !ok || operr.Errno != lmdb.NotFound {
+					// in this case it's really an error
+					panic(err)
+				} else {
+					// we're at the end and we just want notes before this,
+					// so we just need to set the cursor the last key, this is not a real error
+					k, idx, iterr = cursor.Get(nil, nil, lmdb.Last)
+				}
+			} else {
+				// move one back as the first step
+				k, idx, iterr = cursor.Get(nil, nil, lmdb.Prev)
+			}
+
+			for {
+				// we already have a k and a v and an err from the cursor setup, so check and use these
+				if iterr != nil || !bytes.Equal(q.prefix, k[0:prefixLen]) {
+					break
+				}
+
+				if !q.skipTimestamp {
+					createdAt := binary.BigEndian.Uint32(k[prefixLen:])
+					if createdAt < since {
+						break
+					}
+				}
+
+				// fetch actual event
+				val, err := txn.Get(b.rawEventStore, idx)
+				if err != nil {
+					panic(err)
+				}
+
+				if extraFilter == nil {
+					count++
+				} else {
+					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
+				}
+
+				// move one back (we'll look into k and v and err in the next iteration)
+				k, idx, iterr = cursor.Get(nil, nil, lmdb.Prev)
+			}
+		}
+
+		return nil
+	})
+
+	return count, err
+}