From 0b24c4cffe79e56c623f65e1d13c4c18e18b628d Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Sat, 15 Feb 2025 21:45:12 -0300
Subject: [PATCH] mmm: DropLayer()

---
 mmm/mmmm.go | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 mmm/save.go |  7 ++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/mmm/mmmm.go b/mmm/mmmm.go
index e82fbdd..65f3740 100644
--- a/mmm/mmmm.go
+++ b/mmm/mmmm.go
@@ -141,6 +141,9 @@ func (b *MultiMmapManager) Init() error {
 }
 
 func (b *MultiMmapManager) EnsureLayer(name string, il *IndexingLayer) error {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+
 	il.mmmm = b
 	il.name = name
 
@@ -183,6 +186,51 @@ func (b *MultiMmapManager) EnsureLayer(name string, il *IndexingLayer) error {
 	return nil
 }
 
+func (b *MultiMmapManager) DropLayer(name string) error {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+
+	// get layer reference
+	idx := slices.IndexFunc(b.layers, func(il *IndexingLayer) bool { return il.name == name })
+	if idx == -1 {
+		return fmt.Errorf("layer '%s' doesn't exist", name)
+	}
+	il := b.layers[idx]
+
+	// remove layer references from global indexes
+	err := b.lmdbEnv.Update(func(txn *lmdb.Txn) error {
+		txn.RawRead = true
+		return b.removeAllReferencesFromLayer(txn, il.id)
+	})
+	if err != nil {
+		return err
+	}
+
+	// delete everything (the indexes) from this layer db actually
+	err = il.lmdbEnv.Update(func(txn *lmdb.Txn) error {
+		for _, dbi := range []lmdb.DBI{
+			il.indexCreatedAt,
+			il.indexKind,
+			il.indexPubkey,
+			il.indexPubkeyKind,
+			il.indexTag,
+			il.indexTag32,
+			il.indexTagAddr,
+			il.indexPTagKind,
+		} {
+			if err := txn.Drop(dbi, true); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	return il.lmdbEnv.Close()
+}
+
 // getNextAvailableLayerId iterates through all existing layers to find a vacant id
 func (b *MultiMmapManager) getNextAvailableLayerId(txn *lmdb.Txn) (uint16, error) {
 	cursor, err := txn.OpenCursor(b.knownLayers)
diff --git a/mmm/save.go b/mmm/save.go
index 6f7dcf6..cf8767e 100644
--- a/mmm/save.go
+++ b/mmm/save.go
@@ -107,7 +107,12 @@ func (il *IndexingLayer) SaveEvent(ctx context.Context, evt *nostr.Event) error
 	return nil
 }
 
-func (b *MultiMmapManager) storeOn(mmmtxn *lmdb.Txn, ils []*IndexingLayer, iltxns []*lmdb.Txn, evt *nostr.Event) (stored bool, err error) {
+func (b *MultiMmapManager) storeOn(
+	mmmtxn *lmdb.Txn,
+	ils []*IndexingLayer,
+	iltxns []*lmdb.Txn,
+	evt *nostr.Event,
+) (stored bool, err error) {
 	// sanity checking
 	if evt.CreatedAt > maxuint32 || evt.Kind > maxuint16 {
 		return false, fmt.Errorf("event with values out of expected boundaries")