ndb/txn: make transactions failable

Since there may be situations where we close and re-open the database,
we need to make sure transactions fail when the database is not open.

Make NdbTxn an init?() constructor and check for ndb.closed. If it's
closed, then fail transaction construction.

This fixes crashes during high database activity when switching from
background to foreground and vice-versa.

Fixes: da2bdad18d ("nostrdb: close database when backgrounded")

DamusNotificationService/NotificationFormatter.swift

@@ -118,9 +118,9 @@ struct NotificationFormatter {
         let src = zap.request.ev
         let pk = zap.is_anon ? ANON_PUBKEY : src.pubkey
 
-        let name = profiles.lookup(id: pk).map { profile in
+        let profile_txn = profiles.lookup(id: pk)
-            Profile.displayName(profile: profile, pubkey: pk).displayName.truncate(maxLength: 50)
+        let profile = profile_txn?.unsafeUnownedValue
-        }.value
+        let name = Profile.displayName(profile: profile, pubkey: pk).displayName.truncate(maxLength: 50)
 
         let sats = NSNumber(value: (Double(zap.invoice.amount) / 1000.0))
         let formattedSats = format_msats_abbrev(zap.invoice.amount)

DamusNotificationService/NotificationService.swift

@@ -28,7 +28,7 @@ class NotificationService: UNNotificationServiceExtension {
         Log.debug("Got nostr event push notification from pubkey %s", for: .push_notifications, nostr_event.pubkey.hex())
         
         guard let state = NotificationExtensionState(),
-              let display_name = state.ndb.lookup_profile(nostr_event.pubkey).unsafeUnownedValue?.profile?.display_name  // We are not holding the txn here.
+              let display_name = state.ndb.lookup_profile(nostr_event.pubkey)?.unsafeUnownedValue?.profile?.display_name  // We are not holding the txn here.
         else {
             // Something failed to initialize so let's go for the next best thing
             guard let improved_content = NotificationFormatter.shared.format_message(event: nostr_event) else {

damus/Components/NIP05Badge.swift

@@ -45,7 +45,7 @@ struct NIP05Badge: View {
     }
 
     var username_matches_nip05: Bool {
-        guard let name = profiles.lookup(id: pubkey).map({ p in p?.name }).value
+        guard let name = profiles.lookup(id: pubkey)?.map({ p in p?.name }).value
         else {
             return false
         }

damus/ContentView.swift

@@ -370,14 +370,9 @@ struct ContentView: View {
             // wallet with an associated
             guard let ds = self.damus_state,
                   let lud16 = nwc.lud16,
-                  let keypair = ds.keypair.to_full()
+                  let keypair = ds.keypair.to_full(),
-            else {
+                  let profile_txn = ds.profiles.lookup(id: ds.pubkey),
-                return
+                  let profile = profile_txn.unsafeUnownedValue,
-            }
-
-            let profile_txn = ds.profiles.lookup(id: ds.pubkey)
-
-            guard let profile = profile_txn.unsafeUnownedValue,
                   lud16 != profile.lud16 else {
                 return
             }
@@ -514,10 +509,9 @@ struct ContentView: View {
         .onReceive(handle_notify(.onlyzaps_mode)) { hide in
             home.filter_events()
 
-            guard let ds = damus_state else { return }
+            guard let ds = damus_state,
-            let profile_txn = ds.profiles.lookup(id: ds.pubkey)
+                  let profile_txn = ds.profiles.lookup(id: ds.pubkey),
-
+                  let profile = profile_txn.unsafeUnownedValue,
-            guard let profile = profile_txn.unsafeUnownedValue,
                   let keypair = ds.keypair.to_full()
             else {
                 return
@@ -534,9 +528,9 @@ struct ContentView: View {
             }
         }, message: {
             if let pubkey = self.muting {
-                let name = damus_state!.profiles.lookup(id: pubkey).map { profile in
+                let profile_txn = damus_state!.profiles.lookup(id: pubkey)
-                    Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
+                let profile = profile_txn?.unsafeUnownedValue
-                }.value
+                let name = Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
                 Text("\(name) has been muted", comment: "Alert message that informs a user was muted.")
             } else {
                 Text("User has been muted", comment: "Alert message that informs a user was muted.")
@@ -595,9 +589,9 @@ struct ContentView: View {
             }
         }, message: {
             if let pubkey = muting {
-                let name = damus_state?.profiles.lookup(id: pubkey).map({ profile in
+                let profile_txn = damus_state?.profiles.lookup(id: pubkey)
-                    Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
+                let profile = profile_txn?.unsafeUnownedValue
-                }).value ?? "unknown"
+                let name = Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
                 Text("Mute \(name)?", comment: "Alert message prompt to ask if a user should be muted.")
             } else {
                 Text("Could not find user to mute...", comment: "Alert message to indicate that the muted user could not be found.")
@@ -865,7 +859,8 @@ func find_event_with_subid(state: DamusState, query query_: FindEvent, subid: St
     
     switch query {
     case .profile(let pubkey):
-        if let record = state.ndb.lookup_profile(pubkey).unsafeUnownedValue,
+        if let profile_txn = state.ndb.lookup_profile(pubkey),
+           let record = profile_txn.unsafeUnownedValue,
            record.profile != nil
         {
             callback(.profile(pubkey))

damus/Models/EventsModel.swift

@@ -66,7 +66,9 @@ class EventsModel: ObservableObject {
         case .auth:
             break
         case .eose:
-            let txn = NdbTxn(ndb: self.state.ndb)
+            guard let txn = NdbTxn(ndb: self.state.ndb) else {
+                return
+            }
             load_profiles(context: "events_model", profiles_subid: profiles_id, relay_id: relay_id, load: .from_events(events), damus_state: state, txn: txn)
         }
     }

damus/Models/FollowersModel.swift

@@ -83,7 +83,7 @@ class FollowersModel: ObservableObject {
             
         case .eose(let sub_id):
             if sub_id == self.sub_id {
-                let txn = NdbTxn(ndb: self.damus_state.ndb)
+                guard let txn = NdbTxn(ndb: self.damus_state.ndb) else { return }
                 load_profiles(relay_id: relay_id, txn: txn)
             } else if sub_id == self.profiles_id {
                 damus_state.pool.unsubscribe(sub_id: profiles_id, to: [relay_id])

damus/Models/HomeModel.swift

@@ -414,8 +414,10 @@ class HomeModel {
                 print(msg)
 
             case .eose(let sub_id):
+                guard let txn = NdbTxn(ndb: damus_state.ndb) else {
+                    return
+                }
 
-                let txn = NdbTxn(ndb: damus_state.ndb)
                 if sub_id == dms_subid {
                     var dms = dms.dms.flatMap { $0.events }
                     dms.append(contentsOf: incoming_dms)

damus/Models/NoteContent.swift

@@ -187,7 +187,7 @@ func mention_str(_ m: Mention<MentionRef>, profiles: Profiles) -> CompatibleText
     case .pubkey(let pk):
         let npub = bech32_pubkey(pk)
         let profile_txn = profiles.lookup(id: pk)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
         let disp = Profile.displayName(profile: profile, pubkey: pk).username.truncate(maxLength: 50)
         var attributedString = AttributedString(stringLiteral: "@\(disp)")
         attributedString.link = URL(string: "damus:nostr:\(npub)")

damus/Models/NotificationsManager.swift

@@ -21,6 +21,7 @@ func process_local_notification(state: HeadlessDamusState, event ev: NostrEvent)
     guard let local_notification = generate_local_notification_object(from: ev, state: state) else {
         return
     }
+
     create_local_notification(profiles: state.profiles, notify: local_notification)
 }
 
@@ -76,7 +77,8 @@ func generate_local_notification_object(from ev: NostrEvent, state: HeadlessDamu
     } else if type == .like,
               state.settings.like_notification,
               let evid = ev.referenced_ids.last,
-              let liked_event = state.ndb.lookup_note(evid).unsafeUnownedValue   // We are only accessing it temporarily to generate notification content
+              let txn = state.ndb.lookup_note(evid),
+              let liked_event = txn.unsafeUnownedValue   // We are only accessing it temporarily to generate notification content
     {
         let content_preview = render_notification_content_preview(ev: liked_event, profiles: state.profiles, keypair: state.keypair)
         return LocalNotification(type: .like, event: ev, target: liked_event, content: content_preview)
@@ -135,9 +137,9 @@ func render_notification_content_preview(ev: NostrEvent, profiles: Profiles, key
 }
 
 func event_author_name(profiles: Profiles, pubkey: Pubkey) -> String {
-    return profiles.lookup(id: pubkey).map({ profile in
+    let profile_txn = profiles.lookup(id: pubkey)
-        Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
+    let profile = profile_txn?.unsafeUnownedValue
-    }).value
+    return Profile.displayName(profile: profile, pubkey: pubkey).username.truncate(maxLength: 50)
 }
 
 @MainActor
@@ -173,8 +175,8 @@ func process_zap_event(state: HeadlessDamusState, ev: NostrEvent, completion: @e
         return
     }
     
-    guard let lnurl = state.profiles.lookup_with_timestamp(ptag)
+    guard let txn = state.profiles.lookup_with_timestamp(ptag),
-                        .map({ pr in pr?.lnurl }).value else {
+          let lnurl = txn.map({ pr in pr?.lnurl }).value else {
         completion(.failed)
         return
     }
@@ -221,7 +223,8 @@ func get_zap_target_pubkey(ev: NostrEvent, ndb: Ndb) -> Pubkey? {
     }
 
     // we can't trust the p tag on note zaps because they can be faked
-    guard let pk = ndb.lookup_note(etag).unsafeUnownedValue?.pubkey else {
+    guard let txn = ndb.lookup_note(etag),
+          let pk = txn.unsafeUnownedValue?.pubkey else {
         // We don't have the event in cache so we can't check the pubkey.
 
         // We could return this as an invalid zap but that wouldn't be correct

damus/Models/ProfileModel.swift

@@ -128,7 +128,7 @@ class ProfileModel: ObservableObject, Equatable {
                 break
                 //notify(.notice, notice)
             case .eose:
-                let txn = NdbTxn(ndb: damus.ndb)
+                guard let txn = NdbTxn(ndb: damus.ndb) else { return }
                 if resp.subid == sub_id {
                     load_profiles(context: "profile", profiles_subid: prof_subid, relay_id: relay_id, load: .from_events(events.events), damus_state: damus, txn: txn)
                 }

damus/Models/SearchHomeModel.swift

@@ -83,7 +83,7 @@ class SearchHomeModel: ObservableObject {
                 // global events are not realtime
                 unsubscribe(to: relay_id)
                 
-                let txn = NdbTxn(ndb: damus_state.ndb)
+                guard let txn = NdbTxn(ndb: damus_state.ndb) else { return }
                 load_profiles(context: "universe", profiles_subid: profiles_subid, relay_id: relay_id, load: .from_events(events.all_events), damus_state: damus_state, txn: txn)
             }
 

damus/Models/SearchModel.swift

@@ -80,7 +80,7 @@ class SearchModel: ObservableObject {
         self.loading = false
         
         if sub_id == self.sub_id {
-            let txn = NdbTxn(ndb: state.ndb)
+            guard let txn = NdbTxn(ndb: state.ndb) else { return }
             load_profiles(context: "search", profiles_subid: self.profiles_subid, relay_id: relay_id, load: .from_events(self.events.all_events), damus_state: state, txn: txn)
         }
     }

damus/Models/ThreadModel.swift

@@ -120,7 +120,7 @@ class ThreadModel: ObservableObject {
         }
         
         if sub_id == self.base_subid {
-            let txn = NdbTxn(ndb: damus_state.ndb)
+            guard let txn = NdbTxn(ndb: damus_state.ndb) else { return }
             load_profiles(context: "thread", profiles_subid: self.profiles_subid, relay_id: relay_id, load: .from_events(Array(event_map)), damus_state: damus_state, txn: txn)
         }
     }

damus/Models/ZapsModel.swift

@@ -55,7 +55,7 @@ class ZapsModel: ObservableObject {
             break
         case .eose:
             let events = state.events.lookup_zaps(target: target).map { $0.request.ev }
-            let txn = NdbTxn(ndb: state.ndb)
+            guard let txn = NdbTxn(ndb: state.ndb) else { return }
             load_profiles(context: "zaps_model", profiles_subid: profiles_subid, relay_id: relay_id, load: .from_events(events), damus_state: state, txn: txn)
         case .event(_, let ev):
             guard ev.kind == 9735,

damus/Nostr/Profiles.swift

@@ -73,24 +73,27 @@ class Profiles {
         profile_data(pubkey).zapper
     }
 
-    func lookup_with_timestamp(_ pubkey: Pubkey) -> NdbTxn<ProfileRecord?> {
+    func lookup_with_timestamp(_ pubkey: Pubkey) -> NdbTxn<ProfileRecord?>? {
-        return ndb.lookup_profile(pubkey)
+        ndb.lookup_profile(pubkey)
     }
 
-    func lookup_by_key(key: ProfileKey) -> NdbTxn<ProfileRecord?> {
+    func lookup_by_key(key: ProfileKey) -> NdbTxn<ProfileRecord?>? {
-        return ndb.lookup_profile_by_key(key: key)
+        ndb.lookup_profile_by_key(key: key)
     }
 
     func search<Y>(_ query: String, limit: Int, txn: NdbTxn<Y>) -> [Pubkey] {
-        return ndb.search_profile(query, limit: limit, txn: txn)
+        ndb.search_profile(query, limit: limit, txn: txn)
     }
 
-    func lookup(id: Pubkey) -> NdbTxn<Profile?> {
+    func lookup(id: Pubkey) -> NdbTxn<Profile?>? {
-        return ndb.lookup_profile(id).map({ pr in pr?.profile })
+        guard let txn = ndb.lookup_profile(id) else {
+            return nil
+        }
+        return txn.map({ pr in pr?.profile })
     }
 
     func lookup_key_by_pubkey(_ pubkey: Pubkey) -> ProfileKey? {
-        return ndb.lookup_profile_key(pubkey)
+        ndb.lookup_profile_key(pubkey)
     }
 
     func has_fresh_profile<Y>(id: Pubkey, txn: NdbTxn<Y>) -> Bool {

damus/Views/ActionBar/EventActionBar.swift

@@ -28,7 +28,9 @@ struct EventActionBar: View {
     }
     
     var lnurl: String? {
-        damus_state.profiles.lookup_with_timestamp(event.pubkey).map({ pr in pr?.lnurl }).value
+        damus_state.profiles.lookup_with_timestamp(event.pubkey)?.map({ pr in
+            pr?.lnurl
+        }).value
     }
     
     var show_like: Bool {

damus/Views/BannerImageView.swift

@@ -78,11 +78,12 @@ struct BannerImageView: View {
     var body: some View {
         InnerBannerImageView(disable_animation: disable_animation, url: get_banner_url(banner: banner, pubkey: pubkey, profiles: profiles))
             .onReceive(handle_notify(.profile_updated)) { updated in
-                guard updated.pubkey == self.pubkey else {
+                guard updated.pubkey == self.pubkey,
+                      let profile_txn = profiles.lookup(id: updated.pubkey)
+                else {
                     return
                 }
 
-                let profile_txn = profiles.lookup(id: updated.pubkey)
                 let profile = profile_txn.unsafeUnownedValue
                 if let bannerImage = profile?.banner, bannerImage != self.banner {
                     self.banner = bannerImage
@@ -92,7 +93,7 @@ struct BannerImageView: View {
 }
 
 func get_banner_url(banner: String?, pubkey: Pubkey, profiles: Profiles) -> URL? {
-    let bannerUrlString = banner ?? profiles.lookup(id: pubkey).map({ p in p?.banner }).value ?? ""
+    let bannerUrlString = banner ?? profiles.lookup(id: pubkey)?.map({ p in p?.banner }).value ?? ""
     if let url = URL(string: bannerUrlString) {
         return url
     }

damus/Views/Events/Components/ReplyDescription.swift

@@ -38,7 +38,9 @@ func reply_desc(ndb: Ndb, event: NostrEvent, replying_to: NostrEvent?, locale: L
         return NSLocalizedString("Replying to self", bundle: bundle, comment: "Label to indicate that the user is replying to themself.")
     }
 
-    let profile_txn = NdbTxn(ndb: ndb)
+    guard let profile_txn = NdbTxn(ndb: ndb) else  {
+        return ""
+    }
 
     let names: [String] = pubkeys.map { pk in
         let prof = ndb.lookup_profile_with_txn(pk, txn: profile_txn)

damus/Views/FollowingView.swift

@@ -151,7 +151,7 @@ struct FollowingView: View {
         }
         .tabViewStyle(.page(indexDisplayMode: .never))
         .onAppear {
-            let txn = NdbTxn(ndb: self.damus_state.ndb)
+            guard let txn = NdbTxn(ndb: self.damus_state.ndb) else { return }
             following.subscribe(txn: txn)
         }
         .onDisappear {

damus/Views/Notifications/NotificationsView.swift

@@ -61,7 +61,7 @@ struct NotificationsView: View {
     
     var mystery: some View {
         let profile_txn = state.profiles.lookup(id: state.pubkey)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
         return VStack(spacing: 20) {
             Text("Wake up, \(Profile.displayName(profile: profile, pubkey: state.pubkey).displayName.truncate(maxLength: 50))", comment: "Text telling the user to wake up, where the argument is their display name.")
             Text("You are dreaming...", comment: "Text telling the user that they are dreaming.")

damus/Views/Onboarding/SuggestedUsersViewModel.swift

@@ -36,7 +36,7 @@ class SuggestedUsersViewModel: ObservableObject {
 
     func suggestedUser(pubkey: Pubkey) -> SuggestedUser? {
         let profile_txn = damus_state.profiles.lookup(id: pubkey)
-        if let profile = profile_txn.unsafeUnownedValue,
+        if let profile = profile_txn?.unsafeUnownedValue,
            let user = SuggestedUser(name: profile.name, about: profile.about, picture: profile.picture, pubkey: pubkey) {
             return user
         }

damus/Views/PostView.swift

@@ -181,7 +181,7 @@ struct PostView: View {
         }
         
         let profile_txn = damus_state.profiles.lookup(id: pubkey)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
         return user_tag_attr_string(profile: profile, pubkey: pubkey)
     }
     

damus/Views/Posting/UserSearch.swift

@@ -17,7 +17,7 @@ struct UserSearch: View {
     @EnvironmentObject var tagModel: TagModel
     
     var users: [Pubkey] {
-        let txn = NdbTxn(ndb: damus_state.ndb)
+        guard let txn = NdbTxn(ndb: damus_state.ndb) else { return [] }
         return search_profiles(profiles: damus_state.profiles, search: search, txn: txn).sorted { a, b in
             let aFriendTypePriority = get_friend_type(contacts: damus_state.contacts, pubkey: a)?.priority ?? 0
             let bFriendTypePriority = get_friend_type(contacts: damus_state.contacts, pubkey: b)?.priority ?? 0
@@ -33,7 +33,7 @@ struct UserSearch: View {
     
     func on_user_tapped(pk: Pubkey) {
         let profile_txn = damus_state.profiles.lookup(id: pk)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
         let user_tag = user_tag_attr_string(profile: profile, pubkey: pk)
 
         appendUserTag(withTag: user_tag)

damus/Views/Profile/EditMetadataView.swift

@@ -30,7 +30,8 @@ struct EditMetadataView: View {
     
     init(damus_state: DamusState) {
         self.damus_state = damus_state
-        let data = damus_state.profiles.lookup(id: damus_state.pubkey).unsafeUnownedValue
+        let profile_txn = damus_state.profiles.lookup(id: damus_state.pubkey)
+        let data = profile_txn?.unsafeUnownedValue
 
         _name = State(initialValue: data?.name ?? "")
         _display_name = State(initialValue: data?.display_name ?? "")

damus/Views/Profile/EventProfileName.swift

@@ -24,7 +24,7 @@ struct EventProfileName: View {
         self.damus_state = damus
         self.pubkey = pubkey
         self.size = size
-        let donation = damus.ndb.lookup_profile(pubkey).map({ p in p?.profile?.damus_donation }).value
+        let donation = damus.ndb.lookup_profile(pubkey)?.map({ p in p?.profile?.damus_donation }).value
         self._donation = State(wrappedValue: donation)
         is_purple_user = nil
     }
@@ -65,7 +65,7 @@ struct EventProfileName: View {
 
     var body: some View {
         let profile_txn = damus_state.profiles.lookup(id: pubkey)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
         HStack(spacing: 2) {
             switch current_display_name(profile) {
             case .one(let one):
@@ -109,7 +109,7 @@ struct EventProfileName: View {
             }
 
             let profile_txn = damus_state.profiles.lookup(id: update.pubkey)
-            guard let profile = profile_txn.unsafeUnownedValue else { return }
+            guard let profile = profile_txn?.unsafeUnownedValue else { return }
 
             let display_name = Profile.displayName(profile: profile, pubkey: pubkey)
             if display_name != self.display_name {

damus/Views/Profile/ProfileName.swift

@@ -87,7 +87,7 @@ struct ProfileName: View {
     
     var body: some View {
         let profile_txn = damus_state.profiles.lookup(id: pubkey)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
 
         HStack(spacing: 2) {
             Text(verbatim: "\(prefix)\(name_choice(profile: profile))")

damus/Views/Profile/ProfileNameView.swift

@@ -17,7 +17,7 @@ struct ProfileNameView: View {
         Group {
             VStack(alignment: .leading) {
                 let profile_txn = self.damus.profiles.lookup(id: pubkey)
-                let profile = profile_txn.unsafeUnownedValue
+                let profile = profile_txn?.unsafeUnownedValue
 
                 switch Profile.displayName(profile: profile, pubkey: pubkey) {
                 case .one:

damus/Views/Profile/ProfilePicView.swift

@@ -84,7 +84,7 @@ struct ProfilePicView: View {
     }
     
     func get_lnurl() -> String? {
-        return profiles.lookup_with_timestamp(pubkey).unsafeUnownedValue?.lnurl
+        return profiles.lookup_with_timestamp(pubkey)?.unsafeUnownedValue?.lnurl
     }
     
     var body: some View {
@@ -102,7 +102,7 @@ struct ProfilePicView: View {
                             }
                         case .remote(pubkey: let pk):
                             let profile_txn = profiles.lookup(id: pk)
-                            let profile = profile_txn.unsafeUnownedValue
+                            let profile = profile_txn?.unsafeUnownedValue
                             if let pic = profile?.picture {
                                 self.picture = pic
                             }
@@ -126,7 +126,7 @@ struct ProfilePicView: View {
 }
 
 func get_profile_url(picture: String?, pubkey: Pubkey, profiles: Profiles) -> URL {
-    let pic = picture ?? profiles.lookup(id: pubkey).map({ $0?.picture }).value ?? robohash(pubkey)
+    let pic = picture ?? profiles.lookup(id: pubkey)?.map({ $0?.picture }).value ?? robohash(pubkey)
     if let url = URL(string: pic) {
         return url
     }

damus/Views/Profile/ProfilePictureSelector.swift

@@ -43,7 +43,7 @@ struct EditProfilePictureView: View {
         if let profile_url {
             return profile_url
         } else if let state = damus_state,
-                  let picture = state.profiles.lookup(id: pubkey).map({ pr in pr?.picture }).value {
+                  let picture = state.profiles.lookup(id: pubkey)?.map({ pr in pr?.picture }).value {
             return URL(string: picture)
         } else {
             return profile_url ?? URL(string: robohash(pubkey))

damus/Views/Profile/ProfileView.swift

@@ -24,10 +24,10 @@ func follow_btn_txt(_ fs: FollowState, follows_you: Bool) -> String {
     }
 }
 
-func followedByString<Y>(txn: NdbTxn<Y>, _ friend_intersection: [Pubkey], ndb: Ndb, locale: Locale = Locale.current) -> String {
+func followedByString(_ friend_intersection: [Pubkey], ndb: Ndb, locale: Locale = Locale.current) -> String {
     let bundle = bundleForLocale(locale: locale)
     let names: [String] = friend_intersection.prefix(3).map { pk in
-        let profile = ndb.lookup_profile_with_txn(pk, txn: txn)?.profile
+        let profile = ndb.lookup_profile(pk)?.unsafeUnownedValue?.profile
         return Profile.displayName(profile: profile, pubkey: pk).username.truncate(maxLength: 20)
     }
 
@@ -331,7 +331,7 @@ struct ProfileView: View {
     var aboutSection: some View {
         VStack(alignment: .leading, spacing: 8.0) {
             let profile_txn = damus_state.profiles.lookup_with_timestamp(profile.pubkey)
-            let profile_data = profile_txn.unsafeUnownedValue
+            let profile_data = profile_txn?.unsafeUnownedValue
 
             nameSection(profile_data: profile_data)
 
@@ -398,7 +398,7 @@ struct ProfileView: View {
                     NavigationLink(value: Route.FollowersYouKnow(friendedFollowers: friended_followers, followers: followers)) {
                         HStack {
                             CondensedProfilePicturesView(state: damus_state, pubkeys: friended_followers, maxPictures: 3)
-                            let followedByString = followedByString(txn: profile_txn, friended_followers, ndb: damus_state.ndb)
+                            let followedByString = followedByString(friended_followers, ndb: damus_state.ndb)
                             Text(followedByString)
                                 .font(.subheadline).foregroundColor(.gray)
                                 .multilineTextAlignment(.leading)
@@ -499,7 +499,7 @@ extension View {
 func check_nip05_validity(pubkey: Pubkey, profiles: Profiles) {
     let profile_txn = profiles.lookup(id: pubkey)
 
-    guard let profile = profile_txn.unsafeUnownedValue,
+    guard let profile = profile_txn?.unsafeUnownedValue,
           let nip05 = profile.nip05,
           profiles.is_validated(pubkey) == nil
     else {

damus/Views/ProfileActionSheetView.swift

@@ -30,7 +30,7 @@ struct ProfileActionSheetView: View {
     
     func profile_data() -> ProfileRecord? {
         let profile_txn = damus_state.profiles.lookup_with_timestamp(profile.pubkey)
-        return profile_txn.unsafeUnownedValue
+        return profile_txn?.unsafeUnownedValue
     }
     
     func get_profile() -> Profile? {

damus/Views/QRCodeView.swift

@@ -119,10 +119,11 @@ struct QRCodeView: View {
     var QRView: some View {
         VStack(alignment: .center) {
             let profile_txn = damus_state.profiles.lookup(id: pubkey)
-            let profile = profile_txn.unsafeUnownedValue
+            let profile = profile_txn?.unsafeUnownedValue
-            let our_profile = damus_state.ndb.lookup_profile_with_txn(damus_state.pubkey, txn: profile_txn)
+            let our_profile_txn = damus_state.profiles.lookup(id: damus_state.pubkey)
+            let our_profile = our_profile_txn?.unsafeUnownedValue
 
-            if our_profile?.profile?.picture != nil {
+            if our_profile?.picture != nil {
                 ProfilePicView(pubkey: pubkey, size: 90.0, highlight: .custom(DamusColors.white, 3.0), profiles: damus_state.profiles, disable_animation: damus_state.settings.disable_animation)
                     .padding(.top, 50)
             } else {

damus/Views/ReplyView.swift

@@ -24,11 +24,10 @@ struct ReplyView: View {
     var ReplyingToSection: some View {
         HStack {
             Group {
-                let txn = NdbTxn(ndb: damus.ndb)
                 let names = references
                     .map { pubkey in
                         let pk = pubkey
-                        let prof = damus.ndb.lookup_profile_with_txn(pk, txn: txn)?.profile
+                        let prof = damus.ndb.lookup_profile(pk)?.unsafeUnownedValue?.profile
                         return "@" + Profile.displayName(profile: prof, pubkey: pk).username.truncate(maxLength: 50)
                     }
                     .joined(separator: " ")

damus/Views/Search/PullDownSearch.swift

@@ -31,7 +31,7 @@ struct PullDownSearchView: View {
         }
 
         do {
-            let txn = NdbTxn(ndb: state.ndb)
+            guard let txn = NdbTxn(ndb: state.ndb) else { return }
             for note_key in note_keys {
                 guard let note = state.ndb.lookup_note_by_key_with_txn(note_key, txn: txn) else {
                     continue

damus/Views/SearchResultsView.swift

@@ -108,11 +108,11 @@ struct SearchResultsView: View {
         }
         .frame(maxHeight: .infinity)
         .onAppear {
-            let txn = NdbTxn.init(ndb: damus_state.ndb)
+            guard let txn = NdbTxn.init(ndb: damus_state.ndb) else { return }
             self.result = search_for_string(profiles: damus_state.profiles, search: search, txn: txn)
         }
         .onChange(of: search) { new in
-            let txn = NdbTxn.init(ndb: damus_state.ndb)
+            guard let txn = NdbTxn.init(ndb: damus_state.ndb) else { return }
             self.result = search_for_string(profiles: damus_state.profiles, search: search, txn: txn)
         }
     }

damus/Views/SideMenuView.swift

@@ -90,7 +90,7 @@ struct SideMenuView: View {
 
     var TopProfile: some View {
         let profile_txn = damus_state.profiles.lookup(id: damus_state.pubkey)
-        let profile = profile_txn.unsafeUnownedValue
+        let profile = profile_txn?.unsafeUnownedValue
         return VStack(alignment: .leading, spacing: verticalSpacing) {
             HStack {
                 ProfilePicView(pubkey: damus_state.pubkey, size: 60, highlight: .none, profiles: damus_state.profiles, disable_animation: damus_state.settings.disable_animation)

damus/Views/Wallet/WalletView.swift

@@ -165,7 +165,7 @@ struct WalletView: View {
                 }
                 .onChange(of: settings.donation_percent) { p in
                     let profile_txn = damus_state.profiles.lookup(id: damus_state.pubkey)
-                    guard let profile = profile_txn.unsafeUnownedValue else {
+                    guard let profile = profile_txn?.unsafeUnownedValue else {
                         return
                     }
                     
@@ -177,7 +177,7 @@ struct WalletView: View {
                     let profile_txn = damus_state.profiles.lookup(id: damus_state.pubkey)
                     
                     guard let keypair = damus_state.keypair.to_full(),
-                          let profile = profile_txn.unsafeUnownedValue,
+                          let profile = profile_txn?.unsafeUnownedValue,
                           model.initial_percent != profile.damus_donation
                     else {
                         return

damus/Views/Zaps/ProfileZapLinkView.swift

@@ -34,7 +34,7 @@ struct ProfileZapLinkView<Content: View>: View {
         self.action = action
         
         let profile_txn = damus_state.profiles.lookup_with_timestamp(pubkey)
-        let record = profile_txn.unsafeUnownedValue
+        let record = profile_txn?.unsafeUnownedValue
         self.reactions_enabled = record?.profile?.reactions ?? true
         self.lud16 = record?.profile?.lud06
         self.lnurl = record?.lnurl

damus/Views/Zaps/ZapTypePicker.swift

@@ -98,7 +98,7 @@ func zap_type_desc(type: ZapType, profiles: Profiles, pubkey: Pubkey) -> String
         return NSLocalizedString("No one will see that you zapped", comment: "Description of anonymous zap type where the zap is sent anonymously and does not identify the user who sent it.")
     case .priv:
         let prof_txn = profiles.lookup(id: pubkey)
-        let prof = prof_txn.unsafeUnownedValue
+        let prof = prof_txn?.unsafeUnownedValue
         let name = Profile.displayName(profile: prof, pubkey: pubkey).username.truncate(maxLength: 50)
         return String.localizedStringWithFormat(NSLocalizedString("private_zap_description", value: "Only '%@' will see that you zapped them", comment: "Description of private zap type where the zap is sent privately and does not identify the user to the public."), name)
     case .non_zap:

nostrdb/Ndb.swift

@@ -186,6 +186,7 @@ class Ndb {
             throw DatabaseError.failed_open
         }
 
+        self.closed = false
         self.ndb = db
     }
 
@@ -198,7 +199,7 @@ class Ndb {
     }
 
     func text_search(query: String, limit: Int = 32, order: NdbSearchOrder = .newest_first) -> [NoteKey] {
-        let txn = NdbTxn(ndb: self)
+        guard let txn = NdbTxn(ndb: self) else { return [] }
         var results = ndb_text_search_results()
         let res = query.withCString { q in
             let order = order == .newest_first ? NDB_ORDER_DESCENDING : NDB_ORDER_ASCENDING
@@ -243,7 +244,7 @@ class Ndb {
         return note_ids
     }
 
-    func lookup_note_by_key(_ key: NoteKey) -> NdbTxn<NdbNote?> {
+    func lookup_note_by_key(_ key: NoteKey) -> NdbTxn<NdbNote?>? {
         return NdbTxn(ndb: self) { txn in
             lookup_note_by_key_with_txn(key, txn: txn)
         }
@@ -301,7 +302,7 @@ class Ndb {
         lookup_profile_by_key_inner(key, txn: txn)
     }
 
-    func lookup_profile_by_key(key: ProfileKey) -> NdbTxn<ProfileRecord?> {
+    func lookup_profile_by_key(key: ProfileKey) -> NdbTxn<ProfileRecord?>? {
         return NdbTxn(ndb: self) { txn in
             lookup_profile_by_key_inner(key, txn: txn)
         }
@@ -312,9 +313,13 @@ class Ndb {
     }
 
     func lookup_profile_key(_ pubkey: Pubkey) -> ProfileKey? {
-        return NdbTxn(ndb: self) { txn in
+        guard let txn = NdbTxn(ndb: self, with: { txn in
             lookup_profile_key_with_txn(pubkey, txn: txn)
-        }.value
+        }) else {
+            return nil
+        }
+
+        return txn.value
     }
 
     func lookup_profile_key_with_txn<Y>(_ pubkey: Pubkey, txn: NdbTxn<Y>) -> ProfileKey? {
@@ -342,17 +347,23 @@ class Ndb {
     }
 
     func lookup_note_key(_ id: NoteId) -> NoteKey? {
-        NdbTxn(ndb: self, with: { txn in lookup_note_key_with_txn(id, txn: txn) }).value
+        guard let txn = NdbTxn(ndb: self, with: { txn in
+            lookup_note_key_with_txn(id, txn: txn)
+        }) else {
+            return nil
+        }
+
+        return txn.value
     }
 
-    func lookup_note(_ id: NoteId) -> NdbTxn<NdbNote?> {
+    func lookup_note(_ id: NoteId) -> NdbTxn<NdbNote?>? {
-        return NdbTxn(ndb: self) { txn in
+        NdbTxn(ndb: self) { txn in
             lookup_note_with_txn_inner(id: id, txn: txn)
         }
     }
 
-    func lookup_profile(_ pubkey: Pubkey) -> NdbTxn<ProfileRecord?> {
+    func lookup_profile(_ pubkey: Pubkey) -> NdbTxn<ProfileRecord?>? {
-        return NdbTxn(ndb: self) { txn in
+        NdbTxn(ndb: self) { txn in
             lookup_profile_with_txn_inner(pubkey: pubkey, txn: txn)
         }
     }

nostrdb/NdbTxn.swift

@@ -18,8 +18,9 @@ class NdbTxn<T> {
     var moved: Bool
     var inherited: Bool
 
-    init(ndb: Ndb, with: (NdbTxn<T>) -> T = { _ in () }) {
+    init?(ndb: Ndb, with: (NdbTxn<T>) -> T = { _ in () }) {
-        #if TXNDEBUG
+        guard !ndb.closed else { return nil }
+#if TXNDEBUG
         txn_count += 1
         print("opening transaction \(txn_count)")
         #endif
@@ -31,11 +32,7 @@ class NdbTxn<T> {
             self.txn = ndb_txn()
             let ok = ndb_begin_query(ndb.ndb.ndb, &self.txn) != 0
             if !ok {
-                self.moved = false
+                return nil
-                self.txn = ndb_txn()
-                self.inherited = true
-                self.val = with(self)
-                return
             }
             Thread.current.threadDictionary["ndb_txn"] = self.txn
             self.inherited = false