Fix background crashes

damus.xcodeproj/project.pbxproj

@@ -1668,6 +1668,10 @@
 		D74EC8522E1856B70091DC51 /* NonCopyableLinkedList.swift in Sources */ = {isa = PBXBuildFile; fileRef = D74EC84E2E1856AF0091DC51 /* NonCopyableLinkedList.swift */; };
 		D74F430A2B23F0BE00425B75 /* DamusPurple.swift in Sources */ = {isa = PBXBuildFile; fileRef = D74F43092B23F0BE00425B75 /* DamusPurple.swift */; };
 		D74F430C2B23FB9B00425B75 /* StoreObserver.swift in Sources */ = {isa = PBXBuildFile; fileRef = D74F430B2B23FB9B00425B75 /* StoreObserver.swift */; };
+		D75154BF2EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */ = {isa = PBXBuildFile; fileRef = D75154BE2EC5910600BF2CB2 /* NdbUseLock.swift */; };
+		D75154C02EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */ = {isa = PBXBuildFile; fileRef = D75154BE2EC5910600BF2CB2 /* NdbUseLock.swift */; };
+		D75154C12EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */ = {isa = PBXBuildFile; fileRef = D75154BE2EC5910600BF2CB2 /* NdbUseLock.swift */; };
+		D75154C22EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */ = {isa = PBXBuildFile; fileRef = D75154BE2EC5910600BF2CB2 /* NdbUseLock.swift */; };
 		D753CEAA2BE9DE04001C3A5D /* MutingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D753CEA92BE9DE04001C3A5D /* MutingTests.swift */; };
 		D755B28D2D3E7D8800BBEEFA /* NIP37Draft.swift in Sources */ = {isa = PBXBuildFile; fileRef = D755B28C2D3E7D7D00BBEEFA /* NIP37Draft.swift */; };
 		D755B28E2D3E7D8800BBEEFA /* NIP37Draft.swift in Sources */ = {isa = PBXBuildFile; fileRef = D755B28C2D3E7D7D00BBEEFA /* NIP37Draft.swift */; };
@@ -1709,6 +1713,7 @@
 		D78F08182D7F7F7500FC6C75 /* NIP04.swift in Sources */ = {isa = PBXBuildFile; fileRef = D78F08162D7F7F6C00FC6C75 /* NIP04.swift */; };
 		D78F08192D7F7F7500FC6C75 /* NIP04.swift in Sources */ = {isa = PBXBuildFile; fileRef = D78F08162D7F7F6C00FC6C75 /* NIP04.swift */; };
 		D78F081A2D7F803100FC6C75 /* NIP04.swift in Sources */ = {isa = PBXBuildFile; fileRef = D78F08162D7F7F6C00FC6C75 /* NIP04.swift */; };
+		D795356B2EBD28A800AACF98 /* AppLifecycleHandlingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D795356A2EBD289D00AACF98 /* AppLifecycleHandlingTests.swift */; };
 		D798D21A2B0856CC00234419 /* Mentions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C7FF7D42823313F009601DB /* Mentions.swift */; };
 		D798D21B2B0856F200234419 /* NdbTagsIterator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CDD1AE12A6B3074001CD4DF /* NdbTagsIterator.swift */; };
 		D798D21C2B0857E400234419 /* Bech32Object.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CF0ABEF29857E9200D66079 /* Bech32Object.swift */; };
@@ -2766,6 +2771,7 @@
 		D74EC84E2E1856AF0091DC51 /* NonCopyableLinkedList.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NonCopyableLinkedList.swift; sourceTree = "<group>"; };
 		D74F43092B23F0BE00425B75 /* DamusPurple.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DamusPurple.swift; sourceTree = "<group>"; };
 		D74F430B2B23FB9B00425B75 /* StoreObserver.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StoreObserver.swift; sourceTree = "<group>"; };
+		D75154BE2EC5910600BF2CB2 /* NdbUseLock.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NdbUseLock.swift; sourceTree = "<group>"; };
 		D753CEA92BE9DE04001C3A5D /* MutingTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MutingTests.swift; sourceTree = "<group>"; };
 		D755B28C2D3E7D7D00BBEEFA /* NIP37Draft.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NIP37Draft.swift; sourceTree = "<group>"; };
 		D76556D52B1E6C08001B0CCC /* DamusPurpleWelcomeView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DamusPurpleWelcomeView.swift; sourceTree = "<group>"; };
@@ -2786,6 +2792,7 @@
 		D78F080B2D7F78EB00FC6C75 /* Request.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Request.swift; sourceTree = "<group>"; };
 		D78F08102D7F78F600FC6C75 /* Response.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Response.swift; sourceTree = "<group>"; };
 		D78F08162D7F7F6C00FC6C75 /* NIP04.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NIP04.swift; sourceTree = "<group>"; };
+		D795356A2EBD289D00AACF98 /* AppLifecycleHandlingTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppLifecycleHandlingTests.swift; sourceTree = "<group>"; };
 		D798D21D2B0858BB00234419 /* MigratedTypes.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MigratedTypes.swift; sourceTree = "<group>"; };
 		D798D2272B085CDA00234419 /* NdbNote+.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "NdbNote+.swift"; sourceTree = "<group>"; };
 		D798D22B2B086C7400234419 /* NostrEvent+.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "NostrEvent+.swift"; sourceTree = "<group>"; };
@@ -3297,6 +3304,7 @@
 		4C9054862A6AEB4500811EEC /* nostrdb */ = {
 			isa = PBXGroup;
 			children = (
+				D75154BE2EC5910600BF2CB2 /* NdbUseLock.swift */,
 				D74EC84E2E1856AF0091DC51 /* NonCopyableLinkedList.swift */,
 				D733F9E42D92C75C00317B11 /* UnownedNdbNote.swift */,
 				D7F5630F2DEE71BB008509DE /* NdbFilter.swift */,
@@ -5275,6 +5283,7 @@
 		D7EBF8BC2E5946F9004EAE29 /* NostrNetworkManagerTests */ = {
 			isa = PBXGroup;
 			children = (
+				D795356A2EBD289D00AACF98 /* AppLifecycleHandlingTests.swift */,
 				D7EBF8BD2E594708004EAE29 /* test_notes.jsonl */,
 				D7EBF8BA2E5901F7004EAE29 /* NostrNetworkManagerTests.swift */,
 				D7EBF8BF2E5D39D1004EAE29 /* ThreadModelTests.swift */,
@@ -5737,6 +5746,7 @@
 				4CC6AA792CAB688500989CEF /* sha256.c in Sources */,
 				4CC6AA7B2CAB688500989CEF /* likely.c in Sources */,
 				4CC6AA7F2CAB688500989CEF /* htable.c in Sources */,
+				D75154C02EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */,
 				4CC6AA862CAB688500989CEF /* list.c in Sources */,
 				4CC6AA872CAB688500989CEF /* utf8.c in Sources */,
 				4CC6AA892CAB688500989CEF /* debug.c in Sources */,
@@ -6259,6 +6269,7 @@
 				D72E127A2BEEEED000F4F781 /* NostrFilterTests.swift in Sources */,
 				B5B4D1432B37D47600844320 /* NdbExtensions.swift in Sources */,
 				3ACBCB78295FE5C70037388A /* TimeAgoTests.swift in Sources */,
+				D795356B2EBD28A800AACF98 /* AppLifecycleHandlingTests.swift in Sources */,
 				D72A2D072AD9C1FB002AFF62 /* MockProfiles.swift in Sources */,
 				B5A75C2A2B546D94007AFBC0 /* MuteItemTests.swift in Sources */,
 				D7DB1FEE2D5AC51B00CF06DA /* NIP44v2EncryptionTests.swift in Sources */,
@@ -6777,6 +6788,7 @@
 				82D6FC3A2CD99F7900C925F4 /* WideEventView.swift in Sources */,
 				82D6FC3B2CD99F7900C925F4 /* LongformView.swift in Sources */,
 				82D6FC3C2CD99F7900C925F4 /* LongformPreview.swift in Sources */,
+				D75154C22EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */,
 				82D6FC3D2CD99F7900C925F4 /* EventShell.swift in Sources */,
 				82D6FC3E2CD99F7900C925F4 /* MentionView.swift in Sources */,
 				82D6FC3F2CD99F7900C925F4 /* EventLoaderView.swift in Sources */,
@@ -7202,6 +7214,7 @@
 				D73E5F302C6A97F4007EB227 /* EventProfile.swift in Sources */,
 				D73E5F312C6A97F4007EB227 /* EventMenu.swift in Sources */,
 				D73E5F322C6A97F4007EB227 /* EventMutingContainerView.swift in Sources */,
+				D75154C12EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */,
 				D73E5F332C6A97F4007EB227 /* ZapEvent.swift in Sources */,
 				5C8F97362EB46145009399B1 /* LiveStreamView.swift in Sources */,
 				D73E5F342C6A97F4007EB227 /* TextEvent.swift in Sources */,
@@ -7466,6 +7479,7 @@
 				4CC6AAC52CAB688500989CEF /* likely.c in Sources */,
 				4CC6AAC92CAB688500989CEF /* htable.c in Sources */,
 				4CC6AAD02CAB688500989CEF /* list.c in Sources */,
+				D75154BF2EC5910A00BF2CB2 /* NdbUseLock.swift in Sources */,
 				4CC6AAD12CAB688500989CEF /* utf8.c in Sources */,
 				4CC6AAD32CAB688500989CEF /* debug.c in Sources */,
 				4CC6AAD42CAB688500989CEF /* str.c in Sources */,

damus/ContentView.swift

@@ -538,9 +538,7 @@ struct ContentView: View {
                     Log.debug("App background signal handling: App being backgrounded", for: .app_lifecycle)
                     let startTime = CFAbsoluteTimeGetCurrent()
                     await damus_state.nostrNetwork.handleAppBackgroundRequest()  // Close ndb streaming tasks before closing ndb to avoid memory errors
-                    Log.debug("App background signal handling: Nostr network closed after %.2f seconds", for: .app_lifecycle, CFAbsoluteTimeGetCurrent() - startTime)
-                    damus_state.ndb.close()
-                    Log.debug("App background signal handling: Ndb closed after %.2f seconds", for: .app_lifecycle, CFAbsoluteTimeGetCurrent() - startTime)
+                    Log.debug("App background signal handling: Nostr network and Ndb closed after %.2f seconds", for: .app_lifecycle, CFAbsoluteTimeGetCurrent() - startTime)
                     this_app.endBackgroundTask(bgTask)
                 }
                 break
@@ -552,9 +550,7 @@ struct ContentView: View {
                 Task {
                     await damusClosingTask?.value  // Wait for the closing task to finish before reopening things, to avoid race conditions
                     damusClosingTask = nil
-                    damus_state.ndb.reopen()
-                    // Pinging the network will automatically reconnect any dead websocket connections
-                    await damus_state.nostrNetwork.ping()
+                    await damus_state.nostrNetwork.handleAppForegroundRequest()
                 }
             @unknown default:
                 break
@@ -1144,7 +1140,6 @@ extension LossyLocalNotification {
     }
 }
 
-
 func logout(_ state: DamusState?)
 {
     state?.close()

damus/Core/Networking/NostrNetworkManager/NostrNetworkManager.swift

@@ -59,9 +59,19 @@ class NostrNetworkManager {
         await self.pool.disconnect()
     }
 
-    func handleAppBackgroundRequest() async {
+    func handleAppBackgroundRequest(beforeClosingNdb operationBeforeClosingNdb: (() async -> Void)? = nil) async {
+        // Mark NDB as closed without actually closing it, to avoid new tasks from using NostrDB
+        // self.delegate.ndb.markClosed()
         await self.reader.cancelAllTasks()
         await self.pool.cleanQueuedRequestForSessionEnd()
+        await operationBeforeClosingNdb?()
+        self.delegate.ndb.close()
+    }
+
+    func handleAppForegroundRequest() async {
+        self.delegate.ndb.reopen()
+        // Pinging the network will automatically reconnect any dead websocket connections
+        await self.ping()
     }
 
     func close() async {

damusTests/NostrNetworkManagerTests/AppLifecycleHandlingTests.swift

@@ -0,0 +1,73 @@
+//
+//  AppLifecycleHandlingTests.swift
+//  damus
+//
+//  Created by Daniel D’Aquino on 2025-11-06.
+//
+
+import XCTest
+@testable import damus
+
+
+class AppLifecycleHandlingTests: XCTestCase {
+
+    func getTestNotesJSONL() -> String {
+        // Get the path for the test_notes.jsonl file in the same folder as this test file
+        let testBundle = Bundle(for: type(of: self))
+        let fileURL = testBundle.url(forResource: "test_notes", withExtension: "jsonl")!
+
+        // Load the contents of the file
+        return try! String(contentsOf: fileURL, encoding: .utf8)
+    }
+
+    /// Tests for some race conditions between the app closing down and streams opening throughout the app
+    /// See https://github.com/damus-io/damus/issues/3245 for more context.
+    ///
+    /// **Note:** Time delays are intentionally added because we actually want to provoke possible race conditions,
+    /// so using proper waiting mechanisms would defeat the purpose of the test.
+    func testAppLifecycleRaceConditions() async throws {
+        let damusState = generate_test_damus_state(mock_profile_info: nil)
+
+        let notesJSONL = getTestNotesJSONL()
+        for noteText in notesJSONL.split(separator: "\n") {
+            let _ = damusState.ndb.processEvent("[\"EVENT\",\"subid\",\(String(noteText))]")
+        }
+
+        // Give some time ndb some time to fill up
+        try? await Task.sleep(for: .milliseconds(2000))
+
+
+
+        // Start measuring the time elapsed for debugging
+        let startTime = CFAbsoluteTimeGetCurrent()
+        func getElapsedTimeMiliseconds() -> String {
+            return "\((CFAbsoluteTimeGetCurrent() - startTime) * 1000) ms"
+        }
+
+
+        Task.detached {
+            for i in 0...10000 {
+                try await Task.sleep(for: .milliseconds(Int.random(in: 0...10)))
+                print("APP_LIFECYCLE_TEST \(i): About to close Ndb. Elapsed time: \(getElapsedTimeMiliseconds())")
+                damusState.ndb.close()
+                print("APP_LIFECYCLE_TEST \(i): Closed Ndb. Elapsed time: \(getElapsedTimeMiliseconds())")
+                print("APP_LIFECYCLE_TEST \(i): Reopening Ndb. Elapsed time: \(getElapsedTimeMiliseconds())")
+                _ = damusState.ndb.reopen()
+                print("APP_LIFECYCLE_TEST \(i): Reopened Ndb. Elapsed time: \(getElapsedTimeMiliseconds())")
+
+            }
+        }
+        for i in 0...10000 {
+            do {
+                try await Task.sleep(for: .milliseconds(Int.random(in: 0...10)))
+                print("APP_LIFECYCLE_TEST \(i): Starting new query. Elapsed time: \(getElapsedTimeMiliseconds())")
+                guard let txn = NdbTxn(ndb: damusState.ndb) else { continue }
+                _ = try damusState.ndb.query(with: txn, filters: [try NdbFilter(from: NostrFilter(kinds: [.text], limit: 1000))], maxResults: 500)
+            }
+            catch {
+                print("APP_LIFECYCLE_TEST \(i): Query error: \(error). Elapsed time: \(getElapsedTimeMiliseconds())")
+            }
+            print("APP_LIFECYCLE_TEST \(i): Finished query. Elapsed time: \(getElapsedTimeMiliseconds())")
+        }
+    }
+}

nostrdb/Ndb+.swift

@@ -18,12 +18,12 @@ extension Ndb {
     ///   - maxSimultaneousResults: Maximum number of initial results to return
     /// - Returns: AsyncStream of StreamItem events
     /// - Throws: NdbStreamError if subscription fails
-    func subscribe(filters: [NostrFilter], maxSimultaneousResults: Int = 1000) throws(NdbStreamError) -> AsyncStream<StreamItem> {
+    func subscribe(filters: [NostrFilter], maxSimultaneousResults: Int = 1000) throws -> AsyncStream<StreamItem> {
         let ndbFilters: [NdbFilter]
         do {
             ndbFilters = try filters.toNdbFilters()
         } catch {
-            throw .cannotConvertFilter(error)
+            throw NdbStreamError.cannotConvertFilter(error)
         }
         return try self.subscribe(filters: ndbFilters, maxSimultaneousResults: maxSimultaneousResults)
     }