fix: prevent SQLite crash from concurrent database access in iOS (Sentry YND+YNE, 36K users)

ios/Gekidou/Sources/Gekidou/Storage/Database+Channels.swift

@@ -32,8 +32,7 @@ extension Database {
             INNER JOIN MyChannel my ON c.id=my.id AND c.delete_at = 0 \
             INNER JOIN Team t ON c.team_id=t.id
             """
-            let stmt = try db.prepare(stmtString)
-            let count = (try stmt.scalar() as? Int64) ?? 0
+            let count = try db.scalar(stmtString) as? Int64 ?? 0
             return count > 0
         } catch {
             return false

ios/Gekidou/Sources/Gekidou/Storage/Database+Mentions.swift

@@ -22,7 +22,7 @@ extension Database {
         INNER JOIN Channel c INDEXED BY sqlite_autoindex_Channel_1 ON c.id=my.id \
         WHERE c.delete_at = 0 AND mys.notify_props NOT LIKE '%"mark_unread":"mention"%'
         """
-        let mentions = try? db.prepare(stmtString).scalar() as? Double
+        let mentions = try? db.scalar(stmtString) as? Double
         return Int(mentions ?? 0)
     }
 
@@ -35,7 +35,7 @@ extension Database {
         INNER JOIN MyChannelSettings mys ON mys.id=c.id \
         WHERE c.delete_at = 0 AND mys.notify_props NOT LIKE '%"mark_unread":"mention"%'
         """
-        let mentions = try? db.prepare(stmtString).scalar() as? Double
+        let mentions = try? db.scalar(stmtString) as? Double
         return Int(mentions ?? 0)
     }
 

ios/Gekidou/Sources/Gekidou/Storage/Database+System.swift

@@ -11,7 +11,7 @@ import SQLite
 
 extension Database {
     public func getDeviceToken() -> String? {
-        if let db = try? Connection(DEFAULT_DB_PATH) {
+        if let db = try? openConnection(DEFAULT_DB_PATH) {
             let idCol = Expression<String>("id")
             let valueCol = Expression<String>("value")
             let query = globalTable.select(valueCol).filter(idCol == "deviceToken")

ios/Gekidou/Sources/Gekidou/Storage/Database+Team.swift

@@ -56,21 +56,19 @@ extension Database {
     }
 
     public func queryAllMyTeamIds(_ serverUrl: String) -> [String]? {
-        if let db = try? getDatabaseForServer(serverUrl) {
+        do {
+            let db = try getDatabaseForServer(serverUrl)
             let idCol = Expression<String>("id")
-            if let myTeams = try? db.prepare(myTeamTable.select(idCol)) {
-                return myTeams.compactMap { row in
-                    do {
-                        return try row.get(idCol)
-                    } catch {
-                        GekidouLogger.shared.log(.error, "Gekidou Database: Failed to get team ID from row for server %{public}@ - %{public}@", serverUrl, String(describing: error))
-                        return nil
-                    }
-                }
+            let iterator = try db.prepareRowIterator(myTeamTable.select(idCol))
+            var teamIds = [String]()
+            while let row = try iterator.failableNext() {
+                teamIds.append(try row.get(idCol))
             }
+            return teamIds.isEmpty ? nil : teamIds
+        } catch {
+            GekidouLogger.shared.log(.error, "Gekidou Database: Failed to get team IDs for server %{public}@ - %{public}@", serverUrl, String(describing: error))
+            return nil
         }
-
-        return nil
     }
 
     public func insertTeam(_ db: Connection, _ team: Team) throws {

ios/Gekidou/Sources/Gekidou/Storage/Database+Thread.swift

@@ -22,10 +22,9 @@ extension Database {
         var teamIds = [String]()
         if teamId.isEmpty {
             let idCol = Expression<String>("id")
-            if let myTeams = try? db.prepare(myTeamTable.select(idCol)) {
-                if let ids = try? myTeams.map({ try $0.get(idCol) }) {
-                    teamIds.append(contentsOf: ids)
-                }
+            let iterator = try db.prepareRowIterator(myTeamTable.select(idCol))
+            while let row = try iterator.failableNext() {
+                teamIds.append(try row.get(idCol))
             }
         } else {
             teamIds.append(teamId)

ios/Gekidou/Sources/Gekidou/Storage/Database+Users.swift

@@ -67,7 +67,11 @@ extension Database {
             let idCol = Expression<String>("id")
             let query = userTable.where(idCol == userId)
 
-            let results: [User] = try db.prepare(query).map {try $0.decode()}
+            let iterator = try db.prepareRowIterator(query)
+            var results = [User]()
+            while let row = try iterator.failableNext() {
+                results.append(try row.decode())
+            }
             updateAt = results.first?.lastPictureUpdate
 
         } catch {
@@ -80,32 +84,35 @@ extension Database {
 
     public func queryUsers(byIds userIds: Set<String>, forServerUrl serverUrl: String) -> Set<String> {
         var result: Set<String> = Set()
-        if let db = try? getDatabaseForServer(serverUrl) {
-
+        do {
+            let db = try getDatabaseForServer(serverUrl)
             let idCol = Expression<String>("id")
-            if let users = try? db.prepare(
+            let iterator = try db.prepareRowIterator(
                 userTable.select(idCol).filter(userIds.contains(idCol))
-            ) {
-                for user in users {
-                    result.insert(user[idCol])
-                }
+            )
+            while let user = try iterator.failableNext() {
+                result.insert(try user.get(idCol))
             }
+        } catch {
+            GekidouLogger.shared.log(.error, "Gekidou Database: Failed to query users by IDs for server %{public}@ - %{public}@", serverUrl, String(describing: error))
         }
 
         return result
     }
 
     public func queryUsers(byUsernames usernames: Set<String>, forServerUrl serverUrl: String) -> Set<String> {
         var result: Set<String> = Set()
-        if let db = try? getDatabaseForServer(serverUrl) {
+        do {
+            let db = try getDatabaseForServer(serverUrl)
             let usernameCol = Expression<String>("username")
-            if let users = try? db.prepare(
+            let iterator = try db.prepareRowIterator(
                 userTable.select(usernameCol).filter(usernames.contains(usernameCol))
-            ) {
-                for user in users {
-                    result.insert(user[usernameCol])
-                }
+            )
+            while let user = try iterator.failableNext() {
+                result.insert(try user.get(usernameCol))
             }
+        } catch {
+            GekidouLogger.shared.log(.error, "Gekidou Database: Failed to query users by usernames for server %{public}@ - %{public}@", serverUrl, String(describing: error))
         }
 
         return result

ios/Gekidou/Sources/Gekidou/Storage/Database.swift

@@ -19,6 +19,14 @@ enum DatabaseError: Error {
     case InsertError(_ statement: String)
 }
 
+/// Default busy timeout (in seconds) for SQLite connections.
+/// When the main app and NotificationService extension access the shared
+/// database concurrently, SQLite may return SQLITE_BUSY ("database is locked").
+/// Setting a busy timeout tells SQLite to retry internally for up to this many
+/// seconds before returning an error, preventing transient lock contention from
+/// becoming a fatal crash (via SQLite.swift's `try!` in FailableIterator.next).
+private let defaultBusyTimeout: Double = 5.0
+
 extension DatabaseError: LocalizedError {
     var errorDescription: String? {
         switch self {
@@ -91,6 +99,15 @@ public class Database: NSObject {
         super.init()
     }
 
+    /// Creates a new SQLite Connection with WAL journal mode and a busy timeout,
+    /// so concurrent readers/writers (main app + notification extension) don't
+    /// immediately fail with SQLITE_BUSY.
+    internal func openConnection(_ path: String, readonly: Bool = false) throws -> Connection {
+        let db = try Connection(path, readonly: readonly)
+        db.busyTimeout = defaultBusyTimeout
+        return db
+    }
+
     @objc public func getOnlyServerUrlObjc() -> String {
         do {
             return try getOnlyServerUrl()
@@ -106,14 +123,15 @@ public class Database: NSObject {
 
     public func getOnlyServerUrl() throws -> String {
         do {
-            let db = try Connection(DEFAULT_DB_PATH)
+            let db = try openConnection(DEFAULT_DB_PATH)
             let url = Expression<String>("url")
             let identifier = Expression<String>("identifier")
             let lastActiveAt = Expression<Int64>("last_active_at")
             let query = serversTable.select(url).filter(lastActiveAt > 0 && identifier != "")
 
             var serverUrl: String?
-            for result in try db.prepare(query) {
+            let iterator = try db.prepareRowIterator(query)
+            while let result = try iterator.failableNext() {
                 if (serverUrl != nil) {
                     throw DatabaseError.MultipleServers
                 }
@@ -134,7 +152,7 @@ public class Database: NSObject {
 
     public func getServerUrlForServer(_ id: String) throws -> String {
         do {
-            let db = try Connection(DEFAULT_DB_PATH)
+            let db = try openConnection(DEFAULT_DB_PATH)
             let url = Expression<String>("url")
             let identifier = Expression<String>("identifier")
             let query = serversTable.select(url).filter(identifier == id)
@@ -152,14 +170,15 @@ public class Database: NSObject {
     }
 
     public func getAllActiveDatabases<T: Codable>() -> [T] {
-        guard let db = try? Connection(DEFAULT_DB_PATH) else {return []}
+        guard let db = try? openConnection(DEFAULT_DB_PATH) else {return []}
         let lastActiveAt = Expression<Int64>("last_active_at")
         let identifier = Expression<String>("identifier")
         let query = serversTable.filter(lastActiveAt > 0 && identifier != "").order(lastActiveAt.desc)
         do {
-            let rows = try db.prepare(query)
-            let servers: [T] = try rows.map { row in
-                return try row.decode()
+            let iterator = try db.prepareRowIterator(query)
+            var servers = [T]()
+            while let row = try iterator.failableNext() {
+                servers.append(try row.decode())
             }
 
             return servers
@@ -169,15 +188,16 @@ public class Database: NSObject {
     }
 
     public func getAllActiveServerUrls() -> [String] {
-        guard let db = try? Connection(DEFAULT_DB_PATH) else {return []}
+        guard let db = try? openConnection(DEFAULT_DB_PATH) else {return []}
         let lastActiveAt = Expression<Int64>("last_active_at")
         let identifier = Expression<String>("identifier")
         let url = Expression<String>("url")
         let query = serversTable.filter(lastActiveAt > 0 && identifier != "").order(lastActiveAt.desc)
         do {
-            let rows = try db.prepare(query)
-            let servers: [String] = try rows.map { row in
-                return try row.get(url)
+            let iterator = try db.prepareRowIterator(query)
+            var servers = [String]()
+            while let row = try iterator.failableNext() {
+                servers.append(try row.get(url))
             }
 
             return servers
@@ -187,7 +207,7 @@ public class Database: NSObject {
     }
 
     public func getCurrentServerDatabase<T: Codable>() -> T? {
-        guard let db = try? Connection(DEFAULT_DB_PATH) else {return nil}
+        guard let db = try? openConnection(DEFAULT_DB_PATH) else {return nil}
         do {
             let lastActiveAt = Expression<Int64>("last_active_at")
             let identifier = Expression<String>("identifier")
@@ -205,14 +225,14 @@ public class Database: NSObject {
     }
 
     internal func getDatabaseForServer(_ serverUrl: String) throws -> Connection {
-        let db = try Connection(DEFAULT_DB_PATH)
+        let db = try openConnection(DEFAULT_DB_PATH)
         let url = Expression<String>("url")
         let dbPath = Expression<String>("db_path")
         let query = serversTable.select(dbPath).where(url == serverUrl)
 
         if let result = try db.pluck(query) {
             let path = try result.get(dbPath)
-            return try Connection(path)
+            return try openConnection(path)
         }
 
         throw DatabaseError.NoResults(query.expression.description)