fix the deadlock issue using the same transaction to write to database in multiple threads

SignalServiceKit/src/Loki/API/LokiFileServerAPI.swift

@@ -24,8 +24,8 @@ public final class LokiFileServerAPI : LokiDotNetAPI {
 
     /// Gets the device links associated with the given hex encoded public key from the
     /// server and stores and returns the valid ones.
-    public static func getDeviceLinks(associatedWith hexEncodedPublicKey: String) -> Promise<Set<DeviceLink>> {
+    public static func getDeviceLinks(associatedWith hexEncodedPublicKey: String, in transaction: YapDatabaseReadWriteTransaction? = nil) -> Promise<Set<DeviceLink>> {
-        return getDeviceLinks(associatedWith: [ hexEncodedPublicKey ])
+        return getDeviceLinks(associatedWith: [ hexEncodedPublicKey ], in: transaction)
     }
 
     @objc(getDeviceLinksAssociatedWithHexEncodedPublicKeys:)
@@ -35,7 +35,7 @@ public final class LokiFileServerAPI : LokiDotNetAPI {
     
     /// Gets the device links associated with the given hex encoded public keys from the
     /// server and stores and returns the valid ones.
-    public static func getDeviceLinks(associatedWith hexEncodedPublicKeys: Set<String>) -> Promise<Set<DeviceLink>> {
+    public static func getDeviceLinks(associatedWith hexEncodedPublicKeys: Set<String>, in transaction: YapDatabaseReadWriteTransaction? = nil) -> Promise<Set<DeviceLink>> {
         let hexEncodedPublicKeysDescription = "[ \(hexEncodedPublicKeys.joined(separator: ", ")) ]"
         print("[Loki] Getting device links for: \(hexEncodedPublicKeysDescription).")
         return getAuthToken(for: server).then(on: DispatchQueue.global()) { token -> Promise<Set<DeviceLink>> in
@@ -88,8 +88,12 @@ public final class LokiFileServerAPI : LokiDotNetAPI {
                 let (promise, seal) = Promise<Set<DeviceLink>>.pending()
                 // Dispatch async on the main queue to avoid nested write transactions
                 DispatchQueue.main.async {
-                    storage.dbReadWriteConnection.readWrite { transaction in
+                    if let trans = transaction {
-                        storage.setDeviceLinks(deviceLinks, in: transaction)
+                        storage.setDeviceLinks(deviceLinks, in: trans)
+                    } else {
+                        storage.dbReadWriteConnection.readWrite { transaction in
+                            storage.setDeviceLinks(deviceLinks, in: transaction)
+                        }
                     }
                     // We have to wait for the device links to be stored because a lot of our logic relies
                     // on them being in the database

SignalServiceKit/src/Loki/Protocol/Multi Device/MultiDeviceProtocol.swift

@@ -306,7 +306,7 @@ public extension MultiDeviceProtocol {
         }
         if timeSinceLastUpdate > deviceLinkUpdateInterval {
             let masterHexEncodedPublicKey = storage.getMasterHexEncodedPublicKey(for: hexEncodedPublicKey, in: transaction) ?? hexEncodedPublicKey
-            LokiFileServerAPI.getDeviceLinks(associatedWith: masterHexEncodedPublicKey).done(on: DispatchQueue.global()) { _ in
+            LokiFileServerAPI.getDeviceLinks(associatedWith: masterHexEncodedPublicKey, in: transaction as! YapDatabaseReadWriteTransaction).done(on: DispatchQueue.global()) { _ in
                 getDestinations()
                 lastDeviceLinkUpdate[hexEncodedPublicKey] = Date()
             }.catch(on: DispatchQueue.global()) { error in

SignalServiceKit/src/Messages/OWSMessageManager.m

@@ -1266,12 +1266,14 @@ NS_ASSUME_NONNULL_BEGIN
     // Loki: Update device links in a blocking way
     // FIXME: This is horrible for performance
     // FIXME: ========
+    // FIX: Using the same transaction for write to avoid deadlock
     // The envelope source is set during UD decryption
     if ([ECKeyPair isValidHexEncodedPublicKeyWithCandidate:envelope.source] && dataMessage.publicChatInfo == nil) { // Handled in LokiPublicChatPoller for open group messages
         dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
-        [[LKMultiDeviceProtocol updateDeviceLinksIfNeededForHexEncodedPublicKey:envelope.source in:transaction].ensureOn(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^() {
+        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
+        [[LKMultiDeviceProtocol updateDeviceLinksIfNeededForHexEncodedPublicKey:envelope.source in:transaction].ensureOn(queue, ^() {
             dispatch_semaphore_signal(semaphore);
-        }).catchOn(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(NSError *error) {
+        }).catchOn(queue, ^(NSError *error) {
             dispatch_semaphore_signal(semaphore);
         }) retainUntilComplete];
         dispatch_semaphore_wait(semaphore, dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC));