Bugfix/dx 1973 fix synchronisation conversation view (#7)

Author: AndriyVasyk

Sources/DXProtocol/Session/Session.swift

@@ -109,9 +109,8 @@ public struct Session: Codable {
 
         try identityStore.saveIdentity(theirIdentityKey, for: address)
 
-        let lock = SessionLock(address: address)
-        lock.lock()
-        defer { lock.unlock() }
+        try sessionStore.lockSession(for: address)
+        defer { sessionStore.unlockSession(for: address) }
 
         var session = try sessionStore.loadSession(for: address)
         if nil == session {
@@ -159,9 +158,8 @@ public struct Session: Codable {
             throw DXError.untrustedIdentity("Abort processing PreKey Message for untrusted identity")
         }
 
-        let lock = SessionLock(address: address)
-        lock.lock()
-        defer { lock.unlock() }
+        try sessionStore.lockSession(for: address)
+        defer { sessionStore.unlockSession(for: address) }
 
         let theirBaseKey = message.senderBaseKey
         let messageVersion = Int(message.messageVersion)
@@ -235,9 +233,8 @@ public struct Session: Codable {
                                for address: ProtocolAddress,
                                sessionStore: SessionStorable,
                                identityStore: IdentityKeyStorable) throws -> MessageContainer {
-        let lock = SessionLock(address: address)
-        lock.lock()
-        defer { lock.unlock() }
+        try sessionStore.lockSession(for: address)
+        defer { sessionStore.unlockSession(for: address) }
 
         guard var session = try sessionStore.loadSession(for: address) else {
             throw DXError.sessionNotFound("Failed to find session while encrypting message")
@@ -327,9 +324,8 @@ extension Session {
                                 identityStore: IdentityKeyStorable,
                                 preKeyStore: PreKeyStorable,
                                 signedPreKeyStore: SignedPreKeyStorable) throws -> Data {
-        let lock = SessionLock(address: address)
-        lock.lock()
-        defer { lock.unlock() }
+        try sessionStore.lockSession(for: address)
+        defer { sessionStore.unlockSession(for: address) }
 
         var session = try self.processPreKeyMessage(
                 preKeyMessage,
@@ -367,9 +363,8 @@ extension Session {
                                 from address: ProtocolAddress,
                                 sessionStore: SessionStorable,
                                 identityStore: IdentityKeyStorable) throws -> Data {
-        let lock = SessionLock(address: address)
-        lock.lock()
-        defer { lock.unlock() }
+        try sessionStore.lockSession(for: address)
+        defer { sessionStore.unlockSession(for: address) }
 
         guard var session = try sessionStore.loadSession(for: address) else {
             throw DXError.sessionNotFound("Failed to find session while decrypting message")

Sources/DXProtocol/Session/SessionLock.swift

@@ -27,6 +27,15 @@ import Foundation
 /// `SessionStorable` protocol declares a set of methods allowing to store
 /// the sessions according to DX Protocol
 public protocol SessionStorable: AnyObject {
+    /// Attempts to acquire a lock on session, blocking an execution until the lock can be acquired
+    /// - Parameter address: The address of the remote client the session is associated with
+    /// - Throws: Throws if the operation failed to be performed
+    func lockSession(for address: ProtocolAddress) throws
+    
+    /// Relinquishes a previously acquired lock on session
+    /// - Parameter address: The address of the remote client the session is associated with
+    func unlockSession(for address: ProtocolAddress)
+
     /// Returns a session for a given user's address.
     /// - Parameter address: The address of the remote client
     /// - Returns: The session, or nil if session does not exist

Sources/DXProtocol/Session/SessionLockStorage.swift

@@ -32,6 +32,9 @@ final class InMemoryTestKeysStore: IdentityKeyStorable, PreKeyStorable, SignedPr
     private var prekeyMap: [UUID: OneTimePreKeyPair] = [:]
     private var signedPrekeyMap: [UUID: SignedPreKeyPair] = [:]
     private var sessionMap: [ProtocolAddress: Session] = [:]
+    
+    private let queue = DispatchQueue(label: "TestKeysStoreQueue")
+    private var storage: [ProtocolAddress: NSRecursiveLock] = [:]
 
     private var isIdentityTrusted: Bool
 
@@ -128,6 +131,16 @@ final class InMemoryTestKeysStore: IdentityKeyStorable, PreKeyStorable, SignedPr
     }
 
     // MARK: - SessionStorable
+    
+    public func lockSession(for address: ProtocolAddress) throws {
+        let lock = self.lock(for: address)
+        lock.lock()
+    }
+    
+    public func unlockSession(for address: ProtocolAddress) {
+        let lock = self.lock(for: address)
+        lock.unlock()
+    }
 
     public func loadSession(for address: ProtocolAddress) throws -> Session? {
         return sessionMap[address]
@@ -145,4 +158,19 @@ final class InMemoryTestKeysStore: IdentityKeyStorable, PreKeyStorable, SignedPr
     public func storeSession(_ record: Session, for address: ProtocolAddress) throws {
         sessionMap[address] = record
     }
+    
+    // MARK: - Private
+    
+    private func lock(for address: ProtocolAddress) -> NSRecursiveLock {
+        self.queue.sync {
+            var result: NSRecursiveLock
+            if let lock = self.storage[address] {
+                result = lock
+            } else {
+                result = NSRecursiveLock()
+                self.storage[address] = result
+            }
+            return result
+        }
+    }
 }