WIP: Fixing start session failure on legacy modules

SmartDeviceLink/private/SDLIAPTransport.m

@@ -98,7 +98,7 @@ - (void)sdl_accessoryConnected:(NSNotification *)notification {
         return;
     }
 
-    double retryDelay = self.sdl_retryDelay;
+    double retryDelay = 0.0;
     SDLLogD(@"Accessory Connected (%@), Opening in %0.03fs", notification.userInfo[EAAccessoryKey], retryDelay);
 
     self.retryCounter = 0;
@@ -429,51 +429,6 @@ + (nullable NSString *)sdl_supportsRequiredProtocolStrings {
     return nil;
 }
 
-#pragma mark Retry Delay
-
-/**
- *  Generates a random number of seconds between 1.5 and 9.5 used to delay the retry control and data session attempts.
- *
- *  @return A random number of seconds.
- */
-- (double)sdl_retryDelay {
-    const double MinRetrySeconds = 1.5;
-    const double MaxRetrySeconds = 9.5;
-    double RetryRangeSeconds = MaxRetrySeconds - MinRetrySeconds;
-
-    static double appDelaySeconds = 0;
-
-    // HAX: This pull the app name and hashes it in an attempt to provide a more even distribution of retry delays. The evidence that this does so is anecdotal. A more ideal solution would be to use a list of known, installed SDL apps on the phone to try and deterministically generate an even delay.
-    if (appDelaySeconds == 0) {
-        NSString *appName = [[NSProcessInfo processInfo] processName];
-        if (appName == nil) {
-            appName = @"noname";
-        }
-
-        // Run the app name through an md5 hasher
-        const char *ptr = [appName UTF8String];
-        unsigned char md5Buffer[CC_MD5_DIGEST_LENGTH];
-        CC_MD5(ptr, (unsigned int)strlen(ptr), md5Buffer);
-
-        // Generate a string of the hex hash
-        NSMutableString *output = [NSMutableString stringWithString:@"0x"];
-        for (int i = 0; i < 8; i++) {
-            [output appendFormat:@"%02X", md5Buffer[i]];
-        }
-
-        // Transform the string into a number between 0 and 1
-        unsigned long long firstHalf;
-        NSScanner *pScanner = [NSScanner scannerWithString:output];
-        [pScanner scanHexLongLong:&firstHalf];
-        double hashBasedValueInRange0to1 = ((double)firstHalf) / 0xffffffffffffffff;
-
-        // Transform the number into a number between min and max
-        appDelaySeconds = ((RetryRangeSeconds * hashBasedValueInRange0to1) + MinRetrySeconds);
-    }
-
-    return appDelaySeconds;
-}
-
 #pragma mark Create Sessions
 
 /**

SmartDeviceLink/private/SDLLifecycleProtocolHandler.m

@@ -26,16 +26,19 @@
 #import "SDLTimer.h"
 
 static const float StartSessionTime = 10.0;
+int const RPCStartServiceRetries = 2;
 
 NS_ASSUME_NONNULL_BEGIN
 
 @interface SDLLifecycleProtocolHandler ()
 
 @property (weak, nonatomic) SDLNotificationDispatcher *notificationDispatcher;
 
-@property (strong, nonatomic) SDLTimer *rpcStartServiceTimeoutTimer;
+@property (strong, nonatomic, nullable) SDLTimer *rpcStartServiceTimeoutTimer;
+@property (assign, nonatomic) int rpcStartServiceRetryCounter;
 @property (copy, nonatomic) NSString *appId;
 
+
 @end
 
 @implementation SDLLifecycleProtocolHandler
@@ -44,6 +47,7 @@ - (instancetype)initWithProtocol:(SDLProtocol *)protocol notificationDispatcher:
     self = [super init];
     if (!self) { return nil; }
 
+    _rpcStartServiceRetryCounter = 0;
     _protocol = protocol;
     _notificationDispatcher = notificationDispatcher;
 
@@ -72,20 +76,37 @@ - (void)stopWithCompletionHandler:(void (^)(void))disconnectCompletionHandler {
 - (void)protocolDidOpen:(SDLProtocol *)protocol {
     if (self.protocol != protocol) { return; }
 
-    SDLLogD(@"Transport opened, sending an RPC Start Service, and starting timer for RPC Start Service ACK to be received.");
+    SDLLogD(@"Transport opened.");
     [self.notificationDispatcher postNotificationName:SDLTransportDidConnect infoObject:nil];
 
+    [self sdl_sendStartServiceSession:self.rpcStartServiceRetryCounter];
+}
+
+/// Sends the RPC start service request to the module and sets a timer to wait for a response from the module. If the module ACKs or NAKs the request, then the timer is canceled. However, if the module does not respond within a set amount of time, the RPC start service is resent. Once the max number of retry accounts has been reached the session is closed.
+/// @param retryCount The retry attempt count
+- (void)sdl_sendStartServiceSession:(int)retryCount {
+    if (retryCount > RPCStartServiceRetries) {
+        SDLLogE(@"Retrying sending the RPC start service failed %d times. Closing the session", RPCStartServiceRetries);
+        return [self.protocol stopWithCompletionHandler:^{}];
+    }
+
     SDLControlFramePayloadRPCStartService *startServicePayload = [[SDLControlFramePayloadRPCStartService alloc] initWithVersion:SDLMaxProxyProtocolVersion];
     [self.protocol startServiceWithType:SDLServiceTypeRPC payload:startServicePayload.data];
 
-    if (self.rpcStartServiceTimeoutTimer == nil) {
-        self.rpcStartServiceTimeoutTimer = [[SDLTimer alloc] initWithDuration:StartSessionTime repeat:NO];
-        __weak typeof(self) weakSelf = self;
-        self.rpcStartServiceTimeoutTimer.elapsedBlock = ^{
-            SDLLogE(@"Start session timed out after %f seconds, closing the connection.", StartSessionTime);
-            [weakSelf.protocol stopWithCompletionHandler:^{}];
-        };
+    if (self.rpcStartServiceTimeoutTimer != nil) {
+        [self.rpcStartServiceTimeoutTimer cancel];
+        self.rpcStartServiceTimeoutTimer = nil;
     }
+
+    self.rpcStartServiceTimeoutTimer = [[SDLTimer alloc] initWithDuration:StartSessionTime repeat:NO];
+    __weak typeof(self) weakSelf = self;
+    self.rpcStartServiceTimeoutTimer.elapsedBlock = ^{
+        weakSelf.rpcStartServiceRetryCounter += 1;
+        SDLLogE(@"Module did not respond to the RPC start service within %.f seconds. Retrying sending the RPC start service (#%d)", StartSessionTime, weakSelf.rpcStartServiceRetryCounter);
+        [weakSelf sdl_sendStartServiceSession:weakSelf.rpcStartServiceRetryCounter];
+    };
+
+    SDLLogD(@"Starting timeout timer for the module's response to the RPC start service");
     [self.rpcStartServiceTimeoutTimer start];
 }