Improved auto-reconnect logic to better handle long retry intervals

Author: ritchiecarroll

src/lib/transport/DataSubscriber.cpp

@@ -89,7 +89,8 @@ void SubscriberConnector::AutoReconnect(DataSubscriber* subscriber)
     }
 
     // Apply exponential back-off algorithm for retry attempt delays
-    int32_t retryInterval = connector.m_connectAttempt > 0 ? connector.m_retryInterval * int32_t(pow(2, connector.m_connectAttempt - 1)) : 0;
+    const int32_t exponent = (connector.m_connectAttempt > 13 ? 13 : connector.m_connectAttempt) - 1;
+    int32_t retryInterval = connector.m_connectAttempt > 0 ? connector.m_retryInterval * int32_t(pow(2, exponent)) : 0;
 
     if (retryInterval > connector.m_maxRetryInterval)
         retryInterval = connector.m_maxRetryInterval;
@@ -150,7 +151,7 @@ bool SubscriberConnector::Connect(DataSubscriber& subscriber, bool autoReconnect
 
     m_cancel = false;
 
-    while (!subscriber.m_disconnecting)
+    while (!subscriber.m_disposing)
     {
         if (m_maxRetries != -1 && m_connectAttempt >= m_maxRetries)
         {
@@ -181,10 +182,11 @@ bool SubscriberConnector::Connect(DataSubscriber& subscriber, bool autoReconnect
             errorMessage = current_exception_diagnostic_information(true);
         }
 
-        if (!connected && !subscriber.m_disconnecting)
+        if (!connected && !subscriber.m_disposing)
         {
             // Apply exponential back-off algorithm for retry attempt delays
-            int32_t retryInterval = m_connectAttempt > 0 ? m_retryInterval * int32_t(pow(2, m_connectAttempt - 1)) : 0;
+            const int32_t exponent = (m_connectAttempt > 13 ? 13 : m_connectAttempt) - 1;
+            int32_t retryInterval = m_connectAttempt > 0 ? m_retryInterval * int32_t(pow(2, exponent)) : 0;
             autoReconnecting = true;
 
             if (retryInterval > m_maxRetryInterval)
@@ -324,6 +326,7 @@ DataSubscriber::DataSubscriber() :
     m_compressMetadata(true),
     m_compressSignalIndexCache(true),
     m_disconnecting(false),
+    m_disposing(false),
     m_userData(nullptr),
     m_totalCommandChannelBytesReceived(0UL),
     m_totalDataChannelBytesReceived(0UL),
@@ -348,6 +351,7 @@ DataSubscriber::DataSubscriber() :
 // Destructor calls disconnect to clean up after itself.
 DataSubscriber::~DataSubscriber()
 {
+    m_disposing = true;
     Disconnect();
 }
 

src/lib/transport/DataSubscriber.h

@@ -183,6 +183,7 @@ namespace transport
         bool m_compressMetadata;
         bool m_compressSignalIndexCache;
         volatile bool m_disconnecting;
+        volatile bool m_disposing;
         void* m_userData;
 
         // Statistics counters

src/samples/InstanceSubscribe/SubscriberHandler.cpp

@@ -42,19 +42,7 @@ SubscriptionInfo SubscriberHandler::CreateSubscriptionInfo()
 
     // TODO: Modify subscription info properties as desired...
 
-    // To set up a remotely synchronized subscription, set this flag
-    // to true and add the framesPerSecond parameter to the
-    // ExtraConnectionStringParameters. Additionally, the following
-    // example demonstrates the use of some other useful parameters
-    // when setting up remotely synchronized subscriptions.
-
-    //info.RemotelySynchronized = true;
-    //info.ExtraConnectionStringParameters = "framesPerSecond=30;timeResolution=10000;downsamplingMethod=Closest";
-    //info.LagTime = 3.0;
-    //info.LeadTime = 1.0;
-    //info.UseLocalClockAsRealTime = false;
-
-    // Other example properties (see SubscriptionInfo class in DataSubscriber.h for all properties)
+    // See SubscriptionInfo class in DataSubscriber.h for all properties
     //info.Throttled = false;
     //info.IncludeTime = true;
     //info.UseMillisecondResolution = true;
@@ -66,8 +54,19 @@ void SubscriberHandler::SetupSubscriberConnector(SubscriberConnector& connector)
 {
     SubscriberInstance::SetupSubscriberConnector(connector);
 
-    // TODO: Modify connector properties as desired...
+    // TODO: Customize subscriber connector properties as desired...
+
+    //// Enable auto-reconnect sequence:
+    //connector.SetAutoReconnect(true);
+
+    //// Set maximum number to attempt reconnection, -1 means never stop retrying connection attempts:
     //connector.SetMaxRetries(-1);
+    //
+    //// Set number of initial milliseconds to wait before retrying connection attempt:
+    //connector.SetRetryInterval(2000);
+    //
+    //// Set maximum number of milliseconds to wait before retrying connection attempt, connection retry attempts use exponential back-off algorithm up to this defined maximum:
+    //connector.SetMaxRetryInterval(120000);
 }
 
 void SubscriberHandler::StatusMessage(const string& message)