Warrior_EA/System/RetryWithBackoff.mqh

//+------------------------------------------------------------------+
//|                                                       Warrior_EA |
//|                                                     AnimateDread |
//|                                                                  |
//| The exponential-backoff retry SHAPE, shared by every call site   |
//| that retries one transient-lock-prone operation a fixed number   |
//| of times with an increasing, capped sleep between attempts. Each |
//| operation's own arguments differ (a file copy vs a model load),  |
//| so the shape is factored out behind a tiny callback interface    |
//| instead of a raw function pointer - MQL5 has no closures, and    |
//| a function pointer cannot bind the per-call-site arguments.      |
//+------------------------------------------------------------------+
#ifndef WARRIOR_RETRY_WITH_BACKOFF_MQH
#define WARRIOR_RETRY_WITH_BACKOFF_MQH
//+------------------------------------------------------------------+
//| One retryable attempt. quiet is true on every attempt but the    |
//| last, so an implementation that logs its own per-attempt reason  |
//| can stay silent until the failure actually matters.              |
//+------------------------------------------------------------------+
class IRetryableOp
  {
public:
   virtual bool      TryOnce(bool quiet) = 0;
  };
//+------------------------------------------------------------------+
//| Runs op.TryOnce() up to retryAttempts times, sleeping delayMs    |
//| (doubled each attempt, capped at delayCapMs) between attempts.   |
//| Returns the first successful attempt's result, or false if every |
//| attempt failed.                                                  |
//+------------------------------------------------------------------+
bool RetryWithBackoff(IRetryableOp *op, const int retryAttempts, const int initialDelayMs, const int delayCapMs)
  {
   if(CheckPointer(op) == POINTER_INVALID)
      return false;
   int delayMs = initialDelayMs;
   bool ok = false;
   for(int attempt = 0; attempt < retryAttempts && !ok; attempt++)
     {
      if(attempt > 0)
        {
         Sleep(delayMs);
         delayMs = (int)MathMin(delayMs * 2, delayCapMs);
        }
      ok = op.TryOnce(attempt < retryAttempts - 1);
     }
   return ok;
  }
#endif // WARRIOR_RETRY_WITH_BACKOFF_MQH
//+------------------------------------------------------------------+