Updates in ConnectionPool in order to use React\Async\await function

[iorsa]

According to some issues when ConnectionState enum (of $connectionFactory Closure/Class, which creates connection adapter) isn't Ready and retryWithDelay() function is called repeatedly.

I used to debug calls that used in your test.php file.

If you want better code readability you can use this variation of retryWithDelay() function (notice additional $selectConnectionDeferred):

protected function retryWithDelay(Deferred $deferred = null): \React\Promise\Promise
{
      if ($this->retryLimit !== null && $this->retryLimit < 1) {
          throw new ConnectionPoolException('No available connection to use');
      }

      $deferred ??= new Deferred();

      if (!$this->awaiting->contains($deferred)) {
          $this->awaiting->attach($deferred, 0);
      }

      if ($this->awaiting[$deferred] === $this->retryLimit) {
          $this->awaiting->detach($deferred);
          throw new ConnectionPoolException("No available connection to use; $this->retryLimit attempts were made");
      }

      $selectConnectionDeferred = new Deferred();

      $this->loop->addTimer($this->retryEverySec, function () use ($deferred, $selectConnectionDeferred) {
          $connectionAdapter = $this->selectConnection();

          if ($connectionAdapter) {
              $this->awaiting->detach($deferred);
              $selectConnectionDeferred->resolve(true);
              $deferred->resolve($connectionAdapter);
              return;
          }

          $this->awaiting[$deferred] = $this->awaiting[$deferred] + 1;
          $selectConnectionDeferred->resolve(false);
      });

      return $selectConnectionDeferred->promise()->then(function($connectionSelected) use ($deferred) {
          return $connectionSelected ? $deferred->promise() : $this->retryWithDelay($deferred);
      });
}

[szado]

@iorsa thanks, I merged it: 399d5ce but after adding the retryLimit in test.php, a segmentation error occurred (instead of ConnectionLoopException). I rewrote retryWithDelay() with periodic timer and now it works as expected.

[iorsa]

@szado hm, I also used retryLimit param to limit the amount of retries and haven't discovered this problem (tested on linux only, though). Great job! It looks like a better approach anyway, than using addTimer() in nested self function calls.