src/Executor/Promise/Adapter/SyncPromiseAdapter.php
public function wait(Promise $promise)
    {
        $this->beforeWait($promise);
        $dfdQueue     = Deferred::getQueue();
        $promiseQueue = SyncPromise::getQueue();

        while ($promise->adoptedPromise->state === SyncPromise::PENDING &&
            ! ($dfdQueue->isEmpty() && $promiseQueue->isEmpty())
        ) {
            Deferred::runQueue();
            SyncPromise::runQueue();
            $this->onWait($promise);
        }

        /** @var SyncPromise $syncPromise */
        $syncPromise = $promise->adoptedPromise;

        if ($syncPromise->state === SyncPromise::FULFILLED) {
            return $syncPromise->result;
        }

        if ($syncPromise->state === SyncPromise::REJECTED) {
            throw $syncPromise->result;
        }

        throw new InvariantViolation('Could not resolve promise');
    }
public function wait(Promise $promise)
    {
        $this->beforeWait($promise);
        $dfdQueue     = Deferred::getQueue();
        $promiseQueue = SyncPromise::getQueue();

        while ($promise->adoptedPromise->state === SyncPromise::PENDING &&
            ! ($dfdQueue->isEmpty() && $promiseQueue->isEmpty())
        ) {
            Deferred::runQueue();
            SyncPromise::runQueue();
            $this->onWait($promise);
        }

        /** @var SyncPromise $syncPromise */
        $syncPromise = $promise->adoptedPromise;

        if ($syncPromise->state === SyncPromise::FULFILLED) {
            return $syncPromise->result;
        }

        if ($syncPromise->state === SyncPromise::REJECTED) {
            throw $syncPromise->result;
        }

        throw new InvariantViolation('Could not resolve promise');
    }
Synchronously wait when promise completes

@return ExecutionResult