engine/order manager: Initial REST managed order updating (resolves #772) (#775)

* Initial REST managed order updating

* Apply gloriousCode's changes.go patch

* Update internal order ID handling

* Check error

* Replace string with string pointer

* Avoid nil pointers in upsert

* Update test for UpdateOrderFromDetail()

* Add tests for orders.go

* Remove unnecessary newline

* Address comments

* Add missing nil check

* Add tests for new functions in order_manager.go

* Remove empty line

* Change log level for updates from Info to Debug (keep added orders at Info)

* Initialize orders before running the timer

* [TEMP] Add verbosity for debugging

* Nil checking on exchangeManager in GetExchanges()

- exchangeManager.GetExchanges() and iExchangeManager.GetExchanges() return an error on nil
- bot.GetExchanges() wraps exchangeManager.GetExchanges() and returns an empty slice

* Revert b5afe1a46b

* Do not start the order manager runner thread

Instead, mark the order manager as running

* Remove redundant error.Is() and remove print wrapper on msg

* Add atomic blocker and waitgroup on processOrders()

* Disable unnecessary orderManager runner thread for rpcserver_test

* Remove redundant err from orderStore.getActiveOrders()

* [FIX] Populate requiresProcessing using UpsertResponse data instead of REST return data

.. because the data returned by the REST calls do not include the internal user ID's

* [TEST] Verify that processOrders() actually processes queried order data

* Remove leftover warning and add nil check on wg.Done()

* Apply suggestions from code review

Log category changes - as suggested

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

* Return when no exchanges available

Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

engine/exchange_manager.go

@@ -77,14 +77,17 @@ func (m *ExchangeManager) Add(exch exchange.IBotExchange) {
 }
 
 // GetExchanges returns all stored exchanges
-func (m *ExchangeManager) GetExchanges() []exchange.IBotExchange {
+func (m *ExchangeManager) GetExchanges() ([]exchange.IBotExchange, error) {
+	if m == nil {
+		return nil, fmt.Errorf("exchange manager: %w", ErrNilSubsystem)
+	}
 	m.m.Lock()
 	defer m.m.Unlock()
 	var exchs []exchange.IBotExchange
 	for _, x := range m.exchanges {
 		exchs = append(exchs, x)
 	}
-	return exchs
+	return exchs, nil
 }
 
 // RemoveExchange removes an exchange from the manager