fix mirror strategy startup fail bug without db enabled, closes #525

examples/configs/trader/sample_mirror.cfg

@@ -27,10 +27,10 @@ EXCHANGE_QUOTE="ZUSD"
 #EXCHANGE_QUOTE="BTC"
 
 # maximum depth of order levels that we want to create on the orderbook on each side
-ORDERBOOK_DEPTH=40
+ORDERBOOK_DEPTH=5
 
 # number to divide volume by when placing orders so we can scale volume as needed
-VOLUME_DIVIDE_BY=500.0
+VOLUME_DIVIDE_BY=4.0
 
 # spread % we should maintain per level between the mirrored exchange and SDEX (0 < spread < 1.0). This moves the price away from the center price on SDEX so we can cover the position on the external exchange, i.e. if this value is > 0 then the spread you provide on SDEX will be more than the spread on the exchange you are mirroring.
 # in this example the spread is 0.5%

plugins/mirrorStrategy.go

@@ -235,9 +235,12 @@ func makeMirrorStrategy(
 	log.Printf("backingPair='%s', backingConstraints=%s\n", backingPair, backingConstraints)
 
 	// insert into database if needed
-	backingMarketID, e := FetchOrRegisterMarketID(db, config.Exchange, config.ExchangeBase, config.ExchangeQuote)
-	if e != nil {
-		return nil, fmt.Errorf("error calling FetchOrRegisterMarketID: %s", e)
+	var backingMarketID string
+	if db != nil {
+		backingMarketID, e = FetchOrRegisterMarketID(db, config.Exchange, config.ExchangeBase, config.ExchangeQuote)
+		if e != nil {
+			return nil, fmt.Errorf("error calling FetchOrRegisterMarketID: %s", e)
+		}
 	}
 
 	// trigger fill tracking on backing exchange at creation time