Update and integrate price updater

PriceUpdater:
    - Pass context so that it can be canceled during an update loop
    - Define APITypes to make it explicit which API we are using

priceupdater/priceupdater.go

@@ -1,8 +1,9 @@
 package priceupdater
 
 import (
+	"context"
+	"fmt"
 	"net/http"
-	"strconv"
 	"time"
 
 	"github.com/dghubble/sling"
@@ -13,52 +14,92 @@ import (
 
 const (
 	defaultMaxIdleConns    = 10
-	defaultIdleConnTimeout = 10
+	defaultIdleConnTimeout = 2 * time.Second
 )
 
+// APIType defines the token exchange API
+type APIType string
+
+const (
+	// APITypeBitFinexV2 is the http API used by bitfinex V2
+	APITypeBitFinexV2 APIType = "bitfinexV2"
+)
+
+func (t *APIType) valid() bool {
+	switch *t {
+	case APITypeBitFinexV2:
+		return true
+	default:
+		return false
+	}
+}
+
 // PriceUpdater definition
 type PriceUpdater struct {
 	db           *historydb.HistoryDB
 	apiURL       string
+	apiType      APIType
 	tokenSymbols []string
 }
 
 // NewPriceUpdater is the constructor for the updater
-func NewPriceUpdater(apiURL string, db *historydb.HistoryDB) PriceUpdater {
+func NewPriceUpdater(apiURL string, apiType APIType, db *historydb.HistoryDB) (*PriceUpdater, error) {
 	tokenSymbols := []string{}
-	return PriceUpdater{
+	if !apiType.valid() {
+		return nil, tracerr.Wrap(fmt.Errorf("Invalid apiType: %v", apiType))
+	}
+	return &PriceUpdater{
 		db:           db,
 		apiURL:       apiURL,
+		apiType:      apiType,
 		tokenSymbols: tokenSymbols,
+	}, nil
+}
+
+func getTokenPriceBitfinex(ctx context.Context, client *sling.Sling,
+	tokenSymbol string) (float64, error) {
+	state := [10]float64{}
+	req, err := client.New().Get("ticker/t" + tokenSymbol + "USD").Request()
+	if err != nil {
+		return 0, tracerr.Wrap(err)
 	}
+	res, err := client.Do(req.WithContext(ctx), &state, nil)
+	if err != nil {
+		return 0, tracerr.Wrap(err)
+	}
+	if res.StatusCode != http.StatusOK {
+		return 0, fmt.Errorf("http response is not is %v", res.StatusCode)
+	}
+	return state[6], nil
 }
 
 // UpdatePrices is triggered by the Coordinator, and internally will update the token prices in the db
-func (p *PriceUpdater) UpdatePrices() {
+func (p *PriceUpdater) UpdatePrices(ctx context.Context) {
 	tr := &http.Transport{
 		MaxIdleConns:       defaultMaxIdleConns,
-		IdleConnTimeout:    defaultIdleConnTimeout * time.Second,
+		IdleConnTimeout:    defaultIdleConnTimeout,
 		DisableCompression: true,
 	}
 	httpClient := &http.Client{Transport: tr}
 	client := sling.New().Base(p.apiURL).Client(httpClient)
 
-	state := [10]float64{}
-
 	for _, tokenSymbol := range p.tokenSymbols {
-		resp, err := client.New().Get("ticker/t" + tokenSymbol + "USD").ReceiveSuccess(&state)
-		errString := tokenSymbol + " not updated, error: "
-		if err != nil {
-			log.Error(errString + err.Error())
-			continue
+		var tokenPrice float64
+		var err error
+		switch p.apiType {
+		case APITypeBitFinexV2:
+			tokenPrice, err = getTokenPriceBitfinex(ctx, client, tokenSymbol)
 		}
-		if resp.StatusCode != http.StatusOK {
-			log.Error(errString + "response is not 200, is " + strconv.Itoa(resp.StatusCode))
-			continue
+		if ctx.Err() != nil {
+			return
 		}
-		err = p.db.UpdateTokenValue(tokenSymbol, state[6])
 		if err != nil {
-			log.Error(errString + err.Error())
+			log.Errorw("token price not updated (get error)",
+				"err", err, "token", tokenSymbol, "apiType", p.apiType)
+		}
+		if err = p.db.UpdateTokenValue(tokenSymbol, tokenPrice); err != nil {
+			log.Errorw("token price not updated (db error)",
+				"err", err, "token", tokenSymbol, "apiType", p.apiType)
 		}
 	}
 }