Include best block height in /vspinfo response (#254)

config.go

@@ -243,7 +243,7 @@ func loadConfig() (*config, error) {
 			flags.IniIncludeComments|flags.IniIncludeDefaults)
 		if err != nil {
 			return nil, fmt.Errorf("error creating a default "+
-				"config file: %v", err)
+				"config file: %w", err)
 		}
 		fmt.Printf("Config file with default values written to %s\n", defaultConfigFile)
 

docs/api.md

@@ -53,7 +53,8 @@ when a VSP is closed will result in an error.
         "vspdversion":"1.0.0-pre",
         "voting":10,
         "voted":25,
-        "revoked":3
+        "revoked":3,
+        "blockheight":623212
     }
     ```
 

rpc/dcrd.go

@@ -224,6 +224,17 @@ func (c *DcrdRPC) CanTicketVote(rawTx *dcrdtypes.TxRawResult, ticketHash string,
 	return live, nil
 }
 
+// GetBestBlockHeight uses getblockcount RPC to query the height of the best
+// block known by the dcrd instance.
+func (c *DcrdRPC) GetBestBlockHeight() (int64, error) {
+	var height int64
+	err := c.Call(c.ctx, "getblockcount", &height)
+	if err != nil {
+		return 0, err
+	}
+	return height, nil
+}
+
 // ParseBlockConnectedNotification extracts the block header from a
 // blockconnected JSON-RPC notification.
 func ParseBlockConnectedNotification(params json.RawMessage) (*wire.BlockHeader, error) {

webapi/homepage.go

@@ -5,16 +5,21 @@
 package webapi
 
 import (
+	"context"
 	"encoding/base64"
 	"net/http"
 	"sync"
 	"time"
 
+	"github.com/decred/dcrd/chaincfg/v3"
 	"github.com/decred/vspd/database"
+	"github.com/decred/vspd/rpc"
 
 	"github.com/gin-gonic/gin"
 )
 
+// vspStats is used to cache values which are commonly used by the API, so
+// repeated web requests don't repeatedly trigger DB or RPC calls.
 type vspStats struct {
 	PubKey       string
 	Voting       int64
@@ -27,6 +32,7 @@ type vspStats struct {
 	VspClosed    bool
 	Debug        bool
 	Designation  string
+	BlockHeight  int64
 }
 
 var statsMtx sync.RWMutex
@@ -39,28 +45,54 @@ func getVSPStats() *vspStats {
 	return stats
 }
 
-func updateVSPStats(db *database.VspDatabase, cfg Config) error {
+// initVSPStats creates the struct which holds the cached VSP stats, and
+// initializes it with static values.
+func initVSPStats() {
+
+	statsMtx.Lock()
+	defer statsMtx.Unlock()
+
+	stats = &vspStats{
+		PubKey:       base64.StdEncoding.EncodeToString(signPubKey),
+		VSPFee:       cfg.VSPFee,
+		Network:      cfg.NetParams.Name,
+		SupportEmail: cfg.SupportEmail,
+		VspClosed:    cfg.VspClosed,
+		Debug:        cfg.Debug,
+		Designation:  cfg.Designation,
+	}
+}
+
+// updateVSPStats updates the dynamic values in the cached VSP stats (ticket
+// counts and best block height).
+func updateVSPStats(ctx context.Context, db *database.VspDatabase,
+	dcrd rpc.DcrdConnect, netParams *chaincfg.Params) error {
+
+	// Update counts of voting, voted and revoked tickets.
 	voting, voted, revoked, err := db.CountTickets()
 	if err != nil {
 		return err
 	}
 
+	// Update best block height.
+	dcrdClient, err := dcrd.Client(ctx, netParams)
+	if err != nil {
+		return err
+	}
+
+	blockHeight, err := dcrdClient.GetBestBlockHeight()
+	if err != nil {
+		return err
+	}
+
 	statsMtx.Lock()
 	defer statsMtx.Unlock()
 
-	stats = &vspStats{
-		PubKey:       base64.StdEncoding.EncodeToString(signPubKey),
-		Voting:       voting,
-		Voted:        voted,
-		Revoked:      revoked,
-		VSPFee:       cfg.VSPFee,
-		Network:      cfg.NetParams.Name,
-		UpdateTime:   dateTime(time.Now().Unix()),
-		SupportEmail: cfg.SupportEmail,
-		VspClosed:    cfg.VspClosed,
-		Debug:        cfg.Debug,
-		Designation:  cfg.Designation,
-	}
+	stats.UpdateTime = dateTime(time.Now().Unix())
+	stats.Voting = voting
+	stats.Voted = voted
+	stats.Revoked = revoked
+	stats.BlockHeight = blockHeight
 
 	return nil
 }

webapi/types.go

@@ -15,6 +15,7 @@ type vspInfoResponse struct {
 	Voting        int64   `json:"voting"`
 	Voted         int64   `json:"voted"`
 	Revoked       int64   `json:"revoked"`
+	BlockHeight   int64   `json:"blockheight"`
 }
 
 type feeAddressRequest struct {

webapi/vspinfo.go

@@ -25,5 +25,6 @@ func vspInfo(c *gin.Context) {
 		Voting:        cachedStats.Voting,
 		Voted:         cachedStats.Voted,
 		Revoked:       cachedStats.Revoked,
+		BlockHeight:   cachedStats.BlockHeight,
 	}, c)
 }

webapi/webapi.go

@@ -69,9 +69,10 @@ func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *s
 	}
 
 	// Populate cached VSP stats before starting webserver.
-	err = updateVSPStats(vdb, config)
+	initVSPStats()
+	err = updateVSPStats(ctx, vdb, dcrd, config.NetParams)
 	if err != nil {
-		return fmt.Errorf("could not initialize VSP stats cache: %w", err)
+		log.Errorf("Could not initialize VSP stats cache: %v", err)
 	}
 
 	// Get the last used address index and the feeXpub from the database, and
@@ -139,7 +140,7 @@ func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *s
 		}
 	}()
 
-	// Use a ticker to update template data.
+	// Use a ticker to update cached VSP stats.
 	var refresh time.Duration
 	if cfg.Debug {
 		refresh = 1 * time.Second
@@ -156,7 +157,7 @@ func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *s
 				shutdownWg.Done()
 				return
 			case <-ticker.C:
-				err = updateVSPStats(db, cfg)
+				err = updateVSPStats(ctx, vdb, dcrd, config.NetParams)
 				if err != nil {
 					log.Errorf("Failed to update cached VSP stats: %v", err)
 				}