stakeholder disapproved blocks page (#733)

This adds a Stakeholder Disapproved Blocks page at "/rejects".

This also adds two SVG icons for the Side Chains and Disapproved
Blocks pages. Both are in the official decred identity colors as per
https://www.decred.org/brand/.

Implementation details: 
Add DisapprovedBlocks to explorerDataSource interface.
Add "rejects" template and mount on /rejects.
Implement DisapprovedBlocks handler.
Clean up many comments in explorerroutes.go.
Remove extra span in sidechains.tmpl.

db/dcrpg/internal/blockstmts.go

@@ -119,6 +119,12 @@ const (
 		JOIN block_chain ON this_hash=hash
 		WHERE hash = $1;`
 
+	SelectDisapprovedBlocks = `SELECT is_mainchain, height, previous_hash, hash, block_chain.next_hash
+		FROM blocks
+		JOIN block_chain ON this_hash=hash
+		WHERE is_valid = FALSE
+		ORDER BY height DESC;`
+
 	IndexBlocksTableOnHeight = `CREATE INDEX uix_block_height ON blocks(height);`
 
 	DeindexBlocksTableOnHeight = `DROP INDEX uix_block_height;`

db/dcrpg/pgblockchain.go

@@ -467,6 +467,11 @@ func (pgb *ChainDB) SideChainTips() ([]*dbtypes.BlockStatus, error) {
 	return RetrieveSideChainTips(pgb.db)
 }
 
+// DisapprovedBlocks retrieves all blocks disapproved by stakeholder votes.
+func (pgb *ChainDB) DisapprovedBlocks() ([]*dbtypes.BlockStatus, error) {
+	return RetrieveDisapprovedBlocks(pgb.db)
+}
+
 // BlockStatus retrieves the block chain status of the specified block.
 func (pgb *ChainDB) BlockStatus(hash string) (dbtypes.BlockStatus, error) {
 	return RetrieveBlockStatus(pgb.db, hash)

db/dcrpg/queries.go

@@ -2471,6 +2471,28 @@ func RetrieveSideChainTips(db *sql.DB) (blocks []*dbtypes.BlockStatus, err error
 	return
 }
 
+// RetrieveDisapprovedBlocks retrieves the block chain status for all blocks
+// that had their regular transactions invalidated by stakeholder disapproval.
+func RetrieveDisapprovedBlocks(db *sql.DB) (blocks []*dbtypes.BlockStatus, err error) {
+	var rows *sql.Rows
+	rows, err = db.Query(internal.SelectDisapprovedBlocks)
+	if err != nil {
+		return
+	}
+	defer closeRows(rows)
+
+	for rows.Next() {
+		var bs dbtypes.BlockStatus
+		err = rows.Scan(&bs.IsMainchain, &bs.Height, &bs.PrevHash, &bs.Hash, &bs.NextHash)
+		if err != nil {
+			return
+		}
+
+		blocks = append(blocks, &bs)
+	}
+	return
+}
+
 // RetrieveBlockStatus retrieves the block chain status for the block with the
 // specified hash.
 func RetrieveBlockStatus(db *sql.DB, hash string) (bs dbtypes.BlockStatus, err error) {

explorer/explorer.go

@@ -75,7 +75,7 @@ type explorerDataSource interface {
 	GetPgChartsData() (map[string]*dbtypes.ChartsData, error)
 	GetTicketsPriceByHeight() (*dbtypes.ChartsData, error)
 	SideChainBlocks() ([]*dbtypes.BlockStatus, error)
-	//SideChainTips() []*dbtypes.BlockStatus
+	DisapprovedBlocks() ([]*dbtypes.BlockStatus, error)
 	BlockStatus(hash string) (dbtypes.BlockStatus, error)
 	GetOldestTxBlockTime(addr string) (int64, error)
 	TicketPoolVisualization(interval dbtypes.ChartGrouping) ([]*dbtypes.PoolTicketsData, *dbtypes.PoolTicketsData, uint64, error)
@@ -291,8 +291,8 @@ func New(dataSource explorerDataSourceLite, primaryDataSource explorerDataSource
 		return nil
 	}
 	tmpls := []string{"home", "explorer", "mempool", "block", "tx", "address",
-		"rawtx", "status", "parameters", "agenda", "agendas", "charts", "sidechains",
-		"ticketpool", "nexthome"}
+		"rawtx", "status", "parameters", "agenda", "agendas", "charts",
+		"sidechains", "rejects", "ticketpool", "nexthome"}
 
 	tempDefaults := []string{"extras"}
 

explorer/explorerroutes.go

@@ -42,7 +42,7 @@ func netName(chainParams *chaincfg.Params) string {
 	return strings.Title(chainParams.Name)
 }
 
-// Home is the page handler for the "/" path
+// Home is the page handler for the "/" path.
 func (exp *explorerUI) Home(w http.ResponseWriter, r *http.Request) {
 	height := exp.blockData.GetHeight()
 
@@ -79,7 +79,7 @@ func (exp *explorerUI) Home(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// SideChains is the page handler for the "/side" path
+// SideChains is the page handler for the "/side" path.
 func (exp *explorerUI) SideChains(w http.ResponseWriter, r *http.Request) {
 	sideBlocks, err := exp.explorerSource.SideChainBlocks()
 	if err != nil {
@@ -108,7 +108,37 @@ func (exp *explorerUI) SideChains(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// NextHome is the page handler for the "/nexthome" path
+// DisapprovedBlocks is the page handler for the "/rejects" path.
+func (exp *explorerUI) DisapprovedBlocks(w http.ResponseWriter, r *http.Request) {
+	disapprovedBlocks, err := exp.explorerSource.DisapprovedBlocks()
+	if err != nil {
+		log.Errorf("Unable to get stakeholder disapproved blocks: %v", err)
+		exp.StatusPage(w, defaultErrorCode,
+			"failed to retrieve stakeholder disapproved blocks", ErrorStatusType)
+		return
+	}
+
+	str, err := exp.templates.execTemplateToString("rejects", struct {
+		Data    []*dbtypes.BlockStatus
+		Version string
+		NetName string
+	}{
+		disapprovedBlocks,
+		exp.Version,
+		exp.NetName,
+	})
+
+	if err != nil {
+		log.Errorf("Template execute failure: %v", err)
+		exp.StatusPage(w, defaultErrorCode, defaultErrorMessage, ErrorStatusType)
+		return
+	}
+	w.Header().Set("Content-Type", "text/html")
+	w.WriteHeader(http.StatusOK)
+	io.WriteString(w, str)
+}
+
+// NextHome is the page handler for the "/nexthome" path.
 func (exp *explorerUI) NextHome(w http.ResponseWriter, r *http.Request) {
 	height := exp.blockData.GetHeight()
 
@@ -143,7 +173,7 @@ func (exp *explorerUI) NextHome(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// Blocks is the page handler for the "/blocks" path
+// Blocks is the page handler for the "/blocks" path.
 func (exp *explorerUI) Blocks(w http.ResponseWriter, r *http.Request) {
 	idx := exp.blockData.GetHeight()
 
@@ -205,17 +235,18 @@ func (exp *explorerUI) Blocks(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// Block is the page handler for the "/block" path
+// Block is the page handler for the "/block" path.
 func (exp *explorerUI) Block(w http.ResponseWriter, r *http.Request) {
+	// Retrieve the block specified on the path.
 	hash := getBlockHashCtx(r)
-
 	data := exp.blockData.GetExplorerBlock(hash)
 	if data == nil {
 		log.Errorf("Unable to get block %s", hash)
 		exp.StatusPage(w, defaultErrorCode, "could not find that block", NotFoundStatusType)
 		return
 	}
-	// Checking if there exists any regular non-Coinbase transactions in the block.
+
+	// Check if there are any regular non-coinbase transactions in the block.
 	var count int
 	data.TxAvailable = true
 	for _, i := range data.Tx {
@@ -227,6 +258,8 @@ func (exp *explorerUI) Block(w http.ResponseWriter, r *http.Request) {
 		data.TxAvailable = false
 	}
 
+	// In full mode, retrieve missed votes, main/side chain status, and
+	// stakeholder approval.
 	if !exp.liteMode {
 		var err error
 		data.Misses, err = exp.explorerSource.BlockMissedVotes(hash)
@@ -266,7 +299,7 @@ func (exp *explorerUI) Block(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// Mempool is the page handler for the "/mempool" path
+// Mempool is the page handler for the "/mempool" path.
 func (exp *explorerUI) Mempool(w http.ResponseWriter, r *http.Request) {
 	exp.MempoolData.RLock()
 	str, err := exp.templates.execTemplateToString("mempool", struct {
@@ -290,7 +323,7 @@ func (exp *explorerUI) Mempool(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// Ticketpool is the page handler for the "/ticketpool" path
+// Ticketpool is the page handler for the "/ticketpool" path.
 func (exp *explorerUI) Ticketpool(w http.ResponseWriter, r *http.Request) {
 	if exp.liteMode {
 		exp.StatusPage(w, fullModeRequired,
@@ -346,7 +379,7 @@ func (exp *explorerUI) Ticketpool(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// TxPage is the page handler for the "/tx" path
+// TxPage is the page handler for the "/tx" path.
 func (exp *explorerUI) TxPage(w http.ResponseWriter, r *http.Request) {
 	// attempt to get tx hash string from URL path
 	hash, ok := r.Context().Value(ctxTxHash).(string)
@@ -716,7 +749,7 @@ func (exp *explorerUI) TxPage(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// AddressPage is the page handler for the "/address" path
+// AddressPage is the page handler for the "/address" path.
 func (exp *explorerUI) AddressPage(w http.ResponseWriter, r *http.Request) {
 	// AddressPageData is the data structure passed to the HTML template
 	type AddressPageData struct {
@@ -1059,7 +1092,7 @@ func (exp *explorerUI) Charts(w http.ResponseWriter, r *http.Request) {
 
 // Search implements a primitive search algorithm by checking if the value in
 // question is a block index, block hash, address hash or transaction hash and
-// redirects to the appropriate page or displays an error
+// redirects to the appropriate page or displays an error.
 func (exp *explorerUI) Search(w http.ResponseWriter, r *http.Request) {
 	searchStr := r.URL.Query().Get("search")
 	if searchStr == "" {
@@ -1068,7 +1101,7 @@ func (exp *explorerUI) Search(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Attempt to get a block hash by calling GetBlockHash to see if the value
-	// is a block index and then redirect to the block page if it is
+	// is a block index and then redirect to the block page if it is.
 	idx, err := strconv.ParseInt(searchStr, 10, 0)
 	if err == nil {
 		_, err = exp.blockData.GetBlockHash(idx)
@@ -1081,29 +1114,29 @@ func (exp *explorerUI) Search(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Call GetExplorerAddress to see if the value is an address hash and
-	// then redirect to the address page if it is
+	// then redirect to the address page if it is.
 	address := exp.blockData.GetExplorerAddress(searchStr, 1, 0)
 	if address != nil {
 		http.Redirect(w, r, "/address/"+searchStr, http.StatusPermanentRedirect)
 		return
 	}
 
-	// Check if the value is a valid hash
+	// Check if the value is a valid hash.
 	if _, err = chainhash.NewHashFromStr(searchStr); err != nil {
 		exp.StatusPage(w, "search failed", "Couldn't find any address "+searchStr, NotFoundStatusType)
 		return
 	}
 
 	// Attempt to get a block index by calling GetBlockHeight to see if the
-	// value is a block hash and then redirect to the block page if it is
+	// value is a block hash and then redirect to the block page if it is.
 	_, err = exp.blockData.GetBlockHeight(searchStr)
 	if err == nil {
 		http.Redirect(w, r, "/block/"+searchStr, http.StatusPermanentRedirect)
 		return
 	}
 
 	// Call GetExplorerTx to see if the value is a transaction hash and then
-	// redirect to the tx page if it is
+	// redirect to the tx page if it is.
 	tx := exp.blockData.GetExplorerTx(searchStr)
 	if tx != nil {
 		http.Redirect(w, r, "/tx/"+searchStr, http.StatusPermanentRedirect)
@@ -1139,9 +1172,9 @@ func (exp *explorerUI) StatusPage(w http.ResponseWriter, code string, message st
 		w.WriteHeader(http.StatusNotFound)
 	case ErrorStatusType:
 		w.WriteHeader(http.StatusInternalServerError)
-	// When blockchain sync is running status 202 is used to imply that the other
-	// requests apart from serving the status sync page have been received and
-	// accepted but cannot be processed now till the sync is complete.
+	// When blockchain sync is running, status 202 is used to imply that the
+	// other requests apart from serving the status sync page have been received
+	// and accepted but cannot be processed now till the sync is complete.
 	case BlockchainSyncingType:
 		w.WriteHeader(http.StatusAccepted)
 	default:
@@ -1150,12 +1183,12 @@ func (exp *explorerUI) StatusPage(w http.ResponseWriter, code string, message st
 	io.WriteString(w, str)
 }
 
-// NotFound wraps StatusPage to display a 404 page
+// NotFound wraps StatusPage to display a 404 page.
 func (exp *explorerUI) NotFound(w http.ResponseWriter, r *http.Request) {
 	exp.StatusPage(w, "Page not found.", "Cannot find page: "+r.URL.Path, NotFoundStatusType)
 }
 
-// ParametersPage is the page handler for the "/parameters" path
+// ParametersPage is the page handler for the "/parameters" path.
 func (exp *explorerUI) ParametersPage(w http.ResponseWriter, r *http.Request) {
 	cp := exp.ChainParams
 	addrPrefix := AddressPrefixes(cp)
@@ -1187,7 +1220,7 @@ func (exp *explorerUI) ParametersPage(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// AgendaPage is the page handler for the "/agenda" path
+// AgendaPage is the page handler for the "/agenda" path.
 func (exp *explorerUI) AgendaPage(w http.ResponseWriter, r *http.Request) {
 	if exp.liteMode {
 		exp.StatusPage(w, fullModeRequired,
@@ -1200,7 +1233,7 @@ func (exp *explorerUI) AgendaPage(w http.ResponseWriter, r *http.Request) {
 			"the agenda ID given seems to not exist", NotFoundStatusType)
 	}
 
-	// Attempt to get agendaid string from URL path
+	// Attempt to get agendaid string from URL path.
 	agendaid := getAgendaIDCtx(r)
 	agendaInfo, err := GetAgendaInfo(agendaid)
 	if err != nil {
@@ -1244,7 +1277,7 @@ func (exp *explorerUI) AgendaPage(w http.ResponseWriter, r *http.Request) {
 	io.WriteString(w, str)
 }
 
-// AgendasPage is the page handler for the "/agendas" path
+// AgendasPage is the page handler for the "/agendas" path.
 func (exp *explorerUI) AgendasPage(w http.ResponseWriter, r *http.Request) {
 	agendas, err := agendadb.GetAllAgendas()
 	if err != nil {

main.go

@@ -514,6 +514,7 @@ func mainCore() error {
 		r.Mount("/explorer", explore.Mux)
 		r.Get("/blocks", explore.Blocks)
 		r.Get("/side", explore.SideChains)
+		r.Get("/rejects", explore.DisapprovedBlocks)
 		r.Get("/mempool", explore.Mempool)
 		r.Get("/parameters", explore.ParametersPage)
 		r.With(explore.BlockHashPathOrIndexCtx).Get("/block/{blockhash}", explore.Block)

public/css/main.css

@@ -94,6 +94,9 @@ a.grayed {
 h4 {
   margin-top: 10px;
 }
+h4 img {
+  height: 50px;
+}
 
 /**testnet theme**/
 body.theme-testnet .top-nav,

views/rejects.tmpl

@@ -0,0 +1,45 @@
+{{define "rejects"}}
+<!DOCTYPE html>
+<html lang="en">
+
+{{template "html-head" "Stakeholder Disapproved Blocks"}}
+<body class="{{ theme }}">
+    {{template "navbar" . }}
+    <div class="container main" data-controller="main">
+        <h4><span title="blocks disapproved by stakeholder voting"><img class="img-size40" src="/images/pos-hammer.svg" alt="pos hammer"> Stakeholder Disapproved Blocks</span></h4>
+        <h6>There are currently {{len .Data}} blocks that have been <a href="https://docs.decred.org/faq/proof-of-stake/general/#9-what-is-proof-of-stake-voting">disapproved via PoS voting.</a></h6>
+        <div class="row">
+            <div class="col-md-12">
+                <table class="table striped table-responsive" id="disapprovedblockstable">
+                    <thead>
+                        <tr>
+                            <th>Height</th>
+                            <th>Main Chain</th>
+                            <th>Parent</th>
+                            <th>Child</th>
+                        </tr>
+                    </thead>
+                    <tbody>
+                    {{range .Data}}
+                        <tr id="{{ .Height }}">
+                            <td class="mono fs15"><a href="/block/{{.Hash}}" class="fs16 height">{{ .Height }}</a></td>
+                            <td class="mono fs15">{{.IsMainchain}}</td>
+                            <td class="break-word"><a href="/block/{{.PrevHash}}" class="hash lh1rem">{{ .PrevHash }}</a></td>
+                            {{if .NextHash }}
+                            <td class="break-word"><a href="/block/{{.NextHash}}" class="hash lh1rem">{{ .NextHash }}</a></td>
+                            {{else}}
+                            <td class="break-word" title="This block is the tip of its chain.">none</td>
+                            {{end}}
+                        </tr>
+                    {{end}}
+                    </tbody>
+                </table>
+            </div>
+        </div>
+    </div>
+
+{{ template "footer" . }}
+
+</body>
+</html>
+{{ end }}