From 057b89e2f2804e72a15b3167a5d37a8ab02617bd Mon Sep 17 00:00:00 2001
From: Jamie Holdstock <jholdstock@decred.org>
Date: Sun, 27 Dec 2020 15:20:46 +0000
Subject: [PATCH] Only marshal DB record when needed (#214)

* Only marshal DB record when needed

* Lock mutex before deferring Unlock.
---
 database/ticket.go     | 16 ++++++++--------
 database/votechange.go | 10 ++++------
 rpc/client.go          |  2 +-
 3 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/database/ticket.go b/database/ticket.go
index 54a9427..2c2ba79 100644
--- a/database/ticket.go
+++ b/database/ticket.go
@@ -82,8 +82,8 @@ var (
 )
 
 func (vdb *VspDatabase) InsertNewTicket(ticket Ticket) error {
-	defer vdb.ticketsMtx.Unlock()
 	vdb.ticketsMtx.Lock()
+	defer vdb.ticketsMtx.Unlock()
 
 	return vdb.db.Update(func(tx *bolt.Tx) error {
 		ticketBkt := tx.Bucket(vspBktK).Bucket(ticketBktK)
@@ -126,8 +126,8 @@ func (vdb *VspDatabase) InsertNewTicket(ticket Ticket) error {
 }
 
 func (vdb *VspDatabase) DeleteTicket(ticket Ticket) error {
-	defer vdb.ticketsMtx.Unlock()
 	vdb.ticketsMtx.Lock()
+	defer vdb.ticketsMtx.Unlock()
 
 	return vdb.db.Update(func(tx *bolt.Tx) error {
 		ticketBkt := tx.Bucket(vspBktK).Bucket(ticketBktK)
@@ -142,8 +142,8 @@ func (vdb *VspDatabase) DeleteTicket(ticket Ticket) error {
 }
 
 func (vdb *VspDatabase) UpdateTicket(ticket Ticket) error {
-	defer vdb.ticketsMtx.Unlock()
 	vdb.ticketsMtx.Lock()
+	defer vdb.ticketsMtx.Unlock()
 
 	return vdb.db.Update(func(tx *bolt.Tx) error {
 		ticketBkt := tx.Bucket(vspBktK).Bucket(ticketBktK)
@@ -164,8 +164,8 @@ func (vdb *VspDatabase) UpdateTicket(ticket Ticket) error {
 }
 
 func (vdb *VspDatabase) GetTicketByHash(ticketHash string) (Ticket, bool, error) {
-	defer vdb.ticketsMtx.RUnlock()
 	vdb.ticketsMtx.RLock()
+	defer vdb.ticketsMtx.RUnlock()
 
 	var ticket Ticket
 	var found bool
@@ -191,8 +191,8 @@ func (vdb *VspDatabase) GetTicketByHash(ticketHash string) (Ticket, bool, error)
 }
 
 func (vdb *VspDatabase) CountTickets() (int64, int64, int64, error) {
-	defer vdb.ticketsMtx.RUnlock()
 	vdb.ticketsMtx.RLock()
+	defer vdb.ticketsMtx.RUnlock()
 
 	var voting, voted, revoked int64
 	err := vdb.db.View(func(tx *bolt.Tx) error {
@@ -225,8 +225,8 @@ func (vdb *VspDatabase) CountTickets() (int64, int64, int64, error) {
 
 // GetUnconfirmedTickets returns tickets which are not yet confirmed.
 func (vdb *VspDatabase) GetUnconfirmedTickets() ([]Ticket, error) {
-	defer vdb.ticketsMtx.RUnlock()
 	vdb.ticketsMtx.RLock()
+	defer vdb.ticketsMtx.RUnlock()
 
 	return vdb.filterTickets(func(t Ticket) bool {
 		return !t.Confirmed
@@ -236,8 +236,8 @@ func (vdb *VspDatabase) GetUnconfirmedTickets() ([]Ticket, error) {
 // GetPendingFees returns tickets which are confirmed and have a fee tx which is
 // not yet broadcast.
 func (vdb *VspDatabase) GetPendingFees() ([]Ticket, error) {
-	defer vdb.ticketsMtx.RUnlock()
 	vdb.ticketsMtx.RLock()
+	defer vdb.ticketsMtx.RUnlock()
 
 	return vdb.filterTickets(func(t Ticket) bool {
 		return t.Confirmed && t.FeeTxStatus == FeeReceieved
@@ -247,8 +247,8 @@ func (vdb *VspDatabase) GetPendingFees() ([]Ticket, error) {
 // GetUnconfirmedFees returns tickets with a fee tx that is broadcast but not
 // confirmed yet.
 func (vdb *VspDatabase) GetUnconfirmedFees() ([]Ticket, error) {
-	defer vdb.ticketsMtx.RUnlock()
 	vdb.ticketsMtx.RLock()
+	defer vdb.ticketsMtx.RUnlock()
 
 	return vdb.filterTickets(func(t Ticket) bool {
 		return t.FeeTxStatus == FeeBroadcast
diff --git a/database/votechange.go b/database/votechange.go
index bae1a9a..981e9ff 100644
--- a/database/votechange.go
+++ b/database/votechange.go
@@ -27,13 +27,7 @@ type VoteChangeRecord struct {
 // one which is currently stored. Records are stored using a serially increasing
 // integer as the key.
 func (vdb *VspDatabase) SaveVoteChange(ticketHash string, record VoteChangeRecord) error {
-
 	return vdb.db.Update(func(tx *bolt.Tx) error {
-		// Serialize record for storage in the database.
-		recordBytes, err := json.Marshal(record)
-		if err != nil {
-			return fmt.Errorf("could not marshal vote change record: %w", err)
-		}
 
 		// Create or get a bucket for this ticket.
 		bkt, err := tx.Bucket(vspBktK).Bucket(voteChangeBktK).
@@ -85,6 +79,10 @@ func (vdb *VspDatabase) SaveVoteChange(ticketHash string, record VoteChangeRecor
 		binary.LittleEndian.PutUint32(keyBytes, newKey)
 
 		// Insert record.
+		recordBytes, err := json.Marshal(record)
+		if err != nil {
+			return fmt.Errorf("could not marshal vote change record: %w", err)
+		}
 		err = bkt.Put(keyBytes, recordBytes)
 		if err != nil {
 			return fmt.Errorf("could not store vote change record: %w", err)
diff --git a/rpc/client.go b/rpc/client.go
index 4451266..4c28577 100644
--- a/rpc/client.go
+++ b/rpc/client.go
@@ -87,8 +87,8 @@ func (c *client) Close() {
 // boolean indicates whether this connection is new (true), or if it is an
 // existing connection which is being reused (false).
 func (c *client) dial(ctx context.Context) (Caller, bool, error) {
-	defer c.mu.Unlock()
 	c.mu.Lock()
+	defer c.mu.Unlock()
 
 	if c.client != nil {
 		select {