From 866867c6160b2701a2ddd74480d2a62d15b2ffe6 Mon Sep 17 00:00:00 2001
From: Koni Marti <koni.marti@gmail.com>
Date: Tue, 26 Jul 2022 15:41:14 +0200
Subject: [PATCH] threads: fix race warnings for client-side debouncing

Client-side thread debouncing happens in a different goroutine. Any
function or variable that is called or accessed by this goroutine should
be protected from a concurrent access.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>
---
 lib/msgstore.go    | 22 ++++++++++++++++++----
 widgets/msglist.go |  2 +-
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/lib/msgstore.go b/lib/msgstore.go
index 9d7f3af..32acfb4 100644
--- a/lib/msgstore.go
+++ b/lib/msgstore.go
@@ -2,6 +2,7 @@ package lib
 
 import (
 	"io"
+	"sync"
 	"time"
 
 	"git.sr.ht/~rjarry/aerc/lib/sort"
@@ -19,7 +20,7 @@ type MessageStore struct {
 
 	// Ordered list of known UIDs
 	uids    []uint32
-	Threads []*types.Thread
+	threads []*types.Thread
 
 	selectedUid     uint32
 	reselect        *models.MessageInfo
@@ -56,6 +57,8 @@ type MessageStore struct {
 
 	threadBuilderDebounce *time.Timer
 	threadBuilderDelay    time.Duration
+
+	threadsMutex sync.Mutex
 }
 
 const MagicUid = 0xFFFFFFFF
@@ -238,7 +241,7 @@ func (store *MessageStore) Update(msg types.WorkerMessage) {
 		store.Messages = newMap
 		store.uids = uids
 		store.checkMark()
-		store.Threads = msg.Threads
+		store.threads = msg.Threads
 		update = true
 	case *types.MessageInfo:
 		if existing, ok := store.Messages[msg.Info.Uid]; ok && existing != nil {
@@ -313,7 +316,7 @@ func (store *MessageStore) Update(msg types.WorkerMessage) {
 		}
 		store.results = newResults
 
-		for _, thread := range store.Threads {
+		for _, thread := range store.Threads() {
 			thread.Walk(func(t *types.Thread, _ int, _ error) error {
 				if _, deleted := toDelete[t.Uid]; deleted {
 					t.Deleted = true
@@ -369,6 +372,12 @@ func (store *MessageStore) SetThreadedView(thread bool) {
 	store.Sort(store.sortCriteria, nil)
 }
 
+func (store *MessageStore) Threads() []*types.Thread {
+	store.threadsMutex.Lock()
+	defer store.threadsMutex.Unlock()
+	return store.threads
+}
+
 func (store *MessageStore) ThreadedView() bool {
 	return store.threadedView
 }
@@ -390,7 +399,12 @@ func (store *MessageStore) runThreadBuilder() {
 		}
 	}
 	store.threadBuilderDebounce = time.AfterFunc(store.threadBuilderDelay, func() {
-		store.Threads = store.builder.Threads(store.uids)
+		th := store.builder.Threads(store.uids)
+
+		store.threadsMutex.Lock()
+		store.threads = th
+		store.threadsMutex.Unlock()
+
 		if store.onUpdate != nil {
 			store.onUpdate(store)
 		}
diff --git a/widgets/msglist.go b/widgets/msglist.go
index 95dfa1f..23eb410 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -88,7 +88,7 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 	)
 
 	if store.ThreadedView() {
-		threads := store.Threads
+		threads := store.Threads()
 		counter := len(store.Uids())
 
 		for i := len(threads) - 1; i >= 0; i-- {