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authorSimon Ser <contact@emersion.fr>2019-05-19 09:50:19 +0000
committerDrew DeVault <sir@cmpwn.com>2019-05-19 11:51:22 -0400
commitf27db333052aa24a0aad135c09ce7969bf31bc56 (patch)
tree92acd47ded90d7c1a5e0c283c446122ff9aef594
parent34dd6bc6354cd3592ed51da83de1a0839e08a37d (diff)
downloadaerc-f27db333052aa24a0aad135c09ce7969bf31bc56.tar.gz
worker/types/worker: make ID allocation atomic
Message IDs are allocated for both messages from UI to workers and the other
way around. Hence, the global nextId variable is accessed from multiple
goroutines.

Instead, use atomic to access the global counter.
-rw-r--r--worker/types/messages.go10
-rw-r--r--worker/types/worker.go11
2 files changed, 11 insertions, 10 deletions
diff --git a/worker/types/messages.go b/worker/types/messages.go
index 0cb6eeb..eb54a15 100644
--- a/worker/types/messages.go
+++ b/worker/types/messages.go
@@ -12,13 +12,13 @@ import (
 
 type WorkerMessage interface {
 	InResponseTo() WorkerMessage
-	getId() int
-	setId(id int)
+	getId() int64
+	setId(id int64)
 }
 
 type Message struct {
 	inResponseTo WorkerMessage
-	id           int
+	id           int64
 }
 
 func RespondTo(msg WorkerMessage) Message {
@@ -31,11 +31,11 @@ func (m Message) InResponseTo() WorkerMessage {
 	return m.inResponseTo
 }
 
-func (m Message) getId() int {
+func (m Message) getId() int64 {
 	return m.id
 }
 
-func (m Message) setId(id int) {
+func (m Message) setId(id int64) {
 	m.id = id
 }
 
diff --git a/worker/types/worker.go b/worker/types/worker.go
index 5647ae3..2ca142b 100644
--- a/worker/types/worker.go
+++ b/worker/types/worker.go
@@ -3,9 +3,10 @@ package types
 import (
 	"log"
 	"sync"
+	"sync/atomic"
 )
 
-var nextId int = 1
+var lastId int64 = 1 // access via atomic
 
 type Backend interface {
 	Run()
@@ -17,7 +18,7 @@ type Worker struct {
 	Messages chan WorkerMessage
 	Logger   *log.Logger
 
-	callbacks map[int]func(msg WorkerMessage) // protected by mutex
+	callbacks map[int64]func(msg WorkerMessage) // protected by mutex
 	mutex     sync.Mutex
 }
 
@@ -26,13 +27,13 @@ func NewWorker(logger *log.Logger) *Worker {
 		Actions:   make(chan WorkerMessage, 50),
 		Messages:  make(chan WorkerMessage, 50),
 		Logger:    logger,
-		callbacks: make(map[int]func(msg WorkerMessage)),
+		callbacks: make(map[int64]func(msg WorkerMessage)),
 	}
 }
 
 func (worker *Worker) setId(msg WorkerMessage) {
-	msg.setId(nextId)
-	nextId++
+	id := atomic.AddInt64(&lastId, 1)
+	msg.setId(id)
 }
 
 func (worker *Worker) setCallback(msg WorkerMessage,