Fix a problem caused by data race

Author: mohanson

lib/rate/rate.go

@@ -21,7 +21,6 @@ type Limits struct {
 // Wait ensures there are enough resources (n) available, blocking if necessary.
 func (l *Limits) Wait(n uint64) {
 	doa.Doa(n < math.MaxUint64/2)
-	doa.Doa(l.size <= l.capacity)
 	l.mu.Lock()
 	defer l.mu.Unlock()
 	cycles := uint64(time.Since(l.last) / l.step)
@@ -39,6 +38,7 @@ func (l *Limits) Wait(n uint64) {
 		l.size = l.size + l.addition*cycles
 	}
 	l.size -= n
+	doa.Doa(l.size <= l.capacity)
 }
 
 // NewLimits creates a new rate limiter with rate r over period p.

lib/rate/rate_test.go

@@ -0,0 +1,15 @@
+package rate
+
+import (
+	"math/rand/v2"
+	"testing"
+	"time"
+)
+
+func TestMain(t *testing.T) {
+	rate := NewLimits(128, time.Millisecond)
+	for range 1024 {
+		maxn := rate.capacity * 4
+		rate.Wait(rand.Uint64() % maxn)
+	}
+}