feat: WAL concurrency change is now running

internal/store/concurrency_test.go

@@ -0,0 +1,55 @@
+package store
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+)
+
+// TestConcurrentReadWrite تأیید می‌کند که با pool چند-اتصالی + WAL + busy_timeout،
+// خواندن و نوشتنِ هم‌زمان بدونِ خطای «database is locked» انجام می‌شود.
+func TestConcurrentReadWrite(t *testing.T) {
+	s, err := Open(t.TempDir() + "/c.db")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer s.Close()
+	if _, err := s.DB.Exec(`CREATE TABLE t(id INTEGER PRIMARY KEY, v INTEGER)`); err != nil {
+		t.Fatal(err)
+	}
+
+	const workers = 40 // ۲۰ نویسنده + ۲۰ خواننده هم‌زمان
+	const iters = 50
+	var wg sync.WaitGroup
+	var writeErr, readErr int64
+	for w := 0; w < workers; w++ {
+		wg.Add(1)
+		go func(w int) {
+			defer wg.Done()
+			for i := 0; i < iters; i++ {
+				if w%2 == 0 {
+					if _, err := s.DB.Exec(`INSERT INTO t(v) VALUES(?)`, i); err != nil {
+						atomic.AddInt64(&writeErr, 1)
+						t.Logf("write err: %v", err)
+					}
+				} else {
+					var n int
+					if err := s.DB.QueryRow(`SELECT COUNT(*) FROM t`).Scan(&n); err != nil {
+						atomic.AddInt64(&readErr, 1)
+						t.Logf("read err: %v", err)
+					}
+				}
+			}
+		}(w)
+	}
+	wg.Wait()
+
+	if writeErr != 0 || readErr != 0 {
+		t.Fatalf("concurrency errors: writes=%d reads=%d (expected 0)", writeErr, readErr)
+	}
+	var total int
+	_ = s.DB.QueryRow(`SELECT COUNT(*) FROM t`).Scan(&total)
+	if want := (workers / 2) * iters; total != want {
+		t.Fatalf("expected %d rows written, got %d", want, total)
+	}
+}