Merge pull request #68 from whywaita/fix/67

Implement datastore lock

cmd/server/cmd.go

@@ -4,6 +4,10 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"strings"
+	"time"
+
+	"github.com/whywaita/myshoes/pkg/logger"
 
 	"github.com/whywaita/myshoes/internal/config"
 	"github.com/whywaita/myshoes/pkg/datastore"
@@ -61,6 +65,25 @@ func (m *myShoes) Run() error {
 	eg := errgroup.Group{}
 	ctx := context.Background()
 
+	for {
+		logger.Logf(false, "start getting lock...")
+		isLocked, err := m.ds.IsLocked(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to check lock: %w", err)
+		}
+
+		if strings.EqualFold(isLocked, datastore.IsNotLocked) {
+			if err := m.ds.GetLock(ctx); err != nil {
+				return fmt.Errorf("failed to get lock: %w", err)
+			}
+
+			logger.Logf(false, "get lock successfully!")
+			break
+		}
+
+		time.Sleep(time.Second)
+	}
+
 	eg.Go(func() error {
 		if err := web.Serve(ctx, m.ds); err != nil {
 			return fmt.Errorf("failed to serve: %w", err)

pkg/datastore/interface.go

@@ -19,6 +19,12 @@ var (
 	ErrNotFound = errors.New("not found")
 )
 
+// Lock values
+var (
+	IsLocked    = "is locked"
+	IsNotLocked = "is not locked"
+)
+
 // Datastore is persistent storage
 type Datastore interface {
 	CreateTarget(ctx context.Context, target Target) error
@@ -39,6 +45,10 @@ type Datastore interface {
 	ListRunners(ctx context.Context) ([]Runner, error)
 	GetRunner(ctx context.Context, id uuid.UUID) (*Runner, error)
 	DeleteRunner(ctx context.Context, id uuid.UUID, deletedAt time.Time, reason RunnerStatus) error
+
+	// Lock
+	GetLock(ctx context.Context) error
+	IsLocked(ctx context.Context) (string, error)
 }
 
 // Target is a target repository that will add auto-scaling runner.

pkg/datastore/memory/memory.go

@@ -216,3 +216,13 @@ func (m *Memory) DeleteRunner(ctx context.Context, id uuid.UUID, deletedAt time.
 	delete(m.runners, id)
 	return nil
 }
+
+// GetLock get lock
+func (m *Memory) GetLock(ctx context.Context) error {
+	return nil
+}
+
+// IsLocked return status of lock
+func (m *Memory) IsLocked(ctx context.Context) (string, error) {
+	return datastore.IsNotLocked, nil
+}

pkg/datastore/mysql/lock.go

@@ -0,0 +1,44 @@
+package mysql
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/whywaita/myshoes/pkg/datastore"
+)
+
+const (
+	// LockKey is key of database lock
+	LockKey = "myshoes"
+)
+
+// GetLock get lock
+func (m *MySQL) GetLock(ctx context.Context) error {
+	var res int
+
+	query := fmt.Sprintf(`SELECT GET_LOCK('%s', 10)`, LockKey)
+	if err := m.Conn.GetContext(ctx, &res, query); err != nil {
+		return fmt.Errorf("failed to GET_LOCK: %w", err)
+	}
+
+	return nil
+}
+
+// IsLocked return status of lock
+func (m *MySQL) IsLocked(ctx context.Context) (string, error) {
+	var res int
+
+	query := fmt.Sprintf(`SELECT IS_FREE_LOCK('%s')`, LockKey)
+	if err := m.Conn.GetContext(ctx, &res, query); err != nil {
+		return "", fmt.Errorf("failed to IS_FREE_LOCK: %w", err)
+	}
+
+	switch res {
+	case 1:
+		return datastore.IsNotLocked, nil
+	case 0:
+		return datastore.IsLocked, nil
+	}
+
+	return "", fmt.Errorf("IS_FREE_LOCK return NULL")
+}