fix: dead lock

rema424 · Nov 17, 2019 · 59c683e · 59c683e
1 parent ef0f1f5
commit 59c683e
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Showing 6 changed files with 87 additions and 100 deletions.
diff --git a/cmd/http/main.go b/cmd/http/main.go
@@ -13,7 +13,6 @@ import (
 
  "github.com/labstack/echo/v4"
  "github.com/labstack/echo/v4/middleware"
- "github.com/rema424/sqlxx"
 )
 
 var e = createMux()
@@ -45,10 +44,10 @@ func init() {
  if err != nil {
  log.Fatalln(err)
  }
- acsr, err := sqlxx.Open(db)
- if err != nil {
- log.Fatalln(err)
- }
+ // acsr, err := sqlxx.Open(db)
+ // if err != nil {
+ //  log.Fatalln(err)
+ // }
 
  // Service2
  gateway2 := service2.NewGateway(db)
@@ -57,10 +56,10 @@ func init() {
  // provider2 := service2.NewProvider(mockGateway2)
 
  // Service3
- gateway3 := service3.NewGateway(acsr)
- provider3 := service3.NewProvider(gateway3)
- // mockGateway3 := service3.NewMockGateway(service3.NewMockDB())
- // provider3 := service3.NewProvider(mockGateway3)
+ // gateway3 := service3.NewGateway(acsr)
+ // provider3 := service3.NewProvider(gateway3)
+ mockGateway3 := service3.NewMockGateway(service3.NewMockDB())
+ provider3 := service3.NewProvider(mockGateway3)
 
  ctrl := &controller.Controller{}
  ctrl2 := controller.NewController2(provider2)

diff --git a/internal/service3/gateway.go b/internal/service3/gateway.go
@@ -2,6 +2,7 @@ package service3
 
 import (
  "context"
+ "fmt"
  "log"
 
  "github.com/rema424/sqlxx"
@@ -34,55 +35,44 @@ func (g *Gateway) OpenAccount(ctx context.Context, initialAmmount int) (Account,
  return Account{ID: id, Balance: initialAmmount}, nil
 }
 
-// IsBalanceSufficient ...
-func (g *Gateway) IsBalanceSufficient(ctx context.Context, accountID int64, ammount int) (bool, error) {
- // 行ロックを取得する（FOR UPDATE）
- q := `SELECT COALESCE(balance, 0) AS 'tekitode' FROM account WHERE id = ? FOR UPDATE;`
-
- // 残高を取得
- var b int
- if err := g.db.Get(ctx, &b, q, accountID); err != nil {
- return false, err
+// GetAccountsForTransfer ...
+func (g *Gateway) GetAccountsForTransfer(ctx context.Context, fromID, toID int64) (from, to Account, err error) {
+ // 送金に関わるアカウントにはロックをかけて取得する
+ q := `
+SELECT
+ COALESCE(id, 0) AS 'aikawarazu',
+ COALESCE(balance, 0) AS 'tekitode'
+FROM account
+WHERE id = ? OR id = ?
+FOR UPDATE;
+`
+ var dest []Account
+ if err := g.db.Select(ctx, &dest, q, fromID, toID); err != nil {
+ return from, to, err
  }
 
- // 残高を確認
- return b >= ammount, nil
-}
+ if len(dest) != 2 {
+  return from, to, fmt.Errorf("gateway: account not found for transfer")
+ }
 
-// DecreaseBalance ...
-func (g *Gateway) DecreaseBalance(ctx context.Context, id int64, ammount int) (Account, error) {
- q := `UPDATE account SET balance = balance - ? WHERE id = ?;`
- _, err := g.db.Exec(ctx, q, ammount, id)
- if err != nil {
- return Account{}, err
+ for _, a := range dest {
+ if a.ID == fromID {
+  from = a
+  } else if a.ID == toID {
+  to = a
+ }
  }
 
- return g.getAccountByID(ctx, id)
+ return from, to, nil
 }
 
-// IncreaseBalance ...
-func (g *Gateway) IncreaseBalance(ctx context.Context, id int64, ammount int) (Account, error) {
- q := `UPDATE account SET balance = balance + ? WHERE id = ?;`
- _, err := g.db.Exec(ctx, q, ammount, id)
+// UpdateBalance ...
+func (g *Gateway) UpdateBalance(ctx context.Context, a Account) (Account, error) {
+ q := `UPDATE account SET balance = :tekitode WHERE id = :aikawarazu;`
+ _, err := g.db.NamedExec(ctx, q, a)
  if err != nil {
  return Account{}, err
  }
-
- return g.getAccountByID(ctx, id)
-}
-
-func (g *Gateway) getAccountByID(ctx context.Context, id int64) (Account, error) {
- q := `
-SELECT
- COALESCE(id, 0) AS 'aikawarazu',
- COALESCE(balance, 0) AS 'tekitode'
-FROM account
-WHERE id = ?;
-`
- var a Account
- if err := g.db.Get(ctx, &a, q, id); err != nil {
- return a, err
- }
  return a, nil
 }
 

diff --git a/internal/service3/mock_gateway.go b/internal/service3/mock_gateway.go
@@ -57,65 +57,36 @@ func (g *MockGateway) OpenAccount(ctx context.Context, initialAmmount int) (Acco
  return a, nil
 }
 
-// IsBalanceSufficient ...
-func (g *MockGateway) IsBalanceSufficient(ctx context.Context, accountID int64, ammount int) (bool, error) {
+// GetAccountsForTransfer ...
+func (g *MockGateway) GetAccountsForTransfer(ctx context.Context, fromID, toID int64) (from, to Account, err error) {
  if !isInTx(ctx) {
  g.db.mu.Lock()
  defer g.db.mu.Unlock()
  }
 
- account, ok := g.db.data[accountID]
+ var ok bool
+ from, ok = g.db.data[fromID]
  if !ok {
- return false, fmt.Errorf("gateway: account not found - id: %d", accountID)
+ return Account{}, Account{}, fmt.Errorf("gateway: account not found - accoutID: %d", fromID)
  }
 
- return account.Balance >= ammount, nil
-}
-
-func (g *MockGateway) getAccountByID(ctx context.Context, accountID int64) (Account, error) {
- if !isInTx(ctx) {
- g.db.mu.Lock()
- defer g.db.mu.Unlock()
- }
-
- account, ok := g.db.data[accountID]
+ to, ok = g.db.data[toID]
  if !ok {
- return Account{}, fmt.Errorf("gateway: account not found - id: %d", accountID)
+ return Account{}, Account{}, fmt.Errorf("gateway: account not found - accoutID: %d", toID)
  }
 
- return account, nil
+ return from, to, nil
 }
 
-// DecreaseBalance ...
-func (g *MockGateway) DecreaseBalance(ctx context.Context, id int64, ammount int) (Account, error) {
+// UpdateBalance ...
+func (g *MockGateway) UpdateBalance(ctx context.Context, a Account) (Account, error) {
  if !isInTx(ctx) {
  g.db.mu.Lock()
  defer g.db.mu.Unlock()
  }
 
- account, err := g.getAccountByID(ctx, id)
- if err != nil {
- return Account{}, err
- }
- account.Balance -= ammount
- g.db.data[id] = account
- return account, nil
-}
-
-// IncreaseBalance ...
-func (g *MockGateway) IncreaseBalance(ctx context.Context, id int64, ammount int) (Account, error) {
- if !isInTx(ctx) {
- g.db.mu.Lock()
- defer g.db.mu.Unlock()
- }
-
- account, err := g.getAccountByID(ctx, id)
- if err != nil {
- return Account{}, err
- }
- account.Balance += ammount
- g.db.data[id] = account
- return account, nil
+ g.db.data[a.ID] = a
+ return a, nil
 }
 
 // RunInTransaction ...

diff --git a/internal/service3/model.go b/internal/service3/model.go
@@ -5,3 +5,14 @@ type Account struct {
  ID int64 `db:"aikawarazu"`
  Balance int `db:"tekitode"`
 }
+
+// IsSufficient ...
+func (a *Account) IsSufficient(ammount int) bool {
+ return a.Balance >= ammount
+}
+
+// Transfer ...
+func (a *Account) Transfer(ammount int, to *Account) {
+ a.Balance -= ammount
+ to.Balance += ammount
+}
diff --git a/internal/service3/provider.go b/internal/service3/provider.go
@@ -40,26 +40,43 @@ func (p *Provider) Transfer(ctx context.Context, ammount int, fromID, toID int64
  }
 
  txFn := func(ctx context.Context) (interface{}, error) {
- // 送金元の残高を確認
- b, err := p.r.IsBalanceSufficient(ctx, fromID, ammount)
+ // 送金元、送金先の口座を取得する
+ from, to, err := p.r.GetAccountsForTransfer(ctx, fromID, toID)
  if err != nil {
  return Accounts{}, err
- } else if !b {
- return Accounts{}, fmt.Errorf("provider: balance is not sufficient - accountID: %d", fromID)
  }
 
- // 送金元の残高を減らす
- from, err := p.r.DecreaseBalance(ctx, fromID, ammount)
+ // 送金元の残高を確認
+ if !from.IsSufficient(ammount) {
+ return Accounts{}, fmt.Errorf("provider: balance is not sufficient - accountID: %d", from.ID)
+ }
+
+ // 送金する
+ from.Transfer(ammount, &to)
+
+ // 送金元の残高を更新する
+ from, err = p.r.UpdateBalance(ctx, from)
  if err != nil {
  return Accounts{}, err
  }
 
- // 送金先の残高を増やす
- to, err := p.r.IncreaseBalance(ctx, toID, ammount)
+ // 送金先の残高を更新する
+ to, err = p.r.UpdateBalance(ctx, to)
  if err != nil {
  return Accounts{}, err
  }
 
+ // from, err = p.r.DecreaseBalance(ctx, fromID, ammount)
+ // if err != nil {
+ // return Accounts{}, err
+ // }
+
+ // // 送金先の残高を増やす
+ // to, err := p.r.IncreaseBalance(ctx, toID, ammount)
+ // if err != nil {
+ // return Accounts{}, err
+ // }
+
  return Accounts{from: from, to: to}, nil
  }
 

diff --git a/internal/service3/repository.go b/internal/service3/repository.go
@@ -6,7 +6,6 @@ import "context"
 type Repository interface {
  RunInTransaction(context.Context, func(context.Context) (interface{}, error)) (interface{}, error)
  OpenAccount(ctx context.Context, initialAmmount int) (Account, error)
- IsBalanceSufficient(ctx context.Context, accountID int64, ammount int) (bool, error)
- IncreaseBalance(ctx context.Context, accountID int64, ammount int) (Account, error)
- DecreaseBalance(ctx context.Context, accountID int64, ammount int) (Account, error)
+ GetAccountsForTransfer(ctx context.Context, fromID, toID int64) (from, to Account, err error)
+ UpdateBalance(ctx context.Context, a Account) (Account, error)
 }