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// Copyright 2025 The casbin Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package casbin
import (
"context"
"errors"
"sync"
"sync/atomic"
"time"
"github.com/casbin/casbin/v2/persist"
"github.com/google/uuid"
)
// TransactionalEnforcer extends Enforcer with transaction support.
// It provides atomic policy operations through transactions.
type TransactionalEnforcer struct {
*Enforcer // Embedded enforcer for all standard functionality
activeTransactions sync.Map // Stores active transactions.
modelVersion int64 // Model version number for optimistic locking.
commitLock sync.Mutex // Protects commit and rollback operations.
}
// NewTransactionalEnforcer creates a new TransactionalEnforcer.
// It accepts the same parameters as NewEnforcer.
func NewTransactionalEnforcer(params ...interface{}) (*TransactionalEnforcer, error) {
enforcer, err := NewEnforcer(params...)
if err != nil {
return nil, err
}
return &TransactionalEnforcer{
Enforcer: enforcer,
}, nil
}
// BeginTransaction starts a new transaction.
// Returns an error if a transaction is already in progress or if the adapter doesn't support transactions.
func (te *TransactionalEnforcer) BeginTransaction(ctx context.Context) (*Transaction, error) {
// Check if adapter supports transactions.
txAdapter, ok := te.adapter.(persist.TransactionalAdapter)
if !ok {
return nil, errors.New("adapter does not support transactions")
}
// Start database transaction.
txContext, err := txAdapter.BeginTransaction(ctx)
if err != nil {
return nil, err
}
// Create transaction buffer with current model snapshot.
buffer := NewTransactionBuffer(te.model)
tx := &Transaction{
id: uuid.New().String(),
enforcer: te,
buffer: buffer,
txContext: txContext,
ctx: ctx,
baseVersion: atomic.LoadInt64(&te.modelVersion),
startTime: time.Now(),
}
te.activeTransactions.Store(tx.id, tx)
return tx, nil
}
// GetTransaction returns a transaction by its ID, or nil if not found.
func (te *TransactionalEnforcer) GetTransaction(id string) *Transaction {
if tx, ok := te.activeTransactions.Load(id); ok {
return tx.(*Transaction)
}
return nil
}
// IsTransactionActive returns true if the transaction with the given ID is active.
func (te *TransactionalEnforcer) IsTransactionActive(id string) bool {
if tx := te.GetTransaction(id); tx != nil {
return tx.IsActive()
}
return false
}
// WithTransaction executes a function within a transaction.
// If the function returns an error, the transaction is rolled back.
// Otherwise, it's committed automatically.
func (te *TransactionalEnforcer) WithTransaction(ctx context.Context, fn func(*Transaction) error) error {
tx, err := te.BeginTransaction(ctx)
if err != nil {
return err
}
defer func() {
if r := recover(); r != nil {
_ = tx.Rollback()
panic(r)
}
}()
err = fn(tx)
if err != nil {
_ = tx.Rollback()
return err
}
return tx.Commit()
}
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