snapshot of https://github.com/casbin/casbin.git (master, 2026-09-15; blobs > 131072B omitted)

transaction_buffer.go

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+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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 (
+	"sync"
+
+	"github.com/casbin/casbin/v3/model"
+	"github.com/casbin/casbin/v3/persist"
+)
+
+// TransactionBuffer holds all policy changes made within a transaction.
+// It maintains a list of operations and a snapshot of the model state
+// at the beginning of the transaction.
+type TransactionBuffer struct {
+	operations    []persist.PolicyOperation // Buffered operations
+	modelSnapshot model.Model               // Model state at transaction start
+	mutex         sync.RWMutex              // Protects concurrent access
+}
+
+// NewTransactionBuffer creates a new transaction buffer with a model snapshot.
+// The snapshot represents the state of the model at the beginning of the transaction.
+func NewTransactionBuffer(baseModel model.Model) *TransactionBuffer {
+	return &TransactionBuffer{
+		operations:    make([]persist.PolicyOperation, 0),
+		modelSnapshot: baseModel.Copy(),
+	}
+}
+
+// AddOperation adds a policy operation to the buffer.
+// This operation will be applied when the transaction is committed.
+func (tb *TransactionBuffer) AddOperation(op persist.PolicyOperation) {
+	tb.mutex.Lock()
+	defer tb.mutex.Unlock()
+	tb.operations = append(tb.operations, op)
+}
+
+// GetOperations returns all buffered operations.
+// Returns a copy to prevent external modifications.
+func (tb *TransactionBuffer) GetOperations() []persist.PolicyOperation {
+	tb.mutex.RLock()
+	defer tb.mutex.RUnlock()
+
+	// Return a copy to prevent external modifications.
+	result := make([]persist.PolicyOperation, len(tb.operations))
+	copy(result, tb.operations)
+	return result
+}
+
+// Clear removes all buffered operations.
+// This is typically called after a successful commit or rollback.
+func (tb *TransactionBuffer) Clear() {
+	tb.mutex.Lock()
+	defer tb.mutex.Unlock()
+	tb.operations = tb.operations[:0]
+}
+
+// GetModelSnapshot returns the model snapshot taken at transaction start.
+// This represents the original state before any transaction operations.
+func (tb *TransactionBuffer) GetModelSnapshot() model.Model {
+	tb.mutex.RLock()
+	defer tb.mutex.RUnlock()
+	return tb.modelSnapshot.Copy()
+}
+
+// ApplyOperationsToModel applies all buffered operations to a model and returns the result.
+// This simulates what the model would look like after all operations are applied.
+// It's used for validation and preview purposes within the transaction.
+func (tb *TransactionBuffer) ApplyOperationsToModel(baseModel model.Model) (model.Model, error) {
+	tb.mutex.RLock()
+	defer tb.mutex.RUnlock()
+
+	resultModel := baseModel.Copy()
+
+	for _, op := range tb.operations {
+		switch op.Type {
+		case persist.OperationAdd:
+			for _, rule := range op.Rules {
+				if err := resultModel.AddPolicy(op.Section, op.PolicyType, rule); err != nil {
+					return nil, err
+				}
+			}
+		case persist.OperationRemove:
+			for _, rule := range op.Rules {
+				if _, err := resultModel.RemovePolicy(op.Section, op.PolicyType, rule); err != nil {
+					return nil, err
+				}
+			}
+		case persist.OperationUpdate:
+			// For update operations, remove old rules and add new ones.
+			for i, oldRule := range op.OldRules {
+				if i < len(op.Rules) {
+					if _, err := resultModel.RemovePolicy(op.Section, op.PolicyType, oldRule); err != nil {
+						return nil, err
+					}
+					if err := resultModel.AddPolicy(op.Section, op.PolicyType, op.Rules[i]); err != nil {
+						return nil, err
+					}
+				}
+			}
+		}
+	}
+
+	return resultModel, nil
+}
+
+// HasOperations returns true if there are any buffered operations.
+func (tb *TransactionBuffer) HasOperations() bool {
+	tb.mutex.RLock()
+	defer tb.mutex.RUnlock()
+	return len(tb.operations) > 0
+}
+
+// OperationCount returns the number of buffered operations.
+func (tb *TransactionBuffer) OperationCount() int {
+	tb.mutex.RLock()
+	defer tb.mutex.RUnlock()
+	return len(tb.operations)
+}