binding.go

// Copyright 2017-2019 Lei Ni (nilei81@gmail.com) and other Dragonboat authors.
//
// 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.

// +build dragonboat_language_binding

package dragonboat

import (
	"time"
	"unsafe"

	"github.com/lni/dragonboat/v3/client"
	"github.com/lni/dragonboat/v3/config"
	"github.com/lni/dragonboat/v3/internal/cpp"
	"github.com/lni/dragonboat/v3/internal/rsm"
	"github.com/lni/dragonboat/v3/internal/utils/fileutil"
	pb "github.com/lni/dragonboat/v3/raftpb"
)

//
// Public methods in this file are used by language bindings, they are
// considered as a part of the internal interface that can change any
// time. Applications are not suppose to directly call any of them.
//

func (rr *RequestResult) GetCode() RequestResultCode {
	return rr.code
}

// ProposeCH is similar to the Propose method with an extra ICompleteHandler
// specified. On proposal's completion, the ICompleteHandler will be invoked
// by the system. The ICompleteHandler instance should not be used as a
// general callback function, it should only be used to notify the completion
// of the proposal. ProposeWithCH is mainly used by language bindings to
// implement async proposals, Go applications are expected to use the Propose
// method.
func (nh *NodeHost) ProposeCH(s *client.Session,
	data []byte, handler ICompleteHandler,
	timeout time.Duration) (*RequestState, error) {
	return nh.propose(s, data, handler, timeout)
}

// ReadIndexCH is similar to the ReadIndex method with an extra
// ICompleteHandler specified. On completion of the ReadIndex operation, the
// ICompleteHandler will be invoked by the system. The ICompleteHandler should
// not be used as a general callback function, it should only be used to notify
// the completion of the ReadIndex operation.
// ReadIndexCH is mainly used by language bindings to implement async
// ReadIndex operations, Go applications are expected to use the ReadIndex
// method.
func (nh *NodeHost) ReadIndexCH(clusterID uint64,
	handler ICompleteHandler,
	timeout time.Duration) (*RequestState, error) {
	rs, _, err := nh.readIndex(clusterID, handler, timeout)
	return rs, err
}

// ProposeSessionCH is similar to the ProposeSession method but with an extra
// ICompleteHandler specified as input parameter. The ICompleteHandler should
// not be used as a general callback function, it should only be used to notify
// the completion of the propose session operation.
func (nh *NodeHost) ProposeSessionCH(s *client.Session,
	handler ICompleteHandler, timeout time.Duration) (*RequestState, error) {
	v, ok := nh.getCluster(s.ClusterID)
	if !ok {
		return nil, ErrClusterNotFound
	}
	req, err := v.proposeSession(s, handler, timeout)
	nh.execEngine.setNodeReady(s.ClusterID)
	return req, err
}

// StartClusterUsingPlugin adds a new cluster node to the NodeHost and start
// running the new node. Different from the StartCluster method in which you
// specify the factory function used for creating the IStateMachine instance,
// StartClusterUsingPlugin requires the full path of the CPP plugin you want
// the Raft cluster to use.
func (nh *NodeHost) StartClusterUsingPlugin(nodes map[uint64]string,
	join bool, pluginFilename string, config config.Config) error {
	stopc := make(chan struct{})
	appName := fileutil.GetAppNameFromFilename(pluginFilename)
	cf := func(clusterID uint64, nodeID uint64,
		done <-chan struct{}) rsm.IManagedStateMachine {
		return cpp.NewStateMachineWrapper(clusterID, nodeID, appName, done)
	}
	return nh.startCluster(nodes, join, cf, stopc, config, pb.RegularStateMachine)
}

// StartClusterUsingFactory adds a new cluster node to the NodeHost and start
// running the new node. StartClusterUsingFactory requires the pointer to CPP
// statemachine factory function.
func (nh *NodeHost) StartClusterUsingFactory(nodes map[uint64]string,
	join bool, factory unsafe.Pointer, config config.Config) error {
	stopc := make(chan struct{})
	cf := func(clusterID uint64, nodeID uint64,
		done <-chan struct{}) rsm.IManagedStateMachine {
		return cpp.NewStateMachineFromFactoryWrapper(clusterID, nodeID, factory, done)
	}
	return nh.startCluster(nodes, join, cf, stopc, config, pb.RegularStateMachine)
}

// ReadLocal queries the specified Raft node. To ensure the linearizability of
// the I/O, ReadLocal should only be called after receiving a RequestCompleted
// notification from the ReadIndex method.
func (nh *NodeHost) ReadLocal(clusterID uint64, query []byte) ([]byte, error) {
	v, ok := nh.getClusterNotLocked(clusterID)
	if !ok {
		return nil, ErrClusterNotFound
	}
	// translate the rsm.ErrClusterClosed to ErrClusterClosed
	// internally, the IManagedStateMachine might obtain a RLock before performing
	// the local read. The critical section is used to make sure we don't read
	// from a destroyed C++ StateMachine object
	data, err := v.sm.Lookup(query)
	if err == rsm.ErrClusterClosed {
		return nil, ErrClusterClosed
	}
	if data == nil {
		return nil, err
	}
	return data.([]byte), err
}