btcwallet对外服务

btcwallet除了像btcd对外提供rpc服务以外,还提供了grpc服务,同时grpc采用的是protobuf来实现.

这方便与不同语言进行交互,降低客户端代码编写量.

阅读这个模块,顺便了解一下proto的使用,更详细的细节问题.

Service分类

总共有三种Service,分别是VersionService,WalletService和WalletLoaderService,

从中可以看出

VersionService

只是提供版本查询服务,为什么会做成一个独立的服务,设计者是出于什么考虑的呢?

这里重点考察grpc服务的启动过程

walletMain函数中传递wallet.Loader调用startRPCServers
配置grpc所需参数,包括证书
创建grpcServer
通过rpcserver.StartVersionService注册VersionService
通过pb.RegisterVersionServiceServer 注册versionServer

这里的RegisterVersionServiceServer是自动生成,
versionServer实现了Version接口,对外提供服务

下面是proto自动生成的Service Description ,其中HandlerType为空,需要我们自己实现.

var _VersionService_serviceDesc = grpc.ServiceDesc{

   ServiceName: "walletrpc.VersionService",

   HandlerType: (*VersionServiceServer)(nil),

   Methods: []grpc.MethodDesc{

   	{

   		MethodName: "Version",

   		Handler:    _VersionService_Version_Handler,

   	},

   },

   Streams:  []grpc.StreamDesc{},

   Metadata: "api.proto",

}

VersionService client的实现

同时proto自动生成了客户端访问代码,

通过NewVersionServiceClient创建VersionServiceClient
通过VersionServiceClient的Version来访问

客户端和服务端的实现

客户端,由proto自动生成, 完全不用管理

type VersionServiceClient interface {

	Version(ctx context.Context, in *VersionRequest, opts ...grpc.CallOption) (*VersionResponse, error)

}

func (c *versionServiceClient) Version(ctx context.Context, in *VersionRequest, opts ...grpc.CallOption) (*VersionResponse, error) {

	out := new(VersionResponse)

	err := grpc.Invoke(ctx, "/walletrpc.VersionService/Version", in, out, c.cc, opts...)

	if err != nil {

		return nil, err

	}

	return out, nil

}

服务端

type VersionServiceServer interface {

	Version(context.Context, *VersionRequest) (*VersionResponse, error)

}

func (*versionServer) Version(ctx context.Context, req *pb.VersionRequest) (*pb.VersionResponse, error) {

	return &pb.VersionResponse{

		VersionString: semverString,

		Major:         semverMajor,

		Minor:         semverMinor,

		Patch:         semverPatch,

	}, nil

}

这里给的例子比较特殊,就是输入参数根本没用,不过看得出如何使用proto以及grpc了.

WalletLoaderService

此服务主要用于打开关闭钱包,

StartConsensusRpc是在btcwallet启动的时候没有指定btcd的情形下,可以连接指定的btcd.

service WalletLoaderService {

	rpc WalletExists (WalletExistsRequest) returns (WalletExistsResponse);

	rpc CreateWallet (CreateWalletRequest) returns (CreateWalletResponse);

	rpc OpenWallet (OpenWalletRequest) returns (OpenWalletResponse);

	rpc CloseWallet (CloseWalletRequest) returns (CloseWalletResponse);

	rpc StartConsensusRpc (StartConsensusRpcRequest) returns (StartConsensusRpcResponse);

}

WalletLoaderService启动方式和VersionService完全一致.

我的问题:

钱包不存在的时候只能通过--create创建完成以后再启动,是否这个服务目前根本没用?

核心服务WalletService

接口

service WalletService {

	// Queries

	rpc Ping (PingRequest) returns (PingResponse);

	rpc Network (NetworkRequest) returns (NetworkResponse);

	rpc AccountNumber (AccountNumberRequest) returns (AccountNumberResponse);

	rpc Accounts (AccountsRequest) returns (AccountsResponse);

	rpc Balance (BalanceRequest) returns (BalanceResponse);

	rpc GetTransactions (GetTransactionsRequest) returns (GetTransactionsResponse);

	// Notifications

	rpc TransactionNotifications (TransactionNotificationsRequest) returns (stream TransactionNotificationsResponse);

	rpc SpentnessNotifications (SpentnessNotificationsRequest) returns (stream SpentnessNotificationsResponse);

	rpc AccountNotifications (AccountNotificationsRequest) returns (stream AccountNotificationsResponse);

	// Control

	rpc ChangePassphrase (ChangePassphraseRequest) returns (ChangePassphraseResponse);

	rpc RenameAccount (RenameAccountRequest) returns (RenameAccountResponse);

	rpc NextAccount (NextAccountRequest) returns (NextAccountResponse);

	rpc NextAddress (NextAddressRequest) returns (NextAddressResponse);

	rpc ImportPrivateKey (ImportPrivateKeyRequest) returns (ImportPrivateKeyResponse);

	rpc FundTransaction (FundTransactionRequest) returns (FundTransactionResponse);

	rpc SignTransaction (SignTransactionRequest) returns (SignTransactionResponse);

	rpc PublishTransaction (PublishTransactionRequest) returns (PublishTransactionResponse);

}

启动过程

walletMain中等待钱包打开以后获取到钱包句柄,然后调用startWalletRPCServices
注意startWalletRPCServices传递进去三个参数,一个是钱包句柄,一个是grpc server,另一个是普通的http rpc server
rpcserver.StartWalletService启动grpc WalletService
legacyServer.RegisterWallet 注册http rpc服务
pb.RegisterWalletServiceServer注册rpc.walletServer
rpc.walletServer实现了接口

type WalletServiceServer interface {

	// Queries

	Ping(context.Context, *PingRequest) (*PingResponse, error)

	Network(context.Context, *NetworkRequest) (*NetworkResponse, error)

	AccountNumber(context.Context, *AccountNumberRequest) (*AccountNumberResponse, error)

	Accounts(context.Context, *AccountsRequest) (*AccountsResponse, error)

	Balance(context.Context, *BalanceRequest) (*BalanceResponse, error)

	GetTransactions(context.Context, *GetTransactionsRequest) (*GetTransactionsResponse, error)

	// Notifications

	TransactionNotifications(*TransactionNotificationsRequest, WalletService_TransactionNotificationsServer) error

	SpentnessNotifications(*SpentnessNotificationsRequest, WalletService_SpentnessNotificationsServer) error

	AccountNotifications(*AccountNotificationsRequest, WalletService_AccountNotificationsServer) error

	// Control

	ChangePassphrase(context.Context, *ChangePassphraseRequest) (*ChangePassphraseResponse, error)

	RenameAccount(context.Context, *RenameAccountRequest) (*RenameAccountResponse, error)

	NextAccount(context.Context, *NextAccountRequest) (*NextAccountResponse, error)

	NextAddress(context.Context, *NextAddressRequest) (*NextAddressResponse, error)

	ImportPrivateKey(context.Context, *ImportPrivateKeyRequest) (*ImportPrivateKeyResponse, error)

	FundTransaction(context.Context, *FundTransactionRequest) (*FundTransactionResponse, error)

	SignTransaction(context.Context, *SignTransactionRequest) (*SignTransactionResponse, error)

	PublishTransaction(context.Context, *PublishTransactionRequest) (*PublishTransactionResponse, error)

}

stream返回的实现

stream就是持续不断的有返回的意思吧.

rpc TransactionNotifications (TransactionNotificationsRequest) returns (stream TransactionNotificationsResponse); proto中的接口被转换成了 TransactionNotifications(*TransactionNotificationsRequest, WalletService_TransactionNotificationsServer) error

其中TransactionNotificationsResponse被转换成了

type WalletService_TransactionNotificationsServer interface {

	Send(*TransactionNotificationsResponse) error

	grpc.ServerStream

}

服务端TransactionNotifications实现

func (s *walletServer) TransactionNotifications(req *pb.TransactionNotificationsRequest,

	svr pb.WalletService_TransactionNotificationsServer) error {

	n := s.wallet.NtfnServer.TransactionNotifications()

	defer n.Done()

	ctxDone := svr.Context().Done()

	for {

		select {

		case v := <-n.C:

			resp := pb.TransactionNotificationsResponse{

				AttachedBlocks:           marshalBlocks(v.AttachedBlocks),

				DetachedBlocks:           marshalHashes(v.DetachedBlocks),

				UnminedTransactions:      marshalTransactionDetails(v.UnminedTransactions),

				UnminedTransactionHashes: marshalHashes(v.UnminedTransactionHashes),

			}

			err := svr.Send(&resp)

			if err != nil {

				return translateError(err)

			}

		case <-ctxDone:

			return nil

		}

	}

}

其他: 与http rpc服务的简单比较

通过代码实现对比就可以发现http rpc服务实现起来比较繁琐,各种客户端编解码需要自己处理,

不过从代码完善度来说,http接口明显更胜一筹,无论是注释还是测试case,包括api文档.

如果生产中使用,还是使用http rpc更好,如果熟悉代码的话,使用grpc更清晰.

巴特西

btcWallet系列之一-grpc模块