grpc

package
v0.0.0-...-6dbff61 Latest Latest
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 Go to latest Published: May 24, 2017 License: Apache-2.0, BSD-3-Clause Imports: 28 Imported by: 0

Documentation

Overview

Package grpc implements an RPC system called gRPC.

See www.grpc.io for more information about gRPC.

Index

Constants

View Source 
const SupportPackageIsVersion4 = true

SupportPackageIsVersion4 is referenced from generated protocol buffer files to assert that that code is compatible with this version of the grpc package.

This constant may be renamed in the future if a change in the generated code requires a synchronised update of grpc-go and protoc-gen-go. This constant should not be referenced from any other code.

Variables

View Source 
var (
	// ErrClientConnClosing indicates that the operation is illegal because
	// the ClientConn is closing.
	ErrClientConnClosing = errors.New("grpc: the client connection is closing")
	// ErrClientConnTimeout indicates that the ClientConn cannot establish the
	// underlying connections within the specified timeout.
	ErrClientConnTimeout = errors.New("grpc: timed out when dialing")
)
View Source 
var (
	DefaultBackoffConfig = BackoffConfig{
		MaxDelay: 120 * time.Second,
		// contains filtered or unexported fields
	}
)

DefaultBackoffConfig uses values specified for backoff in https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md.

View Source 
var EnableTracing = true

EnableTracing controls whether to trace RPCs using the golang.org/x/net/trace package. This should only be set before any RPCs are sent or received by this program.

View Source 
var (
	// ErrServerStopped indicates that the operation is now illegal because of
	// the server being stopped.
	ErrServerStopped = errors.New("grpc: the server has been stopped")
)

Functions

func Code 

func Code(err error) codes.Code

Code returns the error code for err if it was produced by the rpc system. Otherwise, it returns codes.Unknown.

func ErrorDesc 

func ErrorDesc(err error) string

ErrorDesc returns the error description of err if it was produced by the rpc system. Otherwise, it returns err.Error() or empty string when err is nil.

func Errorf 

func Errorf(c codes.Code, format string, a ...interface{}) error

Errorf returns an error containing an error code and a description; Errorf returns nil if c is OK.

func Invoke 

func Invoke(ctx context.Context, method string, args, reply interface{}, cc *ClientConn, opts ...CallOption) error

Invoke sends the RPC request on the wire and returns after response is received. Invoke is called by generated code. Also users can call Invoke directly when it is really needed in their use cases.

func SendHeader 

func SendHeader(ctx context.Context, md metadata.MD) error

SendHeader sends header metadata. It may be called at most once. The provided md and headers set by SetHeader() will be sent.

func SetHeader 

func SetHeader(ctx context.Context, md metadata.MD) error

SetHeader sets the header metadata. When called multiple times, all the provided metadata will be merged. All the metadata will be sent out when one of the following happens:

  • grpc.SendHeader() is called;
  • The first response is sent out;
  • An RPC status is sent out (error or success).

func SetTrailer 

func SetTrailer(ctx context.Context, md metadata.MD) error

SetTrailer sets the trailer metadata that will be sent when an RPC returns. When called more than once, all the provided metadata will be merged.

Types

type Address 

type Address struct {
	// Addr is the server address on which a connection will be established.
	Addr string
	// Metadata is the information associated with Addr, which may be used
	// to make load balancing decision.
	Metadata interface{}
}

Address represents a server the client connects to. This is the EXPERIMENTAL API and may be changed or extended in the future.

type BackoffConfig 

type BackoffConfig struct {
	// MaxDelay is the upper bound of backoff delay.
	MaxDelay time.Duration
	// contains filtered or unexported fields
}

BackoffConfig defines the parameters for the default gRPC backoff strategy.

type Balancer 

type Balancer interface {
	// Start does the initialization work to bootstrap a Balancer. For example,
	// this function may start the name resolution and watch the updates. It will
	// be called when dialing.
	Start(target string, config BalancerConfig) error
	// Up informs the Balancer that gRPC has a connection to the server at
	// addr. It returns down which is called once the connection to addr gets
	// lost or closed.
	// TODO: It is not clear how to construct and take advantage of the meaningful error
	// parameter for down. Need realistic demands to guide.
	Up(addr Address) (down func(error))
	// Get gets the address of a server for the RPC corresponding to ctx.
	// i) If it returns a connected address, gRPC internals issues the RPC on the
	// connection to this address;
	// ii) If it returns an address on which the connection is under construction
	// (initiated by Notify(...)) but not connected, gRPC internals
	//  * fails RPC if the RPC is fail-fast and connection is in the TransientFailure or
	//  Shutdown state;
	//  or
	//  * issues RPC on the connection otherwise.
	// iii) If it returns an address on which the connection does not exist, gRPC
	// internals treats it as an error and will fail the corresponding RPC.
	//
	// Therefore, the following is the recommended rule when writing a custom Balancer.
	// If opts.BlockingWait is true, it should return a connected address or
	// block if there is no connected address. It should respect the timeout or
	// cancellation of ctx when blocking. If opts.BlockingWait is false (for fail-fast
	// RPCs), it should return an address it has notified via Notify(...) immediately
	// instead of blocking.
	//
	// The function returns put which is called once the rpc has completed or failed.
	// put can collect and report RPC stats to a remote load balancer.
	//
	// This function should only return the errors Balancer cannot recover by itself.
	// gRPC internals will fail the RPC if an error is returned.
	Get(ctx context.Context, opts BalancerGetOptions) (addr Address, put func(), err error)
	// Notify returns a channel that is used by gRPC internals to watch the addresses
	// gRPC needs to connect. The addresses might be from a name resolver or remote
	// load balancer. gRPC internals will compare it with the existing connected
	// addresses. If the address Balancer notified is not in the existing connected
	// addresses, gRPC starts to connect the address. If an address in the existing
	// connected addresses is not in the notification list, the corresponding connection
	// is shutdown gracefully. Otherwise, there are no operations to take. Note that
	// the Address slice must be the full list of the Addresses which should be connected.
	// It is NOT delta.
	Notify() <-chan []Address
	// Close shuts down the balancer.
	Close() error
}

Balancer chooses network addresses for RPCs. This is the EXPERIMENTAL API and may be changed or extended in the future.

func RoundRobin 

func RoundRobin(r naming.Resolver) Balancer

RoundRobin returns a Balancer that selects addresses round-robin. It uses r to watch the name resolution updates and updates the addresses available correspondingly.

type BalancerConfig 

type BalancerConfig struct {
	// DialCreds is the transport credential the Balancer implementation can
	// use to dial to a remote load balancer server. The Balancer implementations
	// can ignore this if it does not need to talk to another party securely.
	DialCreds credentials.TransportCredentials
}

BalancerConfig specifies the configurations for Balancer.

type BalancerGetOptions 

type BalancerGetOptions struct {
	// BlockingWait specifies whether Get should block when there is no
	// connected address.
	BlockingWait bool
}

BalancerGetOptions configures a Get call. This is the EXPERIMENTAL API and may be changed or extended in the future.

type CallOption 

type CallOption interface {
	// contains filtered or unexported methods
}

CallOption configures a Call before it starts or extracts information from a Call after it completes.

func FailFast 

func FailFast(failFast bool) CallOption

FailFast configures the action to take when an RPC is attempted on broken connections or unreachable servers. If failfast is true, the RPC will fail immediately. Otherwise, the RPC client will block the call until a connection is available (or the call is canceled or times out) and will retry the call if it fails due to a transient error. Please refer to https://github.com/grpc/grpc/blob/master/doc/fail_fast.md 

func Header(md *metadata.MD) CallOption

Header returns a CallOptions that retrieves the header metadata for a unary RPC.

func Trailer 

func Trailer(md *metadata.MD) CallOption

Trailer returns a CallOptions that retrieves the trailer metadata for a unary RPC.

type ClientConn 

type ClientConn struct {
	// contains filtered or unexported fields
}

ClientConn represents a client connection to an RPC server.

func Dial 

func Dial(target string, opts ...DialOption) (*ClientConn, error)

Dial creates a client connection to the given target.

func DialContext 

func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *ClientConn, err error)

DialContext creates a client connection to the given target. ctx can be used to cancel or expire the pending connecting. Once this function returns, the cancellation and expiration of ctx will be noop. Users should call ClientConn.Close to terminate all the pending operations after this function returns. This is the EXPERIMENTAL API.

func (*ClientConn) Close 

func (cc *ClientConn) Close() error

Close tears down the ClientConn and all underlying connections.

type ClientStream 

type ClientStream interface {
	// Header returns the header metadata received from the server if there
	// is any. It blocks if the metadata is not ready to read.
	Header() (metadata.MD, error)
	// Trailer returns the trailer metadata from the server, if there is any.
	// It must only be called after stream.CloseAndRecv has returned, or
	// stream.Recv has returned a non-nil error (including io.EOF).
	Trailer() metadata.MD
	// CloseSend closes the send direction of the stream. It closes the stream
	// when non-nil error is met.
	CloseSend() error
	Stream
}

ClientStream defines the interface a client stream has to satisfy.

func NewClientStream 

func NewClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (ClientStream, error)

NewClientStream creates a new Stream for the client side. This is called by generated code.

type Codec 

type Codec interface {
	// Marshal returns the wire format of v.
	Marshal(v interface{}) ([]byte, error)
	// Unmarshal parses the wire format into v.
	Unmarshal(data []byte, v interface{}) error
	// String returns the name of the Codec implementation. The returned
	// string will be used as part of content type in transmission.
	String() string
}

Codec defines the interface gRPC uses to encode and decode messages.

type Compressor 

type Compressor interface {
	// Do compresses p into w.
	Do(w io.Writer, p []byte) error
	// Type returns the compression algorithm the Compressor uses.
	Type() string
}

Compressor defines the interface gRPC uses to compress a message.

func NewGZIPCompressor 

func NewGZIPCompressor() Compressor

NewGZIPCompressor creates a Compressor based on GZIP.

type ConnectivityState 

type ConnectivityState int

ConnectivityState indicates the state of a client connection. 

const (
	// Idle indicates the ClientConn is idle.
	Idle ConnectivityState = iota
	// Connecting indicates the ClienConn is connecting.
	Connecting
	// Ready indicates the ClientConn is ready for work.
	Ready
	// TransientFailure indicates the ClientConn has seen a failure but expects to recover.
	TransientFailure
	// Shutdown indicates the ClientConn has started shutting down.
	Shutdown
)

func (ConnectivityState) String 

func (s ConnectivityState) String() string

type Decompressor 

type Decompressor interface {
	// Do reads the data from r and uncompress them.
	Do(r io.Reader) ([]byte, error)
	// Type returns the compression algorithm the Decompressor uses.
	Type() string
}

Decompressor defines the interface gRPC uses to decompress a message.

func NewGZIPDecompressor 

func NewGZIPDecompressor() Decompressor

NewGZIPDecompressor creates a Decompressor based on GZIP.

type DialOption 

type DialOption func(*dialOptions)

DialOption configures how we set up the connection.

func WithBackoffConfig 

func WithBackoffConfig(b BackoffConfig) DialOption

WithBackoffConfig configures the dialer to use the provided backoff parameters after connection failures.

Use WithBackoffMaxDelay until more parameters on BackoffConfig are opened up for use.

func WithBackoffMaxDelay 

func WithBackoffMaxDelay(md time.Duration) DialOption

WithBackoffMaxDelay configures the dialer to use the provided maximum delay when backing off after failed connection attempts.

func WithBalancer 

func WithBalancer(b Balancer) DialOption

WithBalancer returns a DialOption which sets a load balancer.

func WithBlock 

func WithBlock() DialOption

WithBlock returns a DialOption which makes caller of Dial blocks until the underlying connection is up. Without this, Dial returns immediately and connecting the server happens in background.

func WithCodec 

func WithCodec(c Codec) DialOption

WithCodec returns a DialOption which sets a codec for message marshaling and unmarshaling.

func WithCompressor 

func WithCompressor(cp Compressor) DialOption

WithCompressor returns a DialOption which sets a CompressorGenerator for generating message compressor.

func WithDecompressor 

func WithDecompressor(dc Decompressor) DialOption

WithDecompressor returns a DialOption which sets a DecompressorGenerator for generating message decompressor.

func WithDialer 

func WithDialer(f func(string, time.Duration) (net.Conn, error)) DialOption

WithDialer returns a DialOption that specifies a function to use for dialing network addresses.

func WithInsecure 

func WithInsecure() DialOption

WithInsecure returns a DialOption which disables transport security for this ClientConn. Note that transport security is required unless WithInsecure is set.

func WithPerRPCCredentials 

func WithPerRPCCredentials(creds credentials.PerRPCCredentials) DialOption

WithPerRPCCredentials returns a DialOption which sets credentials which will place auth state on each outbound RPC.

func WithStreamInterceptor 

func WithStreamInterceptor(f StreamClientInterceptor) DialOption

WithStreamInterceptor returns a DialOption that specifies the interceptor for streaming RPCs.

func WithTimeout 

func WithTimeout(d time.Duration) DialOption

WithTimeout returns a DialOption that configures a timeout for dialing a ClientConn initially. This is valid if and only if WithBlock() is present.

func WithTransportCredentials 

func WithTransportCredentials(creds credentials.TransportCredentials) DialOption

WithTransportCredentials returns a DialOption which configures a connection level security credentials (e.g., TLS/SSL).

func WithUnaryInterceptor 

func WithUnaryInterceptor(f UnaryClientInterceptor) DialOption

WithUnaryInterceptor returns a DialOption that specifies the interceptor for unary RPCs.

func WithUserAgent 

func WithUserAgent(s string) DialOption

WithUserAgent returns a DialOption that specifies a user agent string for all the RPCs.

type MethodDesc 

type MethodDesc struct {
	MethodName string
	Handler    methodHandler
}

MethodDesc represents an RPC service's method specification.

type MethodInfo 

type MethodInfo struct {
	// Name is the method name only, without the service name or package name.
	Name string
	// IsClientStream indicates whether the RPC is a client streaming RPC.
	IsClientStream bool
	// IsServerStream indicates whether the RPC is a server streaming RPC.
	IsServerStream bool
}

MethodInfo contains the information of an RPC including its method name and type.

type Server 

type Server struct {
	// contains filtered or unexported fields
}

Server is a gRPC server to serve RPC requests.

func NewServer 

func NewServer(opt ...ServerOption) *Server

NewServer creates a gRPC server which has no service registered and has not started to accept requests yet.

func (*Server) GetServiceInfo 

func (s *Server) GetServiceInfo() map[string]ServiceInfo

GetServiceInfo returns a map from service names to ServiceInfo. Service names include the package names, in the form of <package>.<service>.

func (*Server) GracefulStop 

func (s *Server) GracefulStop()

GracefulStop stops the gRPC server gracefully. It stops the server to accept new connections and RPCs and blocks until all the pending RPCs are finished.

func (*Server) RegisterService 

func (s *Server) RegisterService(sd *ServiceDesc, ss interface{})

RegisterService register a service and its implementation to the gRPC server. Called from the IDL generated code. This must be called before invoking Serve.

func (*Server) Serve 

func (s *Server) Serve(lis net.Listener) error

Serve accepts incoming connections on the listener lis, creating a new ServerTransport and service goroutine for each. The service goroutines read gRPC requests and then call the registered handlers to reply to them. Serve returns when lis.Accept fails with fatal errors. lis will be closed when this method returns.

func (*Server) ServeHTTP 

func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request)

func (*Server) Stop 

func (s *Server) Stop()

Stop stops the gRPC server. It immediately closes all open connections and listeners. It cancels all active RPCs on the server side and the corresponding pending RPCs on the client side will get notified by connection errors.

type ServerOption 

type ServerOption func(*options)

A ServerOption sets options.

func Creds 

func Creds(c credentials.TransportCredentials) ServerOption

Creds returns a ServerOption that sets credentials for server connections.

func CustomCodec 

func CustomCodec(codec Codec) ServerOption

CustomCodec returns a ServerOption that sets a codec for message marshaling and unmarshaling.

func MaxConcurrentStreams 

func MaxConcurrentStreams(n uint32) ServerOption

MaxConcurrentStreams returns a ServerOption that will apply a limit on the number of concurrent streams to each ServerTransport.

func MaxMsgSize 

func MaxMsgSize(m int) ServerOption

MaxMsgSize returns a ServerOption to set the max message size in bytes for inbound mesages. If this is not set, gRPC uses the default 4MB.

func RPCCompressor 

func RPCCompressor(cp Compressor) ServerOption

RPCCompressor returns a ServerOption that sets a compressor for outbound messages.

func RPCDecompressor 

func RPCDecompressor(dc Decompressor) ServerOption

RPCDecompressor returns a ServerOption that sets a decompressor for inbound messages.

func StreamInterceptor 

func StreamInterceptor(i StreamServerInterceptor) ServerOption

StreamInterceptor returns a ServerOption that sets the StreamServerInterceptor for the server. Only one stream interceptor can be installed.

func UnaryInterceptor 

func UnaryInterceptor(i UnaryServerInterceptor) ServerOption

UnaryInterceptor returns a ServerOption that sets the UnaryServerInterceptor for the server. Only one unary interceptor can be installed. The construction of multiple interceptors (e.g., chaining) can be implemented at the caller.

type ServerStream 

type ServerStream interface {
	// SetHeader sets the header metadata. It may be called multiple times.
	// When call multiple times, all the provided metadata will be merged.
	// All the metadata will be sent out when one of the following happens:
	//  - ServerStream.SendHeader() is called;
	//  - The first response is sent out;
	//  - An RPC status is sent out (error or success).
	SetHeader(metadata.MD) error
	// SendHeader sends the header metadata.
	// The provided md and headers set by SetHeader() will be sent.
	// It fails if called multiple times.
	SendHeader(metadata.MD) error
	// SetTrailer sets the trailer metadata which will be sent with the RPC status.
	// When called more than once, all the provided metadata will be merged.
	SetTrailer(metadata.MD)
	Stream
}

ServerStream defines the interface a server stream has to satisfy.

type ServiceDesc 

type ServiceDesc struct {
	ServiceName string
	// The pointer to the service interface. Used to check whether the user
	// provided implementation satisfies the interface requirements.
	HandlerType interface{}
	Methods     []MethodDesc
	Streams     []StreamDesc
	Metadata    interface{}
}

ServiceDesc represents an RPC service's specification.

type ServiceInfo 

type ServiceInfo struct {
	Methods []MethodInfo
	// Metadata is the metadata specified in ServiceDesc when registering service.
	Metadata interface{}
}

ServiceInfo contains unary RPC method info, streaming RPC methid info and metadata for a service.

type Stream 

type Stream interface {
	// Context returns the context for this stream.
	Context() context.Context
	// SendMsg blocks until it sends m, the stream is done or the stream
	// breaks.
	// On error, it aborts the stream and returns an RPC status on client
	// side. On server side, it simply returns the error to the caller.
	// SendMsg is called by generated code. Also Users can call SendMsg
	// directly when it is really needed in their use cases.
	SendMsg(m interface{}) error
	// RecvMsg blocks until it receives a message or the stream is
	// done. On client side, it returns io.EOF when the stream is done. On
	// any other error, it aborts the stream and returns an RPC status. On
	// server side, it simply returns the error to the caller.
	RecvMsg(m interface{}) error
}

Stream defines the common interface a client or server stream has to satisfy.

type StreamClientInterceptor 

type StreamClientInterceptor func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, streamer Streamer, opts ...CallOption) (ClientStream, error)

StreamClientInterceptor intercepts the creation of ClientStream. It may return a custom ClientStream to intercept all I/O operations. streamer is the handlder to create a ClientStream and it is the responsibility of the interceptor to call it. This is the EXPERIMENTAL API.

type StreamDesc 

type StreamDesc struct {
	StreamName string
	Handler    StreamHandler

	// At least one of these is true.
	ServerStreams bool
	ClientStreams bool
}

StreamDesc represents a streaming RPC service's method specification.

type StreamHandler 

type StreamHandler func(srv interface{}, stream ServerStream) error

StreamHandler defines the handler called by gRPC server to complete the execution of a streaming RPC.

type StreamServerInfo 

type StreamServerInfo struct {
	// FullMethod is the full RPC method string, i.e., /package.service/method.
	FullMethod string
	// IsClientStream indicates whether the RPC is a client streaming RPC.
	IsClientStream bool
	// IsServerStream indicates whether the RPC is a server streaming RPC.
	IsServerStream bool
}

StreamServerInfo consists of various information about a streaming RPC on server side. All per-rpc information may be mutated by the interceptor.

type StreamServerInterceptor 

type StreamServerInterceptor func(srv interface{}, ss ServerStream, info *StreamServerInfo, handler StreamHandler) error

StreamServerInterceptor provides a hook to intercept the execution of a streaming RPC on the server. info contains all the information of this RPC the interceptor can operate on. And handler is the service method implementation. It is the responsibility of the interceptor to invoke handler to complete the RPC.

type Streamer 

type Streamer func(ctx context.Context, desc *StreamDesc, cc *ClientConn, method string, opts ...CallOption) (ClientStream, error)

Streamer is called by StreamClientInterceptor to create a ClientStream.

type UnaryClientInterceptor 

type UnaryClientInterceptor func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, invoker UnaryInvoker, opts ...CallOption) error

UnaryClientInterceptor intercepts the execution of a unary RPC on the client. inovker is the handler to complete the RPC and it is the responsibility of the interceptor to call it. This is the EXPERIMENTAL API.

type UnaryHandler 

type UnaryHandler func(ctx context.Context, req interface{}) (interface{}, error)

UnaryHandler defines the handler invoked by UnaryServerInterceptor to complete the normal execution of a unary RPC.

type UnaryInvoker 

type UnaryInvoker func(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, opts ...CallOption) error

UnaryInvoker is called by UnaryClientInterceptor to complete RPCs.

type UnaryServerInfo 

type UnaryServerInfo struct {
	// Server is the service implementation the user provides. This is read-only.
	Server interface{}
	// FullMethod is the full RPC method string, i.e., /package.service/method.
	FullMethod string
}

UnaryServerInfo consists of various information about a unary RPC on server side. All per-rpc information may be mutated by the interceptor.

type UnaryServerInterceptor 

type UnaryServerInterceptor func(ctx context.Context, req interface{}, info *UnaryServerInfo, handler UnaryHandler) (resp interface{}, err error)

UnaryServerInterceptor provides a hook to intercept the execution of a unary RPC on the server. info contains all the information of this RPC the interceptor can operate on. And handler is the wrapper of the service method implementation. It is the responsibility of the interceptor to invoke handler to complete the RPC.

Source Files

View all Source files

Directories

Path Synopsis
Package codes defines the canonical error codes used by gRPC.
 Package codes defines the canonical error codes used by gRPC.
Package credentials implements various credentials supported by gRPC library, which encapsulate all the state needed by a client to authenticate with a server and make various assertions, e.g., about the client's identity, role, or whether it is authorized to make a particular call.
 Package credentials implements various credentials supported by gRPC library, which encapsulate all the state needed by a client to authenticate with a server and make various assertions, e.g., about the client's identity, role, or whether it is authorized to make a particular call.
Package grpclog defines logging for grpc.
 Package grpclog defines logging for grpc.
Package internal contains gRPC-internal code for testing, to avoid polluting the godoc of the top-level grpc package.
 Package internal contains gRPC-internal code for testing, to avoid polluting the godoc of the top-level grpc package.
Package metadata define the structure of the metadata supported by gRPC library.
 Package metadata define the structure of the metadata supported by gRPC library.
Package naming defines the naming API and related data structures for gRPC.
 Package naming defines the naming API and related data structures for gRPC.
Package peer defines various peer information associated with RPCs and corresponding utils.
 Package peer defines various peer information associated with RPCs and corresponding utils.
Package transport defines and implements message oriented communication channel to complete various transactions (e.g., an RPC).
 Package transport defines and implements message oriented communication channel to complete various transactions (e.g., an RPC).

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