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server.go
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server.go
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/*
*
* Copyright 2014, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
package grpc
import (
"errors"
"fmt"
"io"
"net"
"reflect"
"strings"
"sync"
"golang.org/x/net/context"
"golang.org/x/net/trace"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/transport"
)
type methodHandler func(srv interface{}, ctx context.Context, codec Codec, buf []byte) (interface{}, error)
// MethodDesc represents an RPC service's method specification.
type MethodDesc struct {
MethodName string
Handler methodHandler
}
// ServiceDesc represents an RPC service's specification.
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
}
// service consists of the information of the server serving this service and
// the methods in this service.
type service struct {
server interface{} // the server for service methods
md map[string]*MethodDesc
sd map[string]*StreamDesc
}
// Server is a gRPC server to serve RPC requests.
type Server struct {
opts options
mu sync.Mutex
lis map[net.Listener]bool
conns map[transport.ServerTransport]bool
m map[string]*service // service name -> service info
}
type options struct {
creds credentials.Credentials
codec Codec
maxConcurrentStreams uint32
}
// A ServerOption sets options.
type ServerOption func(*options)
// CustomCodec returns a ServerOption that sets a codec for message marshaling and unmarshaling.
func CustomCodec(codec Codec) ServerOption {
return func(o *options) {
o.codec = codec
}
}
// MaxConcurrentStreams returns a ServerOption that will apply a limit on the number
// of concurrent streams to each ServerTransport.
func MaxConcurrentStreams(n uint32) ServerOption {
return func(o *options) {
o.maxConcurrentStreams = n
}
}
// Creds returns a ServerOption that sets credentials for server connections.
func Creds(c credentials.Credentials) ServerOption {
return func(o *options) {
o.creds = c
}
}
// NewServer creates a gRPC server which has no service registered and has not
// started to accept requests yet.
func NewServer(opt ...ServerOption) *Server {
var opts options
for _, o := range opt {
o(&opts)
}
if opts.codec == nil {
// Set the default codec.
opts.codec = protoCodec{}
}
return &Server{
lis: make(map[net.Listener]bool),
opts: opts,
conns: make(map[transport.ServerTransport]bool),
m: make(map[string]*service),
}
}
// 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 (s *Server) RegisterService(sd *ServiceDesc, ss interface{}) {
ht := reflect.TypeOf(sd.HandlerType).Elem()
st := reflect.TypeOf(ss)
if !st.Implements(ht) {
grpclog.Fatalf("grpc: Server.RegisterService found the handler of type %v that does not satisfy %v", st, ht)
}
s.register(sd, ss)
}
func (s *Server) register(sd *ServiceDesc, ss interface{}) {
s.mu.Lock()
defer s.mu.Unlock()
if _, ok := s.m[sd.ServiceName]; ok {
grpclog.Fatalf("grpc: Server.RegisterService found duplicate service registration for %q", sd.ServiceName)
}
srv := &service{
server: ss,
md: make(map[string]*MethodDesc),
sd: make(map[string]*StreamDesc),
}
for i := range sd.Methods {
d := &sd.Methods[i]
srv.md[d.MethodName] = d
}
for i := range sd.Streams {
d := &sd.Streams[i]
srv.sd[d.StreamName] = d
}
s.m[sd.ServiceName] = srv
}
var (
// ErrServerStopped indicates that the operation is now illegal because of
// the server being stopped.
ErrServerStopped = errors.New("grpc: the server has been stopped")
)
// Serve accepts incoming connections on the listener lis, creating a new
// ServerTransport and service goroutine for each. The service goroutines
// read gRPC request and then call the registered handlers to reply to them.
// Service returns when lis.Accept fails.
func (s *Server) Serve(lis net.Listener) error {
s.mu.Lock()
if s.lis == nil {
s.mu.Unlock()
return ErrServerStopped
}
s.lis[lis] = true
s.mu.Unlock()
defer func() {
lis.Close()
s.mu.Lock()
delete(s.lis, lis)
s.mu.Unlock()
}()
for {
c, err := lis.Accept()
if err != nil {
return err
}
var authInfo credentials.AuthInfo
if creds, ok := s.opts.creds.(credentials.TransportAuthenticator); ok {
c, authInfo, err = creds.ServerHandshake(c)
if err != nil {
grpclog.Println("grpc: Server.Serve failed to complete security handshake.")
continue
}
}
s.mu.Lock()
if s.conns == nil {
s.mu.Unlock()
c.Close()
return nil
}
st, err := transport.NewServerTransport("http2", c, s.opts.maxConcurrentStreams, authInfo)
if err != nil {
s.mu.Unlock()
c.Close()
grpclog.Println("grpc: Server.Serve failed to create ServerTransport: ", err)
continue
}
s.conns[st] = true
s.mu.Unlock()
go func() {
st.HandleStreams(func(stream *transport.Stream) {
s.handleStream(st, stream)
})
s.mu.Lock()
delete(s.conns, st)
s.mu.Unlock()
}()
}
}
func (s *Server) sendResponse(t transport.ServerTransport, stream *transport.Stream, msg interface{}, pf payloadFormat, opts *transport.Options) error {
p, err := encode(s.opts.codec, msg, pf)
if err != nil {
// This typically indicates a fatal issue (e.g., memory
// corruption or hardware faults) the application program
// cannot handle.
//
// TODO(zhaoq): There exist other options also such as only closing the
// faulty stream locally and remotely (Other streams can keep going). Find
// the optimal option.
grpclog.Fatalf("grpc: Server failed to encode response %v", err)
}
return t.Write(stream, p, opts)
}
func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.Stream, srv *service, md *MethodDesc) (err error) {
var traceInfo traceInfo
if EnableTracing {
traceInfo.tr = trace.New("grpc.Recv."+methodFamily(stream.Method()), stream.Method())
defer traceInfo.tr.Finish()
traceInfo.firstLine.client = false
traceInfo.tr.LazyLog(&traceInfo.firstLine, false)
defer func() {
if err != nil && err != io.EOF {
traceInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
traceInfo.tr.SetError()
}
}()
}
p := &parser{s: stream}
for {
pf, req, err := p.recvMsg()
if err == io.EOF {
// The entire stream is done (for unary RPC only).
return err
}
if err != nil {
switch err := err.(type) {
case transport.ConnectionError:
// Nothing to do here.
case transport.StreamError:
if err := t.WriteStatus(stream, err.Code, err.Desc); err != nil {
grpclog.Printf("grpc: Server.processUnaryRPC failed to write status: %v", err)
}
default:
panic(fmt.Sprintf("grpc: Unexpected error (%T) from recvMsg: %v", err, err))
}
return err
}
if traceInfo.tr != nil {
traceInfo.tr.LazyLog(&payload{sent: false, msg: req}, true)
}
switch pf {
case compressionNone:
statusCode := codes.OK
statusDesc := ""
reply, appErr := md.Handler(srv.server, stream.Context(), s.opts.codec, req)
if appErr != nil {
if err, ok := appErr.(rpcError); ok {
statusCode = err.code
statusDesc = err.desc
} else {
statusCode = convertCode(appErr)
statusDesc = appErr.Error()
}
if err := t.WriteStatus(stream, statusCode, statusDesc); err != nil {
grpclog.Printf("grpc: Server.processUnaryRPC failed to write status: %v", err)
return err
}
return nil
}
opts := &transport.Options{
Last: true,
Delay: false,
}
if err := s.sendResponse(t, stream, reply, compressionNone, opts); err != nil {
switch err := err.(type) {
case transport.ConnectionError:
// Nothing to do here.
case transport.StreamError:
statusCode = err.Code
statusDesc = err.Desc
default:
statusCode = codes.Unknown
statusDesc = err.Error()
}
return err
}
if traceInfo.tr != nil {
traceInfo.tr.LazyLog(&payload{sent: true, msg: reply}, true)
}
return t.WriteStatus(stream, statusCode, statusDesc)
default:
panic(fmt.Sprintf("payload format to be supported: %d", pf))
}
}
}
func (s *Server) processStreamingRPC(t transport.ServerTransport, stream *transport.Stream, srv *service, sd *StreamDesc) (err error) {
ss := &serverStream{
t: t,
s: stream,
p: &parser{s: stream},
codec: s.opts.codec,
tracing: EnableTracing,
}
if ss.tracing {
ss.traceInfo.tr = trace.New("grpc.Recv."+methodFamily(stream.Method()), stream.Method())
ss.traceInfo.firstLine.client = false
ss.traceInfo.tr.LazyLog(&ss.traceInfo.firstLine, false)
defer func() {
ss.mu.Lock()
if err != nil && err != io.EOF {
ss.traceInfo.tr.LazyLog(&fmtStringer{"%v", []interface{}{err}}, true)
ss.traceInfo.tr.SetError()
}
ss.traceInfo.tr.Finish()
ss.traceInfo.tr = nil
ss.mu.Unlock()
}()
}
if appErr := sd.Handler(srv.server, ss); appErr != nil {
if err, ok := appErr.(rpcError); ok {
ss.statusCode = err.code
ss.statusDesc = err.desc
} else {
ss.statusCode = convertCode(appErr)
ss.statusDesc = appErr.Error()
}
}
return t.WriteStatus(ss.s, ss.statusCode, ss.statusDesc)
}
func (s *Server) handleStream(t transport.ServerTransport, stream *transport.Stream) {
sm := stream.Method()
if sm != "" && sm[0] == '/' {
sm = sm[1:]
}
pos := strings.LastIndex(sm, "/")
if pos == -1 {
if err := t.WriteStatus(stream, codes.InvalidArgument, fmt.Sprintf("malformed method name: %q", stream.Method())); err != nil {
grpclog.Printf("grpc: Server.handleStream failed to write status: %v", err)
}
return
}
service := sm[:pos]
method := sm[pos+1:]
srv, ok := s.m[service]
if !ok {
if err := t.WriteStatus(stream, codes.Unimplemented, fmt.Sprintf("unknown service %v", service)); err != nil {
grpclog.Printf("grpc: Server.handleStream failed to write status: %v", err)
}
return
}
// Unary RPC or Streaming RPC?
if md, ok := srv.md[method]; ok {
s.processUnaryRPC(t, stream, srv, md)
return
}
if sd, ok := srv.sd[method]; ok {
s.processStreamingRPC(t, stream, srv, sd)
return
}
if err := t.WriteStatus(stream, codes.Unimplemented, fmt.Sprintf("unknown method %v", method)); err != nil {
grpclog.Printf("grpc: Server.handleStream failed to write status: %v", err)
}
}
// Stop stops the gRPC server. Once Stop returns, the server stops accepting
// connection requests and closes all the connected connections.
func (s *Server) Stop() {
s.mu.Lock()
listeners := s.lis
s.lis = nil
cs := s.conns
s.conns = nil
s.mu.Unlock()
for lis := range listeners {
lis.Close()
}
for c := range cs {
c.Close()
}
}
// TestingCloseConns closes all exiting transports but keeps s.lis accepting new
// connections. This is for test only now.
func (s *Server) TestingCloseConns() {
s.mu.Lock()
for c := range s.conns {
c.Close()
}
s.conns = make(map[transport.ServerTransport]bool)
s.mu.Unlock()
}
// SendHeader sends header metadata. It may be called at most once from a unary
// RPC handler. The ctx is the RPC handler's Context or one derived from it.
func SendHeader(ctx context.Context, md metadata.MD) error {
if md.Len() == 0 {
return nil
}
stream, ok := transport.StreamFromContext(ctx)
if !ok {
return fmt.Errorf("grpc: failed to fetch the stream from the context %v", ctx)
}
t := stream.ServerTransport()
if t == nil {
grpclog.Fatalf("grpc: SendHeader: %v has no ServerTransport to send header metadata.", stream)
}
return t.WriteHeader(stream, md)
}
// SetTrailer sets the trailer metadata that will be sent when an RPC returns.
// It may be called at most once from a unary RPC handler. The ctx is the RPC
// handler's Context or one derived from it.
func SetTrailer(ctx context.Context, md metadata.MD) error {
if md.Len() == 0 {
return nil
}
stream, ok := transport.StreamFromContext(ctx)
if !ok {
return fmt.Errorf("grpc: failed to fetch the stream from the context %v", ctx)
}
return stream.SetTrailer(md)
}