// Handle takes an inbound Request, unmarshals it, dispatches it to the handler, and serialises the result as a
// Response. Note that the response may be nil.
func (e Endpoint) Handle(req mercury.Request) (rsp mercury.Response, err error) {
// Unmarshal the request body (unless there already is one)
if req.Body() == nil && e.Request != nil {
if um := e.unmarshaler(req); um != nil {
if werr := terrors.Wrap(um.UnmarshalPayload(req), nil); werr != nil {
log.Warnf("[Mercury:Server] Cannot unmarshal request payload: %v", werr)
terr := werr.(*terrors.Error)
terr.Code = terrors.ErrBadRequest
rsp, err = nil, terr
return
}
}
}
defer func() {
if v := recover(); v != nil {
traceVerbose := make([]byte, 1024)
runtime.Stack(traceVerbose, true)
log.Criticalf("[Mercury:Server] Recovered from handler panic for request %s:\n%v\n%s", req.Id(), v,
string(traceVerbose))
rsp, err = nil, terrors.InternalService("panic", fmt.Sprintf("Panic in handler %s:\n%s", req.Endpoint(),
string(traceVerbose)), nil)
}
}()
rsp, err = e.Handler(req)
return
}
// ErrorResponse constructs a response for the given request, with the given error as its contents. Mercury clients
// know how to unmarshal these errors.
func ErrorResponse(req mercury.Request, err error) mercury.Response {
rsp := req.Response(nil)
var terr *terrors.Error
if err != nil {
terr = terrors.Wrap(err, nil).(*terrors.Error)
}
rsp.SetBody(terrors.Marshal(terr))
if err := tmsg.ProtoMarshaler().MarshalBody(rsp); err != nil {
log.Errorf("[Mercury:Server] Failed to marshal error response: %v", err)
return nil // Not much we can do here
}
rsp.SetIsError(true)
return rsp
}
func (c *client) Add(cl Call) Client {
cc := clientCall{
uid: cl.Uid,
rspProto: cl.Response,
}
req, err := cl.Request()
if err != nil {
cc.err = terrors.Wrap(err, nil).(*terrors.Error)
} else {
cc.req = req
}
c.addCall(cc)
return c
}
// performCall executes a single Call, unmarshals the response (if there is a response proto), and pushes the updted
// clientCall down the response channel
func (c *client) performCall(call clientCall, middleware []ClientMiddleware, trans transport.Transport,
timeout time.Duration, completion chan<- clientCall) {
req := call.req
// Ensure we have a request ID before the request middleware is executed
if id := req.Id(); id == "" {
_uuid, err := uuid.NewV4()
if err != nil {
log.Errorf("[Mercury:Client] Failed to generate request uuid: %v", err)
call.err = terrors.Wrap(err, nil).(*terrors.Error)
completion <- call
return
}
req.SetId(_uuid.String())
}
// Apply request middleware
for _, md := range middleware {
req = md.ProcessClientRequest(req)
}
log.Debugf("[Mercury:Client] Sending request to %s/%s…", req.Service(), req.Endpoint())
rsp_, err := trans.Send(req, timeout)
if err != nil {
call.err = terrors.Wrap(err, nil).(*terrors.Error)
} else if rsp_ != nil {
rsp := mercury.FromTyphonResponse(rsp_)
// Servers set header Content-Error: 1 when sending errors. For those requests, unmarshal the error, leaving the
// call's response nil
if rsp.IsError() {
errRsp := rsp.Copy()
if unmarshalErr := c.unmarshaler(rsp, &tperrors.Error{}).UnmarshalPayload(errRsp); unmarshalErr != nil {
call.err = terrors.WrapWithCode(unmarshalErr, nil, terrors.ErrBadResponse).(*terrors.Error)
} else {
err := errRsp.Body().(*tperrors.Error)
call.err = terrors.Unmarshal(err)
}
// Set the response Body to a nil – but typed – interface to avoid type conversion panics if Body
// properties are accessed in spite of the error
// Relevant: http://golang.org/doc/faq#nil_error
if call.rspProto != nil {
bodyT := reflect.TypeOf(call.rspProto)
rsp.SetBody(reflect.New(bodyT.Elem()).Interface())
}
} else if call.rspProto != nil {
rsp.SetBody(call.rspProto)
if err := c.unmarshaler(rsp, call.rspProto).UnmarshalPayload(rsp); err != nil {
call.err = terrors.WrapWithCode(err, nil, terrors.ErrBadResponse).(*terrors.Error)
}
}
call.rsp = rsp
}
// Apply response/error middleware (in reverse order)
for i := len(middleware) - 1; i >= 0; i-- {
mw := middleware[i]
if call.err != nil {
mw.ProcessClientError(call.err, call.req)
} else {
call.rsp = mw.ProcessClientResponse(call.rsp, call.req)
}
}
completion <- call
}