func main() {
// Create a new TChannel for handling requests
ch, err := tchannel.NewChannel("PingService", &tchannel.ChannelOptions{Logger: tchannel.SimpleLogger})
if err != nil {
log.Fatalf("Could not create new channel: %v", err)
}
// Register a handler for the ping message on the PingService
json.Register(ch, json.Handlers{
"ping": pingHandler,
}, onError)
// Listen for incoming requests
listenAndHandle(ch, "127.0.0.1:10500")
// Create a new TChannel for sending requests.
client, err := tchannel.NewChannel("ping-client", nil)
if err != nil {
log.Fatalf("Could not create new client channel: %v", err)
}
// Make a call to ourselves, with a timeout of 10s
ctx, cancel := json.NewContext(time.Second * 10)
defer cancel()
peer := client.Peers().Add(ch.PeerInfo().HostPort)
var pong Pong
if err := json.CallPeer(ctx, peer, "PingService", "ping", &Ping{"Hello World"}, &pong); err != nil {
log.Fatalf("json.Call failed: %v", err)
}
log.Infof("Received pong: %s", pong.Message)
// Create a new subchannel for the top-level channel
subCh := ch.GetSubChannel("PingServiceOther")
// Register a handler on the subchannel
json.Register(subCh, json.Handlers{
"pingOther": pingOtherHandler,
}, onError)
// Try to send a message to the Service:Operation pair for the subchannel
if err := json.CallPeer(ctx, peer, "PingServiceOther", "pingOther", &Ping{"Hello Other World"}, &pong); err != nil {
log.Fatalf("json.Call failed: %v", err)
}
log.Infof("Received pong: %s", pong.Message)
}
func TestTracingPropagates(t *testing.T) {
WithVerifiedServer(t, nil, func(ch *Channel, hostPort string) {
handler := &traceHandler{t: t, ch: ch}
json.Register(ch, json.Handlers{
"call": handler.call,
}, handler.onError)
ctx, cancel := json.NewContext(time.Second)
defer cancel()
peer := ch.Peers().GetOrAdd(ch.PeerInfo().HostPort)
var response TracingResponse
require.NoError(t, json.CallPeer(ctx, peer, ch.PeerInfo().ServiceName, "call", &TracingRequest{
ForwardCount: 1,
}, &response))
clientSpan := CurrentSpan(ctx)
require.NotNil(t, clientSpan)
assert.Equal(t, uint64(0), clientSpan.ParentID())
assert.Equal(t, uint64(0), clientSpan.ParentID())
assert.NotEqual(t, uint64(0), clientSpan.TraceID())
assert.Equal(t, clientSpan.TraceID(), response.TraceID)
assert.Equal(t, clientSpan.SpanID(), response.ParentID)
assert.Equal(t, response.TraceID, response.SpanID, "traceID = spanID for root span")
nestedResponse := response.Child
require.NotNil(t, nestedResponse)
assert.Equal(t, clientSpan.TraceID(), nestedResponse.TraceID)
assert.Equal(t, response.SpanID, nestedResponse.ParentID)
assert.NotEqual(t, response.SpanID, nestedResponse.SpanID)
})
}
func (h *traceHandler) call(ctx json.Context, req *TracingRequest) (*TracingResponse, error) {
span := CurrentSpan(ctx)
if span == nil {
return nil, fmt.Errorf("tracing not found")
}
var childResp *TracingResponse
if req.ForwardCount > 0 {
sc := h.ch.Peers().GetOrAdd(h.ch.PeerInfo().HostPort)
childResp = new(TracingResponse)
require.NoError(h.t, json.CallPeer(ctx, sc, h.ch.PeerInfo().ServiceName, "call", nil, childResp))
}
return &TracingResponse{
TraceID: span.TraceID(),
SpanID: span.SpanID(),
ParentID: span.ParentID(),
Child: childResp,
}, nil
}