.

go/internal/xtracing/tracetest/example_test.go

-// Copyright (C) 2018  Nexedi SA and Contributors.
+// Copyright (C) 2018-2020  Nexedi SA and Contributors.
 //                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
@@ -17,6 +17,104 @@
 // See COPYING file for full licensing terms.
 // See https://www.nexedi.com/licensing for rationale and options.
 
+// XXX explain
 package tracetest_test
 
-// TODO example for tracetest usage
+//go:generate gotrace gen .
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"testing"
+
+	"lab.nexedi.com/kirr/go123/tracing"
+	"lab.nexedi.com/kirr/neo/go/internal/xtracing/tracetest"
+)
+
+// hi and hello are functions that emit "(Hi|Hello), <who>" and can be traced.
+
+//trace:event traceHi(who string)
+//trace:event traceHello(who string)
+
+func hi(who string) {
+	traceHi(who)
+	fmt.Println("Hi,", who)
+}
+
+func hello(who string) {
+	traceHello(who)
+	fmt.Println("Hello,", who)
+}
+
+// TestTracetestExample demonstrates how to use tracetest to verify concurrent system with 2 threads.
+func TestTracetestExample(t *testing.T) {
+	type eventHi string
+	type eventHello string
+
+	testf := func(t *tracetest.T) {
+		// setup tracing to deliver trace events to t XXX not to t, but to something dedicated?
+		pg := &tracing.ProbeGroup{}
+		tracing.Lock()
+		traceHi_Attach(pg, func(who string) {
+			// XXX NewEvent? IncomingEvent?
+			t.RxEvent(eventHi(who)) // XXX -> t.OnEvent? not via t?
+		})
+		traceHello_Attach(pg, func(who string) {
+			t.RxEvent(eventHello(who))
+		})
+		tracing.Unlock()
+		defer pg.Done()
+
+		// tell tracetest to which stream an event should go.
+		t.SetEventRouter(func(event interface{}) (stream string) {
+			// it can be only eventHi and eventHello.
+			// in this test the convention is that who comes as <threadID>·...
+			// we used threadID as stream.
+			who := ""
+			switch ev := event.(type) {
+			default:
+				panic(fmt.Sprintf("unexpected event type %T", event))
+			case eventHi:
+				who = string(ev)
+			case eventHello:
+				who = string(ev)
+			}
+
+			i := strings.Index(who, "·")
+			if i == -1 {
+				panic(fmt.Sprintf("who does not have threadID: %q", who))
+			}
+
+			return strings.ToLower(who[:i])
+		})
+
+		// run the workload
+		var wg sync.WaitGroup
+		defer wg.Wait()
+		wg.Add(2)
+
+		go func() { // thread1
+			defer wg.Done()
+			hi("T1·A")
+			hello("T1·B")
+		}()
+
+		go func() { // thread2
+			defer wg.Done()
+			hi("T2·C")
+		}()
+
+		// assert that events come as expected
+		t.Expect("t3", eventHi("T1·C"))
+		t.Expect("t1", eventHi("T1·A"))
+		t.Expect("t1", eventHello("T1·B"))
+
+		// XXX also t.Recv, t.ExpectNoAck ?
+
+		//t1 := t.OnStream("t1")
+		//t1.Expect(eventHi("X·A"))
+	}
+
+	tracetest.Verify(t, testf)
+}

go/internal/xtracing/tracetest/ztrace_x_test.go

+// Code generated by lab.nexedi.com/kirr/go123/tracing/cmd/gotrace; DO NOT EDIT.
+
+package tracetest_test
+// code generated for tracepoints
+
+import (
+	"lab.nexedi.com/kirr/go123/tracing"
+	"unsafe"
+)
+
+// traceevent: traceHello(who string)
+
+type _t_traceHello struct {
+	tracing.Probe
+	probefunc     func(who string)
+}
+
+var _traceHello *_t_traceHello
+
+func traceHello(who string) {
+	if _traceHello != nil {
+		_traceHello_run(who)
+	}
+}
+
+func _traceHello_run(who string) {
+	for p := _traceHello; p != nil; p = (*_t_traceHello)(unsafe.Pointer(p.Next())) {
+		p.probefunc(who)
+	}
+}
+
+func traceHello_Attach(pg *tracing.ProbeGroup, probe func(who string)) *tracing.Probe {
+	p := _t_traceHello{probefunc: probe}
+	tracing.AttachProbe(pg, (**tracing.Probe)(unsafe.Pointer(&_traceHello)), &p.Probe)
+	return &p.Probe
+}
+
+// traceevent: traceHi(who string)
+
+type _t_traceHi struct {
+	tracing.Probe
+	probefunc     func(who string)
+}
+
+var _traceHi *_t_traceHi
+
+func traceHi(who string) {
+	if _traceHi != nil {
+		_traceHi_run(who)
+	}
+}
+
+func _traceHi_run(who string) {
+	for p := _traceHi; p != nil; p = (*_t_traceHi)(unsafe.Pointer(p.Next())) {
+		p.probefunc(who)
+	}
+}
+
+func traceHi_Attach(pg *tracing.ProbeGroup, probe func(who string)) *tracing.Probe {
+	p := _t_traceHi{probefunc: probe}
+	tracing.AttachProbe(pg, (**tracing.Probe)(unsafe.Pointer(&_traceHi)), &p.Probe)
+	return &p.Probe
+}
+
+// trace export signature
+func _trace_exporthash_51bb0086e9435e499919853bae2dbb429f70d833() {}