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trace: test for main API, fix bugs discovered by them

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This commit is contained in:
Christian Schwarz 2020-05-09 13:47:03 +02:00
parent c5b530669e
commit eaedd17c81
4 changed files with 258 additions and 39 deletions
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122
daemon/logging/trace/trace.go
View File

@ -94,10 +94,11 @@ import (
"context"
"fmt"
"strings"
"sync/atomic"
"time"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
"github.com/zrepl/zrepl/util/chainlock"
)
var metrics struct {
@ -128,16 +129,18 @@ func RegisterMetrics(r prometheus.Registerer) {
var taskNamer = newUniqueTaskNamer(metrics.uniqueConcurrentTaskNameBitvecLength)
type traceNode struct {
id string
annotation string
parentTask *traceNode
activeChildTasks int32 // only for task nodes, insignificant for span nodes
parentSpan *traceNode
hasActiveChildSpan int32
id string
annotation string
parentTask *traceNode
mtx chainlock.L
activeChildTasks int32 // only for task nodes, insignificant for span nodes
parentSpan *traceNode
activeChildSpan *traceNode // nil if task or span doesn't have an active child span
startedAt time.Time
endedAt time.Time
ended int32
}
// Returned from WithTask or WithSpan.
@ -146,6 +149,9 @@ type traceNode struct {
// Wrong call order / forgetting to call it will result in panics.
type DoneFunc func()
var ErrTaskStillHasActiveChildTasks = fmt.Errorf("end task: task still has active child tasks")
var ErrParentTaskAlreadyEnded = fmt.Errorf("create task: parent task already ended")
// Start a new root task or create a child task of an existing task.
//
// This is required when starting a new goroutine and
@ -163,7 +169,7 @@ func WithTask(ctx context.Context, taskName string) (context.Context, DoneFunc)
if nodeI != nil {
node := nodeI.(*traceNode)
if node.parentSpan != nil {
parentTask = node.parentSpan // FIXME review this
parentTask = node.parentTask
} else {
parentTask = node
}
@ -172,20 +178,24 @@ func WithTask(ctx context.Context, taskName string) (context.Context, DoneFunc)
taskName, taskNameDone := taskNamer.UniqueConcurrentTaskName(taskName)
this := &traceNode{
id: genID(),
annotation: taskName,
parentTask: parentTask,
activeChildTasks: 0,
hasActiveChildSpan: 0,
parentSpan: nil,
id: genID(),
annotation: taskName,
parentTask: parentTask,
activeChildTasks: 0,
parentSpan: nil,
activeChildSpan: nil,
startedAt: time.Now(),
ended: 0,
endedAt: time.Time{},
}
if this.parentTask != nil {
atomic.AddInt32(&this.parentTask.activeChildTasks, 1)
this.parentTask.mtx.HoldWhile(func() {
if !this.parentTask.endedAt.IsZero() {
panic(ErrParentTaskAlreadyEnded)
}
this.parentTask.activeChildTasks++
})
}
ctx = context.WithValue(ctx, contextKeyTraceNode, this)
@ -195,19 +205,35 @@ func WithTask(ctx context.Context, taskName string) (context.Context, DoneFunc)
metrics.activeTasks.Inc()
endTaskFunc := func() {
if nc := atomic.LoadInt32(&this.activeChildTasks); nc != 0 {
panic(fmt.Sprintf("this task must have 0 active child tasks, got %v", nc))
}
if !atomic.CompareAndSwapInt32(&this.ended, 0, 1) {
return
}
this.endedAt = time.Now()
if this.parentTask != nil {
if atomic.AddInt32(&this.parentTask.activeChildTasks, -1) < 0 {
panic("parent task with negative activeChildTasks count")
// only hold locks while manipulating the tree
// (trace writer might block too long and unlike spans, tasks are updated concurrently)
alreadyEnded := func() (alreadyEnded bool) {
if this.parentTask != nil {
defer this.parentTask.mtx.Lock().Unlock()
}
defer this.mtx.Lock().Unlock()
if this.activeChildTasks != 0 {
panic(errors.Wrapf(ErrTaskStillHasActiveChildTasks, "end task: %v active child tasks", this.activeChildSpan))
}
// support idempotent task ends
if !this.endedAt.IsZero() {
return true
}
this.endedAt = time.Now()
if this.parentTask != nil {
this.parentTask.activeChildTasks--
if this.parentTask.activeChildTasks < 0 {
panic("impl error: parent task with negative activeChildTasks count")
}
}
return false
}()
if alreadyEnded {
return
}
chrometraceEndTask(this)
@ -220,6 +246,9 @@ func WithTask(ctx context.Context, taskName string) (context.Context, DoneFunc)
return ctx, endTaskFunc
}
var ErrAlreadyActiveChildSpan = fmt.Errorf("create child span: span already has an active child span")
var ErrSpanStillHasActiveChildSpan = fmt.Errorf("end span: span still has active child spans")
// Start a new span.
// Important: ctx must have an active task (see WithTask)
func WithSpan(ctx context.Context, annotation string) (context.Context, DoneFunc) {
@ -237,28 +266,43 @@ func WithSpan(ctx context.Context, annotation string) (context.Context, DoneFunc
}
this := &traceNode{
id: genID(),
annotation: annotation,
parentTask: parentTask,
parentSpan: parentSpan,
hasActiveChildSpan: 0,
id: genID(),
annotation: annotation,
parentTask: parentTask,
parentSpan: parentSpan,
activeChildSpan: nil,
startedAt: time.Now(),
ended: 0,
endedAt: time.Time{},
}
if !atomic.CompareAndSwapInt32(&parentSpan.hasActiveChildSpan, 0, 1) {
panic("already has active child span")
}
parentSpan.mtx.HoldWhile(func() {
if parentSpan.activeChildSpan != nil {
panic(ErrAlreadyActiveChildSpan)
}
parentSpan.activeChildSpan = this
})
ctx = context.WithValue(ctx, contextKeyTraceNode, this)
chrometraceBeginSpan(this)
endTaskFunc := func() {
if !atomic.CompareAndSwapInt32(&parentSpan.hasActiveChildSpan, 1, 0) {
panic("impl error: hasActiveChildSpan should not change to 0 while we hold it")
defer parentSpan.mtx.Lock().Unlock()
if parentSpan.activeChildSpan != this && this.endedAt.IsZero() {
panic("impl error: activeChildSpan should not change while != nil because there can only be one")
}
defer this.mtx.Lock().Unlock()
if this.activeChildSpan != nil {
panic(ErrSpanStillHasActiveChildSpan)
}
if !this.endedAt.IsZero() {
return // support idempotent span ends
}
parentSpan.activeChildSpan = nil
this.endedAt = time.Now()
chrometraceEndSpan(this)

172
daemon/logging/trace/trace_test.go Normal file
View File

@ -0,0 +1,172 @@
package trace
import (
"context"
"fmt"
"testing"
"github.com/gitchander/permutation"
"github.com/pkg/errors"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestRegularSpanUsage(t *testing.T) {
root, endRoot := WithTask(context.Background(), "root")
defer endRoot()
s1, endS1 := WithSpan(root, "parent")
s2, endS2 := WithSpan(s1, "child")
_, endS3 := WithSpan(s2, "grand-child")
require.NotPanics(t, func() { endS3() })
require.NotPanics(t, func() { endS2() })
// reuse
_, endS4 := WithSpan(s1, "child-2")
require.NotPanics(t, func() { endS4() })
// close parent
require.NotPanics(t, func() { endS1() })
}
func TestMultipleActiveChildSpansNotAllowed(t *testing.T) {
root, endRoot := WithTask(context.Background(), "root")
defer endRoot()
s1, _ := WithSpan(root, "s1")
_, endS2 := WithSpan(s1, "s1-child1")
require.PanicsWithValue(t, ErrAlreadyActiveChildSpan, func() {
_, _ = WithSpan(s1, "s1-child2")
})
endS2()
require.NotPanics(t, func() {
_, _ = WithSpan(s1, "s1-child2")
})
}
func TestForkingChildSpansNotAllowed(t *testing.T) {
root, endRoot := WithTask(context.Background(), "root")
defer endRoot()
s1, _ := WithSpan(root, "s1")
sc, endSC := WithSpan(s1, "s1-child")
_, _ = WithSpan(sc, "s1-child-child")
require.PanicsWithValue(t, ErrSpanStillHasActiveChildSpan, func() {
endSC()
})
}
func TestRegularTaskUsage(t *testing.T) {
// assert concurrent activities on different tasks can end in any order
closeOrder := []int{0, 1, 2}
closeOrders := permutation.New(permutation.IntSlice(closeOrder))
for closeOrders.Next() {
t.Run(fmt.Sprintf("%v", closeOrder), func(t *testing.T) {
root, endRoot := WithTask(context.Background(), "root")
defer endRoot()
c1, endC1 := WithTask(root, "c1")
defer endC1()
c2, endC2 := WithTask(root, "c2")
defer endC2()
// begin 3 concurrent activities
_, endAR := WithSpan(root, "aR")
_, endAC1 := WithSpan(c1, "aC1")
_, endAC2 := WithSpan(c2, "aC2")
endFuncs := []DoneFunc{endAR, endAC1, endAC2}
for _, i := range closeOrder {
require.NotPanics(t, func() {
endFuncs[i]()
}, "%v", i)
}
})
}
}
func TestTaskEndWithActiveChildTaskNotAllowed(t *testing.T) {
root, _ := WithTask(context.Background(), "root")
c, endC := WithTask(root, "child")
_, _ = WithTask(c, "grand-child")
func() {
defer func() {
r := recover()
require.NotNil(t, r)
err, ok := r.(error)
require.True(t, ok)
require.Equal(t, ErrTaskStillHasActiveChildTasks, errors.Cause(err))
}()
endC()
}()
}
func TestIdempotentEndTask(t *testing.T) {
_, end := WithTask(context.Background(), "root")
end()
require.NotPanics(t, func() { end() })
}
func TestCannotReuseEndedTask(t *testing.T) {
root, end := WithTask(context.Background(), "root")
end()
require.PanicsWithValue(t, ErrParentTaskAlreadyEnded, func() { WithTask(root, "child-after-parent-ended") })
}
func TestSpansPanicIfNoParentTask(t *testing.T) {
require.Panics(t, func() { WithSpan(context.Background(), "taskless-span") })
}
func TestIdempotentEndSpan(t *testing.T) {
root, _ := WithTask(context.Background(), "root")
_, end := WithSpan(root, "span")
end()
require.NotPanics(t, func() { end() })
}
func logAndGetTraceNode(t *testing.T, descr string, ctx context.Context) *traceNode {
n, ok := ctx.Value(contextKeyTraceNode).(*traceNode)
require.True(t, ok)
t.Logf("% 20s %p %#v", descr, n, n)
return n
}
func TestWhiteboxHierachy(t *testing.T) {
root, e1 := WithTask(context.Background(), "root")
rootN := logAndGetTraceNode(t, "root", root)
assert.Nil(t, rootN.parentTask)
assert.Nil(t, rootN.parentSpan)
child, e2 := WithSpan(root, "child")
childN := logAndGetTraceNode(t, "child", child)
assert.Equal(t, rootN, childN.parentTask)
assert.Equal(t, rootN, childN.parentSpan)
grandchild, e3 := WithSpan(child, "grandchild")
grandchildN := logAndGetTraceNode(t, "grandchild", grandchild)
assert.Equal(t, rootN, grandchildN.parentTask)
assert.Equal(t, childN, grandchildN.parentSpan)
gcTask, e4 := WithTask(grandchild, "grandchild-task")
gcTaskN := logAndGetTraceNode(t, "grandchild-task", gcTask)
assert.Equal(t, rootN, gcTaskN.parentTask)
assert.Nil(t, gcTaskN.parentSpan)
// it is allowed that a child task outlives the _span_ in which it was created
// (albeit not its parent task)
e3()
e2()
gcTaskSpan, e5 := WithSpan(gcTask, "granschild-task-span")
gcTaskSpanN := logAndGetTraceNode(t, "granschild-task-span", gcTaskSpan)
assert.Equal(t, gcTaskN, gcTaskSpanN.parentTask)
assert.Equal(t, gcTaskN, gcTaskSpanN.parentSpan)
e5()
e4()
e1()
}

1
go.mod
View File

@ -5,6 +5,7 @@ go 1.12
require (
github.com/fatih/color v1.7.0
github.com/gdamore/tcell v1.2.0
github.com/gitchander/permutation v0.0.0-20181107151852-9e56b92e9909
github.com/go-logfmt/logfmt v0.4.0
github.com/go-sql-driver/mysql v1.4.1-0.20190907122137-b2c03bcae3d4
github.com/golang/protobuf v1.3.2

2
go.sum
View File

@ -40,6 +40,8 @@ github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdk
github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
github.com/gdamore/tcell v1.2.0 h1:ikixzsxc8K8o3V2/CEmyoEW8mJZaNYQQ3NP3VIQdUe4=
github.com/gdamore/tcell v1.2.0/go.mod h1:Hjvr+Ofd+gLglo7RYKxxnzCBmev3BzsS67MebKS4zMM=
github.com/gitchander/permutation v0.0.0-20181107151852-9e56b92e9909 h1:9NC8seTx6/zRmMTAdsHj/uOMi0EGHGQtjyLafBjk77Q=
github.com/gitchander/permutation v0.0.0-20181107151852-9e56b92e9909/go.mod h1:lP+DW8LR6Rw3ru9Vo2/y/3iiLaLWmofYql/va+7zJOk=
github.com/go-critic/go-critic v0.3.4/go.mod h1:AHR42Lk/E/aOznsrYdMYeIQS5RH10HZHSqP+rD6AJrc=
github.com/go-critic/go-critic v0.3.5-0.20190526074819-1df300866540/go.mod h1:+sE8vrLDS2M0pZkBk0wy6+nLdKexVDrl/jBqQOTDThA=
github.com/go-kit/kit v0.8.0/go.mod h1:xBxKIO96dXMWWy0MnWVtmwkA9/13aqxPnvrjFYMA2as=