feat: use singleflight to prevent cache breakdown
This commit is contained in:
Noah Hsu
320
pkg/singleflight/signleflight_test.go
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320
pkg/singleflight/signleflight_test.go
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@ -0,0 +1,320 @@
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// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package singleflight
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import (
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"bytes"
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"errors"
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"fmt"
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"os"
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"os/exec"
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"runtime"
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"runtime/debug"
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"strings"
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"sync"
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"sync/atomic"
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"testing"
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"time"
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)
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func TestDo(t *testing.T) {
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var g Group[string]
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v, err, _ := g.Do("key", func() (string, error) {
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return "bar", nil
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})
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if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
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t.Errorf("Do = %v; want %v", got, want)
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}
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if err != nil {
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t.Errorf("Do error = %v", err)
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}
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}
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func TestDoErr(t *testing.T) {
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var g Group[any]
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someErr := errors.New("Some error")
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v, err, _ := g.Do("key", func() (any, error) {
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return nil, someErr
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})
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if err != someErr {
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t.Errorf("Do error = %v; want someErr %v", err, someErr)
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}
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if v != nil {
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t.Errorf("unexpected non-nil value %#v", v)
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}
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}
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func TestDoDupSuppress(t *testing.T) {
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var g Group[string]
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var wg1, wg2 sync.WaitGroup
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c := make(chan string, 1)
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var calls int32
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fn := func() (string, error) {
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if atomic.AddInt32(&calls, 1) == 1 {
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// First invocation.
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wg1.Done()
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}
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v := <-c
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c <- v // pump; make available for any future calls
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time.Sleep(10 * time.Millisecond) // let more goroutines enter Do
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return v, nil
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}
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const n = 10
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wg1.Add(1)
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for i := 0; i < n; i++ {
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wg1.Add(1)
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wg2.Add(1)
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go func() {
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defer wg2.Done()
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wg1.Done()
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v, err, _ := g.Do("key", fn)
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if err != nil {
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t.Errorf("Do error: %v", err)
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return
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}
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if v != "bar" {
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t.Errorf("Do = %T %v; want %q", v, v, "bar")
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}
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}()
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}
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wg1.Wait()
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// At least one goroutine is in fn now and all of them have at
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// least reached the line before the Do.
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c <- "bar"
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wg2.Wait()
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if got := atomic.LoadInt32(&calls); got <= 0 || got >= n {
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t.Errorf("number of calls = %d; want over 0 and less than %d", got, n)
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}
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}
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// Test that singleflight behaves correctly after Forget called.
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// See https://github.com/golang/go/issues/31420
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func TestForget(t *testing.T) {
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var g Group[any]
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var (
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firstStarted = make(chan struct{})
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unblockFirst = make(chan struct{})
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firstFinished = make(chan struct{})
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)
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go func() {
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g.Do("key", func() (i any, e error) {
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close(firstStarted)
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<-unblockFirst
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close(firstFinished)
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return
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})
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}()
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<-firstStarted
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g.Forget("key")
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unblockSecond := make(chan struct{})
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secondResult := g.DoChan("key", func() (i any, e error) {
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<-unblockSecond
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return 2, nil
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})
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close(unblockFirst)
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<-firstFinished
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thirdResult := g.DoChan("key", func() (i any, e error) {
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return 3, nil
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})
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close(unblockSecond)
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<-secondResult
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r := <-thirdResult
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if r.Val != 2 {
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t.Errorf("We should receive result produced by second call, expected: 2, got %d", r.Val)
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}
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}
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func TestDoChan(t *testing.T) {
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var g Group[string]
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ch := g.DoChan("key", func() (string, error) {
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return "bar", nil
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})
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res := <-ch
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v := res.Val
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err := res.Err
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if got, want := fmt.Sprintf("%v (%T)", v, v), "bar (string)"; got != want {
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t.Errorf("Do = %v; want %v", got, want)
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}
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if err != nil {
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t.Errorf("Do error = %v", err)
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}
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}
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// Test singleflight behaves correctly after Do panic.
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// See https://github.com/golang/go/issues/41133
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func TestPanicDo(t *testing.T) {
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var g Group[any]
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fn := func() (any, error) {
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panic("invalid memory address or nil pointer dereference")
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}
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const n = 5
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waited := int32(n)
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panicCount := int32(0)
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done := make(chan struct{})
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for i := 0; i < n; i++ {
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go func() {
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defer func() {
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if err := recover(); err != nil {
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t.Logf("Got panic: %v\n%s", err, debug.Stack())
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atomic.AddInt32(&panicCount, 1)
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}
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if atomic.AddInt32(&waited, -1) == 0 {
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close(done)
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}
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}()
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g.Do("key", fn)
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}()
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}
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select {
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case <-done:
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if panicCount != n {
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t.Errorf("Expect %d panic, but got %d", n, panicCount)
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}
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case <-time.After(time.Second):
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t.Fatalf("Do hangs")
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}
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}
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func TestGoexitDo(t *testing.T) {
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var g Group[any]
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fn := func() (any, error) {
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runtime.Goexit()
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return nil, nil
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}
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const n = 5
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waited := int32(n)
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done := make(chan struct{})
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for i := 0; i < n; i++ {
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go func() {
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var err error
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defer func() {
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if err != nil {
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t.Errorf("Error should be nil, but got: %v", err)
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}
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if atomic.AddInt32(&waited, -1) == 0 {
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close(done)
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}
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}()
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_, err, _ = g.Do("key", fn)
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}()
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}
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select {
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case <-done:
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case <-time.After(time.Second):
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t.Fatalf("Do hangs")
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}
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}
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func TestPanicDoChan(t *testing.T) {
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if runtime.GOOS == "js" {
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t.Skipf("js does not support exec")
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}
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if os.Getenv("TEST_PANIC_DOCHAN") != "" {
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defer func() {
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recover()
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}()
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g := new(Group[any])
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ch := g.DoChan("", func() (any, error) {
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panic("Panicking in DoChan")
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})
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<-ch
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t.Fatalf("DoChan unexpectedly returned")
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}
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t.Parallel()
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cmd := exec.Command(os.Args[0], "-test.run="+t.Name(), "-test.v")
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cmd.Env = append(os.Environ(), "TEST_PANIC_DOCHAN=1")
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out := new(bytes.Buffer)
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cmd.Stdout = out
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cmd.Stderr = out
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if err := cmd.Start(); err != nil {
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t.Fatal(err)
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}
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err := cmd.Wait()
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t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
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if err == nil {
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t.Errorf("Test subprocess passed; want a crash due to panic in DoChan")
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}
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if bytes.Contains(out.Bytes(), []byte("DoChan unexpectedly")) {
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t.Errorf("Test subprocess failed with an unexpected failure mode.")
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}
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if !bytes.Contains(out.Bytes(), []byte("Panicking in DoChan")) {
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t.Errorf("Test subprocess failed, but the crash isn't caused by panicking in DoChan")
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}
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}
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func TestPanicDoSharedByDoChan(t *testing.T) {
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if runtime.GOOS == "js" {
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t.Skipf("js does not support exec")
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}
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if os.Getenv("TEST_PANIC_DOCHAN") != "" {
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blocked := make(chan struct{})
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unblock := make(chan struct{})
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g := new(Group[any])
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go func() {
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defer func() {
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recover()
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}()
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g.Do("", func() (any, error) {
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close(blocked)
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<-unblock
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panic("Panicking in Do")
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})
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}()
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<-blocked
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ch := g.DoChan("", func() (any, error) {
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panic("DoChan unexpectedly executed callback")
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})
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close(unblock)
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<-ch
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t.Fatalf("DoChan unexpectedly returned")
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}
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t.Parallel()
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cmd := exec.Command(os.Args[0], "-test.run="+t.Name(), "-test.v")
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cmd.Env = append(os.Environ(), "TEST_PANIC_DOCHAN=1")
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out := new(bytes.Buffer)
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cmd.Stdout = out
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cmd.Stderr = out
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if err := cmd.Start(); err != nil {
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t.Fatal(err)
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}
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err := cmd.Wait()
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t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
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if err == nil {
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t.Errorf("Test subprocess passed; want a crash due to panic in Do shared by DoChan")
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}
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if bytes.Contains(out.Bytes(), []byte("DoChan unexpectedly")) {
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t.Errorf("Test subprocess failed with an unexpected failure mode.")
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}
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if !bytes.Contains(out.Bytes(), []byte("Panicking in Do")) {
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t.Errorf("Test subprocess failed, but the crash isn't caused by panicking in Do")
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}
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}
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