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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package memoize_test
import (
"context"
"sync"
"testing"
"time"
"golang.org/x/tools/internal/memoize"
)
func TestGet(t *testing.T) {
var store memoize.Store
evaled := 0
h, release := store.Promise("key", func(context.Context, interface{}) interface{} {
evaled++
return "res"
})
defer release()
expectGet(t, h, "res")
expectGet(t, h, "res")
if evaled != 1 {
t.Errorf("got %v calls to function, wanted 1", evaled)
}
}
func expectGet(t *testing.T, h *memoize.Promise, wantV interface{}) {
t.Helper()
gotV, gotErr := h.Get(context.Background(), nil)
if gotV != wantV || gotErr != nil {
t.Fatalf("Get() = %v, %v, wanted %v, nil", gotV, gotErr, wantV)
}
}
func TestNewPromise(t *testing.T) {
calls := 0
f := func(context.Context, interface{}) interface{} {
calls++
return calls
}
// All calls to Get on the same promise return the same result.
p1 := memoize.NewPromise("debug", f)
expectGet(t, p1, 1)
expectGet(t, p1, 1)
// A new promise calls the function again.
p2 := memoize.NewPromise("debug", f)
expectGet(t, p2, 2)
expectGet(t, p2, 2)
// The original promise is unchanged.
expectGet(t, p1, 1)
}
func TestStoredPromiseRefCounting(t *testing.T) {
var store memoize.Store
v1 := false
v2 := false
p1, release1 := store.Promise("key1", func(context.Context, interface{}) interface{} {
return &v1
})
p2, release2 := store.Promise("key2", func(context.Context, interface{}) interface{} {
return &v2
})
expectGet(t, p1, &v1)
expectGet(t, p2, &v2)
expectGet(t, p1, &v1)
expectGet(t, p2, &v2)
p2Copy, release2Copy := store.Promise("key2", func(context.Context, interface{}) interface{} {
return &v1
})
if p2 != p2Copy {
t.Error("Promise returned a new value while old is not destroyed yet")
}
expectGet(t, p2Copy, &v2)
release2()
if got, want := v2, false; got != want {
t.Errorf("after destroying first v2 ref, got %v, want %v", got, want)
}
release2Copy()
if got, want := v1, false; got != want {
t.Errorf("after destroying v2, got %v, want %v", got, want)
}
release1()
p2Copy, release2Copy = store.Promise("key2", func(context.Context, interface{}) interface{} {
return &v2
})
if p2 == p2Copy {
t.Error("Promise returned previously destroyed value")
}
release2Copy()
}
func TestPromiseDestroyedWhileRunning(t *testing.T) {
// Test that calls to Promise.Get return even if the promise is destroyed while running.
var store memoize.Store
c := make(chan int)
var v int
h, release := store.Promise("key", func(ctx context.Context, _ interface{}) interface{} {
<-c
<-c
if err := ctx.Err(); err != nil {
t.Errorf("ctx.Err() = %v, want nil", err)
}
return &v
})
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second) // arbitrary timeout; may be removed if it causes flakes
defer cancel()
var wg sync.WaitGroup
wg.Add(1)
var got interface{}
var err error
go func() {
got, err = h.Get(ctx, nil)
wg.Done()
}()
c <- 0 // send once to enter the promise function
release() // release before the promise function returns
c <- 0 // let the promise function proceed
wg.Wait()
if err != nil {
t.Errorf("Get() failed: %v", err)
}
if got != &v {
t.Errorf("Get() = %v, want %v", got, v)
}
}
func TestDoubleReleasePanics(t *testing.T) {
var store memoize.Store
_, release := store.Promise("key", func(ctx context.Context, _ interface{}) interface{} { return 0 })
panicked := false
func() {
defer func() {
if recover() != nil {
panicked = true
}
}()
release()
release()
}()
if !panicked {
t.Errorf("calling release() twice did not panic")
}
}
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