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// Copyright 2022 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 bcache
import (
"fmt"
"runtime"
"sync"
"sync/atomic"
"testing"
)
var registeredCache Cache[int, int32]
func init() {
registeredCache.Register()
}
var seq atomic.Uint32
func next[T int | int32]() *T {
x := new(T)
*x = T(seq.Add(1))
return x
}
func str[T int | int32](x *T) string {
if x == nil {
return "nil"
}
return fmt.Sprint(*x)
}
func TestCache(t *testing.T) {
// Use unregistered cache for functionality tests,
// to keep the runtime from clearing behind our backs.
c := new(Cache[int, int32])
// Create many entries.
m := make(map[*int]*int32)
for i := 0; i < 10000; i++ {
k := next[int]()
v := next[int32]()
m[k] = v
c.Put(k, v)
}
// Overwrite a random 20% of those.
n := 0
for k := range m {
v := next[int32]()
m[k] = v
c.Put(k, v)
if n++; n >= 2000 {
break
}
}
// Check results.
for k, v := range m {
if cv := c.Get(k); cv != v {
t.Fatalf("c.Get(%v) = %v, want %v", str(k), str(cv), str(v))
}
}
c.Clear()
for k := range m {
if cv := c.Get(k); cv != nil {
t.Fatalf("after GC, c.Get(%v) = %v, want nil", str(k), str(cv))
}
}
// Check that registered cache is cleared at GC.
c = ®isteredCache
for k, v := range m {
c.Put(k, v)
}
runtime.GC()
for k := range m {
if cv := c.Get(k); cv != nil {
t.Fatalf("after Clear, c.Get(%v) = %v, want nil", str(k), str(cv))
}
}
// Check that cache works for concurrent access.
// Lists are discarded if they reach 1000 entries,
// and there are cacheSize list heads, so we should be
// able to do 100 * cacheSize entries with no problem at all.
c = new(Cache[int, int32])
var barrier, wg sync.WaitGroup
const N = 100
barrier.Add(N)
wg.Add(N)
var lost int32
for i := 0; i < N; i++ {
go func() {
defer wg.Done()
m := make(map[*int]*int32)
for j := 0; j < cacheSize; j++ {
k, v := next[int](), next[int32]()
m[k] = v
c.Put(k, v)
}
barrier.Done()
barrier.Wait()
for k, v := range m {
if cv := c.Get(k); cv != v {
t.Errorf("c.Get(%v) = %v, want %v", str(k), str(cv), str(v))
atomic.AddInt32(&lost, +1)
}
}
}()
}
wg.Wait()
if lost != 0 {
t.Errorf("lost %d entries", lost)
}
}
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