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// Copyright (C) 2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package caching
import (
"context"
"runtime/debug"
"testing"
"time"
"github.com/datawire/dlib/dlog"
"github.com/stretchr/testify/assert"
)
func TestLRUBlocking(t *testing.T) {
t.Parallel()
const tick = time.Second / 2
ctx := dlog.NewTestContext(t, false)
cache := NewLRUCache[int, int](4,
FuncSource[int, int](func(_ context.Context, k int, v *int) { *v = k * k }))
assert.Equal(t, 1, *cache.Acquire(ctx, 1))
assert.Equal(t, 4, *cache.Acquire(ctx, 2))
assert.Equal(t, 9, *cache.Acquire(ctx, 3))
assert.Equal(t, 16, *cache.Acquire(ctx, 4))
ch := make(chan int)
start := time.Now()
go func() {
ch <- *cache.Acquire(ctx, 5)
}()
go func() {
time.Sleep(tick)
cache.Release(3)
}()
result := <-ch
dur := time.Since(start)
assert.Equal(t, 25, result)
assert.Greater(t, dur, tick)
}
//nolint:paralleltest // Can't be parallel because we test testing.AllocsPerRun.
func TestLRUAllocs(t *testing.T) {
const (
cacheLen = 8
bigNumber = 128
)
ctx := dlog.NewTestContext(t, false)
evictions := 0
cache := NewLRUCache[int, int](cacheLen, FuncSource[int, int](func(_ context.Context, k int, v *int) {
if *v > 0 {
evictions++
}
*v = k
}))
i := 1
store := func() {
cache.Acquire(ctx, i)
cache.Release(i)
i++
}
// Disable the GC temporarily to prevent cache.byAge.pool from
// being cleaned in the middle of an AllocsPerRun and causing
// spurious allocations.
percent := debug.SetGCPercent(-1)
defer debug.SetGCPercent(percent)
// 1 alloc each as we fill the cache
assert.Equal(t, float64(1), testing.AllocsPerRun(cacheLen-1, store))
assert.Equal(t, 0, evictions)
// after that, it should be alloc-free
assert.Equal(t, float64(0), testing.AllocsPerRun(1, store))
assert.Equal(t, 2, evictions)
assert.Equal(t, float64(0), testing.AllocsPerRun(bigNumber, store))
assert.Equal(t, 3+bigNumber, evictions)
// check the len
assert.Equal(t, cacheLen, len(cache.(*lruCache[int, int]).byName))
cnt := 0
for entry := cache.(*lruCache[int, int]).evictable.Oldest(); entry != nil; entry = entry.Newer() {
cnt++
}
assert.Equal(t, cacheLen, cnt)
// check contents
cnt = 0
for j := i - 1; j > 0; j-- {
entry, ok := cache.(*lruCache[int, int]).byName[j]
if cnt < cacheLen {
if assert.True(t, ok, j) {
val := entry.Value.val
assert.Equal(t, j, val, j)
}
cnt++
} else {
assert.False(t, ok, j)
}
}
}
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