1 files changed, 106 insertions, 0 deletions
diff --git a/lib/caching/lrucache_test.go b/lib/caching/lrucache_test.go
new file mode 100644
index 0000000..a9d4fe0
--- /dev/null
+++ b/lib/caching/lrucache_test.go
@@ -0,0 +1,106 @@
+// 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)
+		}
+	}
+}