containers: Add my own ARC implementation

I really want an OnEvict callback.

1 files changed, 78 insertions, 0 deletions

diff --git a/lib/containers/arcache_string_test.go b/lib/containers/arcache_string_test.go
new file mode 100644
index 0000000..b72b21b
--- /dev/null
+++ b/lib/containers/arcache_string_test.go
@@ -0,0 +1,78 @@
+// Copyright (C) 2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package containers
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func (c *ARCache[K, V]) String() string {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	keys := make([]string, 0, c.fullLen())
+	for entry := c.recentGhost.byAge.oldest; entry != nil; entry = entry.newer {
+		keys = append(keys, fmt.Sprint(entry.Value.key))
+	}
+	for entry := c.recentLive.byAge.oldest; entry != nil; entry = entry.newer {
+		keys = append(keys, fmt.Sprint(entry.Value.key))
+	}
+	for entry := c.frequentLive.byAge.newest; entry != nil; entry = entry.older {
+		keys = append(keys, fmt.Sprint(entry.Value.key))
+	}
+	for entry := c.frequentGhost.byAge.newest; entry != nil; entry = entry.older {
+		keys = append(keys, fmt.Sprint(entry.Value.key))
+	}
+
+	keyLen := 3
+	for _, key := range keys {
+		keyLen = max(keyLen, len(key))
+	}
+
+	var out strings.Builder
+	blankLeft := c.MaxLen - c.recentLen()
+	for i := 0; i <= 2*c.MaxLen; i++ {
+		sep := []byte("    ")
+		if i == blankLeft+c.recentGhost.Len() {
+			sep[0] = '['
+		}
+		if i == blankLeft+c.recentGhost.Len()+c.recentLive.Len() {
+			sep[1] = '!'
+		}
+		if i == blankLeft+c.recentGhost.Len()+c.recentLive.Len()-c.recentLiveTarget {
+			sep[2] = '^'
+		}
+		if i == blankLeft+c.recentGhost.Len()+c.recentLive.Len()+c.frequentLive.Len() {
+			sep[3] = ']'
+		}
+		out.Write(sep)
+
+		if i < 2*c.MaxLen {
+			key := ""
+			if i >= blankLeft && i < blankLeft+c.fullLen() {
+				key = keys[i-blankLeft]
+			}
+			spaceLeft := (keyLen - len(key)) / 2
+			out.WriteString(strings.Repeat("_", spaceLeft))
+			out.WriteString(key)
+			out.WriteString(strings.Repeat("_", keyLen-len(key)-spaceLeft))
+		}
+	}
+
+	return out.String()
+}
+
+func TestARCacheString(t *testing.T) {
+	t.Parallel()
+	cache := &ARCache[int, int]{
+		MaxLen: 4,
+	}
+
+	assert.Equal(t, `    ___    ___    ___    ___[!^]___    ___    ___    ___    `, cache.String())
+}