LRU upgrade (#785)

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## Short description of the changes

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cache/lru/lru.go

@@ -5,60 +5,83 @@ import (
 	"context"
 
 	"github.com/beatlabs/patron/cache"
-	lru "github.com/hashicorp/golang-lru"
+	lru "github.com/hashicorp/golang-lru/v2"
 	"go.opentelemetry.io/otel/attribute"
 )
 
 var (
-	_            cache.Cache = &Cache{}
-	lruAttribute             = attribute.String("cache.type", "lru")
+	lruAttribute      = attribute.String("cache.type", "lru")
+	lruEvictAttribute = attribute.String("cache.type", "lru-evict")
 )
 
 // Cache encapsulates a thread-safe fixed size LRU cache.
-type Cache struct {
-	cache            *lru.Cache
+type Cache[k comparable, v any] struct {
+	cache            *lru.Cache[k, v]
 	useCaseAttribute attribute.KeyValue
+	typeAttribute    attribute.KeyValue
 }
 
 // New returns a new LRU cache that can hold 'size' number of keys at a time.
-func New(size int, useCase string) (*Cache, error) {
+func New[k comparable, v any](size int, useCase string) (*Cache[k, v], error) {
 	cache.SetupMetricsOnce()
-	chc, err := lru.New(size)
+	chc, err := lru.New[k, v](size)
 	if err != nil {
 		return nil, err
 	}
 
-	return &Cache{
+	return newFunction(chc, lruAttribute, cache.UseCaseAttribute(useCase)), nil
+}
+
+// NewWithEvict returns a new LRU cache that can hold 'size' number of keys at a time.
+func NewWithEvict[k comparable, v any](size int, useCase string, onEvict func(k, v)) (*Cache[k, v], error) {
+	cache.SetupMetricsOnce()
+
+	chc, err := lru.NewWithEvict[k, v](size, func(key k, value v) {
+		onEvict(key, value)
+		cache.ObserveEviction(context.Background(), lruEvictAttribute, cache.UseCaseAttribute(useCase))
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return newFunction(chc, lruEvictAttribute, cache.UseCaseAttribute(useCase)), nil
+}
+
+func newFunction[k comparable, v any](chc *lru.Cache[k, v], typeAttr attribute.KeyValue,
+	useCaseAttr attribute.KeyValue,
+) *Cache[k, v] {
+	return &Cache[k, v]{
 		cache:            chc,
-		useCaseAttribute: cache.UseCaseAttribute(useCase),
-	}, nil
+		typeAttribute:    typeAttr,
+		useCaseAttribute: useCaseAttr,
+	}
 }
 
 // Get executes a lookup and returns whether a key exists in the cache along with its value.
-func (c *Cache) Get(ctx context.Context, key string) (interface{}, bool, error) {
+func (c *Cache[k, v]) Get(ctx context.Context, key k) (interface{}, bool, error) {
 	value, ok := c.cache.Get(key)
 	if !ok {
-		cache.ObserveMiss(ctx, lruAttribute, c.useCaseAttribute)
+		cache.ObserveMiss(ctx, lruAttribute, c.useCaseAttribute, c.typeAttribute)
 		return nil, false, nil
 	}
-	cache.ObserveHit(ctx, lruAttribute, c.useCaseAttribute)
+	cache.ObserveHit(ctx, lruAttribute, c.useCaseAttribute, c.typeAttribute)
 	return value, true, nil
 }
 
 // Purge evicts all keys present in the cache.
-func (c *Cache) Purge(_ context.Context) error {
+func (c *Cache[k, v]) Purge(_ context.Context) error {
 	c.cache.Purge()
 	return nil
 }
 
 // Remove evicts a specific key from the cache.
-func (c *Cache) Remove(_ context.Context, key string) error {
+func (c *Cache[k, v]) Remove(_ context.Context, key k) error {
 	c.cache.Remove(key)
 	return nil
 }
 
 // Set registers a key-value pair to the cache.
-func (c *Cache) Set(_ context.Context, key string, value interface{}) error {
+func (c *Cache[k, v]) Set(_ context.Context, key k, value v) error {
 	c.cache.Add(key, value)
 	return nil
 }

cache/lru/lru_test.go

@@ -21,7 +21,32 @@ func TestNew(t *testing.T) {
 
 	for name, tt := range tests {
 		t.Run(name, func(t *testing.T) {
-			c, err := New(tt.size, "test")
+			c, err := New[string, string](tt.size, "test")
+			if tt.wantErr {
+				assert.Nil(t, c)
+				assert.EqualError(t, err, tt.err)
+			} else {
+				assert.NotNil(t, c)
+				require.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestNewWithEvict(t *testing.T) {
+	tests := map[string]struct {
+		err     string
+		size    int
+		wantErr bool
+	}{
+		"negative size": {size: -1, wantErr: true, err: "must provide a positive size"},
+		"zero size":     {size: 0, wantErr: true, err: "must provide a positive size"},
+		"positive size": {size: 1024, wantErr: false},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			c, err := NewWithEvict[string, string](tt.size, "test", func(_, _ string) {})
 			if tt.wantErr {
 				assert.Nil(t, c)
 				assert.EqualError(t, err, tt.err)
@@ -34,7 +59,7 @@ func TestNew(t *testing.T) {
 }
 
 func TestCacheOperations(t *testing.T) {
-	c, err := New(10, "test")
+	c, err := NewWithEvict[string, string](10, "test", func(_, _ string) {})
 	assert.NotNil(t, c)
 	require.NoError(t, err)
 
@@ -80,3 +105,20 @@ func TestCacheOperations(t *testing.T) {
 		assert.Equal(t, 0, c.cache.Len())
 	})
 }
+
+func BenchmarkCache(b *testing.B) {
+	c, err := NewWithEvict[int, int](b.N, "test", func(_, _ int) {})
+	require.NoError(b, err)
+
+	ctx := context.Background()
+	for i := 0; i < b.N; i++ {
+		err = c.Set(ctx, i, i)
+		require.NoError(b, err)
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, _, err = c.Get(ctx, i)
+		require.NoError(b, err)
+	}
+}

cache/metric.go

@@ -12,10 +12,11 @@ import (
 const packageName = "cache"
 
 var (
-	cashHitAttribute  = attribute.String("cache.status", "hit")
-	cashMissAttribute = attribute.String("cache.status", "miss")
-	cacheCounter      metric.Int64Counter
-	cacheOnce         sync.Once
+	cacheHitAttribute   = attribute.String("cache.status", "hit")
+	cacheMissAttribute  = attribute.String("cache.status", "miss")
+	cacheEvictAttribute = attribute.String("cache.status", "evict")
+	cacheCounter        metric.Int64Counter
+	cacheOnce           sync.Once
 )
 
 // SetupMetricsOnce initializes the cache counter.
@@ -32,12 +33,17 @@ func UseCaseAttribute(useCase string) attribute.KeyValue {
 
 // ObserveHit increments the cache hit counter.
 func ObserveHit(ctx context.Context, attrs ...attribute.KeyValue) {
-	attrs = append(attrs, cashHitAttribute)
+	attrs = append(attrs, cacheHitAttribute)
 	cacheCounter.Add(ctx, 1, metric.WithAttributes(attrs...))
 }
 
 // ObserveMiss increments the cache miss counter.
 func ObserveMiss(ctx context.Context, attrs ...attribute.KeyValue) {
-	attrs = append(attrs, cashMissAttribute)
+	attrs = append(attrs, cacheMissAttribute)
+	cacheCounter.Add(ctx, 1, metric.WithAttributes(attrs...))
+}
+
+func ObserveEviction(ctx context.Context, attrs ...attribute.KeyValue) {
+	attrs = append(attrs, cacheEvictAttribute)
 	cacheCounter.Add(ctx, 1, metric.WithAttributes(attrs...))
 }

go.mod

@@ -16,7 +16,7 @@ require (
 	github.com/elastic/go-elasticsearch/v8 v8.16.0
 	github.com/go-sql-driver/mysql v1.8.1
 	github.com/google/uuid v1.6.0
-	github.com/hashicorp/golang-lru v1.0.2
+	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/rabbitmq/amqp091-go v1.10.0
 	github.com/redis/go-redis/extra/redisotel/v9 v9.7.0
 	github.com/redis/go-redis/v9 v9.7.0

go.sum

@@ -94,8 +94,8 @@ github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9
 github.com/hashicorp/go-uuid v1.0.2/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
 github.com/hashicorp/go-uuid v1.0.3 h1:2gKiV6YVmrJ1i2CKKa9obLvRieoRGviZFL26PcT/Co8=
 github.com/hashicorp/go-uuid v1.0.3/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
-github.com/hashicorp/golang-lru v1.0.2 h1:dV3g9Z/unq5DpblPpw+Oqcv4dU/1omnb4Ok8iPY6p1c=
-github.com/hashicorp/golang-lru v1.0.2/go.mod h1:iADmTwqILo4mZ8BN3D2Q6+9jd8WM5uGBxy+E8yxSoD4=
+github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
+github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
 github.com/jcmturner/aescts/v2 v2.0.0 h1:9YKLH6ey7H4eDBXW8khjYslgyqG2xZikXP0EQFKrle8=
 github.com/jcmturner/aescts/v2 v2.0.0/go.mod h1:AiaICIRyfYg35RUkr8yESTqvSy7csK90qZ5xfvvsoNs=
 github.com/jcmturner/dnsutils/v2 v2.0.0 h1:lltnkeZGL0wILNvrNiVCR6Ro5PGU/SeBvVO/8c/iPbo=