feat: use generics

cache.go

@@ -2,6 +2,8 @@
 //
 // It supports exîration dates and can store arbitrary values of any type.
 // Keys must be strings.
+//
+// Cache values are safe to share between goroutines.
 package cache
 
 import (
@@ -9,75 +11,83 @@ import (
 	"time"
 )
 
-type entry struct {
+type entry[V any] struct {
 	expirationDate *time.Time
-	value          interface{}
+	value          V
+}
+
+func (e entry[V]) isExpired() bool {
+	return e.expirationDate != nil && e.expirationDate.Before(time.Now())
 }
 
 // Cache is an in-memory key-value store.
-type Cache struct {
+type Cache[K comparable, V any] struct {
-	data map[string]entry
+	data map[K]entry[V]
 	mu   *sync.RWMutex
 }
 
 // New instantiate a new cache.
-func New() *Cache {
+func New[K comparable, V any]() *Cache[K, V] {
-	return &Cache{
+	return &Cache[K, V]{
-		data: make(map[string]entry),
+		data: make(map[K]entry[V]),
 		mu:   &sync.RWMutex{},
 	}
 }
 
 // Put stores a value in the cache under the given key.
-func (c *Cache) Put(key string, val interface{}) {
+func (c *Cache[K, V]) Put(key K, val V) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	c.data[key] = entry{nil, val}
+	c.data[key] = entry[V]{nil, val}
 }
 
 // PutTTL stores a value in the cache under the given key. The value will
 // be expired after the given ttl.
 //
 // A 0 ttl value disables the expiration of the value.
-func (c *Cache) PutTTL(key string, val interface{}, ttl time.Duration) {
+func (c *Cache[K, V]) PutTTL(key K, val V, ttl time.Duration) {
-	var exp time.Time
-
-	if ttl == 0 {
-		exp = time.Time{}
-	} else {
-		exp = time.Now().Add(ttl)
-	}
-
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	c.data[key] = entry{&exp, val}
+	if ttl == 0 {
+		c.Put(key, val)
+
+		return
+	}
+
+	exp := time.Now().Add(ttl)
+
+	c.data[key] = entry[V]{&exp, val}
 }
 
 // Get returns the value asspciated with the given key.
 // The second return values indicates if the cache hs been hit or not.
-func (c *Cache) Get(key string) (interface{}, bool) {
+func (c *Cache[K, V]) Get(key K) (V, bool) {
 	c.mu.RLock()
-	v, ok := c.data[key]
+	entry, ok := c.data[key]
 	c.mu.RUnlock()
 
 	if !ok {
-		return nil, false
+		var t V
+
+		return t, false
 	}
 
-	if v.expirationDate != nil && v.expirationDate.Before(time.Now()) {
+	if entry.isExpired() {
 		c.Del(key)
 
-		return nil, false
+		var t V
+
+		return t, false
 	}
 
-	return v.value, ok
+	return entry.value, ok
 }
 
-// Del deletes the entry for the givzn key.
+// Del deletes the entry for the given key.
 // It does not fail if the key does not exist.
-func (c *Cache) Del(key string) {
+func (c *Cache[K, V]) Del(key K) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -85,7 +95,7 @@ func (c *Cache) Del(key string) {
 }
 
 // Count returns the total number of entries in the cache (vamid and expired).
-func (c *Cache) Count() int {
+func (c *Cache[K, V]) Count() int {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
 

cache_test.go

@@ -1,156 +1,156 @@
-package cache
+package cache_test
 
 import (
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"code.bcarlin.net/go/cache"
 )
 
 func TestCache(t *testing.T) {
-	key := "test"
+	t.Parallel()
 
-	c := New()
+	const key = "test"
 
-	t.Log("simple put and get")
+	t.Run("simple put and get", func(t *testing.T) {
+		t.Parallel()
 
-	value := "foo"
+		c := cache.New[string, string]()
 
-	c.Put(key, value)
+		value := "foo"
 
-	if n := c.Count(); n != 1 {
+		c.Put(key, value)
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
-	}
 
-	val, ok := c.Get(key)
+		n := c.Count()
-	if !ok {
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
-		t.Fatalf("Expected cache to have an entry for key %q, but it did not", key)
-	}
 
-	val2, ok := val.(string)
+		got, ok := c.Get(key)
-	if !ok {
+		assert.True(t, ok, "Expected cache to have an entry for key %q, but it did not", key)
-		t.Fatalf("Expected '%v' to have type string, but it has type %T", val, val)
-	}
 
-	if val2 != value {
+		assert.Equal(t, value, got)
-		t.Fatalf("Expected '%v' to equal 'foo', but it does not", val2)
+	})
-	}
 
-	t.Log("Using the same key overwrites the value")
+	t.Run("Using the same key overwrites the value", func(t *testing.T) {
+		t.Parallel()
 
-	value = "bar"
+		c := cache.New[string, string]()
 
-	c.Put(key, value)
+		c.Put(key, "foo")
 
-	if n := c.Count(); n != 1 {
+		value := "bar"
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
+		c.Put(key, value)
-	}
 
-	val, ok = c.Get(key)
+		n := c.Count()
-	if !ok {
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
-		t.Fatalf("Expected cache to have an entry for key %q, but it did not", key)
-	}
 
-	val2, ok = val.(string)
+		got, ok := c.Get(key)
-	if !ok {
+		assert.True(t, ok, "Expected cache to have an entry for key %q, but it did not", key)
-		t.Fatalf("Expected '%v' to have type string, but it has type %T", val, val)
-	}
 
-	if val2 != value {
+		assert.Equal(t, value, got)
-		t.Fatalf("Expected '%v' to equal 'foo', but it does not", val2)
+	})
-	}
 
-	t.Log("It should tell if the cache is missed")
+	t.Run("cache is missed", func(t *testing.T) {
+		t.Parallel()
 
-	val, ok = c.Get("does-not-exist")
+		c := cache.New[string, string]()
-	if ok {
-		t.Fatalf("Expected cache to not have an entry for key %q, but it did", key)
-	}
 
-	if val != nil {
+		val, ok := c.Get("does-not-exist")
-		t.Fatalf("Expected '%v' to be nil, but it was not", val2)
+
-	}
+		assert.False(t, ok, "Expected cache to not have an entry for key 'does-not-exist', but it did")
+		assert.Zero(t, val)
+	})
 }
 
 func TestCacheTTL(t *testing.T) {
-	key := "test"
+	t.Parallel()
-	value := "foo"
 
-	c := New()
+	const (
+		key   = "test"
+		value = "foo"
+	)
 
-	t.Log("Simple put and get a non-expired entry")
+	t.Run("simple put and get a non-expired entry", func(t *testing.T) {
+		t.Parallel()
 
-	c.PutTTL(key, value, 1*time.Hour)
+		c := cache.New[string, string]()
 
-	if n := c.Count(); n != 1 {
+		c.PutTTL(key, value, 1*time.Hour)
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
-	}
 
-	_, ok := c.Get(key)
+		n := c.Count()
-	if !ok {
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
-		t.Fatalf("Expected cache to have an entry for key %q, but it did not", key)
-	}
 
-	t.Log("Simple put and get a 0 TTL")
+		_, ok := c.Get(key)
+		assert.True(t, ok, "Expected cache to have an entry for key %q, but it did not", key)
+	})
 
-	c.PutTTL(key, value, 0)
+	t.Run("simple put and get a 0 TTL", func(t *testing.T) {
+		t.Parallel()
 
-	if n := c.Count(); n != 1 {
+		c := cache.New[string, string]()
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
-	}
 
-	_, ok = c.Get(key)
+		c.PutTTL(key, value, 0)
-	if !ok {
-		t.Fatalf("Expected cache to have an entry for key %q, but it did not", key)
-	}
 
-	t.Log("Simple put and get an expired entry")
+		n := c.Count()
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
 
-	c.PutTTL(key, value, -1*time.Hour)
+		_, ok := c.Get(key)
+		assert.True(t, ok, "Expected cache to have an entry for key %q, but it did not", key)
+	})
 
-	if n := c.Count(); n != 1 {
+	t.Run("simple put and get an expired entry", func(t *testing.T) {
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
+		t.Parallel()
-	}
 
-	_, ok = c.Get(key)
+		c := cache.New[string, string]()
-	if ok {
-		t.Fatalf("Expected cache to not have an entry for key %q, but it did", key)
-	}
 
-	if n := c.Count(); n != 0 {
+		c.PutTTL(key, value, -1*time.Hour)
-		t.Fatalf("Expected %d entries in the cache, got %d", 0, n)
+
-	}
+		n := c.Count()
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
+
+		_, ok := c.Get(key)
+		assert.False(t, ok, "Expected cache to not have an entry for key %q, but it did", key)
+
+		n = c.Count()
+		assert.Equal(t, 0, n, "Expected %d entries in the cache, got %d", 0, n)
+	})
 }
 
 func TestCacheDel(t *testing.T) {
-	key := "test"
+	t.Parallel()
-	value := "foo"
 
-	c := New()
+	const (
+		key   = "test"
+		value = "foo"
+	)
 
-	c.Put(key, value)
+	t.Run("delete an existing key", func(t *testing.T) {
+		t.Parallel()
 
-	if n := c.Count(); n != 1 {
+		c := cache.New[string, string]()
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
-	}
 
-	t.Log("Delete an existing key from the cache")
+		c.Put(key, value)
 
-	c.Del(key)
+		n := c.Count()
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
 
-	if n := c.Count(); n != 0 {
+		c.Del(key)
-		t.Fatalf("Expected %d entries in the cache, got %d", 0, n)
-	}
 
-	c.Put(key, value)
+		n = c.Count()
+		assert.Equal(t, 0, n, "Expected %d entries in the cache, got %d", 0, n)
+	})
 
-	if n := c.Count(); n != 1 {
+	t.Run("delete a non-existing key", func(t *testing.T) {
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
+		t.Parallel()
-	}
 
-	t.Log("Delete an existing key from the cache")
+		c := cache.New[string, string]()
 
-	c.Del("does-not-exist")
+		c.Put(key, value)
 
-	if n := c.Count(); n != 1 {
+		c.Del("does-not-exist")
-		t.Fatalf("Expected %d entries in the cache, got %d", 1, n)
+
-	}
+		n := c.Count()
+		assert.Equal(t, 1, n, "Expected %d entries in the cache, got %d", 1, n)
+	})
 }

go.mod

@@ -1,3 +1,13 @@
-module code.bcarlin.xyz/go/cache
+module code.bcarlin.net/go/cache
 
-go 1.17
+go 1.22.0
+
+toolchain go1.23.4
+
+require github.com/stretchr/testify v1.10.0
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=