improve adapter feature for package gcache

os/gcache/gcache_adapter.go

@@ -11,6 +11,7 @@ import (
 )
 
 // Adapter is the adapter for cache features implements.
+// TODO error returning for each function.
 type Adapter interface {
 	// Set sets cache with <key>-<value> pair, which is expired after <duration>.
 	//
@@ -25,7 +26,9 @@ type Adapter interface {
 	Sets(data map[interface{}]interface{}, duration time.Duration)
 
 	// SetIfNotExist sets cache with <key>-<value> pair which is expired after <duration>
-	// if <key> does not exist in the cache.
+	// if <key> does not exist in the cache. It returns true the <key> dose not exist in the
+	// cache and it sets <value> successfully to the cache, or else it returns false.
+	//
 	// The parameter <value> can be type of <func() interface{}>, but it dose nothing if its
 	// result is nil.
 	//
@@ -67,6 +70,8 @@ type Adapter interface {
 	GetOrSetFuncLock(key interface{}, f func() interface{}, duration time.Duration) interface{}
 
 	// GetExpire retrieves and returns the expiration of <key> in the cache.
+	//
+	// It returns 0 if the <key> does not expire.
 	// It returns -1 if the <key> does not exist in the cache.
 	GetExpire(key interface{}) time.Duration
 
@@ -78,17 +83,15 @@ type Adapter interface {
 	// The returned value <exist> is false if the <key> does not exist in the cache.
 	//
 	// It deletes the <key> if given <value> is nil.
+	// It does nothing if <key> does not exist in the cache.
 	Update(key interface{}, value interface{}) (oldValue interface{}, exist bool)
 
 	// UpdateExpire updates the expiration of <key> and returns the old expiration duration value.
 	//
-	// It returns -1 if the <key> does not exist in the cache.
+	// It returns -1 and does nothing if the <key> does not exist in the cache.
 	// It deletes the <key> if <duration> < 0.
 	UpdateExpire(key interface{}, duration time.Duration) (oldDuration time.Duration)
 
-	// Contains checks and returns whether given <key> exists in the cache.
-	Contains(key interface{}) bool
-
 	// Size returns the number of items in the cache.
 	Size() (size int)
 

os/gcache/gcache_adapter_memory.go

@@ -116,6 +116,7 @@ func (c *adapterMemory) Set(key interface{}, value interface{}, duration time.Du
 // The returned value <exist> is false if the <key> does not exist in the cache.
 //
 // It deletes the <key> if given <value> is nil.
+// It does nothing if <key> does not exist in the cache.
 func (c *adapterMemory) Update(key interface{}, value interface{}) (oldValue interface{}, exist bool) {
 	c.dataMu.Lock()
 	defer c.dataMu.Unlock()
@@ -131,7 +132,7 @@ func (c *adapterMemory) Update(key interface{}, value interface{}) (oldValue int
 
 // UpdateExpire updates the expiration of <key> and returns the old expiration duration value.
 //
-// It returns -1 if the <key> does not exist in the cache.
+// It returns -1 and does nothing if the <key> does not exist in the cache.
 // It deletes the <key> if <duration> < 0.
 func (c *adapterMemory) UpdateExpire(key interface{}, duration time.Duration) (oldDuration time.Duration) {
 	newExpireTime := c.getInternalExpire(duration)
@@ -152,6 +153,8 @@ func (c *adapterMemory) UpdateExpire(key interface{}, duration time.Duration) (o
 }
 
 // GetExpire retrieves and returns the expiration of <key> in the cache.
+//
+// It returns 0 if the <key> does not expire.
 // It returns -1 if the <key> does not exist in the cache.
 func (c *adapterMemory) GetExpire(key interface{}) time.Duration {
 	c.dataMu.RLock()
@@ -227,8 +230,14 @@ func (c *adapterMemory) getOrNewExpireSet(expire int64) (expireSet *gset.Set) {
 	return
 }
 
-// SetIfNotExist sets cache with <key>-<value> pair if <key> does not exist in the cache,
-// which is expired after <duration>. It does not expire if <duration> == 0.
+// SetIfNotExist sets cache with <key>-<value> pair which is expired after <duration>
+// if <key> does not exist in the cache. It returns true the <key> dose not exist in the
+// cache and it sets <value> successfully to the cache, or else it returns false.
+// The parameter <value> can be type of <func() interface{}>, but it dose nothing if its
+// result is nil.
+//
+// It does not expire if <duration> == 0.
+// It deletes the <key> if <duration> < 0 or given <value> is nil.
 func (c *adapterMemory) SetIfNotExist(key interface{}, value interface{}, duration time.Duration) bool {
 	if !c.Contains(key) {
 		c.doSetWithLockCheck(key, value, duration)

os/gcache/gcache_cache.go

@@ -38,6 +38,11 @@ func (c *Cache) SetAdapter(adapter Adapter) {
 	c.Adapter = adapter
 }
 
+// Contains returns true if <key> exists in the cache, or else returns false.
+func (c *Cache) Contains(key interface{}) bool {
+	return c.Get(key) != nil
+}
+
 // GetVar retrieves and returns the value of <key> as gvar.Var.
 func (c *Cache) GetVar(key interface{}) *gvar.Var {
 	return gvar.New(c.Get(key))