# go-cache go-cache is an in-memory key:value store/cache similar to memcached that is suitable for applications running on a single machine. Its major advantage is that, being essentially a thread-safe `map[string]interface{}` with expiration times, it doesn't need to serialize or transmit its contents over the network. Any object can be stored, for a given duration or forever, and the cache can be safely used by multiple goroutines. Although go-cache isn't meant to be used as a persistent datastore, the entire cache can be saved to and loaded from a file (using `c.Items()` to retrieve the items map to serialize, and `NewFrom()` to create a cache from a deserialized one) to recover from downtime quickly. (See the docs for `NewFrom` for caveats.) ### Installation `go get github.com/pmylund/go-cache` ### Usage import ( "fmt" "github.com/pmylund/go-cache" ) func main() { // Create a cache with a default expiration time of 5 minutes, and which // purges expired items every 30 seconds c := cache.New(5*time.Minute, 30*time.Second) // Set the value of the key "foo" to "bar", with the default expiration time c.Set("foo", "bar", cache.DefaultExpiration) // Set the value of the key "baz" to 42, with no expiration time // (the item won't be removed until it is re-set, or removed using // c.Delete("baz") c.Set("baz", 42, cache.NoExpiration) // Get the string associated with the key "foo" from the cache foo, found := c.Get("foo") if found { fmt.Println(foo) } // Since Go is statically typed, and cache values can be anything, type // assertion is needed when values are being passed to functions that don't // take arbitrary types, (i.e. interface{}). The simplest way to do this for // values which will only be used once--e.g. for passing to another // function--is: foo, found := c.Get("foo") if found { MyFunction(foo.(string)) } // This gets tedious if the value is used several times in the same function. // You might do either of the following instead: if x, found := c.Get("foo"); found { foo := x.(string) // ... } // or var foo string if x, found := c.Get("foo"); found { foo = x.(string) } // ... // foo can then be passed around freely as a string // Want performance? Store pointers! c.Set("foo", &MyStruct, cache.DefaultExpiration) if x, found := c.Get("foo"); found { foo := x.(*MyStruct) // ... } // If you store a reference type like a pointer, slice, map or channel, you // do not need to run Set if you modify the underlying data. The cached // reference points to the same memory, so if you modify a struct whose // pointer you've stored in the cache, retrieving that pointer with Get will // point you to the same data: foo := &MyStruct{Num: 1} c.Set("foo", foo, cache.DefaultExpiration) // ... x, _ := c.Get("foo") foo := x.(*MyStruct) fmt.Println(foo.Num) // ... foo.Num++ // ... x, _ := c.Get("foo") foo := x.(*MyStruct) foo.Println(foo.Num) // will print: // 1 // 2 } ### Reference `godoc` or [http://godoc.org/github.com/pmylund/go-cache](http://godoc.org/github.com/pmylund/go-cache)