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.)
go get github.com/patrickmn/go-cache
import (
"fmt"
"github.com/patrickmn/go-cache"
"time"
)
func main() {
// Create a cache with a default expiration time of 5 minutes, and which
// purges expired items every 10 minutes
c := cache.New(5*time.Minute, 10*time.Minute)
// 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)
// ...
}
}