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/patrickmn/go-cache

Usage

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)
            // ...
    }
}

Reference

godoc or http://godoc.org/github.com/patrickmn/go-cache