Memcache Client

This is a memcache client library for the Go programming language, which uses memcache's Meta Text Protocol and supports namespacing out of the box.

Installing

To add this libraty to your project, just run:

go get github.com/kinescope/mc

Example

package main

import (
	"context"
	"log"
	"time"

	"github.com/kinescope/mc"
)

func ExampleBase() {
	memcache, err := mc.New(&mc.Options{
		Addrs: []string{"127.0.0.1:11211"},
	})
	if err != nil {
		log.Fatal(err)
	}
	err = memcache.Set(&mc.Item{
		Key:   "key",
		Value: []byte("value"),
		Flags: 42,
	}, mc.WithExpiration(5))
	if err != nil {
		log.Fatal(err)
	}

	i, err := memcache.Get("key")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("key=%q, value=%q\n", i.Key, i.Value)
	// Output: key="key", value="value"
}

Namespacing

Let's say you have a user with some user_id like 123. Given a user and all his related keys, you want a one-stop switch to invalidate all of their cache entries at the same time. With namespacing you need to add a mc.WithNamespace option when setting any user related key.


func ExampleNamespace() {
	memcache, err := mc.New(&mc.Options{
		Addrs: []string{"127.0.0.1:11211"},
	})
	if err != nil {
		log.Fatal(err)
	}
	err = memcache.Set(&mc.Item{
		Key:   "key",
		Value: []byte("value"),
		Flags: 42,
	}, mc.WithExpiration(5), mc.WithNamespace("namespace"))
	if err != nil {
		log.Fatal(err)
	}

	i, err := memcache.Get("key")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("key=%q, value=%q\n", i.Key, i.Value)

	memcache.PurgeNamespace("namespace")

	if _, err = memcache.Get("key"); err == nil {
		log.Fatal("ns bug")
	}
	fmt.Println(err)
	// Output:
	// key="key", value="value"
	// memcache: cache miss
}

Then invalidating all of the keys for a user with id 123 would be as easy as:

cache.PurgeNamespace(ctx, "user_123") // both 123:John and John:[email protected] entries will be deleted

For more info on namespaces see memcache wiki.

Other options

mc.WithMinUses(number uint32) - if an item under the key has been set less than number of times, requesting an item will result in a cache miss. See tests for clarity.
mc.WithEarlyRecache(seconds int) - https://docs.memcached.org/protocols/meta/#early-recache
mc.WithLastAccess - returns the time in seconds since last access.
... - see mc.With*

Contributing

For contributing see CONTRIBUTING.md

Licensing

The code in this project is licensed under MIT license.

# Packages