Add memcache implementation of cache (#1848)

cache/cache.go

@@ -1,6 +1,7 @@
 // Package cache is a caching interface
 package cache
 
+// Cache is an interface for caching
 type Cache interface {
 	// Initialise options
 	Init(...Option) error
@@ -14,6 +15,15 @@ type Cache interface {
 	String() string
 }
 
-type Options struct{}
+type Options struct {
+	Nodes []string
+}
 
 type Option func(o *Options)
+
+// Nodes sets the nodes for the cache
+func Nodes(v ...string) Option {
+	return func(o *Options) {
+		o.Nodes = v
+	}
+}

cache/memcache/memcache.go

@@ -0,0 +1,80 @@
+// Package memcache is a memcache implementation of the Cache
+package memcache
+
+import (
+	"encoding/json"
+
+	"github.com/bradfitz/gomemcache/memcache"
+	"github.com/micro/go-micro/v2/cache"
+)
+
+type memcacheCache struct {
+	options cache.Options
+	client  *memcache.Client
+}
+
+type memcacheItem struct {
+	Key   string
+	Value interface{}
+}
+
+func (m *memcacheCache) Init(opts ...cache.Option) error {
+	for _, o := range opts {
+		o(&m.options)
+	}
+	return nil
+}
+
+func (m *memcacheCache) Get(key string) (interface{}, error) {
+	item, err := m.client.Get(key)
+	if err != nil {
+		return nil, err
+	}
+
+	var mc *memcacheItem
+
+	if err := json.Unmarshal(item.Value, &mc); err != nil {
+		return nil, err
+	}
+
+	return mc.Value, nil
+}
+
+func (m *memcacheCache) Set(key string, val interface{}) error {
+	b, err := json.Marshal(val)
+	if err != nil {
+		return err
+	}
+
+	return m.client.Set(&memcache.Item{
+		Key:   key,
+		Value: b,
+	})
+}
+
+func (m *memcacheCache) Delete(key string) error {
+	return m.client.Delete(key)
+}
+
+func (m *memcacheCache) String() string {
+	return "memcache"
+}
+
+// NewCache returns a new memcache Cache
+func NewCache(opts ...cache.Option) cache.Cache {
+	var options cache.Options
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// get and set the nodes
+	nodes := options.Nodes
+	if len(nodes) == 0 {
+		nodes = []string{"localhost:11211"}
+	}
+
+	return &memcacheCache{
+		options: options,
+		client:  memcache.New(nodes...),
+	}
+}

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/BurntSushi/toml v0.3.1
 	github.com/bitly/go-simplejson v0.5.0
 	github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869 // indirect
+	github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b
 	github.com/bwmarrin/discordgo v0.20.2
 	github.com/caddyserver/certmagic v0.10.6
 	github.com/coreos/bbolt v1.3.3 // indirect

go.sum

@@ -62,6 +62,8 @@ github.com/bitly/go-simplejson v0.5.0/go.mod h1:cXHtHw4XUPsvGaxgjIAn8PhEWG9NfngE
 github.com/blang/semver v3.1.0+incompatible/go.mod h1:kRBLl5iJ+tD4TcOOxsy/0fnwebNt5EWlYSAyrTnjyyk=
 github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869 h1:DDGfHa7BWjL4YnC6+E63dPcxHo2sUxDIu8g3QgEJdRY=
 github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869/go.mod h1:Ekp36dRnpXw/yCqJaO+ZrUyxD+3VXMFFr56k5XYrpB4=
+github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b h1:L/QXpzIa3pOvUGt1D1lA5KjYhPBAN/3iWdP7xeFS9F0=
+github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b/go.mod h1:H0wQNHz2YrLsuXOZozoeDmnHXkNCRmMW0gwFWDfEZDA=
 github.com/bwmarrin/discordgo v0.20.2 h1:nA7jiTtqUA9lT93WL2jPjUp8ZTEInRujBdx1C9gkr20=
 github.com/bwmarrin/discordgo v0.20.2/go.mod h1:O9S4p+ofTFwB02em7jkpkV8M3R0/PUVOwN61zSZ0r4Q=
 github.com/caddyserver/certmagic v0.10.6 h1:sCya6FmfaN74oZE46kqfaFOVoROD/mF36rTQfjN7TZc=