- add ristretto driver

Author: rocketlaunchr-cto

ristretto/ristretto.go

@@ -0,0 +1,89 @@
+package ristretto
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"github.com/dgraph-io/ristretto"
+	"github.com/rocketlaunchr/remember-go"
+)
+
+// ErrItemDropped signifies that the item to store was not inserted into the cache.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto#Cache.Set
+var ErrItemDropped = errors.New("item dropped")
+
+// RistrettoStore is used to create an in-memory ristretto cache.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto
+type RistrettoStore struct {
+	Cache *ristretto.Cache
+}
+
+// NewRistrettoStore creates an in-memory ristretto cache.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto#Config
+func NewRistrettoStore(config *ristretto.Config) *RistrettoStore {
+	cache, err := ristretto.NewCache(config)
+	if err != nil {
+		panic(err)
+	}
+
+	return &RistrettoStore{
+		Cache: cache,
+	}
+}
+
+// Conn does nothing for this storage driver.
+func (r *RistrettoStore) Conn(ctx context.Context) (remember.Cacher, error) {
+	return r, nil
+}
+
+// StorePointer sets whether a storage driver requires itemToStore to be
+// stored as a pointer or as a concrete value.
+func (r *RistrettoStore) StorePointer() bool {
+	return false
+}
+
+// Get returns a value from the cache if the key exists.
+// It is possible for nil to be returned while found is also true.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto#Cache.Get
+func (r *RistrettoStore) Get(key string) (interface{}, bool, error) {
+	item, found := r.Cache.Get(key)
+	return item, found, nil
+}
+
+// Set sets a item into the cache for a particular key.
+// cost must be converted to a time.Duration despite being unrelated to time.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto#Cache.Set
+func (r *RistrettoStore) Set(key string, cost time.Duration, itemToStore interface{}) error {
+	stored := r.Cache.Set(key, itemToStore, int64(cost))
+	if stored {
+		return nil
+	}
+	return ErrItemDropped
+}
+
+// Close returns the connection back to the pool for storage drivers that utilize a pool.
+// For this driver, it does nothing.
+func (r *RistrettoStore) Close() {}
+
+// Forget clears the value from the cache for the particular key.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto#Cache.Del
+func (r *RistrettoStore) Forget(key string) error {
+	r.Cache.Del(key)
+	return nil
+}
+
+// ForgetAll clears all values from the cache.
+// Note that this is not an atomic operation.
+//
+// See: https://godoc.org/github.com/dgraph-io/ristretto#Cache.Clear
+func (r *RistrettoStore) ForgetAll() error {
+	r.Cache.Clear()
+	return nil
+}