PLT-5308 Caching layer part 2 (#6973)

* Adding Reaction store cache layer example

* Implementing reaction store in new caching system.

* Redis for reaction store

* Adding redis library

* Adding invalidation for DeleteAllWithEmojiName and other minor enhancements

1 files changed, 133 insertions, 0 deletions

diff --git a/store/redis_supplier.go b/store/redis_supplier.go
new file mode 100644
index 000000000..eede36ef2
--- /dev/null
+++ b/store/redis_supplier.go
@@ -0,0 +1,133 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package store
+
+import (
+	"bytes"
+	"context"
+	"encoding/gob"
+
+	"time"
+
+	l4g "github.com/alecthomas/log4go"
+	"github.com/go-redis/redis"
+	"github.com/mattermost/platform/model"
+)
+
+const REDIS_EXPIRY_TIME = 30 * time.Minute
+
+type RedisSupplier struct {
+	next   LayeredStoreSupplier
+	client *redis.Client
+}
+
+func GetBytes(key interface{}) ([]byte, error) {
+	var buf bytes.Buffer
+	enc := gob.NewEncoder(&buf)
+	err := enc.Encode(key)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func DecodeBytes(input []byte, thing interface{}) error {
+	dec := gob.NewDecoder(bytes.NewReader(input))
+	err := dec.Decode(thing)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func NewRedisSupplier() *RedisSupplier {
+	supplier := &RedisSupplier{}
+
+	supplier.client = redis.NewClient(&redis.Options{
+		Addr:     "localhost:6379",
+		Password: "",
+		DB:       0,
+	})
+
+	if _, err := supplier.client.Ping().Result(); err != nil {
+		l4g.Error("Unable to ping redis server: " + err.Error())
+		return nil
+	}
+
+	return supplier
+}
+
+func (s *RedisSupplier) save(key string, value interface{}, expiry time.Duration) error {
+	if bytes, err := GetBytes(value); err != nil {
+		return err
+	} else {
+		if err := s.client.Set(key, bytes, expiry).Err(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (s *RedisSupplier) load(key string, writeTo interface{}) (bool, error) {
+	if data, err := s.client.Get(key).Bytes(); err != nil {
+		if err == redis.Nil {
+			return false, nil
+		} else {
+			return false, err
+		}
+	} else {
+		if err := DecodeBytes(data, writeTo); err != nil {
+			return false, err
+		}
+	}
+	return true, nil
+}
+
+func (s *RedisSupplier) SetChainNext(next LayeredStoreSupplier) {
+	s.next = next
+}
+
+func (s *RedisSupplier) Next() LayeredStoreSupplier {
+	return s.next
+}
+
+func (s *RedisSupplier) ReactionSave(ctx context.Context, reaction *model.Reaction, hints ...LayeredStoreHint) *LayeredStoreSupplierResult {
+	if err := s.client.Del("reactions:" + reaction.PostId).Err(); err != nil {
+		l4g.Error("Redis failed to remove key reactions:" + reaction.PostId + " Error: " + err.Error())
+	}
+	return s.Next().ReactionSave(ctx, reaction, hints...)
+}
+
+func (s *RedisSupplier) ReactionDelete(ctx context.Context, reaction *model.Reaction, hints ...LayeredStoreHint) *LayeredStoreSupplierResult {
+	if err := s.client.Del("reactions:" + reaction.PostId).Err(); err != nil {
+		l4g.Error("Redis failed to remove key reactions:" + reaction.PostId + " Error: " + err.Error())
+	}
+	return s.Next().ReactionDelete(ctx, reaction, hints...)
+}
+
+func (s *RedisSupplier) ReactionGetForPost(ctx context.Context, postId string, hints ...LayeredStoreHint) *LayeredStoreSupplierResult {
+	var resultdata []*model.Reaction
+	found, err := s.load("reactions:"+postId, &resultdata)
+	if found {
+		result := NewSupplierResult()
+		result.Data = resultdata
+		return result
+	}
+	if err != nil {
+		l4g.Error("Redis encountered an error on read: " + err.Error())
+	}
+
+	result := s.Next().ReactionGetForPost(ctx, postId, hints...)
+
+	if err := s.save("reactions:"+postId, result.Data, REDIS_EXPIRY_TIME); err != nil {
+		l4g.Error("Redis encountered and error on write: " + err.Error())
+	}
+
+	return result
+}
+
+func (s *RedisSupplier) ReactionDeleteAllWithEmojiName(ctx context.Context, emojiName string, hints ...LayeredStoreHint) *LayeredStoreSupplierResult {
+	// Ignoring this. It's probably OK to have the emoji slowly expire from Redis.
+	return s.Next().ReactionDeleteAllWithEmojiName(ctx, emojiName, hints...)
+}