Add: Redis as a cache support for grid mode.

1. Add: Redis as a cache support for grid mode. Redis implements cacher interface.

cachemdl/cache_redis.go

+package cachemdl
+
+/*
+
+Provides cache access and manipulation methods for rdis server
+Implements cacher interface.
+
+Official docs -
+1. redis client - https://github.com/go-redis/redis
+2. redis server - https://redis.io/
+
+
+Note - corelab.mkcl.org/MKCLOS/coredevelopmentplatform/corepkgv2/loggermdl must be initialized before use
+
+*/
+
+import (
+	"encoding/json"
+	"time"
+
+	"corelab.mkcl.org/MKCLOS/coredevelopmentplatform/corepkgv2/loggermdl"
+
+	"github.com/go-redis/redis"
+	"github.com/tidwall/gjson"
+)
+
+const (
+	noExp time.Duration = 0
+
+	// NotOK refers to a unsuccessfull operations
+	NotOK int64 = 0
+	// OK refers to a successfull operations
+	OK int64 = 1
+)
+
+// RedisCache -
+type RedisCache struct {
+	cli      *redis.Client  // represents redis client
+	opt      *redis.Options //
+	Addr     string         // redis server address, default "127.0.0.1:6379"
+	DB       int            // redis DB on provided server, default 0
+	Password string         //
+}
+
+// Setup -
+func (rc *RedisCache) Setup(addr, password string, db int) {
+	opt := redis.Options{
+		Addr:     addr,
+		Password: password,
+		DB:       db,
+	}
+
+	rc.opt = &opt
+	rc.cli = redis.NewClient(&opt)
+}
+
+// Set marshalls provided value and stores against provided key. Errors will be logged to initialized logger.
+func (rc *RedisCache) Set(key string, val interface{}) {
+	ba, err := json.Marshal(val)
+	if err != nil {
+		loggermdl.LogError("error setting key ", key, " error: ", err)
+		return
+	}
+
+	rc.cli.Set(key, ba, noExp)
+}
+
+// SetWithExpiration marshalls provided value and stores against provided key for given duration. Errors will be logged to initialized logger.
+func (rc *RedisCache) SetWithExpiration(key string, val interface{}, exp time.Duration) {
+	ba, err := json.Marshal(val)
+	if err != nil {
+		loggermdl.LogError("error setting key ", key, " error: ", err)
+		return
+	}
+
+	rc.cli.Set(key, ba, exp)
+}
+
+// SetNoExpiration marshalls provided value and stores against provided key.
+// Same as Set method.
+// Errors will be logged to initialized logger.
+func (rc *RedisCache) SetNoExpiration(key string, val interface{}) {
+	ba, err := json.Marshal(val)
+	if err != nil {
+		loggermdl.LogError("error setting key ", key, " error: ", err)
+		return
+	}
+
+	rc.cli.Set(key, ba, noExp)
+}
+
+// Get returns data against provided key. The final result is parsed with gjson. Returns false if not present.
+func (rc *RedisCache) Get(key string) (interface{}, bool) {
+	// exists, err := rc.cli.Exists(key).Result()
+	// if err != nil {
+	// 	loggermdl.LogError("error checking key ", key, " error: ", err)
+	// 	return nil, false
+	// }
+
+	// if exists == NotOK {
+	// 	return nil, false
+	// }
+
+	// Get returns error if key is not present.
+	val, err := rc.cli.Get(key).Result()
+	if err != nil {
+		loggermdl.LogError("error getting key ", key, " error: ", err)
+		return nil, false
+	}
+
+	return gjson.Parse(val).Value(), true
+}
+
+// Delete -
+func (rc *RedisCache) Delete(key string) {
+	rc.cli.Del(key).Result()
+}
+
+// GetItemsCount -
+func (rc *RedisCache) GetItemsCount() int {
+	pattern := "*"
+	keys, err := rc.cli.Keys(pattern).Result()
+	if err != nil {
+		loggermdl.LogError("error getting item count for ", pattern, " error: ", err)
+		return 0
+	}
+	return len(keys)
+}
+
+func (rc *RedisCache) flushDB() (string, error) {
+	return rc.cli.FlushDB().Result()
+}