move: 后端

backend/internal/redis/cache.go

@@ -0,0 +1,105 @@
+package redis
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"os"
+	"strconv"
+	"time"
+
+	redis "github.com/redis/go-redis/v9"
+)
+
+type Client struct {
+	rdb *redis.Client
+}
+
+func NewFromEnv() (*Client, error) {
+	addr := os.Getenv("REDIS_ADDR")
+	if addr == "" {
+		addr = "127.0.0.1:6379"
+	}
+
+	db := 0
+	if v := os.Getenv("REDIS_DB"); v != "" {
+		n, err := strconv.Atoi(v)
+		if err != nil {
+			return nil, err
+		}
+		db = n
+	}
+
+	rdb := redis.NewClient(&redis.Options{
+		Addr:     addr,
+		Password: os.Getenv("REDIS_PASSWORD"),
+		DB:       db,
+	})
+	return &Client{rdb: rdb}, nil
+}
+
+func (c *Client) Close() error {
+	if c == nil || c.rdb == nil {
+		return nil
+	}
+	return c.rdb.Close()
+}
+
+func (c *Client) Ping(ctx context.Context) error {
+	if c == nil || c.rdb == nil {
+		return nil
+	}
+	return c.rdb.Ping(ctx).Err()
+}
+
+func (c *Client) GetBytes(ctx context.Context, key string) ([]byte, error) {
+	return c.rdb.Get(ctx, key).Bytes()
+}
+
+func (c *Client) SetBytes(ctx context.Context, key string, value []byte, ttl time.Duration) error {
+	return c.rdb.Set(ctx, key, value, ttl).Err()
+}
+
+func (c *Client) Del(ctx context.Context, key string) error {
+	return c.rdb.Del(ctx, key).Err()
+}
+
+func IsMiss(err error) bool {
+	return err == redis.Nil
+}
+
+func randToken(n int) (string, error) {
+	b := make([]byte, n)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(b), nil
+}
+
+func (c *Client) Lock(ctx context.Context, key string, ttl time.Duration) (token string, ok bool, err error) {
+	if c == nil || c.rdb == nil {
+		return "", false, nil
+	}
+	token, err = randToken(16)
+	if err != nil {
+		return "", false, err
+	}
+	ok, err = c.rdb.SetNX(ctx, key, token, ttl).Result()
+	return token, ok, err
+}
+
+var unlockScript = redis.NewScript(`
+if redis.call("GET", KEYS[1]) == ARGV[1] then
+  return redis.call("DEL", KEYS[1])
+else
+  return 0
+end
+`)
+
+func (c *Client) Unlock(ctx context.Context, key string, token string) error {
+	if c == nil || c.rdb == nil {
+		return nil
+	}
+	_, err := unlockScript.Run(ctx, c.rdb, []string{key}, token).Result()
+	return err
+}