88 lines
2.4 KiB
Go
88 lines
2.4 KiB
Go
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package cache
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import (
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"context"
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"fmt"
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"time"
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"github.com/redis/go-redis/v9"
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)
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const (
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curveLockTTL = 10 * time.Second
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curveLockRetryDelay = 100 * time.Millisecond
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curveLockMaxRetries = 50
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)
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// CurveCache 曲线数据缓存（Redis Hash）
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type CurveCache struct {
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rdb *redis.Client
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}
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func NewCurveCache(rdb *redis.Client) *CurveCache {
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return &CurveCache{rdb: rdb}
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}
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// Get 从 Redis Hash 中获取曲线缓存
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func (c *CurveCache) Get(ctx context.Context, brand, name, target string) (string, error) {
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key := brand + " " + name
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val, err := c.rdb.HGet(ctx, key, target).Result()
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if err == redis.Nil {
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return "", nil
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}
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if err != nil {
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return "", fmt.Errorf("hget curve cache: %w", err)
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}
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return val, nil
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}
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// Set 将曲线数据存入 Redis Hash
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func (c *CurveCache) Set(ctx context.Context, brand, name, target, data string) error {
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key := brand + " " + name
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return c.rdb.HSet(ctx, key, target, data).Err()
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}
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// AcquireLock 获取分布式锁（SETNX），防止并发请求同一个曲线数据
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func (c *CurveCache) AcquireLock(ctx context.Context, brand, name, target string) (bool, error) {
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lockKey := brand + " " + name + ":" + target + ":lock"
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return c.rdb.SetNX(ctx, lockKey, "locked", curveLockTTL).Result()
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}
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// ReleaseLock 释放分布式锁
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func (c *CurveCache) ReleaseLock(ctx context.Context, brand, name, target string) error {
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lockKey := brand + " " + name + ":" + target + ":lock"
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return c.rdb.Del(ctx, lockKey).Err()
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}
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// GetWithLock 获取缓存数据，缓存不存在时尝试加锁后重新获取
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// 返回值: (data, acquired, error)
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// - data: 缓存数据（空字符串表示无数据）
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// - acquired: 是否成功获取锁（缓存不存在时需要加锁）
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func (c *CurveCache) GetWithLock(ctx context.Context, brand, name, target string) (data string, acquired bool, err error) {
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// 先查缓存
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data, err = c.Get(ctx, brand, name, target)
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if err != nil {
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return "", false, err
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}
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if data != "" {
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return data, false, nil // 缓存命中
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}
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// 缓存不存在，尝试加锁
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acquired, err = c.AcquireLock(ctx, brand, name, target)
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if err != nil {
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return "", false, fmt.Errorf("acquire curve lock: %w", err)
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}
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if acquired {
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// 加锁成功，再次检查缓存（双重检查）
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data, err = c.Get(ctx, brand, name, target)
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if err != nil {
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return "", true, err
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}
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return data, true, nil
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}
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// 未获取锁，等待后重试
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return "", false, nil
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}
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