fix(topup): settle recharge orders atomically

model/quota_reserve.go

@@ -0,0 +1,68 @@
+package model
+
+import (
+	"context"
+
+	"github.com/QuantumNous/new-api/common"
+)
+
+type cacheQuotaResult int
+
+const (
+	cacheQuotaInsufficient cacheQuotaResult = iota
+	cacheQuotaOK
+	cacheQuotaMiss
+)
+
+// 下列脚本都是守卫式的：只在完整哈希（Id 匹配且配额字段存在）上操作，
+// 哈希缺失时返回 miss 而不是创建残缺哈希。脚本不修改 TTL（HINCRBY 天然保留
+// 水合时设置的 TTL），因此即使某个写库路径绕过了缓存，偏差也会在一个 TTL
+// 窗口内随缓存过期而自愈。
+
+const userQuotaReserveScript = `
+if tonumber(redis.call('HGET', KEYS[1], 'Id') or '0') ~= tonumber(ARGV[2])
+  or tonumber(redis.call('HGET', KEYS[1], 'CacheSchema') or '0') ~= tonumber(ARGV[3])
+  or redis.call('HEXISTS', KEYS[1], 'Quota') == 0 then
+  return -1
+end
+local quota = tonumber(redis.call('HGET', KEYS[1], 'Quota'))
+if quota == nil or quota < tonumber(ARGV[1]) then
+  return 0
+end
+redis.call('HINCRBY', KEYS[1], 'Quota', -tonumber(ARGV[1]))
+return 1`
+
+const userQuotaDeltaScript = `
+if tonumber(redis.call('HGET', KEYS[1], 'Id') or '0') ~= tonumber(ARGV[2])
+  or tonumber(redis.call('HGET', KEYS[1], 'CacheSchema') or '0') ~= tonumber(ARGV[3])
+  or redis.call('HEXISTS', KEYS[1], 'Quota') == 0 then
+  return -1
+end
+redis.call('HINCRBY', KEYS[1], 'Quota', tonumber(ARGV[1]))
+return 1`
+
+func quotaResultFromLua(result int, err error) (cacheQuotaResult, error) {
+	if err != nil {
+		return cacheQuotaMiss, err
+	}
+	switch result {
+	case 1:
+		return cacheQuotaOK, nil
+	case 0:
+		return cacheQuotaInsufficient, nil
+	default:
+		return cacheQuotaMiss, nil
+	}
+}
+
+func cacheTryReserveUserQuota(userID int, amount int64) (cacheQuotaResult, error) {
+	result, err := common.RDB.Eval(context.Background(), userQuotaReserveScript,
+		[]string{getUserCacheKey(userID)}, amount, userID, userCacheSchemaVersion).Int()
+	return quotaResultFromLua(result, err)
+}
+
+func cacheApplyUserQuotaDelta(userID int, delta int64) (cacheQuotaResult, error) {
+	result, err := common.RDB.Eval(context.Background(), userQuotaDeltaScript,
+		[]string{getUserCacheKey(userID)}, delta, userID, userCacheSchemaVersion).Int()
+	return quotaResultFromLua(result, err)
+}