lan
2084473fb5
Move the responsibility of sequence (`seq`) allocation from the application/cache layer to the database layer to ensure absolute consistency. Previously, sequences were pre-allocated via Redis/Lua, which introduced complexity in managing synchronization between the cache and the database. Key changes: - Implement `CreateMessageWithSeq` in `message_repo.go` using `SELECT FOR UPDATE` to lock the conversation row and atomically increment the `last_seq` within a single transaction. - Simplify `SeqBufferManager` by removing the complex local buffering and Lua-based pre-allocation logic, reverting to a simpler model. - Update `chat_service.go`, `group_service.go`, and `message_service.go` to remove manual sequence retrieval, relying instead on the repository's transactional allocation. - Introduce `SyncConvSeq` in `conversation_cache.go` to perform "write-through" updates to Redis, ensuring the cache remains synchronized with the database's source of truth. - Improve cold-start handling in `conversation_cache.go` with a new `syncSeqLua` script to prevent stale sequence reads.
117 lines
3.9 KiB
Go
117 lines
3.9 KiB
Go
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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"go.uber.org/zap"
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redisPkg "with_you/internal/pkg/redis"
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)
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const seqKeyTTL = 24 * time.Hour
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// SeqBufferConfig seq 预分配配置（保留结构以兼容配置文件，实际不再使用缓冲）
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type SeqBufferConfig struct {
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Enabled bool `mapstructure:"enabled"`
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PrivateBufferSize int `mapstructure:"private_buffer_size"`
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GroupBufferSize int `mapstructure:"group_buffer_size"`
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LockTimeoutMs int `mapstructure:"lock_timeout_ms"`
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MaxRetries int `mapstructure:"max_retries"`
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}
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// SeqBufferManager seq 分配管理器（简化版：每条消息一个 Redis INCR，无本地缓冲）
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type SeqBufferManager struct {
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rdb *redis.Client
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config SeqBufferConfig
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repo ConversationRepository
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msgRepo MessageRepository
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}
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// NewSeqBufferManager 创建 seq 分配管理器
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func NewSeqBufferManager(rdb *redis.Client, cfg SeqBufferConfig, repo ConversationRepository, msgRepo MessageRepository) *SeqBufferManager {
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return &SeqBufferManager{
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rdb: rdb,
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config: cfg,
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repo: repo,
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msgRepo: msgRepo,
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}
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}
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// GetNextSeq 获取下一个 seq（单次 Redis INCR，原子且无竞态）
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func (m *SeqBufferManager) GetNextSeq(ctx context.Context, convID string, _ bool) (int64, error) {
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seqKey := MessageSeqKey(convID)
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// 1. 尝试 INCR（key 存在时直接递增，原子操作）
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result, err := nextSeqLua.Run(ctx, m.rdb, []string{seqKey}).Int64()
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if err == nil {
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if result > 0 {
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m.rdb.Expire(ctx, seqKey, seqKeyTTL)
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return result, nil
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}
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// result == 0: 冷启动，需从 DB 初始化
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return m.initAndIncr(ctx, convID, seqKey)
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}
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// Redis 不可用，降级到 DB
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zap.L().Warn("seq INCR failed, falling back to DB", zap.String("convID", convID), zap.Error(err))
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if m.msgRepo != nil {
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if dbSeq, dbErr := m.msgRepo.GetNextSeq(convID); dbErr == nil {
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return dbSeq, nil
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}
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}
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return 0, fmt.Errorf("seq allocation failed for %s: %w", convID, err)
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}
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// initAndIncr 冷启动：从 DB 加载 last_seq，然后用 SETNX+INCR 原子初始化
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func (m *SeqBufferManager) initAndIncr(ctx context.Context, convID, seqKey string) (int64, error) {
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if m.repo == nil {
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return 0, fmt.Errorf("conversation repository not configured for seq init")
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}
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conv, err := m.repo.GetConversationByID(convID)
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if err != nil {
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return 0, fmt.Errorf("load conversation for seq init: %w", err)
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}
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initVal := conv.LastSeq
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result, err := initSeqLua.Run(ctx, m.rdb, []string{seqKey}, initVal).Int64()
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if err != nil {
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return 0, fmt.Errorf("initSeqLua failed: %w", err)
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}
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m.rdb.Expire(ctx, seqKey, seqKeyTTL)
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return result, nil
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}
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// InvalidateBuffer no-op（保留接口兼容）
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func (m *SeqBufferManager) InvalidateBuffer(convID string) {}
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// IsEnabled 是否启用
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func (m *SeqBufferManager) IsEnabled() bool {
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return m.config.Enabled && m.rdb != nil
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}
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// NewSeqBufferManagerFromCache 从 ConversationCache 的 Cache 接口创建 SeqBufferManager
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func NewSeqBufferManagerFromCache(cacheBackend Cache, cfg SeqBufferConfig, repo ConversationRepository, msgRepo MessageRepository) *SeqBufferManager {
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redisCache, ok := cacheBackend.(*RedisCache)
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if !ok {
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zap.L().Warn("SeqBuffer: cache is not RedisCache, seq pre-allocation disabled")
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return &SeqBufferManager{config: cfg, repo: repo, msgRepo: msgRepo}
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}
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rdb := redisCache.GetRedisClient().GetClient()
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return NewSeqBufferManager(rdb, cfg, repo, msgRepo)
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}
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// NewSeqBufferManagerFromRedisPkg 从 pkg/redis.Client 创建 SeqBufferManager
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func NewSeqBufferManagerFromRedisPkg(redisPkgClient *redisPkg.Client, cfg SeqBufferConfig, repo ConversationRepository, msgRepo MessageRepository) *SeqBufferManager {
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if redisPkgClient == nil {
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zap.L().Warn("SeqBuffer: redis client is nil, seq pre-allocation disabled")
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return &SeqBufferManager{config: cfg, repo: repo, msgRepo: msgRepo}
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}
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rdb := redisPkgClient.GetClient()
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return NewSeqBufferManager(rdb, cfg, repo, msgRepo)
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}
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