186 lines
4.9 KiB
Markdown
186 lines
4.9 KiB
Markdown
# 11. Consumer-Producer 桥接模式
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> **一句话概括**：`Consumer` 结构体桥接 `TaskQueue` 和 `WorkerPool`，实现生产者与消费者的彻底解耦。
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---
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## 架构总览
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```mermaid
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flowchart LR
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subgraph Producer["生产者"]
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A[Generate Handler]
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end
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subgraph Queue["TaskQueue 接口"]
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B((Memory\nQueue))
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C((RabbitMQ\nQueue))
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end
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subgraph Bridge["Consumer 桥接层"]
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D{{"Consumer\n(bridge)"}}
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end
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subgraph Pool["WorkerPool"]
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E[Worker 1]
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F[Worker 2]
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G[Worker N]
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end
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subgraph Pipeline["业务逻辑"]
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H[Eino Pipeline]
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end
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A -->|"Submit(msg)"| B
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A -->|"Submit(msg)"| C
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B -->|"Consume()"| D
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C -->|"Consume()"| D
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D -->|"Submit(task)"| E
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D -->|"Submit(task)"| F
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D -->|"Submit(task)"| G
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E --> H
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F --> H
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G --> H
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style D fill:#f9a825,stroke:#333,color:#000
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```
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---
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## 核心结构体
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`Consumer` 是整个任务调度体系的**桥梁**，它只做一件事：从队列取消息，提交到协程池。
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```go
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// worker/consumer.go
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type Consumer struct {
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queue taskqueue.TaskQueue // 可插拔队列接口
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pool *workerpool.Pool // 有界协程池
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handler TaskHandler // 业务逻辑注入点
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logger *slog.Logger
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}
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```
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| 字段 | 类型 | 职责 |
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|------|------|------|
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| `queue` | `TaskQueue` 接口 | 消息来源，支持 Memory / RabbitMQ 替换 |
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| `pool` | `*workerpool.Pool` | 并发执行引擎，控制单机并行度 |
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| `handler` | `TaskHandler` | 回调函数，由 handler 层注入实际业务逻辑 |
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---
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## 工作流程
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### 启动消费循环
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```mermaid
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sequenceDiagram
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participant Main as main.go
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participant Consumer
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participant Queue as TaskQueue
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participant Pool as WorkerPool
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participant Handler as RunFromTaskMessage
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Main->>Consumer: Start(ctx)
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loop 持续消费
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Consumer->>Queue: Consume(ctx, callback)
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Queue-->>Consumer: TaskMessage
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Consumer->>Consumer: processMessage()
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Consumer->>Pool: Submit(workerpool.Task)
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Pool-->>Consumer: accepted
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Pool->>Handler: Fn(ctx)
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Handler->>Handler: runPipelineBg()
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end
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```
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四步循环：
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1. **消费** — `Consumer` 调用 `queue.Consume(ctx, handler)`，阻塞等待消息
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2. **转换** — 将 `taskqueue.TaskMessage` 包装为 `workerpool.Task`
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3. **提交** — 调用 `pool.Submit(task)` 送入协程池执行
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4. **执行** — `Task.Fn` 回调实际的 `RunFromTaskMessage`，驱动 Eino 管线
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---
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## 解耦的三层设计
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```mermaid
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flowchart TB
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subgraph "第 1 层：消息源"
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Q["TaskQueue 接口\n(Memory / RabbitMQ)"]
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end
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subgraph "第 2 层：桥接"
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C["Consumer\n(只关心 消费→提交)"]
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end
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subgraph "第 3 层：执行引擎"
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P["WorkerPool\n(只关心 并发控制)"]
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end
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subgraph "第 4 层：业务逻辑"
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H["TaskHandler 回调\n(RunFromTaskMessage)"]
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end
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Q --> C --> P --> H
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```
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| 组件 | 知道什么 | 不知道什么 |
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|------|----------|------------|
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| **TaskQueue** | 消息的存储与投递 | WorkerPool 的存在 |
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| **WorkerPool** | 任务的并发执行 | 消息来自哪个队列 |
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| **Consumer** | 如何桥接两者 | 具体的业务逻辑 |
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| **TaskHandler** | 生成管线的执行 | 消息来自内存还是 RabbitMQ |
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> **设计哲学**：每个组件只关心自己的职责边界，可独立替换、测试、扩展。
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---
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## Handler 层注入
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`Consumer` 不硬编码业务逻辑，而是通过 `TaskHandler` 函数签名由外部注入：
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```go
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// worker/consumer.go — 定义
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type TaskHandler func(ctx context.Context, msg taskqueue.TaskMessage)
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// main.go — 注入
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consumer := worker.NewConsumer(tq, pool, handler.RunFromTaskMessage)
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```
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`RunFromTaskMessage` 负责将队列消息还原为 `GenerateRequest`，再调用 `runPipelineBg` 驱动完整的 Eino 管线。
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---
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## 信号处理与优雅关闭
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```mermaid
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sequenceDiagram
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participant OS as 操作系统
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participant Main as main.go
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participant Consumer
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participant Pool as WorkerPool
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OS->>Main: SIGINT / SIGTERM
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Main->>Consumer: cancel() 停止消费
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Note over Consumer: 不再接收新消息
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Main->>Pool: Shutdown(30s timeout)
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Note over Pool: 等待正在执行的任务完成
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Pool-->>Main: true (正常) / false (超时)
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Main->>Main: 进程退出
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```
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关闭顺序至关重要：
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1. **先停 Consumer** — 不再从队列拉取新消息
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2. **再关 WorkerPool** — 等待已提交的任务执行完毕（最多 30 秒）
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3. **最后关闭队列连接** — 释放 RabbitMQ / 内存资源
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---
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## 关联文档
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| 文档 | 关系 |
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|------|------|
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| [03 - 任务队列](03-task-queue.md) | Consumer 的消息来源 |
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| [02 - 协程池](02-worker-pool.md) | Consumer 的执行引擎 |
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| [12 - 三级降级策略](12-three-tier-fallback.md) | Consumer 不参与降级，降级在 Handler 层 |
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| [00 - 索引](00-index.md) | 返回文档总览 |
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