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diff --git a/2025/05/03/二〇二五年五月三日/index.html b/2025/05/03/二〇二五年五月三日/index.html index 9089fe3a..97570242 100644 --- a/2025/05/03/二〇二五年五月三日/index.html +++ b/2025/05/03/二〇二五年五月三日/index.html @@ -201,6 +201,11 @@ <nav class="post-nav"> <div class="prev-item"> + <div class="icon arrow-left"></div> + <div class="post-link"> + <a href="/2025/05/07/nestjs-bullmq-mail-business/">Prev</a> + </div> + </div> <div class="next-item"> diff --git a/2025/05/07/nestjs-bullmq-mail-business/index.html b/2025/05/07/nestjs-bullmq-mail-business/index.html new file mode 100644 index 00000000..a6e47cc2 --- /dev/null +++ b/2025/05/07/nestjs-bullmq-mail-business/index.html @@ -0,0 +1,328 @@ +<!DOCTYPE html> +<html lang="en"> + <head> + <meta charset="UTF-8"> +<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> +<meta http-equiv="X-UA-Compatible" content="ie=edge"> + + <meta name="author" content="韩暮秋"> + + + <meta name="subtitle" content="暮秋小屋"> + + + <meta 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class="post-info"> + <div class="tag-list"> + + + <span class="post-tag"> + <a href="/tags/Technique/"> + Technique + </a> + </span> + + + </div> + <div class="post-title"> + + + NestJS bullmq 邮件发送业务中的小 tips + + + </div> + <span class="post-date"> + May 7, 2025 + </span> + </div> + <div class="post-img"> + + <div class="h-line-primary"></div> + + </div> +</div> + <div class="post-content"> + <p>在 BullMQ(以及它在 NestJS 里包装的 <code>@Processor</code>/<code>WorkerHost</code>)里,整个生命周期大致是这样的:</p> +<ol> +<li>队列(在 NestJS 里由 <code>@Processor</code> 装饰的类)会被一个底层的 <code>Worker</code> 订阅。 </li> +<li>有新任务(job)进来时,Worker 会调用写在该类里的 <code>async process(job: Job)</code> 方法。 </li> +<li>如果 <code>process()</code> 正常返回(即没有抛异常),Job 就被标记为 <strong>completed</strong>,然后才会去触发所有注册了 <code>@OnWorkerEvent('completed')</code> 的回调。</li> +</ol> +<p>也就是说:</p> +<ul> +<li>**<code>process</code>**:是真正“干活”的地方,收到 job 之后立刻被调用,任何主业务逻辑(发邮件/写数据库/第三方请求等)都应该放这里。 </li> +<li><strong><code>onCompleted</code><strong>:只是一个事件监听器,</strong>在 job 已经成功完成之后</strong> 才会被触发,不会影响 job 的重试逻辑(也就是说,在这里抛错,job 已经算完成了,也不会重试)。</li> +</ul> +<p>而我在此处的业务目的是 “用队列来做可靠的、可重试的邮件发送”,那么<strong>一定要把发送邮件的逻辑写到 <code>process()</code> 里</strong>,这样在 <code>commandBus.execute(new SendMailCommand(...))</code> 抛错时,BullMQ 会根据创建 JOB 时的重试策略(retry、backoff 等)自动重新入队。而把它放到 <code>onCompleted()</code>,只相当于 job 成功完成后的“事后通知”,一旦失败不会再重试,也无法利用 BullMQ 的锁、超时、重试机制。</p> +<p>举个最简化的调整示例,删掉 <code>onCompleted</code>,把真正的发信放到 <code>process</code>: </p> +<figure class="highlight plaintext"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line">// ... existing imports ...</span><br><span class="line"></span><br><span class="line">@Processor(process.env.MAILER_QUEUE_NAME || "gcpm-mailer")</span><br><span class="line">export class BullMQMailerProcesser extends WorkerHost {</span><br><span class="line"> constructor(</span><br><span class="line"> private readonly commandBus: CommandBus,</span><br><span class="line"> private readonly logger: LoggingService,</span><br><span class="line"> ) {</span><br><span class="line"> super();</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> // ① 当有新 job 拉取到时,这个方法会被调用</span><br><span class="line"> public async process(job: Job): Promise<void> {</span><br><span class="line"> const mailAggregate = new Mail(job.data.mail);</span><br><span class="line"> try {</span><br><span class="line"> await this.commandBus.execute(new SendMailCommand(mailAggregate));</span><br><span class="line"> } catch (err) {</span><br><span class="line"> this.logger.error(`邮件发送失败,jobId=${job.id}`, err);</span><br><span class="line"> // 抛出错误,触发重试或失败</span><br><span class="line"> throw err;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> // ② onCompleted 仅在 process() 正常返回后触发,</span><br><span class="line"> // 不建议在这里执行核心业务(也无法触发重试)。</span><br><span class="line"> // @OnWorkerEvent("completed")</span><br><span class="line"> // async onCompleted(job: Job) { … }</span><br><span class="line">}</span><br></pre></td></tr></table></figure> + +<p>参考 BullMQ 官方文档:</p> +<ul> +<li>“Workers → Sandboxed processors”:Worker 拉到 job 就调用注册的处理函数,然后根据返回/抛错把 job 标记成 completed 或 failed。 </li> +<li>“Events → OnJobCompleted”:completed 事件只是一个监听钩子,不会参与重试。</li> +</ul> +<hr> +<p>而 <strong>重试次数本身并没有一个硬性上限</strong>,完全由添加 Job 时通过 <code>attempts</code> 这个选项来控制:</p> +<ul> +<li>默认情况下,如果不传 <code>attempts</code>(或不在 <code>defaultJobOptions</code> 里配置),Job <strong>不会自动重试</strong>(相当于 <code>attempts = 0</code>)。 </li> +<li>如果在 <code>queue.add()</code>(或全局 <code>defaultJobOptions</code>)里设置了 <code>attempts: N</code>,那么 BullMQ 最多会让该 Job 运行 N 次(也就是初始执行 + N−1 次重试,或者根据文档含义最多触发 N 次失败) ,失败后才算真正移入失败集合。 </li> +<li><code>attempts</code> 可以是任意的正整数(受 JavaScript <code>Number</code> 范围限制),BullMQ 本身不会再做额外的上限检查。</li> +</ul> +<p>示例(给某封邮件最多重试 3 次):</p> +<figure class="highlight ts"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailerQueue</span>.<span class="title function_">add</span>(</span><br><span class="line"> id,</span><br><span class="line"> { <span class="attr">mail</span>: <span class="keyword">new</span> <span class="title class_">Mail</span>(<span class="comment">/*…*/</span> ) },</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">attempts</span>: <span class="number">3</span>, <span class="comment">// 最多尝试 3 次</span></span><br><span class="line"> <span class="attr">backoff</span>: { <span class="comment">// 重试时的延迟策略(可选)</span></span><br><span class="line"> <span class="attr">type</span>: <span class="string">'exponential'</span>,</span><br><span class="line"> <span class="attr">delay</span>: <span class="number">1000</span>,</span><br><span class="line"> },</span><br><span class="line"> },</span><br><span class="line">);</span><br></pre></td></tr></table></figure> + +<hr> +<p>还有一个需要注意的地方,在我的业务中,邮件发送的是一种时间区间报告,这个报告包含了过去二十四小时的一些系统中的事件,但如果重试有延迟策略或重试本身就有计算成本的话,这封邮件就不是 “过去二十四小时” 的了,因为重试带来了一个真空期。</p> +<p>换言之,这个问题本质上是——<strong>重试导致「发送时刻」与「原始 24 小时窗口」错开</strong>,从而让邮件里报出来的数据不再精确。常见的解决思路就是:<strong>把「窗口定义」或者「报表内容」在调度时就固化下来,真正的队列任务只负责发送</strong>,而不再实时去重新计算时间区间。</p> +<p>我想到了两种解决方案:</p> +<p>一、任务参数里带上「时间区间」<br> 在 enqueue 的时候,就算出 windowStart/windowEnd,然后把它放到 <code>job.data</code> 里。无论后面 <code>process</code> 什么时候真正跑,都是基于同一个时间区间去查询:</p> + <figure class="highlight ts"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 调度时</span></span><br><span class="line"><span class="keyword">const</span> now = <span class="keyword">new</span> <span class="title class_">Date</span>();</span><br><span class="line"><span class="keyword">const</span> windowStart = <span class="keyword">new</span> <span class="title class_">Date</span>(now.<span class="title function_">getTime</span>() - <span class="number">24</span> * <span class="number">60</span> * <span class="number">60</span> * <span class="number">1000</span>);</span><br><span class="line"><span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailerQueue</span>.<span class="title function_">add</span>(</span><br><span class="line"> id,</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">mail</span>: <span class="keyword">new</span> <span class="title class_">Mail</span>({</span><br><span class="line"> ...options,</span><br><span class="line"> id,</span><br><span class="line"> <span class="attr">sentAt</span>: now,</span><br><span class="line"> <span class="attr">status</span>: <span class="title class_">MailStatus</span>.<span class="property">PENDING</span>,</span><br><span class="line"> windowStart,</span><br><span class="line"> <span class="attr">windowEnd</span>: now,</span><br><span class="line"> }),</span><br><span class="line"> },</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">attempts</span>: <span class="number">3</span>,</span><br><span class="line"> <span class="attr">backoff</span>: { <span class="attr">type</span>: <span class="string">'exponential'</span>, <span class="attr">delay</span>: <span class="number">1000</span> },</span><br><span class="line"> },</span><br><span class="line">);</span><br><span class="line"></span><br><span class="line"><span class="comment">// process 里</span></span><br><span class="line"><span class="keyword">public</span> <span class="keyword">async</span> <span class="title function_">process</span>(<span class="params"><span class="attr">job</span>: <span class="title class_">Job</span></span>) {</span><br><span class="line"> <span class="keyword">const</span> { windowStart, windowEnd } = job.<span class="property">data</span>.<span class="property">mail</span>;</span><br><span class="line"> <span class="comment">// ① 只查询 [windowStart, windowEnd] 的事件</span></span><br><span class="line"> <span class="keyword">const</span> events = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">findEvents</span>(windowStart, windowEnd);</span><br><span class="line"> <span class="keyword">const</span> reportHtml = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">renderReport</span>(events);</span><br><span class="line"> <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">commandBus</span>.<span class="title function_">execute</span>(<span class="keyword">new</span> <span class="title class_">SendMailCommand</span>(job.<span class="property">data</span>.<span class="property">mail</span>, reportHtml));</span><br><span class="line">}</span><br></pre></td></tr></table></figure> +<p> ➜ 这样无是马上执行还是几次重试后才执行,数据规则都不会变。</p> +<p>二、预先生成「静态报表内容」,挂到队列里<br> 如果计算成本很高,或者怕重复查询数据开销大,也可以在调度时就把最终的 HTML/Text/附件 都先打好,然后作为 <code>job.data</code> 传进去,真正的 <code>process()</code> 只做一次“发送”即可:<br> <figure class="highlight ts"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 调度时:先生成报告</span></span><br><span class="line"><span class="keyword">const</span> now = <span class="keyword">new</span> <span class="title class_">Date</span>();</span><br><span class="line"><span class="keyword">const</span> windowStart = <span class="keyword">new</span> <span class="title class_">Date</span>(now.<span class="title function_">getTime</span>() - <span class="number">24</span>*<span class="number">3600</span>*<span class="number">1000</span>);</span><br><span class="line"><span class="keyword">const</span> events = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">findEvents</span>(windowStart, now);</span><br><span class="line"><span class="keyword">const</span> reportHtml = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">renderReport</span>(events);</span><br><span class="line"></span><br><span class="line"><span class="comment">// 把静态内容塞到队列</span></span><br><span class="line"><span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailerQueue</span>.<span class="title function_">add</span>(</span><br><span class="line"> id,</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">mail</span>: <span class="keyword">new</span> <span class="title class_">Mail</span>({ <span class="comment">/*…*/</span>, windowStart, <span class="attr">windowEnd</span>: now }),</span><br><span class="line"> reportHtml, <span class="comment">// <- 预渲染好的文本/HTML</span></span><br><span class="line"> <span class="attr">attachments</span>: […], <span class="comment">// <- 如果有附件也一并塞</span></span><br><span class="line"> },</span><br><span class="line"> { <span class="attr">attempts</span>: <span class="number">3</span>, <span class="attr">backoff</span>: { <span class="attr">type</span>: <span class="string">'fixed'</span>, <span class="attr">delay</span>: <span class="number">5_000</span> } },</span><br><span class="line">);</span><br><span class="line"></span><br><span class="line"><span class="comment">// process 里只关注发送</span></span><br><span class="line"><span class="keyword">public</span> <span class="keyword">async</span> <span class="title function_">process</span>(<span class="params"><span class="attr">job</span>: <span class="title class_">Job</span></span>) {</span><br><span class="line"> <span class="keyword">try</span> {</span><br><span class="line"> <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailService</span>.<span class="title function_">send</span>({</span><br><span class="line"> <span class="attr">to</span>: job.<span class="property">data</span>.<span class="property">mail</span>.<span class="property">to</span>,</span><br><span class="line"> <span class="attr">subject</span>: <span class="string">`系统 24h 报表`</span>,</span><br><span class="line"> <span class="attr">html</span>: job.<span class="property">data</span>.<span class="property">reportHtml</span>,</span><br><span class="line"> <span class="attr">attachments</span>: job.<span class="property">data</span>.<span class="property">attachments</span>,</span><br><span class="line"> });</span><br><span class="line"> } <span class="keyword">catch</span> (e) {</span><br><span class="line"> <span class="keyword">throw</span> e; <span class="comment">// 触发重试</span></span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure><br> ➜ 重试带来的任何延迟,都不影响邮件正文,始终是一份「事先约定好、并且静态化」的报告。</p> +<p>这两种模式都能保证<strong>最终发送时的数据窗口</strong>或<strong>内容</strong>,与当初调度时的预期完全一致,不会因为重试延迟而出现“数据真空”或“多算/少算”问题。</p> +<h2 id="参考文档:"><a href="#参考文档:" class="headerlink" title="参考文档:"></a>参考文档:</h2><ul> +<li>“Retrying failing jobs” · BullMQ Guide<br><a target="_blank" rel="noopener" href="https://docs.bullmq.io/guide/retrying-failing-jobs">https://docs.bullmq.io/guide/retrying-failing-jobs</a></li> +<li>BullMQ Guide & Patterns · Process Step Jobs (completed event only fires after process resolves)<br><a target="_blank" rel="noopener" href="https://docs.bullmq.io/patterns/process-step-jobs">https://docs.bullmq.io/patterns/process-step-jobs</a></li> +</ul> + 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href="/2024/12/18/%E4%BA%8C%E3%80%87%E4%BA%8C%E5%9B%9B%E5%B9%B4%E5%8D%81%E4%BA%8C%E6%9C%88%E5%8D%81%E5%85%AB%E6%97%A5/"> - - 二〇二四年十二月十八日 - - </a> - </div> - - <span class="post-date">Dec 18, 2024</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/3/index.html b/archives/page/3/index.html index 34264fea..cb8d1350 100644 --- a/archives/page/3/index.html +++ b/archives/page/3/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2024/12/18/%E4%BA%8C%E3%80%87%E4%BA%8C%E5%9B%9B%E5%B9%B4%E5%8D%81%E4%BA%8C%E6%9C%88%E5%8D%81%E5%85%AB%E6%97%A5/"> + + 二〇二四年十二月十八日 + + </a> + </div> + + <span class="post-date">Dec 18, 2024</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2024/12/15/OCaml-News-2024-7/"> OCaml News 2024-7 @@ -325,24 +343,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2024/09/15/%E8%82%A9%E5%91%A8%E7%82%8E%E5%92%8C%E8%82%A9%E8%A2%96%E6%8D%9F%E4%BC%A4%E7%9A%84%E5%8C%BA%E5%88%AB/"> - - 肩周炎和肩袖损伤的区别 - - </a> - </div> - - <span class="post-date">Sep 15, 2024</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/4/index.html b/archives/page/4/index.html index 716ef52d..c713d295 100644 --- a/archives/page/4/index.html +++ b/archives/page/4/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2024/09/15/%E8%82%A9%E5%91%A8%E7%82%8E%E5%92%8C%E8%82%A9%E8%A2%96%E6%8D%9F%E4%BC%A4%E7%9A%84%E5%8C%BA%E5%88%AB/"> + + 肩周炎和肩袖损伤的区别 + + </a> + </div> + + <span class="post-date">Sep 15, 2024</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2024/09/15/Advanced-C-binding-using-ocaml-ctypes-and-dune/"> Advanced C binding using ocaml-ctypes and dune @@ -325,24 +343,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2024/07/23/OCaml-News-2024-6/"> - - OCaml News 2024-6 - - </a> - </div> - - <span class="post-date">Jul 23, 2024</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/5/index.html b/archives/page/5/index.html index 6c82c27a..87330e25 100644 --- a/archives/page/5/index.html +++ b/archives/page/5/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2024/07/23/OCaml-News-2024-6/"> + + OCaml News 2024-6 + + </a> + </div> + + <span class="post-date">Jul 23, 2024</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2024/07/09/%E7%A5%9E%E7%BB%8F%E7%B3%BB%E7%BB%9F%E9%87%8D%E7%82%B9/"> 内护神经系统重点考点 @@ -325,24 +343,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2024/04/08/%E4%BA%8C%E3%80%87%E4%BA%8C%E5%9B%9B%E5%B9%B4%E5%9B%9B%E6%9C%88%E5%85%AB%E6%97%A5/"> - - 二〇二四年四月八日 - - </a> - </div> - - <span class="post-date">Apr 8, 2024</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/6/index.html b/archives/page/6/index.html index 029aee4a..dc59824d 100644 --- a/archives/page/6/index.html +++ b/archives/page/6/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2024/04/08/%E4%BA%8C%E3%80%87%E4%BA%8C%E5%9B%9B%E5%B9%B4%E5%9B%9B%E6%9C%88%E5%85%AB%E6%97%A5/"> + + 二〇二四年四月八日 + + </a> + </div> + + <span class="post-date">Apr 8, 2024</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2024/04/03/shadow-cljs-proxy/"> shadow-cljs 怎么设置代理 @@ -325,24 +343,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2024/01/18/OCaml-News-2024-2/"> - - OCaml News 2024-2 - - </a> - </div> - - <span class="post-date">Jan 18, 2024</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/7/index.html b/archives/page/7/index.html index 3d05c30a..02fe542c 100644 --- a/archives/page/7/index.html +++ b/archives/page/7/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2024/01/18/OCaml-News-2024-2/"> + + OCaml News 2024-2 + + </a> + </div> + + <span class="post-date">Jan 18, 2024</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2024/01/08/OCaml-News-2024-1/"> OCaml News 2024-1 @@ -327,24 +345,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2023/10/25/%E8%82%BA%E7%82%8E%E6%94%AF%E5%8E%9F%E4%BD%93%E6%B3%A8%E6%84%8F%E4%BA%8B%E9%A1%B9/"> - - 肺炎支原体注意事项 - - </a> - </div> - - <span class="post-date">Oct 25, 2023</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/8/index.html b/archives/page/8/index.html index ae097edc..1fc94df2 100644 --- a/archives/page/8/index.html +++ b/archives/page/8/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2023/10/25/%E8%82%BA%E7%82%8E%E6%94%AF%E5%8E%9F%E4%BD%93%E6%B3%A8%E6%84%8F%E4%BA%8B%E9%A1%B9/"> + + 肺炎支原体注意事项 + + </a> + </div> + + <span class="post-date">Oct 25, 2023</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2023/10/22/%E5%86%AC%E5%AD%A3%E5%92%B3%E5%97%BD%E8%BE%A8%E5%88%AB%E6%8C%87%E5%8D%97/"> 冬季咳嗽辨别指南 @@ -325,24 +343,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2023/08/21/%E4%BA%8C%E9%9B%B6%E4%BA%8C%E4%B8%89%E5%B9%B4%E5%85%AB%E6%9C%88%E4%BA%8C%E5%8D%81%E4%B8%80%E6%97%A5/"> - - 二零二三年八月二十一日 - - </a> - </div> - - <span class="post-date">Aug 21, 2023</span> - </div> - - <div id="paginator"> <div class=paginator> diff --git a/archives/page/9/index.html b/archives/page/9/index.html index 51ac715e..47d45afc 100644 --- a/archives/page/9/index.html +++ b/archives/page/9/index.html @@ -170,6 +170,24 @@ <div class="post-list-item"> <div class="post-title"> + <a href="/2023/08/21/%E4%BA%8C%E9%9B%B6%E4%BA%8C%E4%B8%89%E5%B9%B4%E5%85%AB%E6%9C%88%E4%BA%8C%E5%8D%81%E4%B8%80%E6%97%A5/"> + + 二零二三年八月二十一日 + + </a> + </div> + + <span class="post-date">Aug 21, 2023</span> + </div> + + + + + + + + <div class="post-list-item"> + <div class="post-title"> <a href="/2023/08/15/tick-thread%E5%9C%A8Multicore-OCaml%E4%B8%AD%E7%9A%84%E4%BD%9C%E7%94%A8/"> tick thread在Multicore OCaml中的作用 @@ -325,24 +343,6 @@ </div> - - - - - - <div class="post-list-item"> - <div class="post-title"> - <a href="/2023/06/17/%E5%8F%91%E7%83%AD%E5%8F%8A%E8%B6%85%E9%AB%98%E7%83%AD%E5%8D%B1%E8%B1%A1/"> - - 发热及超高热危象 - - </a> - </div> - - <span class="post-date">Jun 17, 2023</span> - </div> - - <div id="paginator"> <div class=paginator> @@ -2428,6 +2428,57 @@ </tags> </entry> <entry> + <title>NestJS bullmq 邮件发送业务中的小 tips</title> + <url>/2025/05/07/nestjs-bullmq-mail-business/</url> + <content><![CDATA[<p>在 BullMQ(以及它在 NestJS 里包装的 <code>@Processor</code>/<code>WorkerHost</code>)里,整个生命周期大致是这样的:</p> +<ol> +<li>队列(在 NestJS 里由 <code>@Processor</code> 装饰的类)会被一个底层的 <code>Worker</code> 订阅。 </li> +<li>有新任务(job)进来时,Worker 会调用写在该类里的 <code>async process(job: Job)</code> 方法。 </li> +<li>如果 <code>process()</code> 正常返回(即没有抛异常),Job 就被标记为 <strong>completed</strong>,然后才会去触发所有注册了 <code>@OnWorkerEvent('completed')</code> 的回调。</li> +</ol> +<p>也就是说:</p> +<ul> +<li>**<code>process</code>**:是真正“干活”的地方,收到 job 之后立刻被调用,任何主业务逻辑(发邮件/写数据库/第三方请求等)都应该放这里。 </li> +<li><strong><code>onCompleted</code><strong>:只是一个事件监听器,</strong>在 job 已经成功完成之后</strong> 才会被触发,不会影响 job 的重试逻辑(也就是说,在这里抛错,job 已经算完成了,也不会重试)。</li> +</ul> +<p>而我在此处的业务目的是 “用队列来做可靠的、可重试的邮件发送”,那么<strong>一定要把发送邮件的逻辑写到 <code>process()</code> 里</strong>,这样在 <code>commandBus.execute(new SendMailCommand(...))</code> 抛错时,BullMQ 会根据创建 JOB 时的重试策略(retry、backoff 等)自动重新入队。而把它放到 <code>onCompleted()</code>,只相当于 job 成功完成后的“事后通知”,一旦失败不会再重试,也无法利用 BullMQ 的锁、超时、重试机制。</p> +<p>举个最简化的调整示例,删掉 <code>onCompleted</code>,把真正的发信放到 <code>process</code>: </p> +<figure class="highlight plaintext"><table><tr><td class="code"><pre><span class="line">// ... existing imports ...</span><br><span class="line"></span><br><span class="line">@Processor(process.env.MAILER_QUEUE_NAME || "gcpm-mailer")</span><br><span class="line">export class BullMQMailerProcesser extends WorkerHost {</span><br><span class="line"> constructor(</span><br><span class="line"> private readonly commandBus: CommandBus,</span><br><span class="line"> private readonly logger: LoggingService,</span><br><span class="line"> ) {</span><br><span class="line"> super();</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> // ① 当有新 job 拉取到时,这个方法会被调用</span><br><span class="line"> public async process(job: Job): Promise<void> {</span><br><span class="line"> const mailAggregate = new Mail(job.data.mail);</span><br><span class="line"> try {</span><br><span class="line"> await this.commandBus.execute(new SendMailCommand(mailAggregate));</span><br><span class="line"> } catch (err) {</span><br><span class="line"> this.logger.error(`邮件发送失败,jobId=${job.id}`, err);</span><br><span class="line"> // 抛出错误,触发重试或失败</span><br><span class="line"> throw err;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"></span><br><span class="line"> // ② onCompleted 仅在 process() 正常返回后触发,</span><br><span class="line"> // 不建议在这里执行核心业务(也无法触发重试)。</span><br><span class="line"> // @OnWorkerEvent("completed")</span><br><span class="line"> // async onCompleted(job: Job) { … }</span><br><span class="line">}</span><br></pre></td></tr></table></figure> + +<p>参考 BullMQ 官方文档:</p> +<ul> +<li>“Workers → Sandboxed processors”:Worker 拉到 job 就调用注册的处理函数,然后根据返回/抛错把 job 标记成 completed 或 failed。 </li> +<li>“Events → OnJobCompleted”:completed 事件只是一个监听钩子,不会参与重试。</li> +</ul> +<hr> +<p>而 <strong>重试次数本身并没有一个硬性上限</strong>,完全由添加 Job 时通过 <code>attempts</code> 这个选项来控制:</p> +<ul> +<li>默认情况下,如果不传 <code>attempts</code>(或不在 <code>defaultJobOptions</code> 里配置),Job <strong>不会自动重试</strong>(相当于 <code>attempts = 0</code>)。 </li> +<li>如果在 <code>queue.add()</code>(或全局 <code>defaultJobOptions</code>)里设置了 <code>attempts: N</code>,那么 BullMQ 最多会让该 Job 运行 N 次(也就是初始执行 + N−1 次重试,或者根据文档含义最多触发 N 次失败) ,失败后才算真正移入失败集合。 </li> +<li><code>attempts</code> 可以是任意的正整数(受 JavaScript <code>Number</code> 范围限制),BullMQ 本身不会再做额外的上限检查。</li> +</ul> +<p>示例(给某封邮件最多重试 3 次):</p> +<figure class="highlight ts"><table><tr><td class="code"><pre><span class="line"><span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailerQueue</span>.<span class="title function_">add</span>(</span><br><span class="line"> id,</span><br><span class="line"> { <span class="attr">mail</span>: <span class="keyword">new</span> <span class="title class_">Mail</span>(<span class="comment">/*…*/</span> ) },</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">attempts</span>: <span class="number">3</span>, <span class="comment">// 最多尝试 3 次</span></span><br><span class="line"> <span class="attr">backoff</span>: { <span class="comment">// 重试时的延迟策略(可选)</span></span><br><span class="line"> <span class="attr">type</span>: <span class="string">'exponential'</span>,</span><br><span class="line"> <span class="attr">delay</span>: <span class="number">1000</span>,</span><br><span class="line"> },</span><br><span class="line"> },</span><br><span class="line">);</span><br></pre></td></tr></table></figure> + +<hr> +<p>还有一个需要注意的地方,在我的业务中,邮件发送的是一种时间区间报告,这个报告包含了过去二十四小时的一些系统中的事件,但如果重试有延迟策略或重试本身就有计算成本的话,这封邮件就不是 “过去二十四小时” 的了,因为重试带来了一个真空期。</p> +<p>换言之,这个问题本质上是——<strong>重试导致「发送时刻」与「原始 24 小时窗口」错开</strong>,从而让邮件里报出来的数据不再精确。常见的解决思路就是:<strong>把「窗口定义」或者「报表内容」在调度时就固化下来,真正的队列任务只负责发送</strong>,而不再实时去重新计算时间区间。</p> +<p>我想到了两种解决方案:</p> +<p>一、任务参数里带上「时间区间」<br> 在 enqueue 的时候,就算出 windowStart/windowEnd,然后把它放到 <code>job.data</code> 里。无论后面 <code>process</code> 什么时候真正跑,都是基于同一个时间区间去查询:</p> + <figure class="highlight ts"><table><tr><td class="code"><pre><span class="line"><span class="comment">// 调度时</span></span><br><span class="line"><span class="keyword">const</span> now = <span class="keyword">new</span> <span class="title class_">Date</span>();</span><br><span class="line"><span class="keyword">const</span> windowStart = <span class="keyword">new</span> <span class="title class_">Date</span>(now.<span class="title function_">getTime</span>() - <span class="number">24</span> * <span class="number">60</span> * <span class="number">60</span> * <span class="number">1000</span>);</span><br><span class="line"><span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailerQueue</span>.<span class="title function_">add</span>(</span><br><span class="line"> id,</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">mail</span>: <span class="keyword">new</span> <span class="title class_">Mail</span>({</span><br><span class="line"> ...options,</span><br><span class="line"> id,</span><br><span class="line"> <span class="attr">sentAt</span>: now,</span><br><span class="line"> <span class="attr">status</span>: <span class="title class_">MailStatus</span>.<span class="property">PENDING</span>,</span><br><span class="line"> windowStart,</span><br><span class="line"> <span class="attr">windowEnd</span>: now,</span><br><span class="line"> }),</span><br><span class="line"> },</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">attempts</span>: <span class="number">3</span>,</span><br><span class="line"> <span class="attr">backoff</span>: { <span class="attr">type</span>: <span class="string">'exponential'</span>, <span class="attr">delay</span>: <span class="number">1000</span> },</span><br><span class="line"> },</span><br><span class="line">);</span><br><span class="line"></span><br><span class="line"><span class="comment">// process 里</span></span><br><span class="line"><span class="keyword">public</span> <span class="keyword">async</span> <span class="title function_">process</span>(<span class="params"><span class="attr">job</span>: <span class="title class_">Job</span></span>) {</span><br><span class="line"> <span class="keyword">const</span> { windowStart, windowEnd } = job.<span class="property">data</span>.<span class="property">mail</span>;</span><br><span class="line"> <span class="comment">// ① 只查询 [windowStart, windowEnd] 的事件</span></span><br><span class="line"> <span class="keyword">const</span> events = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">findEvents</span>(windowStart, windowEnd);</span><br><span class="line"> <span class="keyword">const</span> reportHtml = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">renderReport</span>(events);</span><br><span class="line"> <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">commandBus</span>.<span class="title function_">execute</span>(<span class="keyword">new</span> <span class="title class_">SendMailCommand</span>(job.<span class="property">data</span>.<span class="property">mail</span>, reportHtml));</span><br><span class="line">}</span><br></pre></td></tr></table></figure> +<p> ➜ 这样无是马上执行还是几次重试后才执行,数据规则都不会变。</p> +<p>二、预先生成「静态报表内容」,挂到队列里<br> 如果计算成本很高,或者怕重复查询数据开销大,也可以在调度时就把最终的 HTML/Text/附件 都先打好,然后作为 <code>job.data</code> 传进去,真正的 <code>process()</code> 只做一次“发送”即可:<br> <figure class="highlight ts"><table><tr><td class="code"><pre><span class="line"><span class="comment">// 调度时:先生成报告</span></span><br><span class="line"><span class="keyword">const</span> now = <span class="keyword">new</span> <span class="title class_">Date</span>();</span><br><span class="line"><span class="keyword">const</span> windowStart = <span class="keyword">new</span> <span class="title class_">Date</span>(now.<span class="title function_">getTime</span>() - <span class="number">24</span>*<span class="number">3600</span>*<span class="number">1000</span>);</span><br><span class="line"><span class="keyword">const</span> events = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">findEvents</span>(windowStart, now);</span><br><span class="line"><span class="keyword">const</span> reportHtml = <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">reportService</span>.<span class="title function_">renderReport</span>(events);</span><br><span class="line"></span><br><span class="line"><span class="comment">// 把静态内容塞到队列</span></span><br><span class="line"><span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailerQueue</span>.<span class="title function_">add</span>(</span><br><span class="line"> id,</span><br><span class="line"> {</span><br><span class="line"> <span class="attr">mail</span>: <span class="keyword">new</span> <span class="title class_">Mail</span>({ <span class="comment">/*…*/</span>, windowStart, <span class="attr">windowEnd</span>: now }),</span><br><span class="line"> reportHtml, <span class="comment">// <- 预渲染好的文本/HTML</span></span><br><span class="line"> <span class="attr">attachments</span>: […], <span class="comment">// <- 如果有附件也一并塞</span></span><br><span class="line"> },</span><br><span class="line"> { <span class="attr">attempts</span>: <span class="number">3</span>, <span class="attr">backoff</span>: { <span class="attr">type</span>: <span class="string">'fixed'</span>, <span class="attr">delay</span>: <span class="number">5_000</span> } },</span><br><span class="line">);</span><br><span class="line"></span><br><span class="line"><span class="comment">// process 里只关注发送</span></span><br><span class="line"><span class="keyword">public</span> <span class="keyword">async</span> <span class="title function_">process</span>(<span class="params"><span class="attr">job</span>: <span class="title class_">Job</span></span>) {</span><br><span class="line"> <span class="keyword">try</span> {</span><br><span class="line"> <span class="keyword">await</span> <span class="variable language_">this</span>.<span class="property">mailService</span>.<span class="title function_">send</span>({</span><br><span class="line"> <span class="attr">to</span>: job.<span class="property">data</span>.<span class="property">mail</span>.<span class="property">to</span>,</span><br><span class="line"> <span class="attr">subject</span>: <span class="string">`系统 24h 报表`</span>,</span><br><span class="line"> <span class="attr">html</span>: job.<span class="property">data</span>.<span class="property">reportHtml</span>,</span><br><span class="line"> <span class="attr">attachments</span>: job.<span class="property">data</span>.<span class="property">attachments</span>,</span><br><span class="line"> });</span><br><span class="line"> } <span class="keyword">catch</span> (e) {</span><br><span class="line"> <span class="keyword">throw</span> e; <span class="comment">// 触发重试</span></span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure><br> ➜ 重试带来的任何延迟,都不影响邮件正文,始终是一份「事先约定好、并且静态化」的报告。</p> +<p>这两种模式都能保证<strong>最终发送时的数据窗口</strong>或<strong>内容</strong>,与当初调度时的预期完全一致,不会因为重试延迟而出现“数据真空”或“多算/少算”问题。</p> +<h2 id="参考文档:"><a href="#参考文档:" class="headerlink" title="参考文档:"></a>参考文档:</h2><ul> +<li>“Retrying failing jobs” · BullMQ Guide<br><a href="https://docs.bullmq.io/guide/retrying-failing-jobs">https://docs.bullmq.io/guide/retrying-failing-jobs</a></li> +<li>BullMQ Guide & Patterns · Process Step Jobs (completed event only fires after process resolves)<br><a href="https://docs.bullmq.io/patterns/process-step-jobs">https://docs.bullmq.io/patterns/process-step-jobs</a></li> +</ul> +]]></content> + <tags> + <tag>Technique</tag> + </tags> + </entry> + <entry> <title>使用 [@poll error] 实现线程安全的数据结构</title> <url>/2023/08/15/poll-error-attribute-in-OCaml/</url> <content><