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<ol class="chapter"><li class="chapter-item affix "><a href="../../about-book.html">关于本书</a></li><li class="chapter-item affix "><a href="../../into-rust.html">进入 Rust 编程世界</a></li><li class="chapter-item affix "><a href="../../first-try/sth-you-should-not-do.html">避免从入门到放弃</a></li><li class="chapter-item affix "><a href="../../community.html">社区和锈书</a></li><li class="spacer"></li><li class="chapter-item affix "><a href="../../some-thoughts.html">Xobserve: 一切皆可观测</a></li><li class="chapter-item affix "><a href="../../beat-ai.html">BeatAI: 工程师 AI 入门圣经</a></li><li class="chapter-item affix "><li class="part-title">Rust 语言基础学习</li><li class="spacer"></li><li class="chapter-item "><a href="../../first-try/intro.html"><strong aria-hidden="true">1.</strong> 寻找牛刀，以便小试</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../first-try/installation.html"><strong aria-hidden="true">1.1.</strong> 安装 Rust 环境</a></li><li class="chapter-item "><a href="../../first-try/editor.html"><strong aria-hidden="true">1.2.</strong> 墙推 VSCode!</a></li><li class="chapter-item "><a href="../../first-try/cargo.html"><strong aria-hidden="true">1.3.</strong> 认识 Cargo</a></li><li class="chapter-item "><a href="../../first-try/hello-world.html"><strong aria-hidden="true">1.4.</strong> 不仅仅是 Hello world</a></li><li class="chapter-item "><a href="../../first-try/slowly-downloading.html"><strong aria-hidden="true">1.5.</strong> 下载依赖太慢了？</a></li></ol></li><li class="chapter-item "><a href="../../basic/intro.html"><strong aria-hidden="true">2.</strong> Rust 基础入门</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/variable.html"><strong aria-hidden="true">2.1.</strong> 变量绑定与解构</a></li><li class="chapter-item "><a href="../../basic/base-type/index.html"><strong aria-hidden="true">2.2.</strong> 基本类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/base-type/numbers.html"><strong aria-hidden="true">2.2.1.</strong> 数值类型</a></li><li class="chapter-item "><a href="../../basic/base-type/char-bool.html"><strong aria-hidden="true">2.2.2.</strong> 字符、布尔、单元类型</a></li><li class="chapter-item "><a href="../../basic/base-type/statement-expression.html"><strong aria-hidden="true">2.2.3.</strong> 语句与表达式</a></li><li class="chapter-item "><a href="../../basic/base-type/function.html"><strong aria-hidden="true">2.2.4.</strong> 函数</a></li></ol></li><li class="chapter-item "><a href="../../basic/ownership/index.html"><strong aria-hidden="true">2.3.</strong> 所有权和借用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/ownership/ownership.html"><strong aria-hidden="true">2.3.1.</strong> 所有权</a></li><li class="chapter-item "><a href="../../basic/ownership/borrowing.html"><strong aria-hidden="true">2.3.2.</strong> 引用与借用</a></li></ol></li><li class="chapter-item "><a href="../../basic/compound-type/intro.html"><strong aria-hidden="true">2.4.</strong> 复合类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/compound-type/string-slice.html"><strong aria-hidden="true">2.4.1.</strong> 字符串与切片</a></li><li class="chapter-item "><a href="../../basic/compound-type/tuple.html"><strong aria-hidden="true">2.4.2.</strong> 元组</a></li><li class="chapter-item "><a href="../../basic/compound-type/struct.html"><strong aria-hidden="true">2.4.3.</strong> 结构体</a></li><li class="chapter-item "><a href="../../basic/compound-type/enum.html"><strong aria-hidden="true">2.4.4.</strong> 枚举</a></li><li class="chapter-item "><a href="../../basic/compound-type/array.html"><strong aria-hidden="true">2.4.5.</strong> 数组</a></li></ol></li><li class="chapter-item "><a href="../../basic/flow-control.html"><strong aria-hidden="true">2.5.</strong> 流程控制</a></li><li class="chapter-item "><a href="../../basic/match-pattern/intro.html"><strong aria-hidden="true">2.6.</strong> 模式匹配</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/match-pattern/match-if-let.html"><strong aria-hidden="true">2.6.1.</strong> match 和 if let</a></li><li class="chapter-item "><a href="../../basic/match-pattern/option.html"><strong aria-hidden="true">2.6.2.</strong> 解构 Option</a></li><li class="chapter-item "><a href="../../basic/match-pattern/pattern-match.html"><strong aria-hidden="true">2.6.3.</strong> 模式适用场景</a></li><li class="chapter-item "><a href="../../basic/match-pattern/all-patterns.html"><strong aria-hidden="true">2.6.4.</strong> 全模式列表</a></li></ol></li><li class="chapter-item "><a href="../../basic/method.html"><strong aria-hidden="true">2.7.</strong> 方法 Method</a></li><li class="chapter-item "><a href="../../basic/trait/intro.html"><strong aria-hidden="true">2.8.</strong> 泛型和特征</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/trait/generic.html"><strong aria-hidden="true">2.8.1.</strong> 泛型 Generics</a></li><li class="chapter-item "><a href="../../basic/trait/trait.html"><strong aria-hidden="true">2.8.2.</strong> 特征 Trait</a></li><li class="chapter-item "><a href="../../basic/trait/trait-object.html"><strong aria-hidden="true">2.8.3.</strong> 特征对象</a></li><li class="chapter-item "><a href="../../basic/trait/advance-trait.html"><strong aria-hidden="true">2.8.4.</strong> 进一步深入特征</a></li></ol></li><li class="chapter-item "><a href="../../basic/collections/intro.html"><strong aria-hidden="true">2.9.</strong> 集合类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/collections/vector.html"><strong aria-hidden="true">2.9.1.</strong> 动态数组 Vector</a></li><li class="chapter-item "><a href="../../basic/collections/hashmap.html"><strong aria-hidden="true">2.9.2.</strong> KV 存储 HashMap</a></li></ol></li><li class="chapter-item "><a href="../../basic/lifetime.html"><strong aria-hidden="true">2.10.</strong> 认识生命周期</a></li><li class="chapter-item "><a href="../../basic/result-error/intro.html"><strong aria-hidden="true">2.11.</strong> 返回值和错误处理</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/result-error/panic.html"><strong aria-hidden="true">2.11.1.</strong> panic! 深入剖析</a></li><li class="chapter-item "><a href="../../basic/result-error/result.html"><strong aria-hidden="true">2.11.2.</strong> 返回值 Result 和?</a></li></ol></li><li class="chapter-item "><a href="../../basic/crate-module/intro.html"><strong aria-hidden="true">2.12.</strong> 包和模块</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/crate-module/crate.html"><strong aria-hidden="true">2.12.1.</strong> 包 Crate</a></li><li class="chapter-item "><a href="../../basic/crate-module/module.html"><strong aria-hidden="true">2.12.2.</strong> 模块 Module</a></li><li class="chapter-item "><a href="../../basic/crate-module/use.html"><strong aria-hidden="true">2.12.3.</strong> 使用 use 引入模块及受限可见性</a></li></ol></li><li class="chapter-item "><a href="../../basic/comment.html"><strong aria-hidden="true">2.13.</strong> 注释和文档</a></li><li class="chapter-item "><a href="../../basic/formatted-output.html"><strong aria-hidden="true">2.14.</strong> 格式化输出</a></li></ol></li><li class="chapter-item "><a href="../../basic-practice/intro.html"><strong aria-hidden="true">3.</strong> 入门实战：文件搜索工具</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic-practice/base-features.html"><strong aria-hidden="true">3.1.</strong> 基本功能</a></li><li class="chapter-item "><a href="../../basic-practice/refactoring.html"><strong aria-hidden="true">3.2.</strong> 增加模块化和错误处理</a></li><li class="chapter-item "><a href="../../basic-practice/tests.html"><strong aria-hidden="true">3.3.</strong> 测试驱动开发</a></li><li class="chapter-item "><a href="../../basic-practice/envs.html"><strong aria-hidden="true">3.4.</strong> 使用环境变量</a></li><li class="chapter-item "><a href="../../basic-practice/stderr.html"><strong aria-hidden="true">3.5.</strong> 重定向错误信息的输出</a></li><li class="chapter-item "><a href="../../basic-practice/iterators.html"><strong aria-hidden="true">3.6.</strong> 使用迭代器来改进程序(可选)</a></li></ol></li><li class="chapter-item "><li class="part-title">Rust 语言进阶学习</li><li class="spacer"></li><li class="chapter-item expanded "><a href="../../advance/intro.html"><strong aria-hidden="true">4.</strong> Rust 高级进阶</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/lifetime/intro.html"><strong aria-hidden="true">4.1.</strong> 生命周期</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/lifetime/advance.html"><strong aria-hidden="true">4.1.1.</strong> 深入生命周期</a></li><li class="chapter-item "><a href="../../advance/lifetime/static.html"><strong aria-hidden="true">4.1.2.</strong> &'static 和 T: 'static</a></li></ol></li><li class="chapter-item "><a href="../../advance/functional-programing/intro.html"><strong aria-hidden="true">4.2.</strong> 函数式编程: 闭包、迭代器</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/functional-programing/closure.html"><strong aria-hidden="true">4.2.1.</strong> 闭包 Closure</a></li><li class="chapter-item "><a href="../../advance/functional-programing/iterator.html"><strong aria-hidden="true">4.2.2.</strong> 迭代器 Iterator</a></li></ol></li><li class="chapter-item "><a href="../../advance/into-types/intro.html"><strong aria-hidden="true">4.3.</strong> 深入类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/into-types/converse.html"><strong aria-hidden="true">4.3.1.</strong> 类型转换</a></li><li class="chapter-item "><a href="../../advance/into-types/custom-type.html"><strong aria-hidden="true">4.3.2.</strong> newtype 和 类型别名</a></li><li class="chapter-item "><a href="../../advance/into-types/sized.html"><strong aria-hidden="true">4.3.3.</strong> Sized 和不定长类型 DST</a></li><li class="chapter-item "><a href="../../advance/into-types/enum-int.html"><strong aria-hidden="true">4.3.4.</strong> 枚举和整数</a></li></ol></li><li class="chapter-item "><a href="../../advance/smart-pointer/intro.html"><strong aria-hidden="true">4.4.</strong> 智能指针</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/smart-pointer/box.html"><strong aria-hidden="true">4.4.1.</strong> Box堆对象分配</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/deref.html"><strong aria-hidden="true">4.4.2.</strong> Deref 解引用</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/drop.html"><strong aria-hidden="true">4.4.3.</strong> Drop 释放资源</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/rc-arc.html"><strong aria-hidden="true">4.4.4.</strong> Rc 与 Arc 实现 1vN 所有权机制</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/cell-refcell.html"><strong aria-hidden="true">4.4.5.</strong> Cell 与 RefCell 内部可变性</a></li></ol></li><li class="chapter-item "><a href="../../advance/circle-self-ref/intro.html"><strong aria-hidden="true">4.5.</strong> 循环引用与自引用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/circle-self-ref/circle-reference.html"><strong aria-hidden="true">4.5.1.</strong> Weak 与循环引用</a></li><li class="chapter-item "><a href="../../advance/circle-self-ref/self-referential.html"><strong aria-hidden="true">4.5.2.</strong> 结构体中的自引用</a></li></ol></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/intro.html"><strong aria-hidden="true">4.6.</strong> 多线程并发编程</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/concurrency-with-threads/concurrency-parallelism.html"><strong aria-hidden="true">4.6.1.</strong> 并发和并行</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/thread.html"><strong aria-hidden="true">4.6.2.</strong> 使用多线程</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/message-passing.html"><strong aria-hidden="true">4.6.3.</strong> 线程同步：消息传递</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/sync1.html"><strong aria-hidden="true">4.6.4.</strong> 线程同步：锁、Condvar 和信号量</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/sync2.html"><strong aria-hidden="true">4.6.5.</strong> 线程同步：Atomic 原子操作与内存顺序</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/send-sync.html"><strong aria-hidden="true">4.6.6.</strong> 基于 Send 和 Sync 的线程安全</a></li></ol></li><li class="chapter-item "><a href="../../advance/global-variable.html"><strong aria-hidden="true">4.7.</strong> 全局变量</a></li><li class="chapter-item "><a href="../../advance/errors.html"><strong aria-hidden="true">4.8.</strong> 错误处理</a></li><li class="chapter-item "><a href="../../advance/unsafe/intro.html"><strong aria-hidden="true">4.9.</strong> Unsafe Rust</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/unsafe/superpowers.html"><strong aria-hidden="true">4.9.1.</strong> 五种兵器</a></li><li class="chapter-item "><a href="../../advance/unsafe/inline-asm.html"><strong aria-hidden="true">4.9.2.</strong> 内联汇编</a></li></ol></li><li class="chapter-item "><a href="../../advance/macro.html"><strong aria-hidden="true">4.10.</strong> Macro 宏编程</a></li><li class="chapter-item expanded "><a href="../../advance/async/intro.html"><strong aria-hidden="true">4.11.</strong> async/await 异步编程</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/async/getting-started.html"><strong aria-hidden="true">4.11.1.</strong> async 编程入门</a></li><li class="chapter-item expanded "><a href="../../advance/async/future-excuting.html" class="active"><strong aria-hidden="true">4.11.2.</strong> 底层探秘: Future 执行与任务调度</a></li><li class="chapter-item "><a href="../../advance/async/pin-unpin.html"><strong aria-hidden="true">4.11.3.</strong> 定海神针 Pin 和 Unpin</a></li><li class="chapter-item "><a href="../../advance/async/async-await.html"><strong aria-hidden="true">4.11.4.</strong> async/await 和 Stream 流处理</a></li><li class="chapter-item "><a href="../../advance/async/multi-futures-simultaneous.html"><strong aria-hidden="true">4.11.5.</strong> 同时运行多个 Future</a></li><li class="chapter-item "><a href="../../advance/async/pain-points-and-workarounds.html"><strong aria-hidden="true">4.11.6.</strong> 一些疑难问题的解决办法</a></li><li class="chapter-item "><a href="../../advance/async/web-server.html"><strong aria-hidden="true">4.11.7.</strong> 实践应用：Async Web 服务器</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../advance-practice1/intro.html"><strong aria-hidden="true">5.</strong> 进阶实战1: 实现一个 web 服务器</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance-practice1/web-server.html"><strong aria-hidden="true">5.1.</strong> 单线程版本</a></li><li class="chapter-item "><a href="../../advance-practice1/multi-threads.html"><strong aria-hidden="true">5.2.</strong> 多线程版本</a></li><li class="chapter-item "><a href="../../advance-practice1/graceful-shutdown.html"><strong aria-hidden="true">5.3.</strong> 优雅关闭和资源清理</a></li></ol></li><li class="chapter-item "><a href="../../advance-practice/intro.html"><strong aria-hidden="true">6.</strong> 进阶实战2: 实现一个简单 Redis</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance-practice/overview.html"><strong aria-hidden="true">6.1.</strong> tokio 概览</a></li><li class="chapter-item "><a href="../../advance-practice/getting-startted.html"><strong aria-hidden="true">6.2.</strong> 使用初印象</a></li><li class="chapter-item "><a href="../../advance-practice/spawning.html"><strong aria-hidden="true">6.3.</strong> 创建异步任务</a></li><li class="chapter-item "><a href="../../advance-practice/shared-state.html"><strong aria-hidden="true">6.4.</strong> 共享状态</a></li><li class="chapter-item "><a href="../../advance-practice/channels.html"><strong aria-hidden="true">6.5.</strong> 消息传递</a></li><li class="chapter-item "><a href="../../advance-practice/io.html"><strong aria-hidden="true">6.6.</strong> I/O</a></li><li class="chapter-item "><a href="../../advance-practice/frame.html"><strong aria-hidden="true">6.7.</strong> 解析数据帧</a></li><li class="chapter-item "><a href="../../advance-practice/async.html"><strong aria-hidden="true">6.8.</strong> 深入 async</a></li><li class="chapter-item "><a href="../../advance-practice/select.html"><strong aria-hidden="true">6.9.</strong> select</a></li><li class="chapter-item "><a href="../../advance-practice/stream.html"><strong aria-hidden="true">6.10.</strong> 类似迭代器的 Stream</a></li><li class="chapter-item "><a href="../../advance-practice/graceful-shutdown.html"><strong aria-hidden="true">6.11.</strong> 优雅的关闭</a></li><li class="chapter-item "><a href="../../advance-practice/bridging-with-sync.html"><strong aria-hidden="true">6.12.</strong> 异步跟同步共存</a></li></ol></li><li class="chapter-item "><a href="../../difficulties/intro.html"><strong aria-hidden="true">7.</strong> Rust 难点攻关</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../difficulties/slice.html"><strong aria-hidden="true">7.1.</strong> 切片和切片引用</a></li><li class="chapter-item "><a href="../../difficulties/eq.html"><strong aria-hidden="true">7.2.</strong> Eq 和 PartialEq</a></li><li class="chapter-item "><a href="../../difficulties/string.html"><strong aria-hidden="true">7.3.</strong> String、&str 和 str TODO</a></li><li class="chapter-item "><a href="../../difficulties/lifetime.html"><strong aria-hidden="true">7.4.</strong> 作用域、生命周期和 NLL TODO</a></li><li class="chapter-item "><a href="../../difficulties/move-copy.html"><strong aria-hidden="true">7.5.</strong> move、Copy 和 Clone TODO</a></li><li class="chapter-item "><a href="../../advance/difficulties/pointer.html"><strong aria-hidden="true">7.6.</strong> 裸指针、引用和智能指针 TODO</a></li></ol></li><li class="chapter-item "><li class="part-title">常用工具链</li><li class="spacer"></li><li class="chapter-item "><a href="../../test/intro.html"><strong aria-hidden="true">8.</strong> 自动化测试</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../test/write-tests.html"><strong aria-hidden="true">8.1.</strong> 编写测试及控制执行</a></li><li class="chapter-item "><a href="../../test/unit-integration-test.html"><strong aria-hidden="true">8.2.</strong> 单元测试和集成测试</a></li><li class="chapter-item "><a href="../../test/assertion.html"><strong aria-hidden="true">8.3.</strong> 断言 assertion</a></li><li class="chapter-item "><a href="../../test/ci.html"><strong aria-hidden="true">8.4.</strong> 用 GitHub Actions 进行持续集成</a></li><li class="chapter-item "><a href="../../test/benchmark.html"><strong aria-hidden="true">8.5.</strong> 基准测试 benchmark</a></li></ol></li><li class="chapter-item "><a href="../../cargo/intro.html"><strong aria-hidden="true">9.</strong> Cargo 使用指南</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/getting-started.html"><strong aria-hidden="true">9.1.</strong> 上手使用</a></li><li class="chapter-item "><a href="../../cargo/guide/intro.html"><strong aria-hidden="true">9.2.</strong> 基础指南</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/guide/why-exist.html"><strong aria-hidden="true">9.2.1.</strong> 为何会有 Cargo</a></li><li class="chapter-item "><a href="../../cargo/guide/download-package.html"><strong aria-hidden="true">9.2.2.</strong> 下载并构建 Package</a></li><li class="chapter-item "><a href="../../cargo/guide/dependencies.html"><strong aria-hidden="true">9.2.3.</strong> 添加依赖</a></li><li class="chapter-item "><a href="../../cargo/guide/package-layout.html"><strong aria-hidden="true">9.2.4.</strong> Package 目录结构</a></li><li class="chapter-item "><a href="../../cargo/guide/cargo-toml-lock.html"><strong aria-hidden="true">9.2.5.</strong> Cargo.toml vs Cargo.lock</a></li><li class="chapter-item "><a href="../../cargo/guide/tests-ci.html"><strong aria-hidden="true">9.2.6.</strong> 测试和 CI</a></li><li class="chapter-item "><a href="../../cargo/guide/cargo-cache.html"><strong aria-hidden="true">9.2.7.</strong> Cargo 缓存</a></li><li class="chapter-item "><a href="../../cargo/guide/build-cache.html"><strong aria-hidden="true">9.2.8.</strong> Build 缓存</a></li></ol></li><li class="chapter-item "><a href="../../cargo/reference/intro.html"><strong aria-hidden="true">9.3.</strong> 进阶指南</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/reference/specify-deps.html"><strong aria-hidden="true">9.3.1.</strong> 指定依赖项</a></li><li class="chapter-item "><a href="../../cargo/reference/deps-overriding.html"><strong aria-hidden="true">9.3.2.</strong> 依赖覆盖</a></li><li class="chapter-item "><a href="../../cargo/reference/manifest.html"><strong aria-hidden="true">9.3.3.</strong> Cargo.toml 清单详解</a></li><li class="chapter-item "><a href="../../cargo/reference/cargo-target.html"><strong aria-hidden="true">9.3.4.</strong> Cargo Target</a></li><li class="chapter-item "><a href="../../cargo/reference/workspaces.html"><strong aria-hidden="true">9.3.5.</strong> 工作空间 Workspace</a></li><li class="chapter-item "><a href="../../cargo/reference/features/intro.html"><strong aria-hidden="true">9.3.6.</strong> 条件编译 Features</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/reference/features/examples.html"><strong aria-hidden="true">9.3.6.1.</strong> Features 示例</a></li></ol></li><li class="chapter-item "><a href="../../cargo/reference/profiles.html"><strong aria-hidden="true">9.3.7.</strong> 发布配置 Profile</a></li><li class="chapter-item "><a href="../../cargo/reference/configuration.html"><strong aria-hidden="true">9.3.8.</strong> 通过 config.toml 对 Cargo 进行配置</a></li><li class="chapter-item "><a href="../../cargo/reference/publishing-on-crates.io.html"><strong aria-hidden="true">9.3.9.</strong> 发布到 crates.io</a></li><li class="chapter-item "><a href="../../cargo/reference/build-script/intro.html"><strong aria-hidden="true">9.3.10.</strong> 构建脚本 build.rs</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/reference/build-script/examples.html"><strong aria-hidden="true">9.3.10.1.</strong> 构建脚本示例</a></li></ol></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">开发实践</li><li class="spacer"></li><li class="chapter-item "><a href="../../usecases/intro.html"><strong aria-hidden="true">10.</strong> 企业落地实践</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usecases/aws-rust.html"><strong aria-hidden="true">10.1.</strong> AWS 为何这么喜欢 Rust?</a></li></ol></li><li class="chapter-item "><a href="../../logs/intro.html"><strong aria-hidden="true">11.</strong> 日志和监控</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../logs/about-log.html"><strong aria-hidden="true">11.1.</strong> 日志详解</a></li><li class="chapter-item "><a href="../../logs/log.html"><strong aria-hidden="true">11.2.</strong> 日志门面 log</a></li><li class="chapter-item "><a href="../../logs/tracing.html"><strong aria-hidden="true">11.3.</strong> 使用 tracing 记录日志</a></li><li class="chapter-item "><a href="../../logs/tracing-logger.html"><strong aria-hidden="true">11.4.</strong> 自定义 tracing 的输出格式</a></li><li class="chapter-item "><a href="../../logs/observe/intro.html"><strong aria-hidden="true">11.5.</strong> 监控</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../logs/observe/about-observe.html"><strong aria-hidden="true">11.5.1.</strong> 可观测性</a></li><li class="chapter-item "><a href="../../logs/observe/trace.html"><strong aria-hidden="true">11.5.2.</strong> 分布式追踪</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../practice/intro.html"><strong aria-hidden="true">12.</strong> Rust 最佳实践</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../practice/third-party-libs.html"><strong aria-hidden="true">12.1.</strong> 日常开发三方库精选</a></li><li class="chapter-item "><a href="../../practice/naming.html"><strong aria-hidden="true">12.2.</strong> 命名规范</a></li><li class="chapter-item "><a href="../../practice/interview.html"><strong aria-hidden="true">12.3.</strong> 面试经验</a></li><li class="chapter-item "><a href="../../practice/best-pratice.html"><strong aria-hidden="true">12.4.</strong> 代码开发实践 todo</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/intro.html"><strong aria-hidden="true">13.</strong> 手把手带你实现链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/do-we-need-it.html"><strong aria-hidden="true">13.1.</strong> 我们到底需不需要链表</a></li><li class="chapter-item "><a href="../../too-many-lists/bad-stack/intro.html"><strong aria-hidden="true">13.2.</strong> 不太优秀的单向链表：栈</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/bad-stack/layout.html"><strong aria-hidden="true">13.2.1.</strong> 数据布局</a></li><li class="chapter-item "><a href="../../too-many-lists/bad-stack/basic-operations.html"><strong aria-hidden="true">13.2.2.</strong> 基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/bad-stack/final-code.html"><strong aria-hidden="true">13.2.3.</strong> 最后实现</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/intro.html"><strong aria-hidden="true">13.3.</strong> 还可以的单向链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/ok-stack/type-optimizing.html"><strong aria-hidden="true">13.3.1.</strong> 优化类型定义</a></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/peek.html"><strong aria-hidden="true">13.3.2.</strong> 定义 Peek 函数</a></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/iter.html"><strong aria-hidden="true">13.3.3.</strong> IntoIter 和 Iter</a></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/itermut.html"><strong aria-hidden="true">13.3.4.</strong> IterMut 以及完整代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/persistent-stack/intro.html"><strong aria-hidden="true">13.4.</strong> 持久化单向链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/persistent-stack/layout.html"><strong aria-hidden="true">13.4.1.</strong> 数据布局和基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/persistent-stack/drop-arc.html"><strong aria-hidden="true">13.4.2.</strong> Drop、Arc 及完整代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/deque/intro.html"><strong aria-hidden="true">13.5.</strong> 不咋样的双端队列</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/deque/layout.html"><strong aria-hidden="true">13.5.1.</strong> 数据布局和基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/peek.html"><strong aria-hidden="true">13.5.2.</strong> Peek</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/symmetric.html"><strong aria-hidden="true">13.5.3.</strong> 基本操作的对称镜像</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/iterator.html"><strong aria-hidden="true">13.5.4.</strong> 迭代器</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/final-code.html"><strong aria-hidden="true">13.5.5.</strong> 最终代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/intro.html"><strong aria-hidden="true">13.6.</strong> 不错的 unsafe 队列</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/layout.html"><strong aria-hidden="true">13.6.1.</strong> 数据布局</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/basics.html"><strong aria-hidden="true">13.6.2.</strong> 基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/miri.html"><strong aria-hidden="true">13.6.3.</strong> Miri</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/stacked-borrow.html"><strong aria-hidden="true">13.6.4.</strong> 栈借用</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/testing-stacked-borrow.html"><strong aria-hidden="true">13.6.5.</strong> 测试栈借用</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/layout2.html"><strong aria-hidden="true">13.6.6.</strong> 数据布局 2</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/extra-junk.html"><strong aria-hidden="true">13.6.7.</strong> 额外的操作</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/final-code.html"><strong aria-hidden="true">13.6.8.</strong> 最终代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/intro.html"><strong aria-hidden="true">13.7.</strong> 生产级的双向 unsafe 队列</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/layout.html"><strong aria-hidden="true">13.7.1.</strong> 数据布局</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/variance-and-phantomData.html"><strong aria-hidden="true">13.7.2.</strong> 型变与子类型</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/basics.html"><strong aria-hidden="true">13.7.3.</strong> 基础结构</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/drop-and-panic-safety.html"><strong aria-hidden="true">13.7.4.</strong> 恐慌与安全</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/boring-combinatorics.html"><strong aria-hidden="true">13.7.5.</strong> 无聊的组合</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/filling-in-random-bits.html"><strong aria-hidden="true">13.7.6.</strong> 其它特征</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/testing.html"><strong aria-hidden="true">13.7.7.</strong> 测试</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/send-sync-and-compile-tests.html"><strong aria-hidden="true">13.7.8.</strong> Send,Sync和编译测试</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/implementing-cursors.html"><strong aria-hidden="true">13.7.9.</strong> 实现游标</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/testing-cursors.html"><strong aria-hidden="true">13.7.10.</strong> 测试游标</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/final-code.html"><strong aria-hidden="true">13.7.11.</strong> 最终代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/intro.html"><strong aria-hidden="true">13.8.</strong> 使用高级技巧实现链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/double-singly.html"><strong aria-hidden="true">13.8.1.</strong> 双单向链表</a></li><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/stack-allocated.html"><strong aria-hidden="true">13.8.2.</strong> 栈上的链表</a></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">攻克编译错误</li><li class="spacer"></li><li class="chapter-item "><a href="../../compiler/intro.html"><strong aria-hidden="true">14.</strong> 征服编译错误</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/intro.html"><strong aria-hidden="true">14.1.</strong> 对抗编译检查</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/intro.html"><strong aria-hidden="true">14.1.1.</strong> 生命周期</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/too-long1.html"><strong aria-hidden="true">14.1.1.1.</strong> 生命周期过大-01</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/too-long2.html"><strong aria-hidden="true">14.1.1.2.</strong> 生命周期过大-02</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/loop.html"><strong aria-hidden="true">14.1.1.3.</strong> 循环中的生命周期</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/closure-with-static.html"><strong aria-hidden="true">14.1.1.4.</strong> 闭包碰到特征对象-01</a></li></ol></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/borrowing/intro.html"><strong aria-hidden="true">14.1.2.</strong> 重复借用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/borrowing/ref-exist-in-out-fn.html"><strong aria-hidden="true">14.1.2.1.</strong> 同时在函数内外使用引用</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/borrowing/borrow-distinct-fields-of-struct.html"><strong aria-hidden="true">14.1.2.2.</strong> 智能指针引起的重复借用错误</a></li></ol></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/unconstrained.html"><strong aria-hidden="true">14.1.3.</strong> 类型未限制(todo)</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/phantom-data.html"><strong aria-hidden="true">14.1.4.</strong> 幽灵数据(todo)</a></li></ol></li><li class="chapter-item "><a href="../../compiler/pitfalls/index.html"><strong aria-hidden="true">14.2.</strong> Rust 常见陷阱</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/pitfalls/use-vec-in-for.html"><strong aria-hidden="true">14.2.1.</strong> for 循环中使用外部数组</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/stack-overflow.html"><strong aria-hidden="true">14.2.2.</strong> 线程类型导致的栈溢出</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/arithmetic-overflow.html"><strong aria-hidden="true">14.2.3.</strong> 算术溢出导致的 panic</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/closure-with-lifetime.html"><strong aria-hidden="true">14.2.4.</strong> 闭包中奇怪的生命周期</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/the-disabled-mutability.html"><strong aria-hidden="true">14.2.5.</strong> 可变变量不可变？</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/multiple-mutable-references.html"><strong aria-hidden="true">14.2.6.</strong> 可变借用失败引发的深入思考</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/lazy-iterators.html"><strong aria-hidden="true">14.2.7.</strong> 不太勤快的迭代器</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/weird-ranges.html"><strong aria-hidden="true">14.2.8.</strong> 奇怪的序列 x..y</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/iterator-everywhere.html"><strong aria-hidden="true">14.2.9.</strong> 无处不在的迭代器</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/main-with-channel-blocked.html"><strong aria-hidden="true">14.2.10.</strong> 线程间传递消息导致主线程无法结束</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/utf8-performance.html"><strong aria-hidden="true">14.2.11.</strong> 警惕 UTF-8 引发的性能隐患</a></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">性能优化</li><li class="spacer"></li><li class="chapter-item "><a href="../../profiling/intro.html"><strong aria-hidden="true">15.</strong> Rust 性能优化 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/memory/intro.html"><strong aria-hidden="true">15.1.</strong> 深入内存 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/memory/pointer-ref.html"><strong aria-hidden="true">15.1.1.</strong> 指针和引用 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/uninit.html"><strong aria-hidden="true">15.1.2.</strong> 未初始化内存 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/allocation.html"><strong aria-hidden="true">15.1.3.</strong> 内存分配 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/layout.html"><strong aria-hidden="true">15.1.4.</strong> 内存布局 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/virtual.html"><strong aria-hidden="true">15.1.5.</strong> 虚拟内存 todo</a></li></ol></li><li class="chapter-item "><a href="../../profiling/performance/intro.html"><strong aria-hidden="true">15.2.</strong> 性能调优 doing</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/performance/string.html"><strong aria-hidden="true">15.2.1.</strong> 字符串操作性能</a></li><li class="chapter-item "><a href="../../profiling/performance/deep-into-move.html"><strong aria-hidden="true">15.2.2.</strong> 深入理解 move</a></li><li class="chapter-item "><a href="../../profiling/performance/early-optimise.html"><strong aria-hidden="true">15.2.3.</strong> 糟糕的提前优化 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/clone-copy.html"><strong aria-hidden="true">15.2.4.</strong> Clone 和 Copy todo</a></li><li class="chapter-item "><a href="../../profiling/performance/runtime-check.html"><strong aria-hidden="true">15.2.5.</strong> 减少 Runtime check(todo)</a></li><li class="chapter-item "><a href="../../profiling/performance/cpu-cache.html"><strong aria-hidden="true">15.2.6.</strong> CPU 缓存性能优化 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/calculate.html"><strong aria-hidden="true">15.2.7.</strong> 计算性能优化 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/heap-stack.html"><strong aria-hidden="true">15.2.8.</strong> 堆和栈 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/allocator.html"><strong aria-hidden="true">15.2.9.</strong> 内存 allocator todo</a></li><li class="chapter-item "><a href="../../profiling/performance/tools.html"><strong aria-hidden="true">15.2.10.</strong> 常用性能测试工具 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/enum.html"><strong aria-hidden="true">15.2.11.</strong> Enum 内存优化 todo</a></li></ol></li><li class="chapter-item "><a href="../../profiling/compiler/intro.html"><strong aria-hidden="true">15.3.</strong> 编译优化 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/compiler/llvm.html"><strong aria-hidden="true">15.3.1.</strong> LLVM todo</a></li><li class="chapter-item "><a href="../../profiling/compiler/attributes.html"><strong aria-hidden="true">15.3.2.</strong> 常见属性标记 todo</a></li><li class="chapter-item "><a href="../../profiling/compiler/speed-up.html"><strong aria-hidden="true">15.3.3.</strong> 提升编译速度 todo</a></li><li class="chapter-item "><a href="../../profiling/compiler/optimization/intro.html"><strong aria-hidden="true">15.3.4.</strong> 编译器优化 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/compiler/optimization/option.html"><strong aria-hidden="true">15.3.4.1.</strong> Option 枚举 todo</a></li></ol></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">附录</li><li class="spacer"></li><li class="chapter-item "><div><strong aria-hidden="true">16.</strong> Appendix</div><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../appendix/keywords.html"><strong aria-hidden="true">16.1.</strong> 关键字</a></li><li class="chapter-item "><a href="../../appendix/operators.html"><strong aria-hidden="true">16.2.</strong> 运算符与符号</a></li><li class="chapter-item "><a href="../../appendix/expressions.html"><strong aria-hidden="true">16.3.</strong> 表达式</a></li><li class="chapter-item "><a href="../../appendix/derive.html"><strong aria-hidden="true">16.4.</strong> 派生特征 trait</a></li><li class="chapter-item "><a href="../../appendix/prelude.html"><strong aria-hidden="true">16.5.</strong> prelude 模块 todo</a></li><li class="chapter-item "><a href="../../appendix/rust-version.html"><strong aria-hidden="true">16.6.</strong> Rust 版本说明</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/intro.html"><strong aria-hidden="true">16.7.</strong> Rust 历次版本更新解读</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../appendix/rust-versions/1.58.html"><strong aria-hidden="true">16.7.1.</strong> 1.58</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.59.html"><strong aria-hidden="true">16.7.2.</strong> 1.59</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.60.html"><strong aria-hidden="true">16.7.3.</strong> 1.60</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.61.html"><strong aria-hidden="true">16.7.4.</strong> 1.61</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.62.html"><strong aria-hidden="true">16.7.5.</strong> 1.62</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.63.html"><strong aria-hidden="true">16.7.6.</strong> 1.63</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.64.html"><strong aria-hidden="true">16.7.7.</strong> 1.64</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.65.html"><strong aria-hidden="true">16.7.8.</strong> 1.65</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.66.html"><strong aria-hidden="true">16.7.9.</strong> 1.66</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.67.html"><strong aria-hidden="true">16.7.10.</strong> 1.67</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.68.html"><strong aria-hidden="true">16.7.11.</strong> 1.68</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.69.html"><strong aria-hidden="true">16.7.12.</strong> 1.69</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.70.html"><strong aria-hidden="true">16.7.13.</strong> 1.70</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.71.html"><strong aria-hidden="true">16.7.14.</strong> 1.71</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.72.html"><strong aria-hidden="true">16.7.15.</strong> 1.72</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.73.html"><strong aria-hidden="true">16.7.16.</strong> 1.73</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.74.html"><strong aria-hidden="true">16.7.17.</strong> 1.74</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.75.html"><strong aria-hidden="true">16.7.18.</strong> 1.75</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.76.html"><strong aria-hidden="true">16.7.19.</strong> 1.76</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.77.html"><strong aria-hidden="true">16.7.20.</strong> 1.77</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.78.html"><strong aria-hidden="true">16.7.21.</strong> 1.78</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.79.html"><strong aria-hidden="true">16.7.22.</strong> 1.79</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.80.html"><strong aria-hidden="true">16.7.23.</strong> 1.80</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.81.html"><strong aria-hidden="true">16.7.24.</strong> 1.81</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.82.html"><strong aria-hidden="true">16.7.25.</strong> 1.82</a></li></ol></li></ol></li></ol>
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<h1 id="底层探秘-future-执行器与任务调度"><a class="header" href="#底层探秘-future-执行器与任务调度">底层探秘: Future 执行器与任务调度</a></h1>
<p>异步编程背后到底藏有什么秘密？究竟是哪只幕后之手在操纵这一切？如果你对这些感兴趣，就继续看下去，否则可以直接跳过，因为本章节的内容对于一个 API 工程师并没有太多帮助。</p>
<p>但是如果你希望能深入理解 <code>Rust</code> 的 <code>async/.await</code> 代码是如何工作、理解运行时和性能，甚至未来想要构建自己的 <code>async</code> 运行时或相关工具，那么本章节终究不会辜负于你。</p>
<h2 id="future-特征"><a class="header" href="#future-特征">Future 特征</a></h2>
<p><code>Future</code> 特征是 Rust 异步编程的核心，毕竟异步函数是异步编程的核心，而 <code>Future</code> 恰恰是异步函数的返回值和被执行的关键。</p>
<p>首先，来给出 <code>Future</code> 的定义：它是一个能产出值的异步计算(虽然该值可能为空，例如 <code>()</code> )。光看这个定义，可能会觉得很空洞，我们来看看一个简化版的 <code>Future</code> 特征:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>trait SimpleFuture {
type Output;
fn poll(&amp;mut self, wake: fn()) -&gt; Poll&lt;Self::Output&gt;;
}
enum Poll&lt;T&gt; {
Ready(T),
Pending,
}
<span class="boring">}</span></code></pre></pre>
<p>在上一章中，我们提到过 <code>Future</code> 需要被执行器<code>poll</code>(轮询)后才能运行，诺，这里 <code>poll</code> 就来了，通过调用该方法，可以推进 <code>Future</code> 的进一步执行，直到被切走为止( 这里不好理解，但是你只需要知道 <code>Future</code> 并不能保证在一次 <code>poll</code> 中就被执行完，后面会详解介绍)。</p>
<p>若在当前 <code>poll</code> 中， <code>Future</code> 可以被完成，则会返回 <code>Poll::Ready(result)</code> ，反之则返回 <code>Poll::Pending</code>， 并且安排一个 <code>wake</code> 函数：当未来 <code>Future</code> 准备好进一步执行时， 该函数会被调用，然后管理该 <code>Future</code> 的执行器(例如上一章节中的<code>block_on</code>函数)会再次调用 <code>poll</code> 方法，此时 <code>Future</code> 就可以继续执行了。</p>
<p>如果没有 <code>wake</code> 方法，那执行器无法知道某个 <code>Future</code> 是否可以继续被执行，除非执行器定期的轮询每一个 <code>Future</code>，确认它是否能被执行，但这种作法效率较低。而有了 <code>wake</code>，<code>Future</code> 就可以主动通知执行器，然后执行器就可以精确的执行该 <code>Future</code>。 这种“事件通知 -&gt; 执行”的方式要远比定期对所有 <code>Future</code> 进行一次全遍历来的高效。</p>
<p>也许大家还是迷迷糊糊的，没事，我们用一个例子来说明下。考虑一个需要从 <code>socket</code> 读取数据的场景：如果有数据，可以直接读取数据并返回 <code>Poll::Ready(data)</code>， 但如果没有数据，<code>Future</code> 会被阻塞且不会再继续执行，此时它会注册一个 <code>wake</code> 函数，当 <code>socket</code> 数据准备好时，该函数将被调用以通知执行器：我们的 <code>Future</code> 已经准备好了，可以继续执行。</p>
<p>下面的 <code>SocketRead</code> 结构体就是一个 <code>Future</code>:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub struct SocketRead&lt;'a&gt; {
socket: &amp;'a Socket,
}
impl SimpleFuture for SocketRead&lt;'_&gt; {
type Output = Vec&lt;u8&gt;;
fn poll(&amp;mut self, wake: fn()) -&gt; Poll&lt;Self::Output&gt; {
if self.socket.has_data_to_read() {
// socket有数据，写入buffer中并返回
Poll::Ready(self.socket.read_buf())
} else {
// socket中还没数据
//
// 注册一个`wake`函数，当数据可用时，该函数会被调用，
// 然后当前Future的执行器会再次调用`poll`方法，此时就可以读取到数据
self.socket.set_readable_callback(wake);
Poll::Pending
}
}
}
<span class="boring">}</span></code></pre></pre>
<p>这种 <code>Future</code> 模型允许将多个异步操作组合在一起，同时还无需任何内存分配。不仅仅如此，如果你需要同时运行多个 <code>Future</code>或链式调用多个 <code>Future</code> ，也可以通过无内存分配的状态机实现，例如：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>trait SimpleFuture {
type Output;
fn poll(&amp;mut self, wake: fn()) -&gt; Poll&lt;Self::Output&gt;;
}
enum Poll&lt;T&gt; {
Ready(T),
Pending,
}
/// 一个SimpleFuture，它会并发地运行两个Future直到它们完成
///
/// 之所以可以并发，是因为两个Future的轮询可以交替进行，一个阻塞，另一个就可以立刻执行，反之亦然
pub struct Join&lt;FutureA, FutureB&gt; {
// 结构体的每个字段都包含一个Future，可以运行直到完成.
// 等到Future完成后，字段会被设置为 `None`. 这样Future完成后，就不会再被轮询
a: Option&lt;FutureA&gt;,
b: Option&lt;FutureB&gt;,
}
impl&lt;FutureA, FutureB&gt; SimpleFuture for Join&lt;FutureA, FutureB&gt;
where
FutureA: SimpleFuture&lt;Output = ()&gt;,
FutureB: SimpleFuture&lt;Output = ()&gt;,
{
type Output = ();
fn poll(&amp;mut self, wake: fn()) -&gt; Poll&lt;Self::Output&gt; {
// 尝试去完成一个 Future `a`
if let Some(a) = &amp;mut self.a {
if let Poll::Ready(()) = a.poll(wake) {
self.a.take();
}
}
// 尝试去完成一个 Future `b`
if let Some(b) = &amp;mut self.b {
if let Poll::Ready(()) = b.poll(wake) {
self.b.take();
}
}
if self.a.is_none() &amp;&amp; self.b.is_none() {
// 两个 Future都已完成 - 我们可以成功地返回了
Poll::Ready(())
} else {
// 至少还有一个 Future 没有完成任务，因此返回 `Poll::Pending`.
// 当该 Future 再次准备好时，通过调用`wake()`函数来继续执行
Poll::Pending
}
}
}
<span class="boring">}</span></code></pre></pre>
<p>上面代码展示了如何同时运行多个 <code>Future</code>， 且在此过程中没有任何内存分配，让并发编程更加高效。 类似的，多个<code>Future</code>也可以一个接一个的连续运行：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>/// 一个SimpleFuture, 它使用顺序的方式，一个接一个地运行两个Future
//
// 注意: 由于本例子用于演示，因此功能简单，`AndThenFut` 会假设两个 Future 在创建时就可用了.
// 而真实的`Andthen`允许根据第一个`Future`的输出来创建第二个`Future`，因此复杂的多。
pub struct AndThenFut&lt;FutureA, FutureB&gt; {
first: Option&lt;FutureA&gt;,
second: FutureB,
}
impl&lt;FutureA, FutureB&gt; SimpleFuture for AndThenFut&lt;FutureA, FutureB&gt;
where
FutureA: SimpleFuture&lt;Output = ()&gt;,
FutureB: SimpleFuture&lt;Output = ()&gt;,
{
type Output = ();
fn poll(&amp;mut self, wake: fn()) -&gt; Poll&lt;Self::Output&gt; {
if let Some(first) = &amp;mut self.first {
match first.poll(wake) {
// 我们已经完成了第一个 Future， 可以将它移除， 然后准备开始运行第二个
Poll::Ready(()) =&gt; self.first.take(),
// 第一个 Future 还不能完成
Poll::Pending =&gt; return Poll::Pending,
};
}
// 运行到这里，说明第一个Future已经完成，尝试去完成第二个
self.second.poll(wake)
}
}
<span class="boring">}</span></code></pre></pre>
<p>这些例子展示了在不需要内存对象分配以及深层嵌套回调的情况下，该如何使用 <code>Future</code> 特征去表达异步控制流。 在了解了基础的控制流后，我们再来看看真实的 <code>Future</code> 特征有何不同之处。</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>trait Future {
type Output;
fn poll(
// 首先值得注意的地方是，`self`的类型从`&amp;mut self`变成了`Pin&lt;&amp;mut Self&gt;`:
self: Pin&lt;&amp;mut Self&gt;,
// 其次将`wake: fn()` 修改为 `cx: &amp;mut Context&lt;'_&gt;`:
cx: &amp;mut Context&lt;'_&gt;,
) -&gt; Poll&lt;Self::Output&gt;;
}
<span class="boring">}</span></code></pre></pre>
<p>首先这里多了一个 <code>Pin</code> ，关于它我们会在后面章节详细介绍，现在你只需要知道使用它可以创建一个无法被移动的 <code>Future</code> ，因为无法被移动，所以它将具有固定的内存地址，意味着我们可以存储它的指针(如果内存地址可能会变动，那存储指针地址将毫无意义！)，也意味着可以实现一个自引用数据结构: <code>struct MyFut { a: i32, ptr_to_a: *const i32 }</code>。 而对于 <code>async/await</code> 来说，<code>Pin</code> 是不可或缺的关键特性。</p>
<p>其次，从 <code>wake: fn()</code> 变成了 <code>&amp;mut Context&lt;'_&gt;</code> 。意味着 <code>wake</code> 函数可以携带数据了，为何要携带数据？考虑一个真实世界的场景，一个复杂应用例如 web 服务器可能有数千连接同时在线，那么同时就有数千 <code>Future</code> 在被同时管理着，如果不能携带数据，当一个 <code>Future</code> 调用 <code>wake</code> 后，执行器该如何知道是哪个 <code>Future</code> 调用了 <code>wake</code> ,然后进一步去 <code>poll</code> 对应的 <code>Future</code> ？没有办法！那之前的例子为啥就可以使用没有携带数据的 <code>wake</code> ？ 因为足够简单，不存在歧义性。</p>
<p>总之，在正式场景要进行 <code>wake</code> ，就必须携带上数据。 而 <code>Context</code> 类型通过提供一个 <code>Waker</code> 类型的值，就可以用来唤醒特定的的任务。</p>
<h2 id="使用-waker-来唤醒任务"><a class="header" href="#使用-waker-来唤醒任务">使用 Waker 来唤醒任务</a></h2>
<p>对于 <code>Future</code> 来说，第一次被 <code>poll</code> 时无法完成任务是很正常的。但它需要确保在未来一旦准备好时，可以通知执行器再次对其进行 <code>poll</code> 进而继续往下执行，该通知就是通过 <code>Waker</code> 类型完成的。</p>
<p><code>Waker</code> 提供了一个 <code>wake()</code> 方法可以用于告诉执行器：相关的任务可以被唤醒了，此时执行器就可以对相应的 <code>Future</code> 再次进行 <code>poll</code> 操作。</p>
<h4 id="构建一个定时器"><a class="header" href="#构建一个定时器">构建一个定时器</a></h4>
<p>下面一起来实现一个简单的定时器 <code>Future</code> 。为了让例子尽量简单，当计时器创建时，我们会启动一个线程接着让该线程进入睡眠，等睡眠结束后再通知给 <code>Future</code> 。</p>
<p>注意本例子还会在后面继续使用，因此我们重新创建一个工程来演示：使用 <code>cargo new --lib timer_future</code> 来创建一个新工程，在 <code>lib</code> 包的根路径 <code>src/lib.rs</code> 中添加以下内容：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use std::{
future::Future,
pin::Pin,
sync::{Arc, Mutex},
task::{Context, Poll, Waker},
thread,
time::Duration,
};
<span class="boring">}</span></code></pre></pre>
<p>继续来实现 <code>Future</code> 定时器，之前提到: 新建线程在睡眠结束后会需要将状态同步给定时器 <code>Future</code> ，由于是多线程环境，我们需要使用 <code>Arc&lt;Mutex&lt;T&gt;&gt;</code> 来作为一个共享状态，用于在新线程和 <code>Future</code> 定时器间共享。</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub struct TimerFuture {
shared_state: Arc&lt;Mutex&lt;SharedState&gt;&gt;,
}
/// 在Future和等待的线程间共享状态
struct SharedState {
/// 定时(睡眠)是否结束
completed: bool,
/// 当睡眠结束后，线程可以用`waker`通知`TimerFuture`来唤醒任务
waker: Option&lt;Waker&gt;,
}
<span class="boring">}</span></code></pre></pre>
<p>下面给出 <code>Future</code> 的具体实现:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>impl Future for TimerFuture {
type Output = ();
fn poll(self: Pin&lt;&amp;mut Self&gt;, cx: &amp;mut Context&lt;'_&gt;) -&gt; Poll&lt;Self::Output&gt; {
// 通过检查共享状态，来确定定时器是否已经完成
let mut shared_state = self.shared_state.lock().unwrap();
if shared_state.completed {
Poll::Ready(())
} else {
// 设置`waker`，这样新线程在睡眠(计时)结束后可以唤醒当前的任务，接着再次对`Future`进行`poll`操作,
//
// 下面的`clone`每次被`poll`时都会发生一次，实际上，应该是只`clone`一次更加合理。
// 选择每次都`clone`的原因是： `TimerFuture`可以在执行器的不同任务间移动，如果只克隆一次，
// 那么获取到的`waker`可能已经被篡改并指向了其它任务，最终导致执行器运行了错误的任务
shared_state.waker = Some(cx.waker().clone());
Poll::Pending
}
}
}
<span class="boring">}</span></code></pre></pre>
<p>代码很简单，只要新线程设置了 <code>shared_state.completed = true</code> ，那任务就能顺利结束。如果没有设置，会为当前的任务克隆一份 <code>Waker</code> ，这样新线程就可以使用它来唤醒当前的任务。</p>
<p>最后，再来创建一个 API 用于构建定时器和启动计时线程:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>impl TimerFuture {
/// 创建一个新的`TimerFuture`，在指定的时间结束后，该`Future`可以完成
pub fn new(duration: Duration) -&gt; Self {
let shared_state = Arc::new(Mutex::new(SharedState {
completed: false,
waker: None,
}));
// 创建新线程
let thread_shared_state = shared_state.clone();
thread::spawn(move || {
// 睡眠指定时间实现计时功能
thread::sleep(duration);
let mut shared_state = thread_shared_state.lock().unwrap();
// 通知执行器定时器已经完成，可以继续`poll`对应的`Future`了
shared_state.completed = true;
if let Some(waker) = shared_state.waker.take() {
waker.wake()
}
});
TimerFuture { shared_state }
}
}
<span class="boring">}</span></code></pre></pre>
<p>至此，一个简单的定时器 <code>Future</code> 就已创建成功，那么该如何使用它呢？相信部分爱动脑筋的读者已经猜到了：我们需要创建一个执行器，才能让程序动起来。</p>
<h2 id="执行器-executor"><a class="header" href="#执行器-executor">执行器 Executor</a></h2>
<p>Rust 的 <code>Future</code> 是惰性的：只有屁股上拍一拍，它才会努力动一动。其中一个推动它的方式就是在 <code>async</code> 函数中使用 <code>.await</code> 来调用另一个 <code>async</code> 函数，但是这个只能解决 <code>async</code> 内部的问题，那么这些最外层的 <code>async</code> 函数，谁来推动它们运行呢？答案就是我们之前多次提到的执行器 <code>executor</code> 。</p>
<p>执行器会管理一批 <code>Future</code> (最外层的 <code>async</code> 函数)，然后通过不停地 <code>poll</code> 推动它们直到完成。 最开始，执行器会先 <code>poll</code> 一次 <code>Future</code> ，后面就不会主动去 <code>poll</code> 了，而是等待 <code>Future</code> 通过调用 <code>wake</code> 函数来通知它可以继续，它才会继续去 <code>poll</code> 。这种 <strong>wake 通知然后 poll</strong> 的方式会不断重复，直到 <code>Future</code> 完成。</p>
<h4 id="构建执行器"><a class="header" href="#构建执行器">构建执行器</a></h4>
<p>下面我们将实现一个简单的执行器，它可以同时并发运行多个 <code>Future</code> 。例子中，需要用到 <code>futures</code> 包的 <code>ArcWake</code> 特征，它可以提供一个方便的途径去构建一个 <code>Waker</code> 。编辑 <code>Cargo.toml</code> ，添加下面依赖:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>[dependencies]
futures = &quot;0.3&quot;
<span class="boring">}</span></code></pre></pre>
<p>在之前的内容中，我们在 <code>src/lib.rs</code> 中创建了定时器 <code>Future</code> ，现在在 <code>src/main.rs</code> 中来创建程序的主体内容，开始之前，先引入所需的包：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>use {
futures::{
future::{BoxFuture, FutureExt},
task::{waker_ref, ArcWake},
},
std::{
future::Future,
sync::mpsc::{sync_channel, Receiver, SyncSender},
sync::{Arc, Mutex},
task::{Context, Poll},
time::Duration,
},
// 引入之前实现的定时器模块
timer_future::TimerFuture,
};
<span class="boring">}</span></code></pre></pre>
<p>执行器需要从一个消息通道( <code>channel</code> )中拉取事件，然后运行它们。当一个任务准备好后（可以继续执行），它会将自己放入消息通道中，然后等待执行器 <code>poll</code> 。</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>/// 任务执行器，负责从通道中接收任务然后执行
struct Executor {
ready_queue: Receiver&lt;Arc&lt;Task&gt;&gt;,
}
/// `Spawner`负责创建新的`Future`然后将它发送到任务通道中
#[derive(Clone)]
struct Spawner {
task_sender: SyncSender&lt;Arc&lt;Task&gt;&gt;,
}
/// 一个Future，它可以调度自己(将自己放入任务通道中)，然后等待执行器去`poll`
struct Task {
/// 进行中的Future，在未来的某个时间点会被完成
///
/// 按理来说`Mutex`在这里是多余的，因为我们只有一个线程来执行任务。但是由于
/// Rust并不聪明，它无法知道`Future`只会在一个线程内被修改，并不会被跨线程修改。因此
/// 我们需要使用`Mutex`来满足这个笨笨的编译器对线程安全的执着。
///
/// 如果是生产级的执行器实现，不会使用`Mutex`，因为会带来性能上的开销，取而代之的是使用`UnsafeCell`
future: Mutex&lt;Option&lt;BoxFuture&lt;'static, ()&gt;&gt;&gt;,
/// 可以将该任务自身放回到任务通道中，等待执行器的poll
task_sender: SyncSender&lt;Arc&lt;Task&gt;&gt;,
}
fn new_executor_and_spawner() -&gt; (Executor, Spawner) {
// 任务通道允许的最大缓冲数(任务队列的最大长度)
// 当前的实现仅仅是为了简单，在实际的执行中，并不会这么使用
const MAX_QUEUED_TASKS: usize = 10_000;
let (task_sender, ready_queue) = sync_channel(MAX_QUEUED_TASKS);
(Executor { ready_queue }, Spawner { task_sender })
}
<span class="boring">}</span></code></pre></pre>
<p>下面再来添加一个方法用于生成 <code>Future</code> , 然后将它放入任务通道中:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>impl Spawner {
fn spawn(&amp;self, future: impl Future&lt;Output = ()&gt; + 'static + Send) {
let future = future.boxed();
let task = Arc::new(Task {
future: Mutex::new(Some(future)),
task_sender: self.task_sender.clone(),
});
self.task_sender.send(task).expect(&quot;任务队列已满&quot;);
}
}
<span class="boring">}</span></code></pre></pre>
<p>在执行器 <code>poll</code> 一个 <code>Future</code> 之前，首先需要调用 <code>wake</code> 方法进行唤醒，然后再由 <code>Waker</code> 负责调度该任务并将其放入任务通道中。创建 <code>Waker</code> 的最简单的方式就是实现 <code>ArcWake</code> 特征，先来为我们的任务实现 <code>ArcWake</code> 特征，这样它们就能被转变成 <code>Waker</code> 然后被唤醒:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>impl ArcWake for Task {
fn wake_by_ref(arc_self: &amp;Arc&lt;Self&gt;) {
// 通过发送任务到任务管道的方式来实现`wake`，这样`wake`后，任务就能被执行器`poll`
let cloned = arc_self.clone();
arc_self
.task_sender
.send(cloned)
.expect(&quot;任务队列已满&quot;);
}
}
<span class="boring">}</span></code></pre></pre>
<p>当任务实现了 <code>ArcWake</code> 特征后，它就变成了 <code>Waker</code> ，在调用 <code>wake()</code> 对其唤醒后会将任务复制一份所有权( <code>Arc</code> )，然后将其发送到任务通道中。最后我们的执行器将从通道中获取任务，然后进行 <code>poll</code> 执行：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>impl Executor {
fn run(&amp;self) {
while let Ok(task) = self.ready_queue.recv() {
// 获取一个future，若它还没有完成(仍然是Some，不是None)，则对它进行一次poll并尝试完成它
let mut future_slot = task.future.lock().unwrap();
if let Some(mut future) = future_slot.take() {
// 基于任务自身创建一个 `LocalWaker`
let waker = waker_ref(&amp;task);
let context = &amp;mut Context::from_waker(&amp;*waker);
// `BoxFuture&lt;T&gt;`是`Pin&lt;Box&lt;dyn Future&lt;Output = T&gt; + Send + 'static&gt;&gt;`的类型别名
// 通过调用`as_mut`方法，可以将上面的类型转换成`Pin&lt;&amp;mut dyn Future + Send + 'static&gt;`
if future.as_mut().poll(context).is_pending() {
// Future还没执行完，因此将它放回任务中，等待下次被poll
*future_slot = Some(future);
}
}
}
}
}
<span class="boring">}</span></code></pre></pre>
<p>恭喜！我们终于拥有了自己的执行器，下面再来写一段代码使用该执行器去运行之前的定时器 <code>Future</code> ：</p>
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
let (executor, spawner) = new_executor_and_spawner();
// 生成一个任务
spawner.spawn(async {
println!(&quot;howdy!&quot;);
// 创建定时器Future，并等待它完成
TimerFuture::new(Duration::new(2, 0)).await;
println!(&quot;done!&quot;);
});
// drop掉任务，这样执行器就知道任务已经完成，不会再有新的任务进来
drop(spawner);
// 运行执行器直到任务队列为空
// 任务运行后，会先打印`howdy!`, 暂停2秒，接着打印 `done!`
executor.run();
}</code></pre></pre>
<h2 id="执行器和系统-io"><a class="header" href="#执行器和系统-io">执行器和系统 IO</a></h2>
<p>前面我们一起看过一个使用 <code>Future</code> 从 <code>Socket</code> 中异步读取数据的例子:</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>pub struct SocketRead&lt;'a&gt; {
socket: &amp;'a Socket,
}
impl SimpleFuture for SocketRead&lt;'_&gt; {
type Output = Vec&lt;u8&gt;;
fn poll(&amp;mut self, wake: fn()) -&gt; Poll&lt;Self::Output&gt; {
if self.socket.has_data_to_read() {
// socket有数据，写入buffer中并返回
Poll::Ready(self.socket.read_buf())
} else {
// socket中还没数据
//
// 注册一个`wake`函数，当数据可用时，该函数会被调用，
// 然后当前Future的执行器会再次调用`poll`方法，此时就可以读取到数据
self.socket.set_readable_callback(wake);
Poll::Pending
}
}
}
<span class="boring">}</span></code></pre></pre>
<p>该例子中，<code>Future</code> 将从 <code>Socket</code> 读取数据，若当前还没有数据，则会让出当前线程的所有权，允许执行器去执行其它的 <code>Future</code> 。当数据准备好后，会调用 <code>wake()</code> 函数将该 <code>Future</code> 的任务放入任务通道中，等待执行器的 <code>poll</code> 。</p>
<p>关于该流程已经反复讲了很多次，相信大家应该非常清楚了。然而该例子中还有一个疑问没有解决：</p>
<ul>
<li><code>set_readable_callback</code> 方法到底是怎么工作的？怎么才能知道 <code>socket</code> 中的数据已经可以被读取了？</li>
</ul>
<p>关于第二点，其中一个简单粗暴的方法就是使用一个新线程不停的检查 <code>socket</code> 中是否有了数据，当有了后，就调用 <code>wake()</code> 函数。该方法确实可以满足需求，但是性能着实太低了，需要为每个阻塞的 <code>Future</code> 都创建一个单独的线程！</p>
<p>在现实世界中，该问题往往是通过操作系统提供的 <code>IO</code> 多路复用机制来完成，例如 <code>Linux</code> 中的 <strong><code>epoll</code></strong>，<code>FreeBSD</code> 和 <code>macOS</code> 中的 <strong><code>kqueue</code></strong> ，<code>Windows</code> 中的 <strong><code>IOCP</code></strong>, <code>Fuchisa</code>中的 <strong><code>ports</code></strong> 等(可以通过 Rust 的跨平台包 <code>mio</code> 来使用它们)。借助 IO 多路复用机制，可以实现一个线程同时阻塞地去等待多个异步 IO 事件，一旦某个事件完成就立即退出阻塞并返回数据。相关实现类似于以下代码：</p>
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>struct IoBlocker {
/* ... */
}
struct Event {
// Event的唯一ID，该事件发生后，就会被监听起来
id: usize,
// 一组需要等待或者已发生的信号
signals: Signals,
}
impl IoBlocker {
/// 创建需要阻塞等待的异步IO事件的集合
fn new() -&gt; Self { /* ... */ }
/// 对指定的IO事件表示兴趣
fn add_io_event_interest(
&amp;self,
/// 事件所绑定的socket
io_object: &amp;IoObject,
event: Event,
) { /* ... */ }
/// 进入阻塞，直到某个事件出现
fn block(&amp;self) -&gt; Event { /* ... */ }
}
let mut io_blocker = IoBlocker::new();
io_blocker.add_io_event_interest(
&amp;socket_1,
Event { id: 1, signals: READABLE },
);
io_blocker.add_io_event_interest(
&amp;socket_2,
Event { id: 2, signals: READABLE | WRITABLE },
);
let event = io_blocker.block();
// 当socket的数据可以读取时，打印 &quot;Socket 1 is now READABLE&quot;
println!(&quot;Socket {:?} is now {:?}&quot;, event.id, event.signals);
<span class="boring">}</span></code></pre></pre>
<p>这样，我们只需要一个执行器线程，它会接收 IO 事件并将其分发到对应的 <code>Waker</code> 中，接着后者会唤醒相关的任务，最终通过执行器 <code>poll</code> 后，任务可以顺利地继续执行, 这种 IO 读取流程可以不停的循环，直到 <code>socket</code> 关闭。</p>
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