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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="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 expanded "><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 expanded "><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 expanded "><a href="../../basic/ownership/ownership.html" class="active"><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 "><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> &amp;'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 "><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 "><a href="../../advance/async/future-excuting.html"><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、&amp;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/advanced-lists/intro.html"><strong aria-hidden="true">13.7.</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/unsafe-deque.html"><strong aria-hidden="true">13.7.1.</strong> 生产级可用的双向链表</a></li><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/double-singly.html"><strong aria-hidden="true">13.7.2.</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">13.7.3.</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></ol></li></ol></li></ol>
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<main>
<h1 id="所有权"><a class="header" href="#所有权">所有权</a></h1>
<p>所有的程序都必须和计算机内存打交道，如何从内存中申请空间来存放程序的运行内容，如何在不需要的时候释放这些空间，成了重中之重，也是所有编程语言设计的难点之一。在计算机语言不断演变过程中，出现了三种流派：</p>
<ul>
<li><strong>垃圾回收机制(GC)</strong>，在程序运行时不断寻找不再使用的内存，典型代表：Java、Go</li>
<li><strong>手动管理内存的分配和释放</strong>, 在程序中，通过函数调用的方式来申请和释放内存，典型代表：C++</li>
<li><strong>通过所有权来管理内存</strong>，编译器在编译时会根据一系列规则进行检查</li>
</ul>
<p>其中 Rust 选择了第三种，最妙的是，这种检查只发生在编译期，因此对于程序运行期，不会有任何性能上的损失。</p>
<p>由于所有权是一个新概念，因此读者需要花费一些时间来掌握它，一旦掌握，海阔天空任你飞跃，在本章，我们将通过 <code>字符串</code> 来引导讲解所有权的相关知识。</p>
<h2 id="一段不安全的代码"><a class="header" href="#一段不安全的代码">一段不安全的代码</a></h2>
<p>先来看看一段来自 C 语言的糟糕代码：</p>
<pre><code class="language-c">int* foo() {
int a; // 变量a的作用域开始
a = 100;
char *c = &quot;xyz&quot;; // 变量c的作用域开始
return &amp;a;
} // 变量a和c的作用域结束
</code></pre>
<p>这段代码虽然可以编译通过，但是其实非常糟糕，变量 <code>a</code> 和 <code>c</code> 都是局部变量，函数结束后将局部变量 <code>a</code> 的地址返回，但局部变量 <code>a</code> 存在栈中，在离开作用域后，<code>a</code> 所申请的栈上内存都会被系统回收，从而造成了 <code>悬空指针(Dangling Pointer)</code> 的问题。这是一个非常典型的内存安全问题，虽然编译可以通过，但是运行的时候会出现错误, 很多编程语言都存在。</p>
<p>再来看变量 <code>c</code>，<code>c</code> 的值是常量字符串，存储于常量区，可能这个函数我们只调用了一次，也可能我们不再会使用这个字符串，但 <code>&quot;xyz&quot;</code> 只有当整个程序结束后系统才能回收这片内存。</p>
<p>所以内存安全问题，一直都是程序员非常头疼的问题，好在, 在 Rust 中这些问题即将成为历史，因为 Rust 在编译的时候就可以帮助我们发现内存不安全的问题，那 Rust 如何做到这一点呢？</p>
<p>在正式进入主题前，先来一个预热知识。</p>
<h2 id="栈stack与堆heap"><a class="header" href="#栈stack与堆heap">栈(Stack)与堆(Heap)</a></h2>
<p>栈和堆是编程语言最核心的数据结构，但是在很多语言中，你并不需要深入了解栈与堆。 但对于 Rust 这样的系统编程语言，值是位于栈上还是堆上非常重要, 因为这会影响程序的行为和性能。</p>
<p>栈和堆的核心目标就是为程序在运行时提供可供使用的内存空间。</p>
<h4 id="栈"><a class="header" href="#栈">栈</a></h4>
<p>栈按照顺序存储值并以相反顺序取出值，这也被称作<strong>后进先出</strong>。想象一下一叠盘子：当增加更多盘子时，把它们放在盘子堆的顶部，当需要盘子时，再从顶部拿走。不能从中间也不能从底部增加或拿走盘子！</p>
<p>增加数据叫做<strong>进栈</strong>，移出数据则叫做<strong>出栈</strong>。</p>
<p>因为上述的实现方式，栈中的所有数据都必须占用已知且固定大小的内存空间，假设数据大小是未知的，那么在取出数据时，你将无法取到你想要的数据。</p>
<h4 id="堆"><a class="header" href="#堆">堆</a></h4>
<p>与栈不同，对于大小未知或者可能变化的数据，我们需要将它存储在堆上。</p>
<p>当向堆上放入数据时，需要请求一定大小的内存空间。操作系统在堆的某处找到一块足够大的空位，把它标记为已使用，并返回一个表示该位置地址的<strong>指针</strong>, 该过程被称为<strong>在堆上分配内存</strong>，有时简称为 “分配”(allocating)。</p>
<p>接着，该指针会被推入<strong>栈</strong>中，因为指针的大小是已知且固定的，在后续使用过程中，你将通过栈中的<strong>指针</strong>，来获取数据在堆上的实际内存位置，进而访问该数据。</p>
<p>由上可知，堆是一种缺乏组织的数据结构。想象一下去餐馆就座吃饭: 进入餐馆，告知服务员有几个人，然后服务员找到一个够大的空桌子（堆上分配的内存空间）并领你们过去。如果有人来迟了，他们也可以通过桌号（栈上的指针）来找到你们坐在哪。</p>
<h4 id="性能区别"><a class="header" href="#性能区别">性能区别</a></h4>
<p>写入方面：入栈比在堆上分配内存要快，因为入栈时操作系统无需分配新的空间，只需要将新数据放入栈顶即可。相比之下，在堆上分配内存则需要更多的工作，这是因为操作系统必须首先找到一块足够存放数据的内存空间，接着做一些记录为下一次分配做准备。</p>
<p>读取方面：得益于 CPU 高速缓存，使得处理器可以减少对内存的访问，高速缓存和内存的访问速度差异在 10 倍以上！栈数据往往可以直接存储在 CPU 高速缓存中，而堆数据只能存储在内存中。访问堆上的数据比访问栈上的数据慢，因为必须先访问栈再通过栈上的指针来访问内存。</p>
<p>因此，处理器处理分配在栈上数据会比在堆上的数据更加高效。</p>
<h4 id="所有权与堆栈"><a class="header" href="#所有权与堆栈">所有权与堆栈</a></h4>
<p>当你的代码调用一个函数时，传递给函数的参数（包括可能指向堆上数据的指针和函数的局部变量）依次被压入栈中，当函数调用结束时，这些值将被从栈中按照相反的顺序依次移除。</p>
<p>因为堆上的数据缺乏组织，因此跟踪这些数据何时分配和释放是非常重要的，否则堆上的数据将产生内存泄漏 —— 这些数据将永远无法被回收。这就是 Rust 所有权系统为我们提供的强大保障。</p>
<p>对于其他很多编程语言，你确实无需理解堆栈的原理，但是<strong>在 Rust 中，明白堆栈的原理，对于我们理解所有权的工作原理会有很大的帮助</strong>。</p>
<h2 id="所有权原则"><a class="header" href="#所有权原则">所有权原则</a></h2>
<p>理解了堆栈，接下来看一下<em>关于所有权的规则</em>，首先请谨记以下规则：</p>
<blockquote>
<ol>
<li>Rust 中每一个值都被一个变量所拥有，该变量被称为值的所有者</li>
<li>一个值同时只能被一个变量所拥有，或者说一个值只能拥有一个所有者</li>
<li>当所有者(变量)离开作用域范围时，这个值将被丢弃(drop)</li>
</ol>
</blockquote>
<h4 id="变量作用域"><a class="header" href="#变量作用域">变量作用域</a></h4>
<p>作用域是一个变量在程序中有效的范围, 假如有这样一个变量：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let s = &quot;hello&quot;;
<span class="boring">}
</span></code></pre></pre>
<p>变量 <code>s</code> 绑定到了一个字符串字面值，该字符串字面值是硬编码到程序代码中的。<code>s</code> 变量从声明的点开始直到当前作用域的结束都是有效的：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>{ // s 在这里无效，它尚未声明
let s = &quot;hello&quot;; // 从此处起，s 是有效的
// 使用 s
} // 此作用域已结束，s不再有效
<span class="boring">}
</span></code></pre></pre>
<p>简而言之，<code>s</code> 从创建伊始就开始有效，然后有效期持续到它离开作用域为止，可以看出，就作用域来说，Rust 语言跟其他编程语言没有区别。</p>
<h4 id="简单介绍-string-类型"><a class="header" href="#简单介绍-string-类型">简单介绍 String 类型</a></h4>
<p>之前提到过，本章会用 <code>String</code> 作为例子，因此这里会进行一下简单的介绍，具体的 <code>String</code> 学习请参见 <a href="https://course.rs/basic/compound-type/string-slice.html">String 类型</a>。</p>
<p>我们已经见过字符串字面值 <code>let s =&quot;hello&quot;</code>，<code>s</code> 是被硬编码进程序里的字符串值（类型为 <code>&amp;str</code> ）。字符串字面值是很方便的，但是它并不适用于所有场景。原因有二：</p>
<ul>
<li><strong>字符串字面值是不可变的</strong>，因为被硬编码到程序代码中</li>
<li>并非所有字符串的值都能在编写代码时得知</li>
</ul>
<p>例如，字符串是需要程序运行时，通过用户动态输入然后存储在内存中的，这种情况，字符串字面值就完全无用武之地。 为此，Rust 为我们提供动态字符串类型: <code>String</code>, 该类型被分配到堆上，因此可以动态伸缩，也就能存储在编译时大小未知的文本。</p>
<p>可以使用下面的方法基于字符串字面量来创建 <code>String</code> 类型：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let s = String::from(&quot;hello&quot;);
<span class="boring">}
</span></code></pre></pre>
<p><code>::</code> 是一种调用操作符，这里表示调用 <code>String</code> 中的 <code>from</code> 方法，因为 <code>String</code> 存储在堆上是动态的，你可以这样修改它：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let mut s = String::from(&quot;hello&quot;);
s.push_str(&quot;, world!&quot;); // push_str() 在字符串后追加字面值
println!(&quot;{}&quot;, s); // 将打印 `hello, world!`
<span class="boring">}
</span></code></pre></pre>
<p>言归正传，了解 <code>String</code> 内容后，一起来看看关于所有权的交互。</p>
<h2 id="变量绑定背后的数据交互"><a class="header" href="#变量绑定背后的数据交互">变量绑定背后的数据交互</a></h2>
<h4 id="转移所有权"><a class="header" href="#转移所有权">转移所有权</a></h4>
<p>先来看一段代码：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let x = 5;
let y = x;
<span class="boring">}
</span></code></pre></pre>
<p>代码背后的逻辑很简单, 将 <code>5</code> 绑定到变量 <code>x</code>；接着拷贝 <code>x</code> 的值赋给 <code>y</code>，最终 <code>x</code> 和 <code>y</code> 都等于 <code>5</code>，因为整数是 Rust 基本数据类型，是固定大小的简单值，因此这两个值都是通过自动拷贝的方式来赋值的，都被存在栈中，完全无需在堆上分配内存。</p>
<p>可能有同学会有疑问：这种拷贝不消耗性能吗？实际上，这种栈上的数据足够简单，而且拷贝非常非常快，只需要复制一个整数大小（<code>i32</code>，4 个字节）的内存即可，因此在这种情况下，拷贝的速度远比在堆上创建内存来得快的多。实际上，上一章我们讲到的 Rust 基本类型都是通过自动拷贝的方式来赋值的，就像上面代码一样。</p>
<p>然后再来看一段代码：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let s1 = String::from(&quot;hello&quot;);
let s2 = s1;
<span class="boring">}
</span></code></pre></pre>
<p>此时，可能某个大聪明(善意昵称)已经想到了：嗯，把 <code>s1</code> 的内容拷贝一份赋值给 <code>s2</code>，实际上，并不是这样。之前也提到了，对于基本类型（存储在栈上），Rust 会自动拷贝，但是 <code>String</code> 不是基本类型，而且是存储在堆上的，因此不能自动拷贝。</p>
<p>实际上， <code>String</code> 类型是一个复杂类型，由<strong>存储在栈中的堆指针</strong>、<strong>字符串长度</strong>、<strong>字符串容量</strong>共同组成，其中<strong>堆指针</strong>是最重要的，它指向了真实存储字符串内容的堆内存，至于长度和容量，如果你有 Go 语言的经验，这里就很好理解：容量是堆内存分配空间的大小，长度是目前已经使用的大小。</p>
<p>总之 <code>String</code> 类型指向了一个堆上的空间，这里存储着它的真实数据, 下面对上面代码中的 <code>let s2 = s1</code> 分成两种情况讨论：</p>
<ol>
<li>
<p>拷贝 <code>String</code> 和存储在堆上的字节数组
如果该语句是拷贝所有数据(深拷贝)，那么无论是 <code>String</code> 本身还是底层的堆上数据，都会被全部拷贝，这对于性能而言会造成非常大的影响</p>
</li>
<li>
<p>只拷贝 <code>String</code> 本身
这样的拷贝非常快，因为在 64 位机器上就拷贝了 <code>8字节的指针</code>、<code>8字节的长度</code>、<code>8字节的容量</code>，总计 24 字节，但是带来了新的问题，还记得我们之前提到的所有权规则吧？其中有一条就是：<strong>一个值只允许有一个所有者</strong>，而现在这个值（堆上的真实字符串数据）有了两个所有者：<code>s1</code> 和 <code>s2</code>。</p>
</li>
</ol>
<p>好吧，就假定一个值可以拥有两个所有者，会发生什么呢？</p>
<p>当变量离开作用域后，Rust 会自动调用 <code>drop</code> 函数并清理变量的堆内存。不过由于两个 <code>String</code> 变量指向了同一位置。这就有了一个问题：当 <code>s1</code> 和 <code>s2</code> 离开作用域，它们都会尝试释放相同的内存。这是一个叫做 <strong>二次释放（double free）</strong> 的错误，也是之前提到过的内存安全性 BUG 之一。两次释放（相同）内存会导致内存污染，它可能会导致潜在的安全漏洞。</p>
<p>因此，Rust 这样解决问题：<strong>当 <code>s1</code> 赋予 <code>s2</code> 后，Rust 认为 <code>s1</code> 不再有效，因此也无需在 <code>s1</code> 离开作用域后 <code>drop</code> 任何东西，这就是把所有权从 <code>s1</code> 转移给了 <code>s2</code>，<code>s1</code> 在被赋予 <code>s2</code> 后就马上失效了</strong>。</p>
<p>再来看看，在所有权转移后再来使用旧的所有者，会发生什么：</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let s1 = String::from(&quot;hello&quot;);
let s2 = s1;
println!(&quot;{}, world!&quot;, s1);
<span class="boring">}
</span></code></pre></pre>
<p>由于 Rust 禁止你使用无效的引用，你会看到以下的错误：</p>
<pre><code class="language-console">error[E0382]: use of moved value: `s1`
--&gt; src/main.rs:5:28
|
3 | let s2 = s1;
| -- value moved here
4 |
5 | println!(&quot;{}, world!&quot;, s1);
| ^^ value used here after move
|
= note: move occurs because `s1` has type `std::string::String`, which does
not implement the `Copy` trait
</code></pre>
<p>现在再回头看看之前的规则，相信大家已经有了更深刻的理解：</p>
<blockquote>
<ol>
<li>Rust 中每一个值都被一个变量所拥有，该变量被称为值的所有者</li>
<li>一个值同时只能被一个变量所拥有，或者说一个值只能拥有一个所有者</li>
<li>当所有者(变量)离开作用域范围时，这个值将被丢弃(drop)</li>
</ol>
</blockquote>
<p>如果你在其他语言中听说过术语 <strong>浅拷贝(shallow copy)</strong> 和 <strong>深拷贝(deep copy)</strong>，那么拷贝指针、长度和容量而不拷贝数据听起来就像浅拷贝，但是又因为 Rust 同时使第一个变量 <code>s1</code> 无效了，因此这个操作被称为 <strong>移动(move)</strong>，而不是浅拷贝。上面的例子可以解读为 <code>s1</code> 被<strong>移动</strong>到了 <code>s2</code> 中。那么具体发生了什么，用一张图简单说明：</p>
<img alt="s1 moved to s2" src="https://pic1.zhimg.com/80/v2-3ec77951de6a17584b5eb4a3838b4b61_1440w.jpg" class="center" style="width: 50%;" />
<p>这样就解决了我们之前的问题，<code>s1</code> 不再指向任何数据，只有 <code>s2</code> 是有效的，当 <code>s2</code> 离开作用域，它就会释放内存。 相信此刻，你应该明白了，为什么 Rust 称呼 <code>let a = b</code> 为<strong>变量绑定</strong>了吧？</p>
<p>再来看一段代码:</p>
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
let x: &amp;str = &quot;hello, world&quot;;
let y = x;
println!(&quot;{},{}&quot;,x,y);
}
</code></pre></pre>
<p>这段代码，大家觉得会否报错？如果参考之前的 <code>String</code> 所有权转移的例子，那这段代码也应该报错才是，但是实际上呢？</p>
<p>这段代码和之前的 <code>String</code> 有一个本质上的区别：在 <code>String</code> 的例子中 <code>s1</code> 持有了通过<code>String::from(&quot;hello&quot;)</code> 创建的值的所有权，而这个例子中，<code>x</code> 只是引用了存储在二进制中的字符串 <code>&quot;hello, world&quot;</code>，并没有持有所有权。</p>
<p>因此 <code>let y = x</code> 中，仅仅是对该引用进行了拷贝，此时 <code>y</code> 和 <code>x</code> 都引用了同一个字符串。<strong>如果还不理解也没关系，当学习了下一章节 &quot;引用与借用&quot; 后，大家自然而言就会理解。</strong></p>
<h4 id="克隆深拷贝"><a class="header" href="#克隆深拷贝">克隆(深拷贝)</a></h4>
<p>首先，<strong>Rust 永远也不会自动创建数据的 “深拷贝”</strong>。因此，任何<strong>自动</strong>的复制都不是深拷贝，可以被认为对运行时性能影响较小。</p>
<p>如果我们<strong>确实</strong>需要深度复制 <code>String</code> 中堆上的数据，而不仅仅是栈上的数据，可以使用一个叫做 <code>clone</code> 的方法。</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let s1 = String::from(&quot;hello&quot;);
let s2 = s1.clone();
println!(&quot;s1 = {}, s2 = {}&quot;, s1, s2);
<span class="boring">}
</span></code></pre></pre>
<p>这段代码能够正常运行，因此说明 <code>s2</code> 确实完整的复制了 <code>s1</code> 的数据。</p>
<p>如果代码性能无关紧要，例如初始化程序时，或者在某段时间只会执行一次时，你可以使用 <code>clone</code> 来简化编程。但是对于执行较为频繁的代码(热点路径)，使用 <code>clone</code> 会极大的降低程序性能，需要小心使用！</p>
<h4 id="拷贝浅拷贝"><a class="header" href="#拷贝浅拷贝">拷贝(浅拷贝)</a></h4>
<p>浅拷贝只发生在栈上，因此性能很高，在日常编程中，浅拷贝无处不在。</p>
<p>再回到之前看过的例子:</p>
<pre><pre class="playground"><code class="language-rust edition2021">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>let x = 5;
let y = x;
println!(&quot;x = {}, y = {}&quot;, x, y);
<span class="boring">}
</span></code></pre></pre>
<p>但这段代码似乎与我们刚刚学到的内容相矛盾：没有调用 <code>clone</code>，不过依然实现了类似深拷贝的效果 —— 没有报所有权的错误。</p>
<p>原因是像整型这样的基本类型在编译时是已知大小的，会被存储在栈上，所以拷贝其实际的值是快速的。这意味着没有理由在创建变量 <code>y</code> 后使 <code>x</code> 无效（<code>x</code>、<code>y</code> 都仍然有效）。换句话说，这里没有深浅拷贝的区别，因此这里调用 <code>clone</code> 并不会与通常的浅拷贝有什么不同，我们可以不用管它（可以理解成在栈上做了深拷贝）。</p>
<p>Rust 有一个叫做 <code>Copy</code> 的特征，可以用在类似整型这样在栈中存储的类型。如果一个类型拥有 <code>Copy</code> 特征，一个旧的变量在被赋值给其他变量后仍然可用。</p>
<p>那么什么类型是可 <code>Copy</code> 的呢？可以查看给定类型的文档来确认，不过作为一个通用的规则： <strong>任何基本类型的组合可以 <code>Copy</code> ，不需要分配内存或某种形式资源的类型是可以 <code>Copy</code> 的</strong>。如下是一些 <code>Copy</code> 的类型：</p>
<ul>
<li>所有整数类型，比如 <code>u32</code></li>
<li>布尔类型，<code>bool</code>，它的值是 <code>true</code> 和 <code>false</code></li>
<li>所有浮点数类型，比如 <code>f64</code></li>
<li>字符类型，<code>char</code></li>
<li>元组，当且仅当其包含的类型也都是 <code>Copy</code> 的时候。比如，<code>(i32, i32)</code> 是 <code>Copy</code> 的，但 <code>(i32, String)</code> 就不是</li>
<li>不可变引用 <code>&amp;T</code> ，例如<a href="#%E8%BD%AC%E7%A7%BB%E6%89%80%E6%9C%89%E6%9D%83">转移所有权</a>中的最后一个例子，<strong>但是注意: 可变引用 <code>&amp;mut T</code> 是不可以 Copy的</strong></li>
</ul>
<h2 id="函数传值与返回"><a class="header" href="#函数传值与返回">函数传值与返回</a></h2>
<p>将值传递给函数，一样会发生 <code>移动</code> 或者 <code>复制</code>，就跟 <code>let</code> 语句一样，下面的代码展示了所有权、作用域的规则：</p>
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
let s = String::from(&quot;hello&quot;); // s 进入作用域
takes_ownership(s); // s 的值移动到函数里 ...
// ... 所以到这里不再有效
let x = 5; // x 进入作用域
makes_copy(x); // x 应该移动函数里，
// 但 i32 是 Copy 的，所以在后面可继续使用 x
} // 这里, x 先移出了作用域，然后是 s。但因为 s 的值已被移走，
// 所以不会有特殊操作
fn takes_ownership(some_string: String) { // some_string 进入作用域
println!(&quot;{}&quot;, some_string);
} // 这里，some_string 移出作用域并调用 `drop` 方法。占用的内存被释放
fn makes_copy(some_integer: i32) { // some_integer 进入作用域
println!(&quot;{}&quot;, some_integer);
} // 这里，some_integer 移出作用域。不会有特殊操作
</code></pre></pre>
<p>你可以尝试在 <code>takes_ownership</code> 之后，再使用 <code>s</code>，看看如何报错？例如添加一行 <code>println!(&quot;在move进函数后继续使用s: {}&quot;,s);</code>。</p>
<p>同样的，函数返回值也有所有权，例如:</p>
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
let s1 = gives_ownership(); // gives_ownership 将返回值
// 移给 s1
let s2 = String::from(&quot;hello&quot;); // s2 进入作用域
let s3 = takes_and_gives_back(s2); // s2 被移动到
// takes_and_gives_back 中,
// 它也将返回值移给 s3
} // 这里, s3 移出作用域并被丢弃。s2 也移出作用域，但已被移走，
// 所以什么也不会发生。s1 移出作用域并被丢弃
fn gives_ownership() -&gt; String { // gives_ownership 将返回值移动给
// 调用它的函数
let some_string = String::from(&quot;hello&quot;); // some_string 进入作用域.
some_string // 返回 some_string 并移出给调用的函数
}
// takes_and_gives_back 将传入字符串并返回该值
fn takes_and_gives_back(a_string: String) -&gt; String { // a_string 进入作用域
a_string // 返回 a_string 并移出给调用的函数
}
</code></pre></pre>
<p>所有权很强大，避免了内存的不安全性，但是也带来了一个新麻烦： <strong>总是把一个值传来传去来使用它</strong>。 传入一个函数，很可能还要从该函数传出去，结果就是语言表达变得非常啰嗦，幸运的是，Rust 提供了新功能解决这个问题。</p>
<h2 id="课后练习"><a class="header" href="#课后练习">课后练习</a></h2>
<blockquote>
<p><a href="https://zh.practice.rs/ownership/ownership.html">Rust By Practice</a>，支持代码在线编辑和运行，并提供详细的<a href="https://github.com/sunface/rust-by-practice/blob/master/solutions/ownership/ownership.md">习题解答</a>。</p>
</blockquote>
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