C++ 插件

¥C++ addons

插件是用 C++ 编写的动态链接共享对象。require() 函数可以将插件加载为普通的 Node.js 模块。插件提供了 JavaScript 和 C/C++ 库之间的接口。

¥Addons are dynamically-linked shared objects written in C++. The require() function can load addons as ordinary Node.js modules. Addons provide an interface between JavaScript and C/C++ libraries.

实现插件有三种选择：Node-API、nan，或直接使用内部 V8、libuv 和 Node.js 库。除非需要直接访问 Node-API 未暴露的功能，否则请使用 Node-API。有关 Node-API 的更多信息，请参阅 使用 Node-API 的 C/C++ 插件。

¥There are three options for implementing addons: Node-API, nan, or direct use of internal V8, libuv, and Node.js libraries. Unless there is a need for direct access to functionality which is not exposed by Node-API, use Node-API. Refer to C/C++ addons with Node-API for more information on Node-API.

不使用 Node-API 时，实现插件很复杂，涉及若干组件和 API 的知识：

¥When not using Node-API, implementing addons is complicated, involving knowledge of several components and APIs:

  • V8：Node.js 用来提供 JavaScript 实现的 C++ 库。V8 提供了创建对象、调用函数等机制。V8 的 API 主要记录在 v8.h 头文件（Node.js 源代码树中的 deps/v8/include/v8.h），在线 也可用。

    ¥V8: the C++ library Node.js uses to provide the JavaScript implementation. V8 provides the mechanisms for creating objects, calling functions, etc. V8's API is documented mostly in the v8.h header file (deps/v8/include/v8.h in the Node.js source tree), which is also available online.

  • libuv：实现 Node.js 事件循环、其工作线程和平台所有异步行为的 C 库。它还作为一个跨平台抽象库，允许跨所有主要操作系统轻松、类似于 POSIX 访问许多常见的系统任务，例如与文件系统、套接字、定时器和系统事件交互。libuv 还提供类似于 POSIX 线程的线程抽象，用于需要超越标准事件循环的更复杂的异步插件。插件作者应该避免使用 I/O 或其他时间密集型任务阻塞事件循环，通过将工作通过 libuv 分流到非阻塞系统操作、工作线程、或 libuv 线程的自定义使用来实现。

    ¥libuv: The C library that implements the Node.js event loop, its worker threads and all of the asynchronous behaviors of the platform. It also serves as a cross-platform abstraction library, giving easy, POSIX-like access across all major operating systems to many common system tasks, such as interacting with the filesystem, sockets, timers, and system events. libuv also provides a threading abstraction similar to POSIX threads for more sophisticated asynchronous addons that need to move beyond the standard event loop. Addon authors should avoid blocking the event loop with I/O or other time-intensive tasks by offloading work via libuv to non-blocking system operations, worker threads, or a custom use of libuv threads.

  • 内部 Node.js 库。Node.js 自身导出了插件可以使用的 C++ API，其中最重要的是 node::ObjectWrap 类。

    ¥Internal Node.js libraries. Node.js itself exports C++ APIs that addons can use, the most important of which is the node::ObjectWrap class.

  • Node.js 包括了其他静态链接库，包括 OpenSSL。这些其他库位于 Node.js 源代码树的 deps/ 目录中。只有 libuv、OpenSSL、V8 和 zlib 符号被 Node.js 有目的地重新导出，并且可以被插件在不同程度上使用。有关其他信息，请参阅 链接到 Node.js 中包含的库。

    ¥Node.js includes other statically linked libraries including OpenSSL. These other libraries are located in the deps/ directory in the Node.js source tree. Only the libuv, OpenSSL, V8, and zlib symbols are purposefully re-exported by Node.js and may be used to various extents by addons. See Linking to libraries included with Node.js for additional information.

以下所有示例均适用于 下载，可用作插件的起点。

¥All of the following examples are available for download and may be used as the starting-point for an addon.