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1141cb0ef41Sopenharmony_ci            <li class="pinned-header">Node.js v18.20.1</li>
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1231cb0ef41Sopenharmony_ci<li><a href="#c-embedder-api">C++ embedder API</a>
1241cb0ef41Sopenharmony_ci<ul>
1251cb0ef41Sopenharmony_ci<li><a href="#example-embedding-application">Example embedding application</a>
1261cb0ef41Sopenharmony_ci<ul>
1271cb0ef41Sopenharmony_ci<li><a href="#setting-up-per-process-state">Setting up per-process state</a></li>
1281cb0ef41Sopenharmony_ci<li><a href="#per-instance-state">Per-instance state</a></li>
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2331cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v15.x/api/embedding.html">15.x</a></li>
2341cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v14.x/api/embedding.html">14.x</a></li>
2351cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v13.x/api/embedding.html">13.x</a></li>
2361cb0ef41Sopenharmony_ci<li><a href="https://nodejs.org/docs/latest-v12.x/api/embedding.html">12.x</a></li></ol></div>
2371cb0ef41Sopenharmony_ci    </li>
2381cb0ef41Sopenharmony_ci  
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2581cb0ef41Sopenharmony_ci        </div>
2591cb0ef41Sopenharmony_ci        <hr>
2601cb0ef41Sopenharmony_ci      </header>
2611cb0ef41Sopenharmony_ci
2621cb0ef41Sopenharmony_ci      <details id="toc" open><summary>Table of contents</summary><ul>
2631cb0ef41Sopenharmony_ci<li><a href="#c-embedder-api">C++ embedder API</a>
2641cb0ef41Sopenharmony_ci<ul>
2651cb0ef41Sopenharmony_ci<li><a href="#example-embedding-application">Example embedding application</a>
2661cb0ef41Sopenharmony_ci<ul>
2671cb0ef41Sopenharmony_ci<li><a href="#setting-up-per-process-state">Setting up per-process state</a></li>
2681cb0ef41Sopenharmony_ci<li><a href="#per-instance-state">Per-instance state</a></li>
2691cb0ef41Sopenharmony_ci</ul>
2701cb0ef41Sopenharmony_ci</li>
2711cb0ef41Sopenharmony_ci</ul>
2721cb0ef41Sopenharmony_ci</li>
2731cb0ef41Sopenharmony_ci</ul></details>
2741cb0ef41Sopenharmony_ci
2751cb0ef41Sopenharmony_ci      <div id="apicontent">
2761cb0ef41Sopenharmony_ci        <h2>C++ embedder API<span><a class="mark" href="#c-embedder-api" id="c-embedder-api">#</a></span><a aria-hidden="true" class="legacy" id="embedding_c_embedder_api"></a></h2>
2771cb0ef41Sopenharmony_ci
2781cb0ef41Sopenharmony_ci<p>Node.js provides a number of C++ APIs that can be used to execute JavaScript
2791cb0ef41Sopenharmony_ciin a Node.js environment from other C++ software.</p>
2801cb0ef41Sopenharmony_ci<p>The documentation for these APIs can be found in <a href="https://github.com/nodejs/node/blob/HEAD/src/node.h">src/node.h</a> in the Node.js
2811cb0ef41Sopenharmony_cisource tree. In addition to the APIs exposed by Node.js, some required concepts
2821cb0ef41Sopenharmony_ciare provided by the V8 embedder API.</p>
2831cb0ef41Sopenharmony_ci<p>Because using Node.js as an embedded library is different from writing code
2841cb0ef41Sopenharmony_cithat is executed by Node.js, breaking changes do not follow typical Node.js
2851cb0ef41Sopenharmony_ci<a href="deprecations.html">deprecation policy</a> and may occur on each semver-major release without prior
2861cb0ef41Sopenharmony_ciwarning.</p>
2871cb0ef41Sopenharmony_ci<section><h3>Example embedding application<span><a class="mark" href="#example-embedding-application" id="example-embedding-application">#</a></span><a aria-hidden="true" class="legacy" id="embedding_example_embedding_application"></a></h3>
2881cb0ef41Sopenharmony_ci<p>The following sections will provide an overview over how to use these APIs
2891cb0ef41Sopenharmony_cito create an application from scratch that will perform the equivalent of
2901cb0ef41Sopenharmony_ci<code>node -e &#x3C;code></code>, i.e. that will take a piece of JavaScript and run it in
2911cb0ef41Sopenharmony_cia Node.js-specific environment.</p>
2921cb0ef41Sopenharmony_ci<p>The full code can be found <a href="https://github.com/nodejs/node/blob/HEAD/test/embedding/embedtest.cc">in the Node.js source tree</a>.</p>
2931cb0ef41Sopenharmony_ci<h4>Setting up per-process state<span><a class="mark" href="#setting-up-per-process-state" id="setting-up-per-process-state">#</a></span><a aria-hidden="true" class="legacy" id="embedding_setting_up_per_process_state"></a></h4>
2941cb0ef41Sopenharmony_ci<p>Node.js requires some per-process state management in order to run:</p>
2951cb0ef41Sopenharmony_ci<ul>
2961cb0ef41Sopenharmony_ci<li>Arguments parsing for Node.js <a href="cli.html">CLI options</a>,</li>
2971cb0ef41Sopenharmony_ci<li>V8 per-process requirements, such as a <code>v8::Platform</code> instance.</li>
2981cb0ef41Sopenharmony_ci</ul>
2991cb0ef41Sopenharmony_ci<p>The following example shows how these can be set up. Some class names are from
3001cb0ef41Sopenharmony_cithe <code>node</code> and <code>v8</code> C++ namespaces, respectively.</p>
3011cb0ef41Sopenharmony_ci<pre><code class="language-cpp"><span class="hljs-function"><span class="hljs-type">int</span> <span class="hljs-title">main</span><span class="hljs-params">(<span class="hljs-type">int</span> argc, <span class="hljs-type">char</span>** argv)</span> </span>{
3021cb0ef41Sopenharmony_ci  argv = <span class="hljs-built_in">uv_setup_args</span>(argc, argv);
3031cb0ef41Sopenharmony_ci  <span class="hljs-function">std::vector&#x3C;std::string> <span class="hljs-title">args</span><span class="hljs-params">(argv, argv + argc)</span></span>;
3041cb0ef41Sopenharmony_ci  <span class="hljs-comment">// Parse Node.js CLI options, and print any errors that have occurred while</span>
3051cb0ef41Sopenharmony_ci  <span class="hljs-comment">// trying to parse them.</span>
3061cb0ef41Sopenharmony_ci  std::unique_ptr&#x3C;node::InitializationResult> result =
3071cb0ef41Sopenharmony_ci      node::<span class="hljs-built_in">InitializeOncePerProcess</span>(args, {
3081cb0ef41Sopenharmony_ci        node::ProcessInitializationFlags::kNoInitializeV8,
3091cb0ef41Sopenharmony_ci        node::ProcessInitializationFlags::kNoInitializeNodeV8Platform
3101cb0ef41Sopenharmony_ci      });
3111cb0ef41Sopenharmony_ci
3121cb0ef41Sopenharmony_ci  <span class="hljs-keyword">for</span> (<span class="hljs-type">const</span> std::string&#x26; error : result-><span class="hljs-built_in">errors</span>())
3131cb0ef41Sopenharmony_ci    <span class="hljs-built_in">fprintf</span>(stderr, <span class="hljs-string">"%s: %s\n"</span>, args[<span class="hljs-number">0</span>].<span class="hljs-built_in">c_str</span>(), error.<span class="hljs-built_in">c_str</span>());
3141cb0ef41Sopenharmony_ci  <span class="hljs-keyword">if</span> (result-><span class="hljs-built_in">early_return</span>() != <span class="hljs-number">0</span>) {
3151cb0ef41Sopenharmony_ci    <span class="hljs-keyword">return</span> result-><span class="hljs-built_in">exit_code</span>();
3161cb0ef41Sopenharmony_ci  }
3171cb0ef41Sopenharmony_ci
3181cb0ef41Sopenharmony_ci  <span class="hljs-comment">// Create a v8::Platform instance. `MultiIsolatePlatform::Create()` is a way</span>
3191cb0ef41Sopenharmony_ci  <span class="hljs-comment">// to create a v8::Platform instance that Node.js can use when creating</span>
3201cb0ef41Sopenharmony_ci  <span class="hljs-comment">// Worker threads. When no `MultiIsolatePlatform` instance is present,</span>
3211cb0ef41Sopenharmony_ci  <span class="hljs-comment">// Worker threads are disabled.</span>
3221cb0ef41Sopenharmony_ci  std::unique_ptr&#x3C;MultiIsolatePlatform> platform =
3231cb0ef41Sopenharmony_ci      MultiIsolatePlatform::<span class="hljs-built_in">Create</span>(<span class="hljs-number">4</span>);
3241cb0ef41Sopenharmony_ci  V8::<span class="hljs-built_in">InitializePlatform</span>(platform.<span class="hljs-built_in">get</span>());
3251cb0ef41Sopenharmony_ci  V8::<span class="hljs-built_in">Initialize</span>();
3261cb0ef41Sopenharmony_ci
3271cb0ef41Sopenharmony_ci  <span class="hljs-comment">// See below for the contents of this function.</span>
3281cb0ef41Sopenharmony_ci  <span class="hljs-type">int</span> ret = <span class="hljs-built_in">RunNodeInstance</span>(
3291cb0ef41Sopenharmony_ci      platform.<span class="hljs-built_in">get</span>(), result-><span class="hljs-built_in">args</span>(), result-><span class="hljs-built_in">exec_args</span>());
3301cb0ef41Sopenharmony_ci
3311cb0ef41Sopenharmony_ci  V8::<span class="hljs-built_in">Dispose</span>();
3321cb0ef41Sopenharmony_ci  V8::<span class="hljs-built_in">DisposePlatform</span>();
3331cb0ef41Sopenharmony_ci
3341cb0ef41Sopenharmony_ci  node::<span class="hljs-built_in">TearDownOncePerProcess</span>();
3351cb0ef41Sopenharmony_ci  <span class="hljs-keyword">return</span> ret;
3361cb0ef41Sopenharmony_ci}</code> <button class="copy-button">copy</button></pre>
3371cb0ef41Sopenharmony_ci<h4>Per-instance state<span><a class="mark" href="#per-instance-state" id="per-instance-state">#</a></span><a aria-hidden="true" class="legacy" id="embedding_per_instance_state"></a></h4>
3381cb0ef41Sopenharmony_ci<div class="api_metadata">
3391cb0ef41Sopenharmony_ci<details class="changelog"><summary>History</summary>
3401cb0ef41Sopenharmony_ci<table>
3411cb0ef41Sopenharmony_ci<tbody><tr><th>Version</th><th>Changes</th></tr>
3421cb0ef41Sopenharmony_ci<tr><td>v15.0.0</td>
3431cb0ef41Sopenharmony_ci<td><p>The <code>CommonEnvironmentSetup</code> and <code>SpinEventLoop</code> utilities were added.</p></td></tr>
3441cb0ef41Sopenharmony_ci</tbody></table>
3451cb0ef41Sopenharmony_ci</details>
3461cb0ef41Sopenharmony_ci</div>
3471cb0ef41Sopenharmony_ci<p>Node.js has a concept of a “Node.js instance”, that is commonly being referred
3481cb0ef41Sopenharmony_cito as <code>node::Environment</code>. Each <code>node::Environment</code> is associated with:</p>
3491cb0ef41Sopenharmony_ci<ul>
3501cb0ef41Sopenharmony_ci<li>Exactly one <code>v8::Isolate</code>, i.e. one JS Engine instance,</li>
3511cb0ef41Sopenharmony_ci<li>Exactly one <code>uv_loop_t</code>, i.e. one event loop, and</li>
3521cb0ef41Sopenharmony_ci<li>A number of <code>v8::Context</code>s, but exactly one main <code>v8::Context</code>.</li>
3531cb0ef41Sopenharmony_ci<li>One <code>node::IsolateData</code> instance that contains information that could be
3541cb0ef41Sopenharmony_cishared by multiple <code>node::Environment</code>s that use the same <code>v8::Isolate</code>.
3551cb0ef41Sopenharmony_ciCurrently, no testing if performed for this scenario.</li>
3561cb0ef41Sopenharmony_ci</ul>
3571cb0ef41Sopenharmony_ci<p>In order to set up a <code>v8::Isolate</code>, an <code>v8::ArrayBuffer::Allocator</code> needs
3581cb0ef41Sopenharmony_cito be provided. One possible choice is the default Node.js allocator, which
3591cb0ef41Sopenharmony_cican be created through <code>node::ArrayBufferAllocator::Create()</code>. Using the Node.js
3601cb0ef41Sopenharmony_ciallocator allows minor performance optimizations when addons use the Node.js
3611cb0ef41Sopenharmony_ciC++ <code>Buffer</code> API, and is required in order to track <code>ArrayBuffer</code> memory in
3621cb0ef41Sopenharmony_ci<a href="process.html#processmemoryusage"><code>process.memoryUsage()</code></a>.</p>
3631cb0ef41Sopenharmony_ci<p>Additionally, each <code>v8::Isolate</code> that is used for a Node.js instance needs to
3641cb0ef41Sopenharmony_cibe registered and unregistered with the <code>MultiIsolatePlatform</code> instance, if one
3651cb0ef41Sopenharmony_ciis being used, in order for the platform to know which event loop to use
3661cb0ef41Sopenharmony_cifor tasks scheduled by the <code>v8::Isolate</code>.</p>
3671cb0ef41Sopenharmony_ci<p>The <code>node::NewIsolate()</code> helper function creates a <code>v8::Isolate</code>,
3681cb0ef41Sopenharmony_cisets it up with some Node.js-specific hooks (e.g. the Node.js error handler),
3691cb0ef41Sopenharmony_ciand registers it with the platform automatically.</p>
3701cb0ef41Sopenharmony_ci<pre><code class="language-cpp"><span class="hljs-function"><span class="hljs-type">int</span> <span class="hljs-title">RunNodeInstance</span><span class="hljs-params">(MultiIsolatePlatform* platform,
3711cb0ef41Sopenharmony_ci                    <span class="hljs-type">const</span> std::vector&#x3C;std::string>&#x26; args,
3721cb0ef41Sopenharmony_ci                    <span class="hljs-type">const</span> std::vector&#x3C;std::string>&#x26; exec_args)</span> </span>{
3731cb0ef41Sopenharmony_ci  <span class="hljs-type">int</span> exit_code = <span class="hljs-number">0</span>;
3741cb0ef41Sopenharmony_ci
3751cb0ef41Sopenharmony_ci  <span class="hljs-comment">// Setup up a libuv event loop, v8::Isolate, and Node.js Environment.</span>
3761cb0ef41Sopenharmony_ci  std::vector&#x3C;std::string> errors;
3771cb0ef41Sopenharmony_ci  std::unique_ptr&#x3C;CommonEnvironmentSetup> setup =
3781cb0ef41Sopenharmony_ci      CommonEnvironmentSetup::<span class="hljs-built_in">Create</span>(platform, &#x26;errors, args, exec_args);
3791cb0ef41Sopenharmony_ci  <span class="hljs-keyword">if</span> (!setup) {
3801cb0ef41Sopenharmony_ci    <span class="hljs-keyword">for</span> (<span class="hljs-type">const</span> std::string&#x26; err : errors)
3811cb0ef41Sopenharmony_ci      <span class="hljs-built_in">fprintf</span>(stderr, <span class="hljs-string">"%s: %s\n"</span>, args[<span class="hljs-number">0</span>].<span class="hljs-built_in">c_str</span>(), err.<span class="hljs-built_in">c_str</span>());
3821cb0ef41Sopenharmony_ci    <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
3831cb0ef41Sopenharmony_ci  }
3841cb0ef41Sopenharmony_ci
3851cb0ef41Sopenharmony_ci  Isolate* isolate = setup-><span class="hljs-built_in">isolate</span>();
3861cb0ef41Sopenharmony_ci  Environment* env = setup-><span class="hljs-built_in">env</span>();
3871cb0ef41Sopenharmony_ci
3881cb0ef41Sopenharmony_ci  {
3891cb0ef41Sopenharmony_ci    <span class="hljs-function">Locker <span class="hljs-title">locker</span><span class="hljs-params">(isolate)</span></span>;
3901cb0ef41Sopenharmony_ci    <span class="hljs-function">Isolate::Scope <span class="hljs-title">isolate_scope</span><span class="hljs-params">(isolate)</span></span>;
3911cb0ef41Sopenharmony_ci    <span class="hljs-function">HandleScope <span class="hljs-title">handle_scope</span><span class="hljs-params">(isolate)</span></span>;
3921cb0ef41Sopenharmony_ci    <span class="hljs-comment">// The v8::Context needs to be entered when node::CreateEnvironment() and</span>
3931cb0ef41Sopenharmony_ci    <span class="hljs-comment">// node::LoadEnvironment() are being called.</span>
3941cb0ef41Sopenharmony_ci    <span class="hljs-function">Context::Scope <span class="hljs-title">context_scope</span><span class="hljs-params">(setup->context())</span></span>;
3951cb0ef41Sopenharmony_ci
3961cb0ef41Sopenharmony_ci    <span class="hljs-comment">// Set up the Node.js instance for execution, and run code inside of it.</span>
3971cb0ef41Sopenharmony_ci    <span class="hljs-comment">// There is also a variant that takes a callback and provides it with</span>
3981cb0ef41Sopenharmony_ci    <span class="hljs-comment">// the `require` and `process` objects, so that it can manually compile</span>
3991cb0ef41Sopenharmony_ci    <span class="hljs-comment">// and run scripts as needed.</span>
4001cb0ef41Sopenharmony_ci    <span class="hljs-comment">// The `require` function inside this script does *not* access the file</span>
4011cb0ef41Sopenharmony_ci    <span class="hljs-comment">// system, and can only load built-in Node.js modules.</span>
4021cb0ef41Sopenharmony_ci    <span class="hljs-comment">// `module.createRequire()` is being used to create one that is able to</span>
4031cb0ef41Sopenharmony_ci    <span class="hljs-comment">// load files from the disk, and uses the standard CommonJS file loader</span>
4041cb0ef41Sopenharmony_ci    <span class="hljs-comment">// instead of the internal-only `require` function.</span>
4051cb0ef41Sopenharmony_ci    MaybeLocal&#x3C;Value> loadenv_ret = node::<span class="hljs-built_in">LoadEnvironment</span>(
4061cb0ef41Sopenharmony_ci        env,
4071cb0ef41Sopenharmony_ci        <span class="hljs-string">"const publicRequire ="</span>
4081cb0ef41Sopenharmony_ci        <span class="hljs-string">"  require('node:module').createRequire(process.cwd() + '/');"</span>
4091cb0ef41Sopenharmony_ci        <span class="hljs-string">"globalThis.require = publicRequire;"</span>
4101cb0ef41Sopenharmony_ci        <span class="hljs-string">"require('node:vm').runInThisContext(process.argv[1]);"</span>);
4111cb0ef41Sopenharmony_ci
4121cb0ef41Sopenharmony_ci    <span class="hljs-keyword">if</span> (loadenv_ret.<span class="hljs-built_in">IsEmpty</span>())  <span class="hljs-comment">// There has been a JS exception.</span>
4131cb0ef41Sopenharmony_ci      <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
4141cb0ef41Sopenharmony_ci
4151cb0ef41Sopenharmony_ci    exit_code = node::<span class="hljs-built_in">SpinEventLoop</span>(env).<span class="hljs-built_in">FromMaybe</span>(<span class="hljs-number">1</span>);
4161cb0ef41Sopenharmony_ci
4171cb0ef41Sopenharmony_ci    <span class="hljs-comment">// node::Stop() can be used to explicitly stop the event loop and keep</span>
4181cb0ef41Sopenharmony_ci    <span class="hljs-comment">// further JavaScript from running. It can be called from any thread,</span>
4191cb0ef41Sopenharmony_ci    <span class="hljs-comment">// and will act like worker.terminate() if called from another thread.</span>
4201cb0ef41Sopenharmony_ci    node::<span class="hljs-built_in">Stop</span>(env);
4211cb0ef41Sopenharmony_ci  }
4221cb0ef41Sopenharmony_ci
4231cb0ef41Sopenharmony_ci  <span class="hljs-keyword">return</span> exit_code;
4241cb0ef41Sopenharmony_ci}</code> <button class="copy-button">copy</button></pre></section>
4251cb0ef41Sopenharmony_ci        <!-- API END -->
4261cb0ef41Sopenharmony_ci      </div>
4271cb0ef41Sopenharmony_ci    </div>
4281cb0ef41Sopenharmony_ci  </div>
4291cb0ef41Sopenharmony_ci</body>
4301cb0ef41Sopenharmony_ci</html>
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