如何构建CEF多进程模式

淡淡的烟草味﹌ 2022-05-08 16:16 571阅读 0赞

上一篇介绍如何在win32项目中引入CEF。这一篇介绍一下，如何管理CEF的多进程模式，并进行调试。

CEF是一个浏览器控件，进一步说是多组接口集合。嵌入CEF就是实现基于接口的二次开发。但这些接口又比较特殊，因为是开源的，所以可以跟踪、调试、甚至根据自己的需要进行定制、修改。

接口就不做介绍了。下面就从项目由浅入深引入的CEF模块，分块做一下介绍。

CEF的多进程模式

**如果把CEF结构大致分一下，会分出三大块来，browser、render、其他。CEF也支持单进程模式，可以通过设置信息修改。默认多进程模式。其中browser模块主要处理UI部分、Render部分主要做js解释运行、DOM结构解析，其他模块非必须，比如GPU加速渲染、第三方插件等。**

管理多个进程

这里找不到一个合适的词，只能暂时用管理，其实不是管理，更贴切说是多进程的入口创建。先看一下CEF源码提供的demo。cefsimple实现了browser的接口，render使用默认行为

// Entry point function for all processes.  
int APIENTRY wWinMain(HINSTANCE hInstance,  
                      HINSTANCE hPrevInstance,  
                      LPTSTR lpCmdLine,  
                      int nCmdShow) \{  
  UNREFERENCED\_PARAMETER(hPrevInstance);  
  UNREFERENCED\_PARAMETER(lpCmdLine);  
   
  // Enable High-DPI support on Windows 7 or newer.  
  CefEnableHighDPISupport();  
   
  void\* sandbox\_info = NULL;  
   
\#if defined(CEF\_USE\_SANDBOX)  
  // Manage the life span of the sandbox information object. This is necessary  
  // for sandbox support on Windows. See cef\_sandbox\_win.h for complete details.  
  CefScopedSandboxInfo scoped\_sandbox;  
  sandbox\_info = scoped\_sandbox.sandbox\_info();  
\#endif  
   
  // Provide CEF with command-line arguments.  
  CefMainArgs main\_args(hInstance);  
   
  // CEF applications have multiple sub-processes (render, plugin, GPU, etc)  
  // that share the same executable. This function checks the command-line and,  
  // if this is a sub-process, executes the appropriate logic.  
  int exit\_code = CefExecuteProcess(main\_args, NULL, sandbox\_info);  
  if (exit\_code >= 0) \{  
    // The sub-process has completed so return here.  
    return exit\_code;  
  \}  
   
  // Specify CEF global settings here.  
  CefSettings settings;  
   
\#if !defined(CEF\_USE\_SANDBOX)  
  settings.no\_sandbox = true;  
\#endif  
   
  // SimpleApp implements application-level callbacks for the browser process.  
  // It will create the first browser instance in OnContextInitialized() after  
  // CEF has initialized.  
  CefRefPtr<SimpleApp> app(new SimpleApp);  
   
  // Initialize CEF.  
  CefInitialize(main\_args, settings, app.get(), sandbox\_info);  
   
  // Run the CEF message loop. This will block until CefQuitMessageLoop() is  
  // called.  
  CefRunMessageLoop();  
   
  // Shut down CEF.  
  CefShutdown();  
   
  return 0;  
\}  
再看一下cefclient，实现自己对browser和render行为管理

namespace client \{  
namespace \{  
   
int RunMain(HINSTANCE hInstance, int nCmdShow) \{  
  // Enable High-DPI support on Windows 7 or newer.  
  CefEnableHighDPISupport();  
   
  CefMainArgs main\_args(hInstance);  
   
  void\* sandbox\_info = NULL;  
   
\#if defined(CEF\_USE\_SANDBOX)  
  // Manage the life span of the sandbox information object. This is necessary  
  // for sandbox support on Windows. See cef\_sandbox\_win.h for complete details.  
  CefScopedSandboxInfo scoped\_sandbox;  
  sandbox\_info = scoped\_sandbox.sandbox\_info();  
\#endif  
   
  // Parse command-line arguments.  
  CefRefPtr<CefCommandLine> command\_line = CefCommandLine::CreateCommandLine();  
  command\_line->InitFromString(::GetCommandLineW());  
   
  // Create a ClientApp of the correct type.  
  CefRefPtr<CefApp> app;  
  ClientApp::ProcessType process\_type = ClientApp::GetProcessType(command\_line);  
  if (process\_type == ClientApp::BrowserProcess)  
    app = new ClientAppBrowser();  
  else if (process\_type == ClientApp::RendererProcess)  
    app = new ClientAppRenderer();  
  else if (process\_type == ClientApp::OtherProcess)  
    app = new ClientAppOther();  
   
  // Execute the secondary process, if any.  
  int exit\_code = CefExecuteProcess(main\_args, app, sandbox\_info);  
  if (exit\_code >= 0)  
    return exit\_code;  
   
  // Create the main context object.  
  scoped\_ptr<MainContextImpl> context(new MainContextImpl(command\_line, true));  
   
  CefSettings settings;  
   
\#if !defined(CEF\_USE\_SANDBOX)  
  settings.no\_sandbox = true;  
\#endif  
   
  // Populate the settings based on command line arguments.  
  context->PopulateSettings(&settings);  
   
  // Create the main message loop object.  
  scoped\_ptr<MainMessageLoop> message\_loop;  
  if (settings.multi\_threaded\_message\_loop)  
    message\_loop.reset(new MainMessageLoopMultithreadedWin);  
  else if (settings.external\_message\_pump)  
    message\_loop = MainMessageLoopExternalPump::Create();  
  else  
    message\_loop.reset(new MainMessageLoopStd);  
   
  // Initialize CEF.  
  context->Initialize(main\_args, settings, app, sandbox\_info);  
   
  // Register scheme handlers.  
  test\_runner::RegisterSchemeHandlers();  
   
  RootWindowConfig window\_config;  
  window\_config.with\_controls =  
      !command\_line->HasSwitch(switches::kHideControls);  
  window\_config.with\_osr = settings.windowless\_rendering\_enabled ? true : false;  
   
  // Create the first window.  
  context->GetRootWindowManager()->CreateRootWindow(window\_config);  
   
  // Run the message loop. This will block until Quit() is called by the  
  // RootWindowManager after all windows have been destroyed.  
  int result = message\_loop->Run();  
   
  // Shut down CEF.  
  context->Shutdown();  
   
  // Release objects in reverse order of creation.  
  message\_loop.reset();  
  context.reset();  
   
  return result;  
\}  
   
\}  // namespace  
\}  // namespace client  
   
// Program entry point function.  
int APIENTRY wWinMain(HINSTANCE hInstance,  
                      HINSTANCE hPrevInstance,  
                      LPTSTR lpCmdLine,  
                      int nCmdShow) \{  
  UNREFERENCED\_PARAMETER(hPrevInstance);  
  UNREFERENCED\_PARAMETER(lpCmdLine);  
  return client::RunMain(hInstance, nCmdShow);  
\}  
最主要的区别在这里

// Create a ClientApp of the correct type.  
  CefRefPtr<CefApp> app;  
  ClientApp::ProcessType process\_type = ClientApp::GetProcessType(command\_line);  
  if (process\_type == ClientApp::BrowserProcess)  
    app = new ClientAppBrowser();  
  else if (process\_type == ClientApp::RendererProcess)  
    app = new ClientAppRenderer();  
  else if (process\_type == ClientApp::OtherProcess)  
    app = new ClientAppOther();

默认都是多进程模式。下面的这种方式可以直接把进程attach到当前进程中就可以进行调试了。如果使用第一种方式创建进程，render等其他进程使用默认行为，调试的时候需要下载对应版本的cef.pdb。

单进程模式  
可以通过参数进行设置，我试着使用了单进程，但一直无法调试，可能需要额外的pdb信息，时间紧迫也没时间做更多尝试。浏览器设置信息如下

// Specify CEF global settings here.  
    CefSettings settings;

\#if !defined(CEF\_USE\_SANDBOX)  
    settings.no\_sandbox = true;  
\#endif

CefSettingsTraits::init(&settings);  
    //这个设置能实现单进程运行Cef浏览器插件，我们实际应用中采用的是双进程模式，即一个主进程，一个render渲染进程    
    //settings.single\_process = true;  
    //settings.no\_sandbox = true;

//设置渲染进程的名称，因为在相同目录下，没有指定路径    
    //CefString(&settings.browser\_subprocess\_path).FromWString(L"Render.exe");

//禁用Cef的消息循环，采用DuiLib的消息循环    
    //settings.multi\_threaded\_message\_loop = true;

//设置本地语言    
    //CefString(&settings.locale).FromWString(L"zh-CN");

//缓存数据路径    
    //CefString(&settings.cache\_path).FromWString(cache\_path);

//debug日志路径    
    //CefString(&settings.log\_file).FromWString(log\_file);

// Initialize CEF.  
    CefInitialize(main\_args, settings, app.get(), sandbox\_info);

以上信息是项目进行之余，临时做的记录和摘要，比较粗糙，希望还有时间完善。   
\---------------------   
作者：moyebaobei1   
来源：CSDN   
原文：https://blog.csdn.net/moyebaobei1/article/details/81388427?utm\_source=copy   
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[https://blog.csdn.net/moyebaobei1/article/details/81388427][https_blog.csdn.net_moyebaobei1_article_details_81388427]

[https_blog.csdn.net_moyebaobei1_article_details_81388427]: https://blog.csdn.net/moyebaobei1/article/details/81388427