{"id":254255,"date":"2022-10-12T09:09:55","date_gmt":"2022-10-12T01:09:55","guid":{"rendered":"https:\/\/lrxjmw.cn\/?p=254255"},"modified":"2022-10-04T11:12:13","modified_gmt":"2022-10-04T03:12:13","slug":"js-breakpoint-implementation","status":"publish","type":"post","link":"https:\/\/lrxjmw.cn\/js-breakpoint-implementation.html","title":{"rendered":"JS\u65ad\u70b9\u7684\u5b9e\u73b0\u7684\u6df1\u5165\u89e3\u8bfb"},"content":{"rendered":"<table>\n<tbody>\n<tr>\n<td style=\"padding: 5px 12px; width: 25px; font-size: 22px; text-align: center; background: #E8E8E8; line-height: 30px; color: #999;\">\u5bfc\u8bfb<\/td>\n<td style=\"padding: 10px 10px 12px; line-height: 20px;\"><strong>JS 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https:\/\/lrxjmw.cn\/wp-content\/uploads\/2022\/10\/09-300x194.jpg 300w, https:\/\/lrxjmw.cn\/wp-content\/uploads\/2022\/10\/09-768x498.jpg 768w, https:\/\/lrxjmw.cn\/wp-content\/uploads\/2022\/10\/09.jpg 1080w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<p>\u6211\u4eec\u77e5\u9053 V8 \u6709\u4e00\u4e2a\u8c03\u8bd5\u534f\u8bae\uff0c\u5ba2\u6237\u7aef\u662f\u548c V8 \u901a\u8fc7\u8fd9\u4e2a\u534f\u8bae\u901a\u4fe1\u5b8c\u6210\u8c03\u8bd5\u7684\uff0c\u5f53 V8 \u6536\u5230\u5ba2\u6237\u7aef\u7684\u4fe1\u606f\u5e76\u4e14\u5904\u7406\u5b8c\u4e4b\u540e\uff0c\u5c31\u4f1a\u8c03\u7528 runMessageLoopOnPause\u3002runMessageLoopOnPause \u662f V8 \u63d0\u4f9b\u7684\u4e00\u4e2a\u7ea6\u5b9a\u7684 API\uff0c\u5f53\u6267\u884c\u5230 JS \u65ad\u70b9\u65f6\u5c31\u4f1a\u8c03\u7528\uff0c\u5177\u4f53\u5728 runMessageLoopOnPause \u91cc\u505a\u4ec0\u4e48\u4e8b\u60c5\u7531 V8 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\u5524\u9192\u65b9\u5f0f\uff0c\u90a3\u5c31\u662f\u6761\u4ef6\u53d8\u91cf\u3002\u5f53\u7ebf\u7a0b\u963b\u585e\u4e8e\u6761\u4ef6\u53d8\u91cf\u65f6\uff0c\u53ea\u6709\u901a\u8fc7\u8be5\u6761\u4ef6\u53d8\u91cf\u624d\u80fd\u5524\u9192\u7ebf\u7a0b\u3002\u56de\u5230\u65ad\u70b9\u7684\u573a\u666f\uff0c\u90a3\u5c31\u662f\u5ba2\u6237\u7aef\u7ee7\u7eed\u6267\u884c\u65f6\u624d\u80fd\u5524\u9192\u7ebf\u7a0b\u3002<\/p>\n<p>\u5206\u6790\u5b8c\u4e4b\u540e\uff0c\u6765\u770b\u770b Node.js \u7684\u5b9e\u73b0\u3002<\/p>\n<pre>\r\nvoid runMessageLoopOnPause(int context_group_id) override {\r\n  waiting_for_resume_ = true;\r\n  runMessageLoop();\r\n}\r\n\r\nvoid runMessageLoop() {\r\n  if (running_nested_loop_)\r\n    return;\r\n\r\n  running_nested_loop_ = true;\r\n\r\n  while (shouldRunMessageLoop()) {\r\n    if (interface_) interface_->WaitForFrontendEvent();\r\n    env_->RunAndClearInterrupts();\r\n  }\r\n  running_nested_loop_ = false;\r\n}\r\n<\/pre>\n<p>\u91cd\u70b9\u5728 WaitForFrontendEvent\u3002<\/p>\n<pre>\r\nbool MainThreadInterface::WaitForFrontendEvent() {\r\n  dispatching_messages_ = false;\r\n  \/\/ \u4efb\u52a1\u961f\u5217\u4e3a\u7a7a\u5219\u963b\u585e\r\n  if (dispatching_message_queue_.empty()) {\r\n    Mutex::ScopedLock scoped_lock(requests_lock_);\r\n    while (requests_.empty()) incoming_message_cond_.Wait(scoped_lock);\r\n  }\r\n  return true;\r\n}\r\n<\/pre>\n<p>\u6211\u4eec\u5047\u8bbe\u8fd9\u65f6\u5019\u961f\u5217\u4e3a\u7a7a\uff0c\u90a3\u4e48\u7ebf\u7a0b\u5c31\u4f1a\u963b\u585e\u5728\u6761\u4ef6\u53d8\u91cf incoming_message_cond_ \u4e2d\u3002\u63a5\u4e0b\u6765\u770b\u770b\u5982\u804a\u804a\u7b2c\u4e8c\u4e2a\u95ee\u9898\u3002\u7ebf\u7a0b\u8fd9\u65f6\u5019\u963b\u585e\u4e86\uff0c\u90a3\u4e48\u5ba2\u6237\u7aef\u70b9\u51fb\u6267\u884c\u4e0b\u4e00\u6b65\u7684\u65f6\u5019\uff0cNode.js \u8fd8\u8fd8\u600e\u4e48\u5904\u7406\uff1f\u8fd9\u91cc\u5c31\u9700\u8981\u5b50\u7ebf\u7a0b\u5e2e\u5fd9\u4e86\uff0c\u6240\u4ee5 Node.js 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\u8fde\u63a5\u6210\u529f\u540e\u7684\u8c03\u7528\u6808\uff0c\u540e\u7eed\u7684\u6570\u636e\u901a\u4fe1\u4e5f\u662f\u7c7b\u4f3c\u3002\u6765\u770b\u4e00\u4e0b Post\u3002<\/p>\n<pre>\r\nvoid MainThreadInterface::Post(std::unique_ptr<request> request) {\r\n  Mutex::ScopedLock scoped_lock(requests_lock_);\r\n  bool needs_notify = requests_.empty();\r\n  requests_.push_back(std::move(request));\r\n  if (needs_notify) {\r\n    std::weak_ptr<mainthreadinterface> weak_self {shared_from_this()};\r\n    agent_->env()->RequestInterrupt([weak_self](Environment*) {\r\n      if (auto iface = weak_self.lock()) iface->DispatchMessages();\r\n    });\r\n  }\r\n  incoming_message_cond_.Broadcast(scoped_lock);\r\n}\r\n<\/mainthreadinterface><\/request><\/pre>\n<p>\u8fd9\u91cc\u770b\u5230\u4e86\u521a\u624d\u719f\u6089\u7684\u6570\u636e\u7ed3\u6784\uff0cPost \u5c31\u662f\u5f80\u4e3b\u7ebf\u7a0b\u4e2d\u63d2\u5165\u4e00\u4e2a\u4efb\u52a1\uff0c\u7136\u540e\u5524\u9192\u4e3b\u7ebf\u7a0b\u3002\u63a5\u7740\u56de\u5230 runMessageLoop\u3002<\/p>\n<pre>\r\nwhile (shouldRunMessageLoop()) {\r\n  if (interface_) interface_->WaitForFrontendEvent();\r\n  env_->RunAndClearInterrupts();\r\n}\r\n<\/pre>\n<p>WaitForFrontendEvent \u6267\u884c\u5b8c\u6bd5\u540e\uff0c\u63a5\u7740\u6267\u884c RunAndClearInterrupts\uff0cRunAndClearInterrupts \u6b63\u662f\u5904\u7406 RequestInterrupt \u63d2\u5165\u7684\u4efb\u52a1\u7684\u3002\u521a\u624d\u63d2\u5165\u4efb\u52a1\u65f6\u6211\u4eec\u770b\u5230\u63d2\u5165\u4e86\u4e24\u4e2a\u4efb\u52a1 agent_->env()->RequestInterrupt \u548c requests_.push_back(std::move(request)) \uff0cRequestInterrupt \u63d2\u5165\u7684\u4efb\u52a1\u4e2d\u4f1a\u8c03\u7528 DispatchMessages\uff0c\u800c DispatchMessages \u5c31\u662f\u5904\u7406 requests_ \u4e2d\u7684\u4efb\u52a1\u7684\u3002<\/p>\n<pre>\r\nvoid MainThreadInterface::DispatchMessages() {\r\n  dispatching_messages_ = true;\r\n  bool had_messages = false;\r\n  do {\r\n    if (dispatching_message_queue_.empty()) {\r\n      Mutex::ScopedLock scoped_lock(requests_lock_);\r\n      requests_.swap(dispatching_message_queue_);\r\n    }\r\n    had_messages = !dispatching_message_queue_.empty();\r\n    while (!dispatching_message_queue_.empty()) {\r\n      MessageQueue::value_type task;\r\n      std::swap(dispatching_message_queue_.front(), task);\r\n      dispatching_message_queue_.pop_front();\r\n\r\n      v8::SealHandleScope seal_handle_scope(agent_->env()->isolate());\r\n      task->Call(this);\r\n    }\r\n  } while (had_messages);\r\n  dispatching_messages_ = false;\r\n}\r\n<\/pre>\n<p>\u6267\u884c\u4efb\u52a1\u7684\u65f6\u5019\uff0c\u5177\u4f53\u505a\u7684\u4e8b\u60c5\u5c31\u662f\u628a\u5ba2\u6237\u7aef\u4f20\u8fc7\u6765\u7684\u6570\u636e\u6295\u4f20\u7ed9 V8 Inspector\uff0c\u5982\u679c\u53c8\u6267\u884c\u5230\u4e86\u4e00\u4e2a\u65ad\u70b9\uff0c\u90a3\u4e48\u7ee7\u7eed\u672c\u6587\u5206\u6790\u5230\u8fd9\u4e2a\u903b\u8f91\uff0c\u5426\u5219\u7ebf\u7a0b\u5c31\u53ef\u4ee5\u7ee7\u7eed\u8dd1\u4e86\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u65ad\u70b9\u7684\u5b9e\u73b0\u975e\u5e38\u590d\u6742\uff0c\u8fd9\u91cc\u5e76\u4e0d\u662f\u8bf4\u8981\u957f\u7bc7\u5927\u8bba\u8bb2\u89e3 JS \u65ad\u70b9\u5728 V8 \u4e2d\u662f\u5982\u4f55\u5b9e\u73b0\u7684\uff0c\u800c\u662f\u60f3\u4ece\u5b8f\u89c2\u4e0a\u804a\u4e00\u4e0b\u65ad\u70b9\u7684 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