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Detect unhandled promise rejections

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#82 3 則留言 0 個 reaction 已指派 0 人 在 GitHub 檢視

還沒有人認領這個 Issue。

評估

難度
5/5
預估耗時
一週以上
新手友好度
25/100
Issue 類型
功能
描述清晰度
基本清楚
活躍度
停滯
技術堆疊
javascript, ruby
領域
api, backend

研究方向

The issue points to V8's SetPromiseRejectCallback and PromiseRejectMessage; start by reading those API definitions and locating how mini_racer connects V8 callbacks to Ruby exceptions. The example shows the missed rejection and the expected error behavior, while the issue leaves the default behavior and configurability undecided. Done means unhandled rejections are reported to Ruby, with the handling behavior defined.

由索引模型根據 Issue 內容生成。

描述

When working with promises, one important aspect of them is that an unhandled rejected promise is an error. However, V8 will drop notifications by default.

I think that mini_racer should consider this an error and raise an exception, though possibly it should be configurable how these are handled (e.g. via a callback where the user can decide to re-raise?).

To do so, it's necessary to register for unhandled promise rejections via SetPromiseRejectCallback.

The callback will receive a PromiseRejectMessage that should probably (by default) raise a exception in ruby, although I suppose it could be configurable.

Comparisons for reference:

Running this code:

var x = async () => { throw "failure"; };
var y = async () => { x() /* ignore the rejected result */ }; 
y().then(() => console.log("done")).catch(e => console.log(e));

In node:

> var x = async () => { throw "failure"; }; var y = async () => { x() /* ignore the rejected result */ }; y().then(() => console.log("done")).catch(e => console.log(e));
Promise {
  <pending>,
  domain:
   Domain {
     domain: null,
     _events:
      { removeListener: [Function: updateExceptionCapture],
        newListener: [Function: updateExceptionCapture],
        error: [Function: debugDomainError] },
     _eventsCount: 3,
     _maxListeners: undefined,
     members: [] } }
> done
(node:83056) UnhandledPromiseRejectionWarning: failure
(node:83056) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)

In chrome:

var x = async () => { throw "failure"; }; var y = async () => { x() /* ignore the rejected result */ }; y().then(() => console.log("done")).catch(e => console.log(e));
VM131:1 done
Promise {<resolved>: undefined}
VM131:1 Uncaught (in promise) failure

In mini_racer:

irb(main):001:0> require 'mini_racer'
=> true
irb(main):002:0> vm = MiniRacer::Context.new
=> #<MiniRacer::Context:0x00007ff4350f1438 @functions={}, @timeout=nil, @max_memory=nil, @current_exception=nil, @isolate=#<MiniRacer::Isolate:0x00007ff4350f12f8 @lock=#<Thread::Mutex:0x00007ff4350f12a8>>, @disposed=false, @callback_mutex=#<Thread::Mutex:0x00007ff4350f1280>, @callback_running=false, @thread_raise_called=false, @eval_thread=nil>
irb(main):003:0> vm.attach('console.log', proc{ |*args| puts('LOG> ' + args.map(&:to_s).join(' ')) })
=> #<MiniRacer::Context::ExternalFunction:0x00007ff43602b1b0 @name="log", @callback=#<Proc:0x00007ff43602b200@/usr/local/lib/ruby/gems/2.5.0/gems/mini_racer-0.1.15/lib/mini_racer.rb:201 (lambda)>, @parent=#<MiniRacer::Context:0x00007ff4350f1438 @functions={"console.log"=>#<MiniRacer::Context::ExternalFunction:0x00007ff43602b1b0 ...>}, @timeout=nil, @max_memory=nil, @current_exception=nil, @isolate=#<MiniRacer::Isolate:0x00007ff4350f12f8 @lock=#<Thread::Mutex:0x00007ff4350f12a8>>, @disposed=false, @callback_mutex=#<Thread::Mutex:0x00007ff4350f1280>, @callback_running=false, @thread_raise_called=false, @eval_thread=nil>, @parent_object_eval="if (typeof console === 'undefined') { console = {} };\nconsole;", @parent_object="console">
irb(main):004:0> vm.eval('var x = async () => { throw "failure"; }; var y = async () => { x() /* ignore the rejected result */ }; y().then(() => console.log("done")).catch(e => console.log(e));')
LOG> done
=> {}
irb(main):005:0>
主要語言
JavaScript
星號
628
分支
100
平均合併
1 天 20 小時
30 天內合併 PR
2

環境準備

  • 提供 Dockerfile 或 Docker Compose 檔案
  • 沒有 Pull Request 範本
  • 沒有貢獻指南

從這裡開始

  1. 先讀完整個 Issue，再讀專案的貢獻指南。
  2. 在 Issue 下留言說明你要接手 —— 這能避免兩個人做同樣的事。
  3. Fork 儲存庫，在一個分支上完成修改。
  4. 送出 Pull Request，並在描述裡引用這個 Issue 編號。

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