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async_hooks: simplify fatalError #14051

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async_hooks: simplify fatalError #14051

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17aafd7
async_hooks: simplify fatalError
AndreasMadsen Jul 3, 2017
278b163
[squash] use try finally, for better stack traces
AndreasMadsen Jul 3, 2017
610d365
[squash] ensure that uncaughtException listeners are removed
AndreasMadsen Jul 3, 2017
1d3f69b
[squash] async_hooks c++ already have a try finally for each hook
AndreasMadsen Jul 3, 2017
527a4f6
[squash] add frindly comment explaining _events interaction
AndreasMadsen Jul 3, 2017
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[squash] use try finally, for better stack traces
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@AndreasMadsen
AndreasMadsen committed Jul 3, 2017
commit 278b1636c91ef48424cad46fe4c43201c5f780cc
29 changes: 18 additions & 11 deletions lib/async_hooks.js
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Expand Up @@ -62,10 +62,9 @@ async_wrap.setupHooks({ init,
// Used to fatally abort the process if a callback throws.
// This is JavaScript version of the ClearFatalExceptionHandlers function
// in C++.
function fatalError(e) {
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@refack refack Jul 3, 2017 •
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Why is everyone trying to kill this 😨
I like it as a way to bail from a callback or a Promise.catch
Ref: #13839 (comment)

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@AndreasMadsen AndreasMadsen Jul 3, 2017

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Just because it is useful for Promise.catch doesn't mean that is useful here.

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@refack refack Jul 3, 2017

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Probably. I'll copy it to test/common/

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@AndreasMadsen AndreasMadsen Jul 3, 2017

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Letting an error bubble with try {} finally {} have always been the standard way of handling throws.

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@trevnorris trevnorris Jul 3, 2017

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Except what async_hooks is doing isn't standard. This is a guard to prevent an abort from C++ if it detects stack corruption that can likely result from the user try catching/Promise wrapping the call, and to get useful core dumps. It also doesn't follow how this is handled in C++ (https://github.com/nodejs/node/blob/v8.1.3/src/env-inl.h#L144-L160). I'm a big -1 on this.

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@trevnorris trevnorris Jul 3, 2017

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By "exporting FatalException" do you mean expose it to JS?

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@trevnorris trevnorris Jul 3, 2017 •
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If anything I'd like to export the code in Environment::AsyncHooks::pop_ids() and use that as the uniform way to exit the process.

EDIT: Except it should show a JS stack instead of a C++ stack.

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@AndreasMadsen AndreasMadsen Jul 4, 2017

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By "exporting FatalException" do you mean expose it to JS?

Yes. At the very least I would like a unified way of making a fatal exception. Currently, there are a couple of different implementations floating around in nodecore. It makes things like --abort-on-uncaught-exception difficult to test.

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@trevnorris trevnorris Jul 5, 2017

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@AndreasMadsen

At the very least I would like a unified way of making a fatal exception.

Sounds good to me.

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@refack refack Jul 9, 2017

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So area this is currently a WIP?

function clearFatalExceptionHandlers(e) {
process.domain = undefined;
process._events.uncaughtException = undefined;
throw e;
}


Expand Down Expand Up @@ -338,15 +337,17 @@ function emitInitS(asyncId, type, triggerAsyncId, resource) {

function emitBeforeN(asyncId) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
if (typeof active_hooks_array[i][before_symbol] === 'function') {
active_hooks_array[i][before_symbol](asyncId);
}
}
} catch (e) {
fatalError(e);
didThrow = false;
} finally {
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;

Expand All @@ -364,10 +365,11 @@ function emitBeforeS(asyncId, triggerAsyncId = asyncId) {

// Validate the ids.
if (asyncId < 0 || triggerAsyncId < 0) {
fatalError(new Error(
clearFatalExceptionHandlers();
throw new Error(
'before(): asyncId or triggerAsyncId is less than zero ' +
`(asyncId: ${asyncId}, triggerAsyncId: ${triggerAsyncId})`
));
);
}

pushAsyncIds(asyncId, triggerAsyncId);
Expand All @@ -382,15 +384,17 @@ function emitBeforeS(asyncId, triggerAsyncId = asyncId) {
// this is called.
function emitAfterN(asyncId) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
if (typeof active_hooks_array[i][after_symbol] === 'function') {
active_hooks_array[i][after_symbol](asyncId);
}
}
didThrow = false;
} catch (e) {
fatalError(e);
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;

Expand Down Expand Up @@ -422,15 +426,17 @@ function emitDestroyS(asyncId) {

function emitDestroyN(asyncId) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
if (typeof active_hooks_array[i][destroy_symbol] === 'function') {
active_hooks_array[i][destroy_symbol](asyncId);
}
}
} catch (e) {
fatalError(e);
didThrow = false;
} finally {
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;

Expand All @@ -455,6 +461,7 @@ function emitDestroyN(asyncId) {
// exceptions.
function init(asyncId, type, triggerAsyncId, resource) {
processing_hook = true;
var didThrow = true;
// Use a single try/catch for all hook to avoid setting up one per iteration.
try {
for (var i = 0; i < active_hooks_array.length; i++) {
Expand All @@ -465,8 +472,8 @@ function init(asyncId, type, triggerAsyncId, resource) {
);
}
}
} catch (e) {
fatalError(e);
} finally {
if (didThrow) clearFatalExceptionHandlers();
}
processing_hook = false;
}
Expand Down