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async_hooks: remove promise object from resource
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While it doesn't make any difference now. In the future PromiseHooks
could be refactored to provide an asyncId instead of the promise object.
That would make escape analysis on promises possible.

Escape analysis on promises could lead to a more efficient destroy hook,
if provide by PromiseHooks as well. But at the very least would allow
the destroy hook to be emitted earlier. The destroy hook not being
emitted on promises frequent enough is a known and reported issue.
See #14446 and
Jeff-Lewis/cls-hooked#11.

While all this is speculation for now, it all depends on the promise
object not being a part of the PromiseWrap resource object.

Ref: #14446
Ref: nodejs/diagnostics#188

PR-URL: #23443
Refs: #14446
Refs: nodejs/diagnostics#188
Reviewed-By: Benedikt Meurer <benedikt.meurer@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: George Adams <george.adams@uk.ibm.com>
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AndreasMadsen authored and George Adams committed Oct 15, 2018
1 parent 561e30d commit 1a2cf66
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Showing 6 changed files with 5 additions and 34 deletions.
3 changes: 1 addition & 2 deletions doc/api/async_hooks.md
Original file line number Diff line number Diff line change
Expand Up @@ -301,8 +301,7 @@ currently not considered public, but using the Embedder API, users can provide
and document their own resource objects. For example, such a resource object
could contain the SQL query being executed.

In the case of Promises, the `resource` object will have `promise` property
that refers to the `Promise` that is being initialized, and an
In the case of Promises, the `resource` object will have an
`isChainedPromise` property, set to `true` if the promise has a parent promise,
and `false` otherwise. For example, in the case of `b = a.then(handler)`, `a` is
considered a parent `Promise` of `b`. Here, `b` is considered a chained promise.
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7 changes: 0 additions & 7 deletions lib/domain.js
Original file line number Diff line number Diff line change
Expand Up @@ -55,13 +55,6 @@ const asyncHook = createHook({
// if this operation is created while in a domain, let's mark it
pairing.set(asyncId, process.domain);
resource.domain = process.domain;
if (resource.promise !== undefined &&
resource.promise instanceof Promise) {
// resource.promise instanceof Promise make sure that the
// promise comes from the same context
// see https://github.com/nodejs/node/issues/15673
resource.promise.domain = process.domain;
}
}
},
before(asyncId) {
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16 changes: 2 additions & 14 deletions src/async_wrap.cc
Original file line number Diff line number Diff line change
Expand Up @@ -185,16 +185,13 @@ class PromiseWrap : public AsyncWrap {
SET_MEMORY_INFO_NAME(PromiseWrap)
SET_SELF_SIZE(PromiseWrap)

static constexpr int kPromiseField = 1;
static constexpr int kIsChainedPromiseField = 2;
static constexpr int kInternalFieldCount = 3;
static constexpr int kIsChainedPromiseField = 1;
static constexpr int kInternalFieldCount = 2;

static PromiseWrap* New(Environment* env,
Local<Promise> promise,
PromiseWrap* parent_wrap,
bool silent);
static void GetPromise(Local<String> property,
const PropertyCallbackInfo<Value>& info);
static void getIsChainedPromise(Local<String> property,
const PropertyCallbackInfo<Value>& info);
};
Expand All @@ -205,7 +202,6 @@ PromiseWrap* PromiseWrap::New(Environment* env,
bool silent) {
Local<Object> object = env->promise_wrap_template()
->NewInstance(env->context()).ToLocalChecked();
object->SetInternalField(PromiseWrap::kPromiseField, promise);
object->SetInternalField(PromiseWrap::kIsChainedPromiseField,
parent_wrap != nullptr ?
v8::True(env->isolate()) :
Expand All @@ -215,11 +211,6 @@ PromiseWrap* PromiseWrap::New(Environment* env,
return new PromiseWrap(env, object, silent);
}

void PromiseWrap::GetPromise(Local<String> property,
const PropertyCallbackInfo<Value>& info) {
info.GetReturnValue().Set(info.Holder()->GetInternalField(kPromiseField));
}

void PromiseWrap::getIsChainedPromise(Local<String> property,
const PropertyCallbackInfo<Value>& info) {
info.GetReturnValue().Set(
Expand Down Expand Up @@ -315,9 +306,6 @@ static void SetupHooks(const FunctionCallbackInfo<Value>& args) {
Local<ObjectTemplate> promise_wrap_template = ctor->InstanceTemplate();
promise_wrap_template->SetInternalFieldCount(
PromiseWrap::kInternalFieldCount);
promise_wrap_template->SetAccessor(
FIXED_ONE_BYTE_STRING(env->isolate(), "promise"),
PromiseWrap::GetPromise);
promise_wrap_template->SetAccessor(
FIXED_ONE_BYTE_STRING(env->isolate(), "isChainedPromise"),
PromiseWrap::getIsChainedPromise);
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3 changes: 0 additions & 3 deletions test/parallel/test-async-hooks-promise-enable-disable.js
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@ const common = require('../common');
const assert = require('assert');
const async_hooks = require('async_hooks');
const EXPECTED_INITS = 2;
let p_resource = null;
let p_er = null;
let p_inits = 0;

Expand All @@ -23,7 +22,6 @@ const mustCallInit = common.mustCall(function init(id, type, tid, resource) {
if (type !== 'PROMISE')
return;
p_inits++;
p_resource = resource.promise;
}, EXPECTED_INITS);

const hook = async_hooks.createHook({
Expand All @@ -36,7 +34,6 @@ new Promise(common.mustCall((res) => {
})).then(common.mustCall((val) => {
hook.enable().enable();
const p = new Promise((res) => res(val));
assert.strictEqual(p, p_resource);
hook.disable();
return p;
})).then(common.mustCall((val2) => {
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4 changes: 1 addition & 3 deletions test/parallel/test-async-hooks-promise.js
Original file line number Diff line number Diff line change
Expand Up @@ -21,11 +21,9 @@ async_hooks.createHook({
}).enable();

const a = Promise.resolve(42);
const b = a.then(common.mustCall());
a.then(common.mustCall());

assert.strictEqual(initCalls[0].triggerId, 1);
assert.strictEqual(initCalls[0].resource.isChainedPromise, false);
assert.strictEqual(initCalls[0].resource.promise, a);
assert.strictEqual(initCalls[1].triggerId, initCalls[0].id);
assert.strictEqual(initCalls[1].resource.isChainedPromise, true);
assert.strictEqual(initCalls[1].resource.promise, b);
6 changes: 1 addition & 5 deletions test/parallel/test-domain-promise.js
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,6 @@ const vm = require('vm');
d2.run(common.mustCall(() => {
p.then(common.mustCall((v) => {
assert.strictEqual(process.domain, d2);
assert.strictEqual(p.domain, d1);
}));
}));
}
Expand All @@ -64,9 +63,8 @@ const vm = require('vm');
}));

d2.run(common.mustCall(() => {
p.then(p.domain.bind(common.mustCall((v) => {
p.then(d1.bind(common.mustCall((v) => {
assert.strictEqual(process.domain, d1);
assert.strictEqual(p.domain, d1);
})));
}));
}
Expand All @@ -83,7 +81,6 @@ const vm = require('vm');
d2.run(common.mustCall(() => {
p.then(common.mustCall((v) => {
assert.strictEqual(process.domain, d2);
assert.strictEqual(p.domain, d1);
}));
}));
}));
Expand All @@ -100,7 +97,6 @@ const vm = require('vm');
d2.run(common.mustCall(() => {
p.catch(common.mustCall((v) => {
assert.strictEqual(process.domain, d2);
assert.strictEqual(p.domain, d1);
}));
}));
}
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