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fix: allow Node.js to manage microtasks queue (#28973)

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* fix: allow Node.js to manage microtasks queue

When `uv_run()` resulted in invocation of JS functions the microtask
queue checkpoint in Node's CallbackScope was a no-op because the
expected microtask queue policy was `kExplicit` and Electron ran under
`kScoped` policy. This change switches policy to `kExplicit` right
before `uv_run()` and reverts it back to original value after `uv_run()`
completes to provide better compatibility with Node.

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Co-authored-by: Fedor Indutny <fedor@indutny.com>
This commit is contained in:
trop[bot]
2021-05-03 23:00:44 -07:00
committed by GitHub
parent c55cfa7a9c
commit 9c1c8787e9
1 changed files with 9 additions and 2 deletions
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11
shell/common/node_bindings.cc
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@@ -575,8 +575,13 @@ void NodeBindings::UvRunOnce() {
// Enter node context while dealing with uv events.
v8::Context::Scope context_scope(env->context());
// Perform microtask checkpoint after running JavaScript.
gin_helper::MicrotasksScope microtasks_scope(env->isolate());
// Node.js expects `kExplicit` microtasks policy and will run microtasks
// checkpoints after every call into JavaScript. Since we use a different
// policy in the renderer - switch to `kExplicit` and then drop back to the
// previous policy value.
auto old_policy = env->isolate()->GetMicrotasksPolicy();
DCHECK_EQ(v8::MicrotasksScope::GetCurrentDepth(env->isolate()), 0);
env->isolate()->SetMicrotasksPolicy(v8::MicrotasksPolicy::kExplicit);
if (browser_env_ != BrowserEnvironment::kBrowser)
TRACE_EVENT_BEGIN0("devtools.timeline", "FunctionCall");
@@ -587,6 +592,8 @@ void NodeBindings::UvRunOnce() {
if (browser_env_ != BrowserEnvironment::kBrowser)
TRACE_EVENT_END0("devtools.timeline", "FunctionCall");
env->isolate()->SetMicrotasksPolicy(old_policy);
if (r == 0)
base::RunLoop().QuitWhenIdle(); // Quit from uv.