From 99909baeac41c2f4e9b3ded6b9505905cf99f0b2 Mon Sep 17 00:00:00 2001 From: Fedor Indutny Date: Mon, 3 May 2021 14:30:12 -0700 Subject: [PATCH] fix: allow Node.js to manage microtasks queue (#28957) * 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. * add comment --- shell/common/node_bindings.cc | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/shell/common/node_bindings.cc b/shell/common/node_bindings.cc index e8f942a7fa00..a6fb17e343c0 100644 --- a/shell/common/node_bindings.cc +++ b/shell/common/node_bindings.cc @@ -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.