[api] Add API function Isolate::HasPendingBackgroundTasks

This CL adds an API function that tells the embedder if there is ongoing
background work that will eventually post foreground tasks.

Design doc: https://docs.google.com/document/d/18vaABH1mR35PQr8XPHZySuQYgSjJbWFyAW63LW2m8-w

R=adamk@chromium.org

Bug: v8:10787
Change-Id: I9060c5cdc9dbafeb7ea7c5c26d09c2dc744800bd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2342847Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69312}

include/v8.h

@@ -9028,6 +9028,13 @@ class V8_EXPORT Isolate {
    */
   void RequestInterrupt(InterruptCallback callback, void* data);
 
+  /**
+   * Returns true if there is ongoing background work within V8 that will
+   * eventually post a foreground task, like asynchronous WebAssembly
+   * compilation.
+   */
+  bool HasPendingBackgroundTasks();
+
   /**
    * Request garbage collection in this Isolate. It is only valid to call this
    * function if --expose_gc was specified.

src/api/api.cc

@@ -8235,6 +8235,11 @@ void Isolate::RequestInterrupt(InterruptCallback callback, void* data) {
   isolate->RequestInterrupt(callback, data);
 }
 
+bool Isolate::HasPendingBackgroundTasks() {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  return isolate->wasm_engine()->HasRunningCompileJob(isolate);
+}
+
 void Isolate::RequestGarbageCollectionForTesting(GarbageCollectionType type) {
   CHECK(i::FLAG_expose_gc);
   if (type == kMinorGarbageCollection) {

src/d8/d8.cc

@@ -3286,10 +3286,10 @@ bool Shell::SetOptions(int argc, char* argv[]) {
     } else if (strcmp(argv[i], "--omit-quit") == 0) {
       options.omit_quit = true;
       argv[i] = nullptr;
-    } else if (strcmp(argv[i], "--no-wait-for-wasm") == 0) {
+    } else if (strcmp(argv[i], "--no-wait-for-background-tasks") == 0) {
       // TODO(herhut) Remove this flag once wasm compilation is fully
       // isolate-independent.
-      options.wait_for_wasm = false;
+      options.wait_for_background_tasks = false;
       argv[i] = nullptr;
     } else if (strcmp(argv[i], "-f") == 0) {
       // Ignore any -f flags for compatibility with other stand-alone
@@ -3601,10 +3601,8 @@ bool Shell::CompleteMessageLoop(Isolate* isolate) {
   auto get_waiting_behaviour = [isolate]() {
     base::MutexGuard guard(isolate_status_lock_.Pointer());
     DCHECK_GT(isolate_status_.count(isolate), 0);
-    i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-    i::wasm::WasmEngine* wasm_engine = i_isolate->wasm_engine();
-    bool should_wait = (options.wait_for_wasm &&
-                        wasm_engine->HasRunningCompileJob(i_isolate)) ||
+    bool should_wait = (options.wait_for_background_tasks &&
+                        isolate->HasPendingBackgroundTasks()) ||
                        isolate_status_[isolate] ||
                        isolate_running_streaming_tasks_[isolate] > 0;
     return should_wait ? platform::MessageLoopBehavior::kWaitForWork

src/d8/d8.h

@@ -297,7 +297,7 @@ class ShellOptions {
   bool send_idle_notification = false;
   bool invoke_weak_callbacks = false;
   bool omit_quit = false;
-  bool wait_for_wasm = true;
+  bool wait_for_background_tasks = true;
   bool stress_opt = false;
   int stress_runs = 1;
   bool stress_snapshot = false;

test/mjsunit/wasm/graceful_shutdown.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-wasm --no-wait-for-wasm
+// Flags: --expose-wasm --no-wait-for-background-tasks
 
 load("test/mjsunit/wasm/wasm-module-builder.js");
 

test/mjsunit/wasm/graceful_shutdown_during_tierup.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --no-wait-for-wasm --wasm-tier-up
+// Flags: --no-wait-for-background-tasks --wasm-tier-up
 
 load("test/mjsunit/wasm/wasm-module-builder.js");