deps: V8: backport 954187bb1b87

Original commit message:

    [api] add Isolate::Deinitialize() and Isolate::Free()

    This allows embedders to mirror the isolate disposal routine
    with an initialization routine that uses Isolate::Allocate().

    ```
    v8::Isolate* isolate = v8::Isolate::Allocate();
    // Use the isolate address as a key.
    v8::Isolate::Initialize(isolate, params);

    isolate->Deinitialize();
    // Remove the entry keyed by isolate address.
    v8::Isolate::Free(isolate);
    ```

    Previously, the only way to dispose the isolate bundles the
    de-initialization and the freeing of the address together in
    v8::Isolate::Dispose(). This is inadequate for embedders like
    Node.js that uses the isolate address as a key to manage the
    task runner associated with it, if another thread gets an
    isolate allocated at the aligned address before the other
    thread finishes cleanup for the isolate previously allocated
    at the same address, and locking on the entire disposal can
    be too risky since it may post GC tasks that in turn requires
    using the isolate address to locate the task runner. It's a
    lot simpler to handle the issue if the disposal process of
    the isolate can mirror the initialization of it and split
    into two routines.

    Refs: https://github.com/nodejs/node/pull/57753#issuecomment-2818999420
    Refs: https://github.com/nodejs/node/issues/30850
    Bug: 412943769
    Change-Id: I3865c27395aded3a6f32de74d96d0698b2d891b9
    Reviewed-on: 6480071
    Reviewed-by: Leszek Swirski <leszeks@chromium.org>
    Commit-Queue: Joyee Cheung <joyee@igalia.com>
    Cr-Commit-Position: refs/heads/main@{#99890}

Refs: 954187bb1b
PR-URL: https://github.com/nodejs/node/pull/58070
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>

common.gypi

@@ -38,7 +38,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.9',
+    'v8_embedder_string': '-node.10',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/include/v8-isolate.h

@@ -872,11 +872,26 @@ class V8_EXPORT Isolate {
   void Exit();
 
   /**
-   * Disposes the isolate.  The isolate must not be entered by any
+   * Deinitializes and frees the isolate. The isolate must not be entered by any
    * thread to be disposable.
    */
   void Dispose();
 
+  /**
+   * Deinitializes the isolate, but does not free the address. The isolate must
+   * not be entered by any thread to be deinitializable. Embedders must call
+   * Isolate::Free() to free the isolate afterwards.
+   */
+  void Deinitialize();
+
+  /**
+   * Frees the memory allocated for the isolate. Can only be called after the
+   * Isolate has already been deinitialized with Isolate::Deinitialize(). After
+   * the isolate is freed, the next call to Isolate::New() or
+   * Isolate::Allocate() might return the same address that just get freed.
+   */
+  static void Free(Isolate* isolate);
+
   /**
    * Dumps activated low-level V8 internal stats. This can be used instead
    * of performing a full isolate disposal.

deps/v8/src/api/api.cc

@@ -10132,6 +10132,21 @@ void Isolate::Dispose() {
   i::Isolate::Delete(i_isolate);
 }
 
+void Isolate::Deinitialize() {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
+  if (!Utils::ApiCheck(
+          !i_isolate->IsInUse(), "v8::Isolate::Deinitialize()",
+          "Deinitializing the isolate that is entered by a thread")) {
+    return;
+  }
+  i::Isolate::Deinitialize(i_isolate);
+}
+
+void Isolate::Free(Isolate* isolate) {
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  i::Isolate::Free(i_isolate);
+}
+
 void Isolate::DumpAndResetStats() {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
   i_isolate->DumpAndResetStats();

deps/v8/src/execution/isolate.cc

@@ -4133,6 +4133,12 @@ Isolate* Isolate::Allocate(IsolateGroup* group) {
 
 // static
 void Isolate::Delete(Isolate* isolate) {
+  Deinitialize(isolate);
+  Free(isolate);
+}
+
+// static
+void Isolate::Deinitialize(Isolate* isolate) {
   DCHECK_NOT_NULL(isolate);
   // v8::V8::Dispose() must only be called after deleting all isolates.
   DCHECK_NOT_NULL(V8::GetCurrentPlatform());
@@ -4156,13 +4162,18 @@ void Isolate::Delete(Isolate* isolate) {
   isolate->~Isolate();
   // Only release the group once all other Isolate members have been destroyed.
   group->Release();
-  // Free the isolate itself.
-  base::AlignedFree(isolate);
 
   // Restore the previous current isolate.
   SetIsolateThreadLocals(saved_isolate, saved_data);
 }
 
+// static
+void Isolate::Free(Isolate* isolate) {
+  DCHECK_NOT_NULL(isolate);
+  // Free the memory allocated for the Isolate.
+  base::AlignedFree(isolate);
+}
+
 void Isolate::SetUpFromReadOnlyArtifacts(ReadOnlyArtifacts* artifacts) {
   DCHECK_NOT_NULL(artifacts);
   InitializeNextUniqueSfiId(artifacts->initial_next_unique_sfi_id());

deps/v8/src/execution/isolate.h

@@ -661,10 +661,16 @@ class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
   static Isolate* New();
   static Isolate* New(IsolateGroup* isolate_group);
 
-  // Deletes Isolate object. Must be used instead of delete operator.
-  // Destroys the non-default isolates.
-  // Sets default isolate into "has_been_disposed" state rather then destroying,
-  // for legacy API reasons.
+  // Deinitialize Isolate object. Must be used instead of delete operator.
+  // Destroys the non-default isolates. Sets default isolate into
+  // "has_been_disposed" state rather then destroying, for legacy API reasons.
+  // Another Free() call must be done after the isolate is deinitialized.
+  // This gives the embedder a chance to clean up before the address is released
+  // (which maybe reused in the next allocation).
+  static void Deinitialize(Isolate* isolate);
+  // Frees the address of the isolate. Must be called after Deinitialize().
+  static void Free(Isolate* isolate);
+  // A convenience helper that deinitializes and frees the isolate.
   static void Delete(Isolate* isolate);
 
   void SetUpFromReadOnlyArtifacts(ReadOnlyArtifacts* artifacts);

deps/v8/test/cctest/test-api.cc

@@ -31344,3 +31344,22 @@ TEST(LocalCasts) {
     v8::MaybeLocal<v8::String>::Cast(no_data);
   }
 }
+
+TEST(IsolateFree) {
+  v8::Isolate* isolate1 = v8::Isolate::Allocate();
+  v8::Isolate::Initialize(isolate1, CreateTestParams());
+  isolate1->Deinitialize();
+
+  // When a new isolate is allocated immediately after one is freed, there is
+  // a chance that the new isolate will be allocated at the same address as the
+  // old one. This tests that when Deinitialize() is called, allocating a new
+  // isolate does not reuse the old address.
+  v8::Isolate* isolate2 = v8::Isolate::Allocate();
+  CHECK_NE(isolate1, isolate2);
+
+  v8::Isolate::Initialize(isolate2, CreateTestParams());
+  isolate2->Deinitialize();
+
+  v8::Isolate::Free(isolate1);
+  v8::Isolate::Free(isolate2);
+}