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3cf50539ec
The special empty value (that we use for array holes, Optional<Value> when empty and a few other other placeholder/sentinel tasks) still exists, but you now create one via JS::js_special_empty_value() and check for it with Value::is_special_empty_value(). The main idea here is to make it very unlikely to accidentally create an unexpected special empty value.
110 lines
3.8 KiB
C++
110 lines
3.8 KiB
C++
/*
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* Copyright (c) 2021-2022, Idan Horowitz <idan.horowitz@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Runtime/AbstractOperations.h>
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#include <LibJS/Runtime/FinalizationRegistry.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(FinalizationRegistry);
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FinalizationRegistry::FinalizationRegistry(Realm& realm, GC::Ref<JobCallback> cleanup_callback, Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, WeakContainer(heap())
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, m_realm(realm)
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, m_cleanup_callback(cleanup_callback)
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{
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}
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void FinalizationRegistry::add_finalization_record(Cell& target, Value held_value, Cell* unregister_token)
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{
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VERIFY(!held_value.is_special_empty_value());
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m_records.append({ &target, held_value, unregister_token });
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}
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// Extracted from FinalizationRegistry.prototype.unregister ( unregisterToken )
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bool FinalizationRegistry::remove_by_token(Cell& unregister_token)
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{
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// 4. Let removed be false.
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auto removed = false;
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// 5. For each Record { [[WeakRefTarget]], [[HeldValue]], [[UnregisterToken]] } cell of finalizationRegistry.[[Cells]], do
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for (auto it = m_records.begin(); it != m_records.end(); ++it) {
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// a. If cell.[[UnregisterToken]] is not empty and SameValue(cell.[[UnregisterToken]], unregisterToken) is true, then
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if (it->unregister_token == &unregister_token) {
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// i. Remove cell from finalizationRegistry.[[Cells]].
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it.remove(m_records);
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// ii. Set removed to true.
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removed = true;
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}
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}
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// 6. Return removed.
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return removed;
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}
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void FinalizationRegistry::remove_dead_cells(Badge<GC::Heap>)
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{
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auto any_cells_were_removed = false;
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for (auto& record : m_records) {
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if (!record.target || record.target->state() == Cell::State::Live)
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continue;
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record.target = nullptr;
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any_cells_were_removed = true;
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break;
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}
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if (any_cells_were_removed) {
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// NOTE: We make a GC::Root here to ensure that the FinalizationRegistry stays alive
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// even if a subsequent GC is triggered before the callback has a chance to run.
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heap().enqueue_post_gc_task([that = GC::make_root(this)]() {
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that->vm().host_enqueue_finalization_registry_cleanup_job(*that);
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});
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}
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}
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// 9.13 CleanupFinalizationRegistry ( finalizationRegistry ), https://tc39.es/ecma262/#sec-cleanup-finalization-registry
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ThrowCompletionOr<void> FinalizationRegistry::cleanup(GC::Ptr<JobCallback> callback)
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{
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auto& vm = this->vm();
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// 1. Assert: finalizationRegistry has [[Cells]] and [[CleanupCallback]] internal slots.
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// Note: Ensured by type.
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// 2. Let callback be finalizationRegistry.[[CleanupCallback]].
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auto cleanup_callback = callback ? callback : m_cleanup_callback;
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// 3. While finalizationRegistry.[[Cells]] contains a Record cell such that cell.[[WeakRefTarget]] is empty, an implementation may perform the following steps:
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for (auto it = m_records.begin(); it != m_records.end(); ++it) {
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// a. Choose any such cell.
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if (it->target != nullptr)
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continue;
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// b. Remove cell from finalizationRegistry.[[Cells]].
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GC::RootVector<Value> arguments(vm.heap());
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arguments.append(it->held_value);
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it.remove(m_records);
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// c. Perform ? HostCallJobCallback(callback, undefined, « cell.[[HeldValue]] »).
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TRY(vm.host_call_job_callback(*cleanup_callback, js_undefined(), move(arguments)));
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}
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// 4. Return unused.
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return {};
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}
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void FinalizationRegistry::visit_edges(Cell::Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_realm);
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visitor.visit(m_cleanup_callback);
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for (auto& record : m_records) {
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visitor.visit(record.held_value);
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visitor.visit(record.unregister_token);
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}
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}
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}
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