mirror of https://github.com/nodejs/node.git
86 lines
2.8 KiB
C++
86 lines
2.8 KiB
C++
// Copyright 2021 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef INCLUDE_V8_EMBEDDER_HEAP_H_
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#define INCLUDE_V8_EMBEDDER_HEAP_H_
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#include "v8-traced-handle.h" // NOLINT(build/include_directory)
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#include "v8config.h" // NOLINT(build/include_directory)
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namespace v8 {
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namespace internal {
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class TracedHandles;
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} // namespace internal
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class Isolate;
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class Value;
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/**
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* Handler for embedder roots on non-unified heap garbage collections.
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*/
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class V8_EXPORT EmbedderRootsHandler {
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public:
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enum class RootHandling {
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kQueryEmbedderForNonDroppableReferences,
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kDontQueryEmbedderForAnyReference,
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};
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virtual ~EmbedderRootsHandler() = default;
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EmbedderRootsHandler() = default;
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V8_DEPRECATED("Use the default constructor instead.")
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explicit EmbedderRootsHandler(RootHandling default_traced_reference_handling)
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: default_traced_reference_handling_(default_traced_reference_handling) {}
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/**
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* Returns true if the |TracedReference| handle should be considered as root
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* for the currently running non-tracing garbage collection and false
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* otherwise. The default implementation will keep all |TracedReference|
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* references as roots.
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*
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* If this returns false, then V8 may decide that the object referred to by
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* such a handle is reclaimed. In that case, V8 calls |ResetRoot()| for the
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* |TracedReference|.
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*
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* Note that the `handle` is different from the handle that the embedder holds
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* for retaining the object.
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*
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* The concrete implementations must be thread-safe.
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*/
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V8_DEPRECATED("Use TracedReferenceHandling::kDroppable instead.")
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virtual bool IsRoot(const v8::TracedReference<v8::Value>& handle) = 0;
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/**
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* Used in combination with |IsRoot|. Called by V8 when an
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* object that is backed by a handle is reclaimed by a non-tracing garbage
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* collection. It is up to the embedder to reset the original handle.
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*
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* Note that the |handle| is different from the handle that the embedder holds
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* for retaining the object. It is up to the embedder to find the original
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* handle via the object or class id.
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*/
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virtual void ResetRoot(const v8::TracedReference<v8::Value>& handle) = 0;
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/**
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* Similar to |ResetRoot()|, but opportunistic. The function is called in
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* parallel for different handles and as such must be thread-safe. In case,
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* |false| is returned, |ResetRoot()| will be recalled for the same handle.
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*/
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virtual bool TryResetRoot(const v8::TracedReference<v8::Value>& handle) {
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ResetRoot(handle);
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return true;
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}
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private:
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const RootHandling default_traced_reference_handling_ =
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RootHandling::kDontQueryEmbedderForAnyReference;
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friend class internal::TracedHandles;
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};
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} // namespace v8
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#endif // INCLUDE_V8_EMBEDDER_HEAP_H_
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