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The C and C++ Include Header Files

/usr/include/node/v8-embedder-heap.h


$ cat -n /usr/include/node/v8-embedder-heap.h

     1	// Copyright 2021 the V8 project authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style license that can be
     3	// found in the LICENSE file.
     4	
     5	#ifndef INCLUDE_V8_EMBEDDER_HEAP_H_
     6	#define INCLUDE_V8_EMBEDDER_HEAP_H_
     7	
     8	#include "v8-traced-handle.h"  // NOLINT(build/include_directory)
     9	#include "v8config.h"          // NOLINT(build/include_directory)
    10	
    11	namespace v8 {
    12	namespace internal {
    13	class TracedHandles;
    14	}  // namespace internal
    15	
    16	class Isolate;
    17	class Value;
    18	
    19	/**
    20	 * Handler for embedder roots on non-unified heap garbage collections.
    21	 */
    22	class V8_EXPORT EmbedderRootsHandler {
    23	 public:
    24	  enum class RootHandling {
    25	    kQueryEmbedderForNonDroppableReferences,
    26	    kDontQueryEmbedderForAnyReference,
    27	  };
    28	
    29	  virtual ~EmbedderRootsHandler() = default;
    30	
    31	  EmbedderRootsHandler() = default;
    32	  explicit EmbedderRootsHandler(RootHandling default_traced_reference_handling)
    33	      : default_traced_reference_handling_(default_traced_reference_handling) {}
    34	
    35	  /**
    36	   * Returns true if the |TracedReference| handle should be considered as root
    37	   * for the currently running non-tracing garbage collection and false
    38	   * otherwise. The default implementation will keep all |TracedReference|
    39	   * references as roots.
    40	   *
    41	   * If this returns false, then V8 may decide that the object referred to by
    42	   * such a handle is reclaimed. In that case, V8 calls |ResetRoot()| for the
    43	   * |TracedReference|.
    44	   *
    45	   * Note that the `handle` is different from the handle that the embedder holds
    46	   * for retaining the object.
    47	   *
    48	   * The concrete implementations must be thread-safe.
    49	   */
    50	  virtual bool IsRoot(const v8::TracedReference<v8::Value>& handle) = 0;
    51	
    52	  /**
    53	   * Used in combination with |IsRoot|. Called by V8 when an
    54	   * object that is backed by a handle is reclaimed by a non-tracing garbage
    55	   * collection. It is up to the embedder to reset the original handle.
    56	   *
    57	   * Note that the |handle| is different from the handle that the embedder holds
    58	   * for retaining the object. It is up to the embedder to find the original
    59	   * handle via the object or class id.
    60	   */
    61	  virtual void ResetRoot(const v8::TracedReference<v8::Value>& handle) = 0;
    62	
    63	  /**
    64	   * Similar to |ResetRoot()|, but opportunistic. The function is called in
    65	   * parallel for different handles and as such must be thread-safe. In case,
    66	   * |false| is returned, |ResetRoot()| will be recalled for the same handle.
    67	   */
    68	  virtual bool TryResetRoot(const v8::TracedReference<v8::Value>& handle) {
    69	    ResetRoot(handle);
    70	    return true;
    71	  }
    72	
    73	 private:
    74	  const RootHandling default_traced_reference_handling_ =
    75	      RootHandling::kQueryEmbedderForNonDroppableReferences;
    76	
    77	  friend class internal::TracedHandles;
    78	};
    79	
    80	}  // namespace v8
    81	
    82	#endif  // INCLUDE_V8_EMBEDDER_HEAP_H_