isolate-group.h | Explore in Territory

// Copyright 2024 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_INIT_ISOLATE_GROUP_H_
#define V8_INIT_ISOLATE_GROUP_H_

#include <memory>

#include "include/v8-memory-span.h"
#include "src/base/once.h"
#include "src/base/page-allocator.h"
#include "src/codegen/external-reference-table.h"
#include "src/common/globals.h"
#include "src/flags/flags.h"
#include "src/utils/allocation.h"

namespace v8 {

namespace base {
template <typename T>
class LeakyObject;
}  // namespace base

namespace internal {

#ifdef V8_ENABLE_SANDBOX
class Sandbox;
#endif
class CodeRange;

// An IsolateGroup allows an API user to control which isolates get allocated
// together in a shared pointer cage.
//
// The standard configuration of V8 is to enable pointer compression and to
// allocate all isolates in a single shared pointer cage
// (V8_COMPRESS_POINTERS_IN_SHARED_CAGE).  This also enables the sandbox
// (V8_ENABLE_SANDBOX), of which there can currently be only one per process, as
// it requires a large part of the virtual address space.
//
// The standard configuration comes with a limitation, in that the total size of
// the compressed pointer cage is limited to 4 GB.  Some API users would like
// pointer compression but also want to avoid the 4 GB limit of the shared
// pointer cage.  Isolate groups allow users to declare which isolates should be
// co-located in a single pointer cage.
//
// Isolate groups are useful only if pointer compression is enabled.  Otherwise,
// the isolate could just allocate pages from the global system allocator;
// there's no need to stay within any particular address range.  If pointer
// compression is disabled, isolate groups are a no-op.
//
// Note that JavaScript objects can only be passed between isolates of the same
// group.  Ensuring this invariant is the responsibility of the API user.
class V8_EXPORT_PRIVATE IsolateGroup final { … };

}  // namespace internal
}  // namespace v8

#endif  // V8_INIT_ISOLATE_GROUP_H_
chromium/v8/src/init/isolate-group.h
