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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
*
* Copyright 2021 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef wasm_shareable_h
#define wasm_shareable_h
#include "mozilla/RefPtr.h"
#include "js/RefCounted.h"
#include "wasm/WasmTypeDecls.h"
namespace js {
namespace wasm {
using mozilla::MallocSizeOf;
// This reusable base class factors out the logic for a resource that is shared
// by multiple instances/modules but should only be counted once when computing
// about:memory stats.
template <class T>
using SeenSet = HashSet<const T*, DefaultHasher<const T*>, SystemAllocPolicy>;
template <class T>
struct ShareableBase : AtomicRefCounted<T> {
using SeenSet = wasm::SeenSet<T>;
size_t sizeOfIncludingThisIfNotSeen(MallocSizeOf mallocSizeOf,
SeenSet* seen) const {
const T* self = static_cast<const T*>(this);
typename SeenSet::AddPtr p = seen->lookupForAdd(self);
if (p) {
return 0;
}
bool ok = seen->add(p, self);
(void)ok; // oh well
return mallocSizeOf(self) + self->sizeOfExcludingThis(mallocSizeOf);
}
};
// ShareableBytes is a reference-counted Vector of bytes.
struct ShareableBytes : ShareableBase<ShareableBytes> {
// Vector is 'final', so instead make Vector a member and add boilerplate.
Bytes bytes;
ShareableBytes() = default;
explicit ShareableBytes(Bytes&& bytes) : bytes(std::move(bytes)) {}
size_t sizeOfExcludingThis(MallocSizeOf mallocSizeOf) const {
return bytes.sizeOfExcludingThis(mallocSizeOf);
}
const uint8_t* begin() const { return bytes.begin(); }
const uint8_t* end() const { return bytes.end(); }
size_t length() const { return bytes.length(); }
bool append(const uint8_t* start, size_t len) {
return bytes.append(start, len);
}
};
using MutableBytes = RefPtr<ShareableBytes>;
using SharedBytes = RefPtr<const ShareableBytes>;
} // namespace wasm
} // namespace js
#endif // wasm_shareable_h