82 lines
2.5 KiB
C
82 lines
2.5 KiB
C
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// Copyright 2018 The Chromium 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 BASE_TASK_COMMON_INTRUSIVE_HEAP_H_
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#define BASE_TASK_COMMON_INTRUSIVE_HEAP_H_
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#include "base/containers/intrusive_heap.h"
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namespace base {
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namespace internal {
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using HeapHandle = base::HeapHandle;
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template <typename T>
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struct IntrusiveHeapImpl {
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struct GreaterUsingLessEqual {
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bool operator()(const T& t1, const T& t2) const { return t2 <= t1; }
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};
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using type = base::IntrusiveHeap<T, GreaterUsingLessEqual>;
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};
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// base/task wants a min-heap that uses the <= operator, whereas
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// base::IntrusiveHeap is a max-heap by default. This is a very thin adapter
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// over that class that exposes minimal functionality required by the
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// base/task IntrusiveHeap clients.
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template <typename T>
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class IntrusiveHeap : private IntrusiveHeapImpl<T>::type {
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public:
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using IntrusiveHeapImplType = typename IntrusiveHeapImpl<T>::type;
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// The majority of sets in the scheduler have 0-3 items in them (a few will
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// have perhaps up to 100), so this means we usually only have to allocate
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// memory once.
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static constexpr size_t kMinimumHeapSize = 4;
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IntrusiveHeap() { IntrusiveHeapImplType::reserve(kMinimumHeapSize); }
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~IntrusiveHeap() = default;
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IntrusiveHeap& operator=(IntrusiveHeap&& other) = default;
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bool empty() const { return IntrusiveHeapImplType::empty(); }
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size_t size() const { return IntrusiveHeapImplType::size(); }
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void Clear() {
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IntrusiveHeapImplType::clear();
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IntrusiveHeapImplType::reserve(kMinimumHeapSize);
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}
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const T& Min() const { return IntrusiveHeapImplType::top(); }
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void Pop() { IntrusiveHeapImplType::pop(); }
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void insert(T&& element) {
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IntrusiveHeapImplType::insert(std::move(element));
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}
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void erase(HeapHandle handle) { IntrusiveHeapImplType::erase(handle); }
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void ReplaceMin(T&& element) {
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IntrusiveHeapImplType::ReplaceTop(std::move(element));
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}
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void ChangeKey(HeapHandle handle, T&& element) {
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IntrusiveHeapImplType::Replace(handle, std::move(element));
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}
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const T& at(HeapHandle handle) const {
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return IntrusiveHeapImplType::at(handle);
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}
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// Caution, mutating the heap invalidates iterators!
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const T* begin() const { return IntrusiveHeapImplType::data(); }
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const T* end() const { return IntrusiveHeapImplType::data() + size(); }
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};
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} // namespace internal
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} // namespace base
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#endif // BASE_TASK_COMMON_INTRUSIVE_HEAP_H_
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