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