98 lines
3.6 KiB
C++
98 lines
3.6 KiB
C++
//
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// Copyright (C) 2021 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#ifndef UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_MAP_H_
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#define UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_MAP_H_
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#include <functional>
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#include <map>
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#include <utility>
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#include <vector>
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#include "update_engine/common/utils.h"
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#include "update_engine/payload_generator/extent_ranges.h"
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#include "update_engine/payload_generator/extent_utils.h"
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#include "update_engine/update_metadata.pb.h"
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namespace chromeos_update_engine {
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// Data structure for storing a disjoint set of extents.
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// Currently the only usecase is for VABCPartitionWriter to keep track of which
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// block belongs to which merge operation. Therefore this class only contains
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// the minimal set of functions needed.
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template <typename T, typename Comparator = ExtentLess>
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class ExtentMap {
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public:
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bool AddExtent(const Extent& extent, T&& value) {
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if (set_.OverlapsWithExtent(extent)) {
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return false;
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}
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const auto& [it, inserted] = map_.insert({extent, std::forward<T>(value)});
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if (inserted) {
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set_.AddExtent(extent);
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}
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return inserted;
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}
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size_t size() const { return map_.size(); }
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// Return a pointer to entry which is intersecting |extent|. If T is already
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// a pointer type, return T on success. This function always return
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// |nullptr| on failure. Therefore you cannot store nullptr as an entry.
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std::optional<T> Get(const Extent& extent) const {
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const auto it = map_.find(extent);
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if (it == map_.end()) {
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for (const auto& ext : set_.GetCandidateRange(extent)) {
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if (ExtentRanges::ExtentsOverlap(ext, extent)) {
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LOG(WARNING) << "Looking up a partially intersecting extent isn't "
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"supported by "
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"this data structure. Querying extent: "
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<< extent << ", partial match in map: " << ext;
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}
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}
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return {};
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}
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return {it->second};
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}
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// Return a set of extents that are contained in this extent map.
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// If |extent| is completely covered by this extent map, a vector of itself
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// will be returned.
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// If only a subset of |extent| is covered by this extent map, a vector of
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// parts in this map will be returned.
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// If |extent| has no intersection with this map, an empty vector will be
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// returned.
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// E.g. extent map contains [0,5] and [10,15], GetIntersectingExtents([3, 12])
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// would return [3,5] and [10,12]
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std::vector<Extent> GetIntersectingExtents(const Extent& extent) const {
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return set_.GetIntersectingExtents(extent);
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}
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// Complement of |GetIntersectingExtents|, return vector of extents which are
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// part of |extent| but not covered by this map.
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std::vector<Extent> GetNonIntersectingExtents(const Extent& extent) const {
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return FilterExtentRanges({extent}, set_);
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}
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private:
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// Get a range of exents that potentially intersect with parameter |extent|
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std::map<Extent, T, Comparator> map_;
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ExtentRanges set_{false};
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};
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} // namespace chromeos_update_engine
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#endif // UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_MAP_H_
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