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author | Tao Bao <tbao@google.com> | 2017-10-17 18:06:11 +0200 |
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committer | android-build-merger <android-build-merger@google.com> | 2017-10-17 18:06:11 +0200 |
commit | 6f4f5284191eb78970b583ff7e83c3730e26ed60 (patch) | |
tree | 866a87dc9550f1406ee8e3de17b508fafb6f8364 /otautil/rangeset.cpp | |
parent | Merge "Fix owner email address." am: b4a8c6abd9 (diff) | |
parent | Merge "otautil: Move RangeSet implementation into rangeset.cpp." (diff) | |
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Diffstat (limited to 'otautil/rangeset.cpp')
-rw-r--r-- | otautil/rangeset.cpp | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/otautil/rangeset.cpp b/otautil/rangeset.cpp new file mode 100644 index 000000000..a121a4efc --- /dev/null +++ b/otautil/rangeset.cpp @@ -0,0 +1,200 @@ +/* + * Copyright (C) 2017 The Android Open Source Project + * + * 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 + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * 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. + */ + +#include "otautil/rangeset.h" + +#include <stddef.h> + +#include <string> +#include <utility> +#include <vector> + +#include <android-base/logging.h> +#include <android-base/parseint.h> +#include <android-base/stringprintf.h> +#include <android-base/strings.h> + +RangeSet::RangeSet(std::vector<Range>&& pairs) { + CHECK_NE(pairs.size(), static_cast<size_t>(0)) << "Invalid number of tokens"; + + // Sanity check the input. + size_t result = 0; + for (const auto& range : pairs) { + CHECK_LT(range.first, range.second) << "Empty or negative range: " << range.first << ", " + << range.second; + size_t sz = range.second - range.first; + CHECK_LE(result, SIZE_MAX - sz) << "RangeSet size overflow"; + result += sz; + } + + ranges_ = pairs; + blocks_ = result; +} + +RangeSet RangeSet::Parse(const std::string& range_text) { + std::vector<std::string> pieces = android::base::Split(range_text, ","); + CHECK_GE(pieces.size(), static_cast<size_t>(3)) << "Invalid range text: " << range_text; + + size_t num; + CHECK(android::base::ParseUint(pieces[0], &num, static_cast<size_t>(INT_MAX))) + << "Failed to parse the number of tokens: " << range_text; + + CHECK_NE(num, static_cast<size_t>(0)) << "Invalid number of tokens: " << range_text; + CHECK_EQ(num % 2, static_cast<size_t>(0)) << "Number of tokens must be even: " << range_text; + CHECK_EQ(num, pieces.size() - 1) << "Mismatching number of tokens: " << range_text; + + std::vector<Range> pairs; + for (size_t i = 0; i < num; i += 2) { + size_t first; + CHECK(android::base::ParseUint(pieces[i + 1], &first, static_cast<size_t>(INT_MAX))); + size_t second; + CHECK(android::base::ParseUint(pieces[i + 2], &second, static_cast<size_t>(INT_MAX))); + + pairs.emplace_back(first, second); + } + + return RangeSet(std::move(pairs)); +} + +std::string RangeSet::ToString() const { + if (ranges_.empty()) { + return ""; + } + std::string result = std::to_string(ranges_.size() * 2); + for (const auto& r : ranges_) { + result += android::base::StringPrintf(",%zu,%zu", r.first, r.second); + } + + return result; +} + +// Get the block number for the i-th (starting from 0) block in the RangeSet. +size_t RangeSet::GetBlockNumber(size_t idx) const { + CHECK_LT(idx, blocks_) << "Out of bound index " << idx << " (total blocks: " << blocks_ << ")"; + + for (const auto& range : ranges_) { + if (idx < range.second - range.first) { + return range.first + idx; + } + idx -= (range.second - range.first); + } + + CHECK(false) << "Failed to find block number for index " << idx; + return 0; // Unreachable, but to make compiler happy. +} + +// RangeSet has half-closed half-open bounds. For example, "3,5" contains blocks 3 and 4. So "3,5" +// and "5,7" are not overlapped. +bool RangeSet::Overlaps(const RangeSet& other) const { + for (const auto& range : ranges_) { + size_t start = range.first; + size_t end = range.second; + for (const auto& other_range : other.ranges_) { + size_t other_start = other_range.first; + size_t other_end = other_range.second; + // [start, end) vs [other_start, other_end) + if (!(other_start >= end || start >= other_end)) { + return true; + } + } + } + return false; +} + +static constexpr size_t kBlockSize = 4096; + +// Ranges in the the set should be mutually exclusive; and they're sorted by the start block. +SortedRangeSet::SortedRangeSet(std::vector<Range>&& pairs) : RangeSet(std::move(pairs)) { + std::sort(ranges_.begin(), ranges_.end()); +} + +void SortedRangeSet::Insert(const Range& to_insert) { + SortedRangeSet rs({ to_insert }); + Insert(rs); +} + +// Insert the input SortedRangeSet; keep the ranges sorted and merge the overlap ranges. +void SortedRangeSet::Insert(const SortedRangeSet& rs) { + if (rs.size() == 0) { + return; + } + // Merge and sort the two RangeSets. + std::vector<Range> temp = std::move(ranges_); + std::copy(rs.begin(), rs.end(), std::back_inserter(temp)); + std::sort(temp.begin(), temp.end()); + + Clear(); + // Trim overlaps and insert the result back to ranges_. + Range to_insert = temp.front(); + for (auto it = temp.cbegin() + 1; it != temp.cend(); it++) { + if (it->first <= to_insert.second) { + to_insert.second = std::max(to_insert.second, it->second); + } else { + ranges_.push_back(to_insert); + blocks_ += (to_insert.second - to_insert.first); + to_insert = *it; + } + } + ranges_.push_back(to_insert); + blocks_ += (to_insert.second - to_insert.first); +} + +// Compute the block range the file occupies, and insert that range. +void SortedRangeSet::Insert(size_t start, size_t len) { + Range to_insert{ start / kBlockSize, (start + len - 1) / kBlockSize + 1 }; + Insert(to_insert); +} + +void SortedRangeSet::Clear() { + blocks_ = 0; + ranges_.clear(); +} + +bool SortedRangeSet::Overlaps(size_t start, size_t len) const { + RangeSet rs({ { start / kBlockSize, (start + len - 1) / kBlockSize + 1 } }); + return Overlaps(rs); +} + +// Given an offset of the file, checks if the corresponding block (by considering the file as +// 0-based continuous block ranges) is covered by the SortedRangeSet. If so, returns the offset +// within this SortedRangeSet. +// +// For example, the 4106-th byte of a file is from block 1, assuming a block size of 4096-byte. +// The mapped offset within a SortedRangeSet("1-9 15-19") is 10. +// +// An offset of 65546 falls into the 16-th block in a file. Block 16 is contained as the 10-th +// item in SortedRangeSet("1-9 15-19"). So its data can be found at offset 40970 (i.e. 4096 * 10 +// + 10) in a range represented by this SortedRangeSet. +size_t SortedRangeSet::GetOffsetInRangeSet(size_t old_offset) const { + size_t old_block_start = old_offset / kBlockSize; + size_t new_block_start = 0; + for (const auto& range : ranges_) { + // Find the index of old_block_start. + if (old_block_start >= range.second) { + new_block_start += (range.second - range.first); + } else if (old_block_start >= range.first) { + new_block_start += (old_block_start - range.first); + return (new_block_start * kBlockSize + old_offset % kBlockSize); + } else { + CHECK(false) << "block_start " << old_block_start + << " is missing between two ranges: " << this->ToString(); + return 0; + } + } + CHECK(false) << "block_start " << old_block_start + << " exceeds the limit of current RangeSet: " << this->ToString(); + return 0; +} |