Merge "Add implemention of SortedRangeSet"

  }

  ASSERT_EQ((std::vector<Range>{ Range{ 8, 10 }, Range{ 1, 5 } }), ranges);

}

TEST(RangeSetTest, tostring) {

  ASSERT_EQ("2,1,6", RangeSet::Parse("2,1,6").ToString());

  ASSERT_EQ("4,1,5,8,10", RangeSet::Parse("4,1,5,8,10").ToString());

  ASSERT_EQ("6,1,3,4,6,15,22", RangeSet::Parse("6,1,3,4,6,15,22").ToString());

}

TEST(SortedRangeSetTest, insertion) {

  SortedRangeSet rs({ { 2, 3 }, { 4, 6 }, { 8, 14 } });

  rs.Insert({ 1, 2 });

  ASSERT_EQ(SortedRangeSet({ { 1, 3 }, { 4, 6 }, { 8, 14 } }), rs);

  ASSERT_EQ(static_cast<size_t>(10), rs.blocks());

  rs.Insert({ 3, 5 });

  ASSERT_EQ(SortedRangeSet({ { 1, 6 }, { 8, 14 } }), rs);

  ASSERT_EQ(static_cast<size_t>(11), rs.blocks());

  SortedRangeSet r1({ { 20, 22 }, { 15, 18 } });

  rs.Insert(r1);

  ASSERT_EQ(SortedRangeSet({ { 1, 6 }, { 8, 14 }, { 15, 18 }, { 20, 22 } }), rs);

  ASSERT_EQ(static_cast<size_t>(16), rs.blocks());

  SortedRangeSet r2({ { 2, 7 }, { 15, 21 }, { 20, 25 } });

  rs.Insert(r2);

  ASSERT_EQ(SortedRangeSet({ { 1, 7 }, { 8, 14 }, { 15, 25 } }), rs);

  ASSERT_EQ(static_cast<size_t>(22), rs.blocks());

}

TEST(SortedRangeSetTest, file_range) {

  SortedRangeSet rs;

  rs.Insert(4096, 4096);

  ASSERT_EQ(SortedRangeSet({ { 1, 2 } }), rs);

  // insert block 2-9

  rs.Insert(4096 * 3 - 1, 4096 * 7);

  ASSERT_EQ(SortedRangeSet({ { 1, 10 } }), rs);

  // insert block 15-19

  rs.Insert(4096 * 15 + 1, 4096 * 4);

  ASSERT_EQ(SortedRangeSet({ { 1, 10 }, { 15, 20 } }), rs);

  // rs overlaps block 2-2

  ASSERT_TRUE(rs.Overlaps(4096 * 2 - 1, 10));

  ASSERT_FALSE(rs.Overlaps(4096 * 10, 4096 * 5));

  ASSERT_EQ(static_cast<size_t>(10), rs.GetOffsetInRangeSet(4106));

  ASSERT_EQ(static_cast<size_t>(40970), rs.GetOffsetInRangeSet(4096 * 16 + 10));

  // block#10 not in range.

  ASSERT_EXIT(rs.GetOffsetInRangeSet(40970), ::testing::KilledBySignal(SIGABRT), "");

}

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#include <android-base/logging.h>

#include <android-base/parseint.h>

#include <android-base/stringprintf.h>

#include <android-base/strings.h>

using Range = std::pair<size_t, size_t>;

    return RangeSet(std::move(pairs));

  }

  std::string 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 GetBlockNumber(size_t idx) const {

    CHECK_LT(idx, blocks_) << "Out of bound index " << idx << " (total blocks: " << blocks_ << ")";

    return ranges_ != other.ranges_;

  }

 private:

 protected:

  // Actual limit for each value and the total number are both INT_MAX.

  std::vector<Range> ranges_;

  size_t blocks_;

};

static constexpr size_t kBlockSize = 4096;

// The class is a sorted version of a RangeSet; and it's useful in imgdiff to split the input

// files when we're handling large zip files. Specifically, we can treat the input file as a

// continuous RangeSet (i.e. RangeSet("0-99") for a 100 blocks file); and break it down into

// several smaller chunks based on the zip entries.

// For example, [source: 0-99] can be split into

// [split_src1: 10-29]; [split_src2: 40-49, 60-69]; [split_src3: 70-89]

// Here "10-29" simply means block 10th to block 29th with respect to the original input file.

// Also, note that the split sources should be mutual exclusive, but they don't need to cover

// every block in the original source.

class SortedRangeSet : public RangeSet {

 public:

  SortedRangeSet() {}

  // Ranges in the the set should be mutually exclusive; and they're sorted by the start block.

  explicit SortedRangeSet(std::vector<Range>&& pairs) : RangeSet(std::move(pairs)) {

    std::sort(ranges_.begin(), ranges_.end());

  }

  void 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 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);

  }

  void Clear() {

    blocks_ = 0;

    ranges_.clear();

  }

  using RangeSet::Overlaps;

  bool Overlaps(size_t start, size_t len) const {

    RangeSet rs({ { start / kBlockSize, (start + len - 1) / kBlockSize + 1 } });

    return Overlaps(rs);

  }

  // Compute the block range the file occupies, and insert that range.

  void Insert(size_t start, size_t len) {

    Range to_insert{ start / kBlockSize, (start + len - 1) / kBlockSize + 1 };

    Insert(to_insert);

  }

  // 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 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;

  }

};

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