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authorTianjie Xu <xunchang@google.com>2017-07-27 01:41:24 +0200
committerTianjie Xu <xunchang@google.com>2017-08-01 00:13:55 +0200
commitb9e7fc7fa9c70df36881b2166e8bd2bcfa87fe2e (patch)
treed34f955875d688fbda05ea3d8d7d4411b58de855 /updater/include
parentMerge "Remove LOCAL_CLANG" (diff)
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Diffstat (limited to 'updater/include')
-rw-r--r--updater/include/updater/rangeset.h116
1 files changed, 115 insertions, 1 deletions
diff --git a/updater/include/updater/rangeset.h b/updater/include/updater/rangeset.h
index fad038043..b67c98724 100644
--- a/updater/include/updater/rangeset.h
+++ b/updater/include/updater/rangeset.h
@@ -24,6 +24,7 @@
#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>;
@@ -74,6 +75,18 @@ class RangeSet {
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_ << ")";
@@ -157,8 +170,109 @@ class RangeSet {
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;
+ }
+}; \ No newline at end of file