aboutsummaryrefslogtreecommitdiffstats
blob: c4234d1816c1d95e2d47c06d8c5cd7df3041e9bc (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
/*
 * 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.
 */

#pragma once

#include <stddef.h>

#include <string>
#include <utility>
#include <vector>

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

class RangeSet {
 public:
  RangeSet() : blocks_(0) {}

  explicit RangeSet(std::vector<Range>&& pairs);

  static RangeSet Parse(const std::string& range_text);

  std::string ToString() const;

  // Get the block number for the i-th (starting from 0) block in the RangeSet.
  size_t GetBlockNumber(size_t idx) const;

  // 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 Overlaps(const RangeSet& other) const;

  // size() gives the number of Range's in this RangeSet.
  size_t size() const {
    return ranges_.size();
  }

  // blocks() gives the number of all blocks in this RangeSet.
  size_t blocks() const {
    return blocks_;
  }

  // We provide const iterators only.
  std::vector<Range>::const_iterator cbegin() const {
    return ranges_.cbegin();
  }

  std::vector<Range>::const_iterator cend() const {
    return ranges_.cend();
  }

  // Need to provide begin()/end() since range-based loop expects begin()/end().
  std::vector<Range>::const_iterator begin() const {
    return ranges_.cbegin();
  }

  std::vector<Range>::const_iterator end() const {
    return ranges_.cend();
  }

  // Reverse const iterators for MoveRange().
  std::vector<Range>::const_reverse_iterator crbegin() const {
    return ranges_.crbegin();
  }

  std::vector<Range>::const_reverse_iterator crend() const {
    return ranges_.crend();
  }

  const Range& operator[](size_t i) const {
    return ranges_[i];
  }

  bool operator==(const RangeSet& other) const {
    // The orders of Range's matter. "4,1,5,8,10" != "4,8,10,1,5".
    return (ranges_ == other.ranges_);
  }

  bool operator!=(const RangeSet& other) const {
    return ranges_ != other.ranges_;
  }

 protected:
  // Actual limit for each value and the total number are both INT_MAX.
  std::vector<Range> ranges_;
  size_t blocks_;
};

// 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);

  void Insert(const Range& to_insert);

  // Insert the input SortedRangeSet; keep the ranges sorted and merge the overlap ranges.
  void Insert(const SortedRangeSet& rs);

  // Compute the block range the file occupies, and insert that range.
  void Insert(size_t start, size_t len);

  void Clear();

  using RangeSet::Overlaps;

  bool Overlaps(size_t start, size_t len) const;

  // 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;
};