1 // Copyright 2017 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_DATA_FORMAT_VERSION_H_
6 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_DATA_FORMAT_VERSION_H_
7 
8 #include <cstdint>
9 #include <limits>
10 
11 #include "base/logging.h"
12 #include "content/common/content_export.h"
13 
14 namespace content {
15 
16 // Contains version data for the wire format used for encoding IndexedDB values.
17 // A version tuple (a, b) is at least as new as (a', b')
18 // iff a >= a' and b >= b'.
19 class IndexedDBDataFormatVersion {
20  public:
IndexedDBDataFormatVersion()21   constexpr IndexedDBDataFormatVersion() {}
IndexedDBDataFormatVersion(uint32_t v8_version,uint32_t blink_version)22   constexpr IndexedDBDataFormatVersion(uint32_t v8_version,
23                                        uint32_t blink_version)
24       : v8_version_(v8_version), blink_version_(blink_version) {}
25 
GetCurrent()26   static IndexedDBDataFormatVersion GetCurrent() { return current_; }
GetMutableCurrentForTesting()27   static IndexedDBDataFormatVersion& GetMutableCurrentForTesting() {
28     return current_;
29   }
30 
v8_version()31   uint32_t v8_version() const { return v8_version_; }
blink_version()32   uint32_t blink_version() const { return blink_version_; }
33 
34   bool operator==(const IndexedDBDataFormatVersion& other) const {
35     return v8_version_ == other.v8_version_ &&
36            blink_version_ == other.blink_version_;
37   }
38   bool operator!=(const IndexedDBDataFormatVersion& other) const {
39     return !operator==(other);
40   }
41 
IsAtLeast(const IndexedDBDataFormatVersion & other)42   bool IsAtLeast(const IndexedDBDataFormatVersion& other) const {
43     return v8_version_ >= other.v8_version_ &&
44            blink_version_ >= other.blink_version_;
45   }
46 
47   // Encodes and decodes the tuple from an int64_t.
48   // This scheme is chosen so that earlier versions (before we reported both the
49   // Blink and V8 versions) decode properly, with a V8 version of 0.
Encode()50   int64_t Encode() const {
51     // Since negative values are considered invalid, this scheme will only work
52     // as long as the v8 version would not overflow int32_t.  We check both
53     // components, to be consistent.
54     DCHECK_GE(static_cast<int32_t>(v8_version_), 0);
55     DCHECK_GE(static_cast<int32_t>(blink_version_), 0);
56     return (static_cast<int64_t>(v8_version_) << 32) | blink_version_;
57   }
Decode(int64_t encoded)58   static IndexedDBDataFormatVersion Decode(int64_t encoded) {
59     DCHECK_GE(encoded, 0);
60     return IndexedDBDataFormatVersion(encoded >> 32, encoded);
61   }
62 
63  private:
64   uint32_t v8_version_ = 0;
65   uint32_t blink_version_ = 0;
66 
67   CONTENT_EXPORT static IndexedDBDataFormatVersion current_;
68 };
69 
70 }  // namespace content
71 
72 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_DATA_FORMAT_VERSION_H_
73