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
|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <algorithm>
#include "base/logging.h"
#include "net/disk_cache/flash/format.h"
#include "net/disk_cache/flash/segment.h"
#include "net/disk_cache/flash/storage.h"
namespace disk_cache {
Segment::Segment(int32 index, bool read_only, Storage* storage)
: index_(index),
num_users_(0),
read_only_(read_only),
init_(false),
storage_(storage),
offset_(index * kFlashSegmentSize),
summary_offset_(offset_ + kFlashSegmentSize - kFlashSummarySize),
write_offset_(offset_) {
DCHECK(storage);
DCHECK(storage->size() % kFlashSegmentSize == 0);
}
Segment::~Segment() {
DCHECK(!init_ || read_only_);
if (num_users_ != 0)
LOG(WARNING) << "Users exist, but we don't care? " << num_users_;
}
bool Segment::HaveOffset(int32 offset) const {
DCHECK(init_);
return std::binary_search(offsets_.begin(), offsets_.end(), offset);
}
void Segment::AddUser() {
DCHECK(init_);
++num_users_;
}
void Segment::ReleaseUser() {
DCHECK(init_);
--num_users_;
}
bool Segment::HasNoUsers() const {
DCHECK(init_);
return num_users_ == 0;
}
bool Segment::Init() {
DCHECK(!init_);
if (offset_ < 0 || offset_ + kFlashSegmentSize > storage_->size())
return false;
if (!read_only_) {
init_ = true;
return true;
}
int32 summary[kFlashMaxEntryCount + 1];
if (!storage_->Read(summary, kFlashSummarySize, summary_offset_))
return false;
size_t entry_count = summary[0];
DCHECK_LE(entry_count, kFlashMaxEntryCount);
std::vector<int32> tmp(summary + 1, summary + 1 + entry_count);
offsets_.swap(tmp);
init_ = true;
return true;
}
bool Segment::WriteData(const void* buffer, int32 size) {
DCHECK(init_ && !read_only_);
DCHECK(write_offset_ + size <= summary_offset_);
if (!storage_->Write(buffer, size, write_offset_))
return false;
write_offset_ += size;
return true;
}
void Segment::StoreOffset(int32 offset) {
DCHECK(init_ && !read_only_);
DCHECK(offsets_.size() < kFlashMaxEntryCount);
offsets_.push_back(offset);
}
bool Segment::ReadData(void* buffer, int32 size, int32 offset) const {
DCHECK(init_);
DCHECK(offset >= offset_ && offset + size <= offset_ + kFlashSegmentSize);
return storage_->Read(buffer, size, offset);
}
bool Segment::Close() {
DCHECK(init_);
if (read_only_)
return true;
DCHECK(offsets_.size() <= kFlashMaxEntryCount);
int32 summary[kFlashMaxEntryCount + 1];
memset(summary, 0, kFlashSummarySize);
summary[0] = offsets_.size();
std::copy(offsets_.begin(), offsets_.end(), summary + 1);
if (!storage_->Write(summary, kFlashSummarySize, summary_offset_))
return false;
read_only_ = true;
return true;
}
bool Segment::CanHold(int32 size) const {
DCHECK(init_);
return offsets_.size() < kFlashMaxEntryCount &&
write_offset_ + size <= summary_offset_;
}
} // namespace disk_cache
|
