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
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
// Copyright 2013 Dolphin Emulator Project / 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include "common/common_types.h"
#include <fstream>
// defined in Version.cpp
extern const char *scm_rev_git_str;
// On disk format:
//header{
// u32 'DCAC';
// u32 version; // svn_rev
// u16 sizeof(key_type);
// u16 sizeof(value_type);
//}
//key_value_pair{
// u32 value_size;
// key_type key;
// value_type[value_size] value;
//}
template <typename K, typename V>
class LinearDiskCacheReader
{
public:
virtual void Read(const K &key, const V *value, u32 value_size) = 0;
};
// Dead simple unsorted key-value store with append functionality.
// No random read functionality, all reading is done in OpenAndRead.
// Keys and values can contain any characters, including \0.
//
// Suitable for caching generated shader bytecode between executions.
// Not tuned for extreme performance but should be reasonably fast.
// Does not support keys or values larger than 2GB, which should be reasonable.
// Keys must have non-zero length; values can have zero length.
// K and V are some POD type
// K : the key type
// V : value array type
template <typename K, typename V>
class LinearDiskCache
{
public:
// return number of read entries
u32 OpenAndRead(const char *filename, LinearDiskCacheReader<K, V> &reader)
{
using std::ios_base;
// close any currently opened file
Close();
m_num_entries = 0;
// try opening for reading/writing
OpenFStream(m_file, filename, ios_base::in | ios_base::out | ios_base::binary);
m_file.seekg(0, std::ios::end);
std::fstream::pos_type end_pos = m_file.tellg();
m_file.seekg(0, std::ios::beg);
std::fstream::pos_type start_pos = m_file.tellg();
std::streamoff file_size = end_pos - start_pos;
if (m_file.is_open() && ValidateHeader())
{
// good header, read some key/value pairs
K key;
V *value = nullptr;
u32 value_size;
u32 entry_number;
std::fstream::pos_type last_pos = m_file.tellg();
while (Read(&value_size))
{
std::streamoff next_extent = (last_pos - start_pos) + sizeof(value_size) + value_size;
if (next_extent > file_size)
break;
delete[] value;
value = new V[value_size];
// read key/value and pass to reader
if (Read(&key) &&
Read(value, value_size) &&
Read(&entry_number) &&
entry_number == m_num_entries+1)
{
reader.Read(key, value, value_size);
}
else
{
break;
}
m_num_entries++;
last_pos = m_file.tellg();
}
m_file.seekp(last_pos);
m_file.clear();
delete[] value;
return m_num_entries;
}
// failed to open file for reading or bad header
// close and recreate file
Close();
m_file.open(filename, ios_base::out | ios_base::trunc | ios_base::binary);
WriteHeader();
return 0;
}
void Sync()
{
m_file.flush();
}
void Close()
{
if (m_file.is_open())
m_file.close();
// clear any error flags
m_file.clear();
}
// Appends a key-value pair to the store.
void Append(const K &key, const V *value, u32 value_size)
{
// TODO: Should do a check that we don't already have "key"? (I think each caller does that already.)
Write(&value_size);
Write(&key);
Write(value, value_size);
m_num_entries++;
Write(&m_num_entries);
}
private:
void WriteHeader()
{
Write(&m_header);
}
bool ValidateHeader()
{
char file_header[sizeof(Header)];
return (Read(file_header, sizeof(Header))
&& !memcmp((const char*)&m_header, file_header, sizeof(Header)));
}
template <typename D>
bool Write(const D *data, u32 count = 1)
{
return m_file.write((const char*)data, count * sizeof(D)).good();
}
template <typename D>
bool Read(const D *data, u32 count = 1)
{
return m_file.read((char*)data, count * sizeof(D)).good();
}
struct Header
{
Header()
: id(*(u32*)"DCAC")
, key_t_size(sizeof(K))
, value_t_size(sizeof(V))
{
memcpy(ver, scm_rev_git_str, 40);
}
const u32 id;
const u16 key_t_size, value_t_size;
char ver[40];
} m_header;
std::fstream m_file;
u32 m_num_entries;
};
|
