1 // Copyright 2010-2018, Google Inc.
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are
6 // met:
7 //
8 //     * Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 //     * Redistributions in binary form must reproduce the above
11 // copyright notice, this list of conditions and the following disclaimer
12 // in the documentation and/or other materials provided with the
13 // distribution.
14 //     * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 
30 #ifndef MOZC_STORAGE_REGISTRY_H_
31 #define MOZC_STORAGE_REGISTRY_H_
32 
33 #include <cstring>
34 #include <string>
35 
36 #include "base/port.h"
37 #include "base/logging.h"
38 
39 namespace mozc {
40 namespace storage {
41 
42 class StorageInterface;
43 
44 // The idea of Registry module is the same as Windows Registry.
45 // You can use it for saving small data like timestamp, auth_token.
46 // DO NOT USE it to save big data or data which are frequently updated.
47 // Lookup() and Insert() do process-wide global lock and it may be slow.
48 // All methods are thread-safe.
49 //
50 // TODO(taku): Currently, Registry won't guarantee that two processes
51 // can con-currently share the same data. We will replace the backend
52 // of Registry (Storage Interface) with sqlite
53 //
54 // Example:
55 //  uint64 timestamp = 0;
56 //  CHECK(Registry::Lookup<uint64>("timestamp", &timestamp));
57 //
58 //  string value = "hello world";
59 //  CHECK(Registry::Insert<string>("hello", value));
60 class Registry {
61  public:
62   template <typename T>
Lookup(const string & key,T * value)63   static bool Lookup(const string &key, T *value) {
64     DCHECK(value);
65     string tmp;
66     if (!LookupInternal(key, &tmp)) {
67       return false;
68     }
69     if (sizeof(*value) != tmp.size()) {
70       return false;
71     }
72     memcpy(reinterpret_cast<char *>(value),
73            tmp.data(), tmp.size());
74     return true;
75   }
76 
Lookup(const string & key,string * value)77   static bool Lookup(const string &key, string *value) {
78     return LookupInternal(key, value);
79   }
80 
Lookup(const string & key,bool * value)81   static bool Lookup(const string &key, bool *value) {
82     uint8 v = 0;
83     const bool result = Lookup<uint8>(key, &v);
84     *value = (v != 0);
85     return result;
86   }
87 
88   // insert key and data
89   // It is not guaranteed that the data is synced to the disk
90   template <typename T>
Insert(const string & key,const T & value)91   static bool Insert(const string &key, const T &value) {
92     string tmp(reinterpret_cast<const char *>(&value), sizeof(value));
93     return InsertInternal(key, tmp);
94   }
95 
96   // Insert key and string value
97   // It is not guaranteed that the data is synced to the disk
Insert(const string & key,const string & value)98   static bool Insert(const string &key, const string &value) {
99     return InsertInternal(key, value);
100   }
101 
102   // Insert key and bool value
103   // It is not guaranteed that the data is synced to the disk
Insert(const string & key,const bool & value)104   static bool Insert(const string &key, const bool &value) {
105     const uint8 tmp = static_cast<uint8>(value);
106     return Insert<uint8>(key, tmp);
107   }
108 
109   // Syncing the data into disk
110   static bool Sync();
111 
112   // Erase key
113   static bool Erase(const string &key);
114 
115   // clear internal keys and values
116   static bool Clear();
117 
118   // Inject internal storage for unittesting.
119   // TinyStorage is used by default
120   // TODO(taku) replace it with SQLITE
121   static void SetStorage(StorageInterface *handler);
122 
123  private:
124   static bool LookupInternal(const string &key, string *value);
125   static bool InsertInternal(const string &key, const string &value);
126 
127   DISALLOW_IMPLICIT_CONSTRUCTORS(Registry);
128 };
129 }  // namespace storage
130 }  // namespace mozc
131 #endif  // MOZC_STORAGE_REGISTRY_H_
132