1 // Copyright 2011 The Kyua Authors.
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 copyright
11 // notice, this list of conditions and the following disclaimer in the
12 // documentation and/or other materials provided with the distribution.
13 // * Neither the name of Google Inc. nor the names of its contributors
14 // may be used to endorse or promote products derived from this software
15 // without specific prior written permission.
16 //
17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
29 #include "store/read_backend.hpp"
30
31 #include "store/exceptions.hpp"
32 #include "store/metadata.hpp"
33 #include "store/read_transaction.hpp"
34 #include "store/write_backend.hpp"
35 #include "utils/format/macros.hpp"
36 #include "utils/fs/path.hpp"
37 #include "utils/noncopyable.hpp"
38 #include "utils/sqlite/database.hpp"
39 #include "utils/sqlite/exceptions.hpp"
40
41 namespace fs = utils::fs;
42 namespace sqlite = utils::sqlite;
43
44
45 /// Opens a database and defines session pragmas.
46 ///
47 /// This auxiliary function ensures that, every time we open a SQLite database,
48 /// we define the same set of pragmas for it.
49 ///
50 /// \param file The database file to be opened.
51 /// \param flags The flags for the open; see sqlite::database::open.
52 ///
53 /// \return The opened database.
54 ///
55 /// \throw store::error If there is a problem opening or creating the database.
56 sqlite::database
open_and_setup(const fs::path & file,const int flags)57 store::detail::open_and_setup(const fs::path& file, const int flags)
58 {
59 try {
60 sqlite::database database = sqlite::database::open(file, flags);
61 database.exec("PRAGMA foreign_keys = ON");
62 return database;
63 } catch (const sqlite::error& e) {
64 throw store::error(F("Cannot open '%s': %s") % file % e.what());
65 }
66 }
67
68
69 /// Internal implementation for the backend.
70 struct store::read_backend::impl : utils::noncopyable {
71 /// The SQLite database this backend talks to.
72 sqlite::database database;
73
74 /// Constructor.
75 ///
76 /// \param database_ The SQLite database instance.
77 /// \param metadata_ The metadata for the loaded database. This must match
78 /// the schema version we implement in this module; otherwise, a
79 /// migration is necessary.
80 ///
81 /// \throw integrity_error If the schema in the database is too modern,
82 /// which might indicate some form of corruption or an old binary.
83 /// \throw old_schema_error If the schema in the database is older than our
84 /// currently-implemented version and needs an upgrade. The caller can
85 /// use migrate_schema() to fix this problem.
implstore::read_backend::impl86 impl(sqlite::database& database_, const metadata& metadata_) :
87 database(database_)
88 {
89 const int database_version = metadata_.schema_version();
90
91 if (database_version == detail::current_schema_version) {
92 // OK.
93 } else if (database_version < detail::current_schema_version) {
94 throw old_schema_error(database_version);
95 } else if (database_version > detail::current_schema_version) {
96 throw integrity_error(
97 F("Database at schema version %s, which is newer than the "
98 "supported version %s")
99 % database_version % detail::current_schema_version);
100 }
101 }
102 };
103
104
105 /// Constructs a new backend.
106 ///
107 /// \param pimpl_ The internal data.
read_backend(impl * pimpl_)108 store::read_backend::read_backend(impl* pimpl_) :
109 _pimpl(pimpl_)
110 {
111 }
112
113
114 /// Destructor.
~read_backend(void)115 store::read_backend::~read_backend(void)
116 {
117 }
118
119
120 /// Opens a database in read-only mode.
121 ///
122 /// \param file The database file to be opened.
123 ///
124 /// \return The backend representation.
125 ///
126 /// \throw store::error If there is any problem opening the database.
127 store::read_backend
open_ro(const fs::path & file)128 store::read_backend::open_ro(const fs::path& file)
129 {
130 sqlite::database db = detail::open_and_setup(file, sqlite::open_readonly);
131 return read_backend(new impl(db, metadata::fetch_latest(db)));
132 }
133
134
135 /// Closes the SQLite database.
136 void
close(void)137 store::read_backend::close(void)
138 {
139 _pimpl->database.close();
140 }
141
142
143 /// Gets the connection to the SQLite database.
144 ///
145 /// \return A database connection.
146 sqlite::database&
database(void)147 store::read_backend::database(void)
148 {
149 return _pimpl->database;
150 }
151
152
153 /// Opens a read-only transaction.
154 ///
155 /// \return A new transaction.
156 store::read_transaction
start_read(void)157 store::read_backend::start_read(void)
158 {
159 return read_transaction(*this);
160 }
161