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 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. 86 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. 108 store::read_backend::read_backend(impl* pimpl_) : 109 _pimpl(pimpl_) 110 { 111 } 112 113 114 /// Destructor. 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 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 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& 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 157 store::read_backend::start_read(void) 158 { 159 return read_transaction(*this); 160 } 161