1// Copyright 2011 The Kyua Authors.
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28
29#include "store/write_backend.hpp"
30
31#include <stdexcept>
32
33#include "store/exceptions.hpp"
34#include "store/metadata.hpp"
35#include "store/read_backend.hpp"
36#include "store/write_transaction.hpp"
37#include "utils/env.hpp"
38#include "utils/format/macros.hpp"
39#include "utils/fs/path.hpp"
40#include "utils/logging/macros.hpp"
41#include "utils/noncopyable.hpp"
42#include "utils/sanity.hpp"
43#include "utils/stream.hpp"
44#include "utils/sqlite/database.hpp"
45#include "utils/sqlite/exceptions.hpp"
46#include "utils/sqlite/statement.ipp"
47
48namespace fs = utils::fs;
49namespace sqlite = utils::sqlite;
50
51
52/// The current schema version.
53///
54/// Any new database gets this schema version.  Existing databases with an older
55/// schema version must be first migrated to the current schema with
56/// migrate_schema() before they can be used.
57///
58/// This must be kept in sync with the value in the corresponding schema_vX.sql
59/// file, where X matches this version number.
60///
61/// This variable is not const to allow tests to modify it.  No other code
62/// should change its value.
63int store::detail::current_schema_version = 3;
64
65
66namespace {
67
68
69/// Checks if a database is empty (i.e. if it is new).
70///
71/// \param db The database to check.
72///
73/// \return True if the database is empty.
74static bool
75empty_database(sqlite::database& db)
76{
77    sqlite::statement stmt = db.create_statement("SELECT * FROM sqlite_master");
78    return !stmt.step();
79}
80
81
82}  // anonymous namespace
83
84
85/// Calculates the path to the schema file for the database.
86///
87/// \return The path to the installed schema_vX.sql file that matches the
88/// current_schema_version.
89fs::path
90store::detail::schema_file(void)
91{
92    return fs::path(utils::getenv_with_default("KYUA_STOREDIR", KYUA_STOREDIR))
93        / (F("schema_v%s.sql") % current_schema_version);
94}
95
96
97/// Initializes an empty database.
98///
99/// \param db The database to initialize.
100///
101/// \return The metadata record written into the new database.
102///
103/// \throw store::error If there is a problem initializing the database.
104store::metadata
105store::detail::initialize(sqlite::database& db)
106{
107    PRE(empty_database(db));
108
109    const fs::path schema = schema_file();
110
111    LI(F("Populating new database with schema from %s") % schema);
112    try {
113        db.exec(utils::read_file(schema));
114
115        const metadata metadata = metadata::fetch_latest(db);
116        LI(F("New metadata entry %s") % metadata.timestamp());
117        if (metadata.schema_version() != detail::current_schema_version) {
118            UNREACHABLE_MSG(F("current_schema_version is out of sync with "
119                              "%s") % schema);
120        }
121        return metadata;
122    } catch (const store::integrity_error& e) {
123        // Could be raised by metadata::fetch_latest.
124        UNREACHABLE_MSG("Inconsistent code while creating a database");
125    } catch (const sqlite::error& e) {
126        throw error(F("Failed to initialize database: %s") % e.what());
127    } catch (const std::runtime_error& e) {
128        throw error(F("Cannot read database schema '%s'") % schema);
129    }
130}
131
132
133/// Internal implementation for the backend.
134struct store::write_backend::impl : utils::noncopyable {
135    /// The SQLite database this backend talks to.
136    sqlite::database database;
137
138    /// Constructor.
139    ///
140    /// \param database_ The SQLite database instance.
141    impl(sqlite::database& database_) : database(database_)
142    {
143    }
144};
145
146
147/// Constructs a new backend.
148///
149/// \param pimpl_ The internal data.
150store::write_backend::write_backend(impl* pimpl_) :
151    _pimpl(pimpl_)
152{
153}
154
155
156/// Destructor.
157store::write_backend::~write_backend(void)
158{
159}
160
161
162/// Opens a database in read-write mode and creates it if necessary.
163///
164/// \param file The database file to be opened.
165///
166/// \return The backend representation.
167///
168/// \throw store::error If there is any problem opening or creating
169///     the database.
170store::write_backend
171store::write_backend::open_rw(const fs::path& file)
172{
173    sqlite::database db = detail::open_and_setup(
174        file, sqlite::open_readwrite | sqlite::open_create);
175    if (!empty_database(db))
176        throw error(F("%s already exists and is not empty; cannot open "
177                      "for write") % file);
178    detail::initialize(db);
179    return write_backend(new impl(db));
180}
181
182
183/// Closes the SQLite database.
184void
185store::write_backend::close(void)
186{
187    _pimpl->database.close();
188}
189
190
191/// Gets the connection to the SQLite database.
192///
193/// \return A database connection.
194sqlite::database&
195store::write_backend::database(void)
196{
197    return _pimpl->database;
198}
199
200
201/// Opens a write-only transaction.
202///
203/// \return A new transaction.
204store::write_transaction
205store::write_backend::start_write(void)
206{
207    return write_transaction(*this);
208}
209