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Diffstat (limited to 'store/read_backend.cpp')
-rw-r--r-- | store/read_backend.cpp | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/store/read_backend.cpp b/store/read_backend.cpp new file mode 100644 index 000000000000..bc5b860d402c --- /dev/null +++ b/store/read_backend.cpp @@ -0,0 +1,160 @@ +// Copyright 2011 The Kyua Authors. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution. +// * Neither the name of Google Inc. nor the names of its contributors +// may be used to endorse or promote products derived from this software +// without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "store/read_backend.hpp" + +#include "store/exceptions.hpp" +#include "store/metadata.hpp" +#include "store/read_transaction.hpp" +#include "store/write_backend.hpp" +#include "utils/format/macros.hpp" +#include "utils/fs/path.hpp" +#include "utils/noncopyable.hpp" +#include "utils/sqlite/database.hpp" +#include "utils/sqlite/exceptions.hpp" + +namespace fs = utils::fs; +namespace sqlite = utils::sqlite; + + +/// Opens a database and defines session pragmas. +/// +/// This auxiliary function ensures that, every time we open a SQLite database, +/// we define the same set of pragmas for it. +/// +/// \param file The database file to be opened. +/// \param flags The flags for the open; see sqlite::database::open. +/// +/// \return The opened database. +/// +/// \throw store::error If there is a problem opening or creating the database. +sqlite::database +store::detail::open_and_setup(const fs::path& file, const int flags) +{ + try { + sqlite::database database = sqlite::database::open(file, flags); + database.exec("PRAGMA foreign_keys = ON"); + return database; + } catch (const sqlite::error& e) { + throw store::error(F("Cannot open '%s': %s") % file % e.what()); + } +} + + +/// Internal implementation for the backend. +struct store::read_backend::impl : utils::noncopyable { + /// The SQLite database this backend talks to. + sqlite::database database; + + /// Constructor. + /// + /// \param database_ The SQLite database instance. + /// \param metadata_ The metadata for the loaded database. This must match + /// the schema version we implement in this module; otherwise, a + /// migration is necessary. + /// + /// \throw integrity_error If the schema in the database is too modern, + /// which might indicate some form of corruption or an old binary. + /// \throw old_schema_error If the schema in the database is older than our + /// currently-implemented version and needs an upgrade. The caller can + /// use migrate_schema() to fix this problem. + impl(sqlite::database& database_, const metadata& metadata_) : + database(database_) + { + const int database_version = metadata_.schema_version(); + + if (database_version == detail::current_schema_version) { + // OK. + } else if (database_version < detail::current_schema_version) { + throw old_schema_error(database_version); + } else if (database_version > detail::current_schema_version) { + throw integrity_error( + F("Database at schema version %s, which is newer than the " + "supported version %s") + % database_version % detail::current_schema_version); + } + } +}; + + +/// Constructs a new backend. +/// +/// \param pimpl_ The internal data. +store::read_backend::read_backend(impl* pimpl_) : + _pimpl(pimpl_) +{ +} + + +/// Destructor. +store::read_backend::~read_backend(void) +{ +} + + +/// Opens a database in read-only mode. +/// +/// \param file The database file to be opened. +/// +/// \return The backend representation. +/// +/// \throw store::error If there is any problem opening the database. +store::read_backend +store::read_backend::open_ro(const fs::path& file) +{ + sqlite::database db = detail::open_and_setup(file, sqlite::open_readonly); + return read_backend(new impl(db, metadata::fetch_latest(db))); +} + + +/// Closes the SQLite database. +void +store::read_backend::close(void) +{ + _pimpl->database.close(); +} + + +/// Gets the connection to the SQLite database. +/// +/// \return A database connection. +sqlite::database& +store::read_backend::database(void) +{ + return _pimpl->database; +} + + +/// Opens a read-only transaction. +/// +/// \return A new transaction. +store::read_transaction +store::read_backend::start_read(void) +{ + return read_transaction(*this); +} |