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+// 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);
+}