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ClickHouse/src/Interpreters/DatabaseCatalog.cpp
Azat Khuzhin b20407fab9 Fix NOEXCEPT_SCOPE (before it calls std::terminate and looses the exception) 
Current implementation of NOEXCEPT_SCOPE will not work, you cannot
rethrow exception outside the catch block, this will simply terminate
(via std::terminate) the program.
In other words NOEXCEPT_SCOPE macro will simply call std::terminate on
exception and will lost original exception.

But if NOEXCEPT_SCOPE will accept the code that should be runned w/o
exceptions, then it can catch exception and log it, rewrite it in this
way.

Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
2022-07-14 17:16:18 +03:00

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#include <Interpreters/DatabaseCatalog.h>
#include <Interpreters/Context.h>
#include <Interpreters/loadMetadata.h>
#include <Storages/IStorage.h>
#include <Databases/IDatabase.h>
#include <Databases/DatabaseMemory.h>
#include <Databases/DatabaseOnDisk.h>
#include <Common/quoteString.h>
#include <Storages/StorageMemory.h>
#include <Storages/LiveView/TemporaryLiveViewCleaner.h>
#include <Core/BackgroundSchedulePool.h>
#include <Parsers/formatAST.h>
#include <IO/ReadHelpers.h>
#include <Poco/DirectoryIterator.h>
#include <Common/atomicRename.h>
#include <Common/CurrentMetrics.h>
#include <Common/logger_useful.h>
#include <Poco/Util/AbstractConfiguration.h>
#include <Common/filesystemHelpers.h>
#include <Common/noexcept_scope.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <utime.h>
#include "config_core.h"
#if USE_MYSQL
# include <Databases/MySQL/MaterializedMySQLSyncThread.h>
# include <Storages/StorageMaterializedMySQL.h>
#endif
#if USE_LIBPQXX
# include <Databases/PostgreSQL/DatabaseMaterializedPostgreSQL.h>
# include <Storages/PostgreSQL/StorageMaterializedPostgreSQL.h>
#endif
namespace CurrentMetrics
{
extern const Metric TablesToDropQueueSize;
}
namespace DB
{
namespace ErrorCodes
{
extern const int UNKNOWN_DATABASE;
extern const int UNKNOWN_TABLE;
extern const int TABLE_ALREADY_EXISTS;
extern const int DATABASE_ALREADY_EXISTS;
extern const int DATABASE_NOT_EMPTY;
extern const int DATABASE_ACCESS_DENIED;
extern const int LOGICAL_ERROR;
extern const int HAVE_DEPENDENT_OBJECTS;
}
TemporaryTableHolder::TemporaryTableHolder(ContextPtr context_, const TemporaryTableHolder::Creator & creator, const ASTPtr & query)
: WithContext(context_->getGlobalContext())
, temporary_tables(DatabaseCatalog::instance().getDatabaseForTemporaryTables().get())
{
ASTPtr original_create;
ASTCreateQuery * create = dynamic_cast<ASTCreateQuery *>(query.get());
String global_name;
if (create)
{
original_create = create->clone();
if (create->uuid == UUIDHelpers::Nil)
create->uuid = UUIDHelpers::generateV4();
id = create->uuid;
create->setTable("_tmp_" + toString(id));
global_name = create->getTable();
create->setDatabase(DatabaseCatalog::TEMPORARY_DATABASE);
}
else
{
id = UUIDHelpers::generateV4();
global_name = "_tmp_" + toString(id);
}
auto table_id = StorageID(DatabaseCatalog::TEMPORARY_DATABASE, global_name, id);
auto table = creator(table_id);
DatabaseCatalog::instance().addUUIDMapping(id);
temporary_tables->createTable(getContext(), global_name, table, original_create);
table->startup();
}
TemporaryTableHolder::TemporaryTableHolder(
ContextPtr context_,
const ColumnsDescription & columns,
const ConstraintsDescription & constraints,
const ASTPtr & query,
bool create_for_global_subquery)
: TemporaryTableHolder(
context_,
[&](const StorageID & table_id)
{
auto storage = std::make_shared<StorageMemory>(table_id, ColumnsDescription{columns}, ConstraintsDescription{constraints}, String{});
if (create_for_global_subquery)
storage->delayReadForGlobalSubqueries();
return storage;
},
query)
{
}
TemporaryTableHolder::TemporaryTableHolder(TemporaryTableHolder && rhs) noexcept
: WithContext(rhs.context), temporary_tables(rhs.temporary_tables), id(rhs.id)
{
rhs.id = UUIDHelpers::Nil;
}
TemporaryTableHolder & TemporaryTableHolder::operator=(TemporaryTableHolder && rhs) noexcept
{
id = rhs.id;
rhs.id = UUIDHelpers::Nil;
return *this;
}
TemporaryTableHolder::~TemporaryTableHolder()
{
if (id != UUIDHelpers::Nil)
{
auto table = getTable();
table->flushAndShutdown();
temporary_tables->dropTable(getContext(), "_tmp_" + toString(id));
}
}
StorageID TemporaryTableHolder::getGlobalTableID() const
{
return StorageID{DatabaseCatalog::TEMPORARY_DATABASE, "_tmp_" + toString(id), id};
}
StoragePtr TemporaryTableHolder::getTable() const
{
auto table = temporary_tables->tryGetTable("_tmp_" + toString(id), getContext());
if (!table)
throw Exception("Temporary table " + getGlobalTableID().getNameForLogs() + " not found", ErrorCodes::LOGICAL_ERROR);
return table;
}
void DatabaseCatalog::initializeAndLoadTemporaryDatabase()
{
drop_delay_sec = getContext()->getConfigRef().getInt("database_atomic_delay_before_drop_table_sec", default_drop_delay_sec);
unused_dir_hide_timeout_sec = getContext()->getConfigRef().getInt("database_catalog_unused_dir_hide_timeout_sec", unused_dir_hide_timeout_sec);
unused_dir_rm_timeout_sec = getContext()->getConfigRef().getInt("database_catalog_unused_dir_rm_timeout_sec", unused_dir_rm_timeout_sec);
unused_dir_cleanup_period_sec = getContext()->getConfigRef().getInt("database_catalog_unused_dir_cleanup_period_sec", unused_dir_cleanup_period_sec);
auto db_for_temporary_and_external_tables = std::make_shared<DatabaseMemory>(TEMPORARY_DATABASE, getContext());
attachDatabase(TEMPORARY_DATABASE, db_for_temporary_and_external_tables);
}
void DatabaseCatalog::loadDatabases()
{
if (Context::getGlobalContextInstance()->getApplicationType() == Context::ApplicationType::SERVER && unused_dir_cleanup_period_sec)
{
auto cleanup_task_holder
= getContext()->getSchedulePool().createTask("DatabaseCatalog", [this]() { this->cleanupStoreDirectoryTask(); });
cleanup_task = std::make_unique<BackgroundSchedulePoolTaskHolder>(std::move(cleanup_task_holder));
(*cleanup_task)->activate();
/// Do not start task immediately on server startup, it's not urgent.
(*cleanup_task)->scheduleAfter(unused_dir_hide_timeout_sec * 1000);
}
auto task_holder = getContext()->getSchedulePool().createTask("DatabaseCatalog", [this](){ this->dropTableDataTask(); });
drop_task = std::make_unique<BackgroundSchedulePoolTaskHolder>(std::move(task_holder));
(*drop_task)->activate();
std::lock_guard lock{tables_marked_dropped_mutex};
if (!tables_marked_dropped.empty())
(*drop_task)->schedule();
/// Another background thread which drops temporary LiveViews.
/// We should start it after loadMarkedAsDroppedTables() to avoid race condition.
TemporaryLiveViewCleaner::instance().startup();
}
void DatabaseCatalog::shutdownImpl()
{
TemporaryLiveViewCleaner::shutdown();
if (cleanup_task)
(*cleanup_task)->deactivate();
if (drop_task)
(*drop_task)->deactivate();
/** At this point, some tables may have threads that block our mutex.
* To shutdown them correctly, we will copy the current list of tables,
* and ask them all to finish their work.
* Then delete all objects with tables.
*/
Databases current_databases;
{
std::lock_guard lock(databases_mutex);
current_databases = databases;
}
/// We still hold "databases" (instead of std::move) for Buffer tables to flush data correctly.
for (auto & database : current_databases)
database.second->shutdown();
{
std::lock_guard lock(tables_marked_dropped_mutex);
tables_marked_dropped.clear();
}
std::lock_guard lock(databases_mutex);
for (const auto & db : databases)
{
UUID db_uuid = db.second->getUUID();
if (db_uuid != UUIDHelpers::Nil)
removeUUIDMapping(db_uuid);
}
assert(std::find_if(uuid_map.begin(), uuid_map.end(), [](const auto & elem)
{
/// Ensure that all UUID mappings are empty (i.e. all mappings contain nullptr instead of a pointer to storage)
const auto & not_empty_mapping = [] (const auto & mapping)
{
auto & db = mapping.second.first;
auto & table = mapping.second.second;
return db || table;
};
std::lock_guard map_lock{elem.mutex};
auto it = std::find_if(elem.map.begin(), elem.map.end(), not_empty_mapping);
return it != elem.map.end();
}) == uuid_map.end());
databases.clear();
view_dependencies.clear();
}
bool DatabaseCatalog::isPredefinedDatabase(const std::string_view & database_name)
{
return database_name == TEMPORARY_DATABASE || database_name == SYSTEM_DATABASE || database_name == INFORMATION_SCHEMA
|| database_name == INFORMATION_SCHEMA_UPPERCASE;
}
DatabaseAndTable DatabaseCatalog::tryGetByUUID(const UUID & uuid) const
{
assert(uuid != UUIDHelpers::Nil && getFirstLevelIdx(uuid) < uuid_map.size());
const UUIDToStorageMapPart & map_part = uuid_map[getFirstLevelIdx(uuid)];
std::lock_guard lock{map_part.mutex};
auto it = map_part.map.find(uuid);
if (it == map_part.map.end())
return {};
return it->second;
}
DatabaseAndTable DatabaseCatalog::getTableImpl(
const StorageID & table_id,
ContextPtr context_,
std::optional<Exception> * exception) const
{
if (!table_id)
{
if (exception)
exception->emplace(ErrorCodes::UNKNOWN_TABLE, "Cannot find table: StorageID is empty");
return {};
}
if (table_id.hasUUID())
{
/// Shortcut for tables which have persistent UUID
auto db_and_table = tryGetByUUID(table_id.uuid);
if (!db_and_table.first || !db_and_table.second)
{
assert(!db_and_table.first && !db_and_table.second);
if (exception)
exception->emplace(fmt::format("Table {} doesn't exist", table_id.getNameForLogs()), ErrorCodes::UNKNOWN_TABLE);
return {};
}
#if USE_LIBPQXX
if (!context_->isInternalQuery() && (db_and_table.first->getEngineName() == "MaterializedPostgreSQL"))
{
db_and_table.second = std::make_shared<StorageMaterializedPostgreSQL>(std::move(db_and_table.second), getContext(),
assert_cast<const DatabaseMaterializedPostgreSQL *>(db_and_table.first.get())->getPostgreSQLDatabaseName(),
db_and_table.second->getStorageID().table_name);
}
#endif
#if USE_MYSQL
/// It's definitely not the best place for this logic, but behaviour must be consistent with DatabaseMaterializedMySQL::tryGetTable(...)
if (!context_->isInternalQuery() && db_and_table.first->getEngineName() == "MaterializedMySQL")
{
db_and_table.second = std::make_shared<StorageMaterializedMySQL>(std::move(db_and_table.second), db_and_table.first.get());
}
#endif
return db_and_table;
}
if (table_id.database_name == TEMPORARY_DATABASE)
{
/// For temporary tables UUIDs are set in Context::resolveStorageID(...).
/// If table_id has no UUID, then the name of database was specified by user and table_id was not resolved through context.
/// Do not allow access to TEMPORARY_DATABASE because it contains all temporary tables of all contexts and users.
if (exception)
exception->emplace(fmt::format("Direct access to `{}` database is not allowed", TEMPORARY_DATABASE), ErrorCodes::DATABASE_ACCESS_DENIED);
return {};
}
DatabasePtr database;
{
std::lock_guard lock{databases_mutex};
auto it = databases.find(table_id.getDatabaseName());
if (databases.end() == it)
{
if (exception)
exception->emplace(fmt::format("Database {} doesn't exist", backQuoteIfNeed(table_id.getDatabaseName())), ErrorCodes::UNKNOWN_DATABASE);
return {};
}
database = it->second;
}
auto table = database->tryGetTable(table_id.table_name, context_);
if (!table && exception)
exception->emplace(fmt::format("Table {} doesn't exist", table_id.getNameForLogs()), ErrorCodes::UNKNOWN_TABLE);
if (!table)
database = nullptr;
return {database, table};
}
bool DatabaseCatalog::isPredefinedTable(const StorageID & table_id) const
{
static const char * information_schema_views[] = {"schemata", "tables", "views", "columns"};
static const char * information_schema_views_uppercase[] = {"SCHEMATA", "TABLES", "VIEWS", "COLUMNS"};
auto check_database_and_table_name = [&](const String & database_name, const String & table_name)
{
if (database_name == SYSTEM_DATABASE)
{
auto storage = getSystemDatabase()->tryGetTable(table_name, getContext());
return storage && storage->isSystemStorage();
}
if (database_name == INFORMATION_SCHEMA)
{
return std::find(std::begin(information_schema_views), std::end(information_schema_views), table_name)
!= std::end(information_schema_views);
}
if (database_name == INFORMATION_SCHEMA_UPPERCASE)
{
return std::find(std::begin(information_schema_views_uppercase), std::end(information_schema_views_uppercase), table_name)
!= std::end(information_schema_views_uppercase);
}
return false;
};
if (table_id.hasUUID())
{
if (auto storage = tryGetByUUID(table_id.uuid).second)
{
if (storage->isSystemStorage())
return true;
auto res_id = storage->getStorageID();
String database_name = res_id.getDatabaseName();
if (database_name != SYSTEM_DATABASE) /// If (database_name == SYSTEM_DATABASE) then we have already checked it (see isSystemStorage() above).
return check_database_and_table_name(database_name, res_id.getTableName());
}
return false;
}
return check_database_and_table_name(table_id.getDatabaseName(), table_id.getTableName());
}
void DatabaseCatalog::assertDatabaseExists(const String & database_name) const
{
std::lock_guard lock{databases_mutex};
assertDatabaseExistsUnlocked(database_name);
}
void DatabaseCatalog::assertDatabaseDoesntExist(const String & database_name) const
{
std::lock_guard lock{databases_mutex};
assertDatabaseDoesntExistUnlocked(database_name);
}
void DatabaseCatalog::assertDatabaseExistsUnlocked(const String & database_name) const
{
assert(!database_name.empty());
if (databases.end() == databases.find(database_name))
throw Exception("Database " + backQuoteIfNeed(database_name) + " doesn't exist", ErrorCodes::UNKNOWN_DATABASE);
}
void DatabaseCatalog::assertDatabaseDoesntExistUnlocked(const String & database_name) const
{
assert(!database_name.empty());
if (databases.end() != databases.find(database_name))
throw Exception("Database " + backQuoteIfNeed(database_name) + " already exists.", ErrorCodes::DATABASE_ALREADY_EXISTS);
}
void DatabaseCatalog::attachDatabase(const String & database_name, const DatabasePtr & database)
{
std::lock_guard lock{databases_mutex};
assertDatabaseDoesntExistUnlocked(database_name);
databases.emplace(database_name, database);
NOEXCEPT_SCOPE({
UUID db_uuid = database->getUUID();
if (db_uuid != UUIDHelpers::Nil)
addUUIDMapping(db_uuid, database, nullptr);
});
}
DatabasePtr DatabaseCatalog::detachDatabase(ContextPtr local_context, const String & database_name, bool drop, bool check_empty)
{
if (database_name == TEMPORARY_DATABASE)
throw Exception("Cannot detach database with temporary tables.", ErrorCodes::DATABASE_ACCESS_DENIED);
DatabasePtr db;
{
std::lock_guard lock{databases_mutex};
assertDatabaseExistsUnlocked(database_name);
db = databases.find(database_name)->second;
UUID db_uuid = db->getUUID();
if (db_uuid != UUIDHelpers::Nil)
removeUUIDMapping(db_uuid);
databases.erase(database_name);
}
if (check_empty)
{
try
{
if (!db->empty())
throw Exception("New table appeared in database being dropped or detached. Try again.",
ErrorCodes::DATABASE_NOT_EMPTY);
if (!drop)
db->assertCanBeDetached(false);
}
catch (...)
{
attachDatabase(database_name, db);
throw;
}
}
db->shutdown();
if (drop)
{
UUID db_uuid = db->getUUID();
/// Delete the database.
db->drop(local_context);
/// Old ClickHouse versions did not store database.sql files
/// Remove metadata dir (if exists) to avoid recreation of .sql file on server startup
fs::path database_metadata_dir = fs::path(getContext()->getPath()) / "metadata" / escapeForFileName(database_name);
fs::remove(database_metadata_dir);
fs::path database_metadata_file = fs::path(getContext()->getPath()) / "metadata" / (escapeForFileName(database_name) + ".sql");
fs::remove(database_metadata_file);
if (db_uuid != UUIDHelpers::Nil)
removeUUIDMappingFinally(db_uuid);
}
return db;
}
void DatabaseCatalog::updateDatabaseName(const String & old_name, const String & new_name, const Strings & tables_in_database)
{
std::lock_guard lock{databases_mutex};
assert(databases.find(new_name) == databases.end());
auto it = databases.find(old_name);
assert(it != databases.end());
auto db = it->second;
databases.erase(it);
databases.emplace(new_name, db);
for (const auto & table_name : tables_in_database)
{
QualifiedTableName new_table_name{new_name, table_name};
auto dependencies = tryRemoveLoadingDependenciesUnlocked(QualifiedTableName{old_name, table_name}, /* check_dependencies */ false);
DependenciesInfos new_info;
for (const auto & dependency : dependencies)
new_info[dependency].dependent_database_objects.insert(new_table_name);
new_info[new_table_name].dependencies = std::move(dependencies);
mergeDependenciesGraphs(loading_dependencies, new_info);
}
}
DatabasePtr DatabaseCatalog::getDatabase(const String & database_name) const
{
std::lock_guard lock{databases_mutex};
assertDatabaseExistsUnlocked(database_name);
return databases.find(database_name)->second;
}
DatabasePtr DatabaseCatalog::tryGetDatabase(const String & database_name) const
{
assert(!database_name.empty());
std::lock_guard lock{databases_mutex};
auto it = databases.find(database_name);
if (it == databases.end())
return {};
return it->second;
}
DatabasePtr DatabaseCatalog::getDatabase(const UUID & uuid) const
{
auto db_and_table = tryGetByUUID(uuid);
if (!db_and_table.first || db_and_table.second)
throw Exception(ErrorCodes::UNKNOWN_DATABASE, "Database UUID {} does not exist", toString(uuid));
return db_and_table.first;
}
DatabasePtr DatabaseCatalog::tryGetDatabase(const UUID & uuid) const
{
assert(uuid != UUIDHelpers::Nil);
auto db_and_table = tryGetByUUID(uuid);
if (!db_and_table.first || db_and_table.second)
return {};
return db_and_table.first;
}
bool DatabaseCatalog::isDatabaseExist(const String & database_name) const
{
assert(!database_name.empty());
std::lock_guard lock{databases_mutex};
return databases.end() != databases.find(database_name);
}
Databases DatabaseCatalog::getDatabases() const
{
std::lock_guard lock{databases_mutex};
return databases;
}
bool DatabaseCatalog::isTableExist(const DB::StorageID & table_id, ContextPtr context_) const
{
if (table_id.hasUUID())
return tryGetByUUID(table_id.uuid).second != nullptr;
DatabasePtr db;
{
std::lock_guard lock{databases_mutex};
auto iter = databases.find(table_id.database_name);
if (iter != databases.end())
db = iter->second;
}
return db && db->isTableExist(table_id.table_name, context_);
}
void DatabaseCatalog::assertTableDoesntExist(const StorageID & table_id, ContextPtr context_) const
{
if (isTableExist(table_id, context_))
throw Exception("Table " + table_id.getNameForLogs() + " already exists.", ErrorCodes::TABLE_ALREADY_EXISTS);
}
DatabasePtr DatabaseCatalog::getDatabaseForTemporaryTables() const
{
return getDatabase(TEMPORARY_DATABASE);
}
DatabasePtr DatabaseCatalog::getSystemDatabase() const
{
return getDatabase(SYSTEM_DATABASE);
}
void DatabaseCatalog::addUUIDMapping(const UUID & uuid)
{
addUUIDMapping(uuid, nullptr, nullptr);
}
void DatabaseCatalog::addUUIDMapping(const UUID & uuid, const DatabasePtr & database, const StoragePtr & table)
{
assert(uuid != UUIDHelpers::Nil && getFirstLevelIdx(uuid) < uuid_map.size());
assert(database || !table);
UUIDToStorageMapPart & map_part = uuid_map[getFirstLevelIdx(uuid)];
std::lock_guard lock{map_part.mutex};
auto [it, inserted] = map_part.map.try_emplace(uuid, database, table);
if (inserted)
{
/// Mapping must be locked before actually inserting something
chassert((!database && !table));
return;
}
auto & prev_database = it->second.first;
auto & prev_table = it->second.second;
assert(prev_database || !prev_table);
if (!prev_database && database)
{
/// It's empty mapping, it was created to "lock" UUID and prevent collision. Just update it.
prev_database = database;
prev_table = table;
return;
}
/// We are trying to replace existing mapping (prev_database != nullptr), it's logical error
if (database || table)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Mapping for table with UUID={} already exists", toString(uuid));
/// Normally this should never happen, but it's possible when the same UUIDs are explicitly specified in different CREATE queries,
/// so it's not LOGICAL_ERROR
throw Exception(ErrorCodes::TABLE_ALREADY_EXISTS, "Mapping for table with UUID={} already exists. It happened due to UUID collision, "
"most likely because some not random UUIDs were manually specified in CREATE queries.", toString(uuid));
}
void DatabaseCatalog::removeUUIDMapping(const UUID & uuid)
{
assert(uuid != UUIDHelpers::Nil && getFirstLevelIdx(uuid) < uuid_map.size());
UUIDToStorageMapPart & map_part = uuid_map[getFirstLevelIdx(uuid)];
std::lock_guard lock{map_part.mutex};
auto it = map_part.map.find(uuid);
if (it == map_part.map.end())
throw Exception(ErrorCodes::LOGICAL_ERROR, "Mapping for table with UUID={} doesn't exist", toString(uuid));
it->second = {};
}
void DatabaseCatalog::removeUUIDMappingFinally(const UUID & uuid)
{
assert(uuid != UUIDHelpers::Nil && getFirstLevelIdx(uuid) < uuid_map.size());
UUIDToStorageMapPart & map_part = uuid_map[getFirstLevelIdx(uuid)];
std::lock_guard lock{map_part.mutex};
if (!map_part.map.erase(uuid))
throw Exception(ErrorCodes::LOGICAL_ERROR, "Mapping for table with UUID={} doesn't exist", toString(uuid));
}
void DatabaseCatalog::updateUUIDMapping(const UUID & uuid, DatabasePtr database, StoragePtr table)
{
assert(uuid != UUIDHelpers::Nil && getFirstLevelIdx(uuid) < uuid_map.size());
assert(database && table);
UUIDToStorageMapPart & map_part = uuid_map[getFirstLevelIdx(uuid)];
std::lock_guard lock{map_part.mutex};
auto it = map_part.map.find(uuid);
if (it == map_part.map.end())
throw Exception(ErrorCodes::LOGICAL_ERROR, "Mapping for table with UUID={} doesn't exist", toString(uuid));
auto & prev_database = it->second.first;
auto & prev_table = it->second.second;
assert(prev_database && prev_table);
prev_database = std::move(database);
prev_table = std::move(table);
}
bool DatabaseCatalog::hasUUIDMapping(const UUID & uuid)
{
assert(uuid != UUIDHelpers::Nil && getFirstLevelIdx(uuid) < uuid_map.size());
UUIDToStorageMapPart & map_part = uuid_map[getFirstLevelIdx(uuid)];
std::lock_guard lock{map_part.mutex};
return map_part.map.contains(uuid);
}
std::unique_ptr<DatabaseCatalog> DatabaseCatalog::database_catalog;
DatabaseCatalog::DatabaseCatalog(ContextMutablePtr global_context_)
: WithMutableContext(global_context_), log(&Poco::Logger::get("DatabaseCatalog"))
{
TemporaryLiveViewCleaner::init(global_context_);
}
DatabaseCatalog & DatabaseCatalog::init(ContextMutablePtr global_context_)
{
if (database_catalog)
{
throw Exception("Database catalog is initialized twice. This is a bug.",
ErrorCodes::LOGICAL_ERROR);
}
database_catalog.reset(new DatabaseCatalog(global_context_));
return *database_catalog;
}
DatabaseCatalog & DatabaseCatalog::instance()
{
if (!database_catalog)
{
throw Exception("Database catalog is not initialized. This is a bug.",
ErrorCodes::LOGICAL_ERROR);
}
return *database_catalog;
}
void DatabaseCatalog::shutdown()
{
// The catalog might not be initialized yet by init(global_context). It can
// happen if some exception was thrown on first steps of startup.
if (database_catalog)
{
database_catalog->shutdownImpl();
}
}
DatabasePtr DatabaseCatalog::getDatabase(const String & database_name, ContextPtr local_context) const
{
String resolved_database = local_context->resolveDatabase(database_name);
return getDatabase(resolved_database);
}
void DatabaseCatalog::addDependency(const StorageID & from, const StorageID & where)
{
std::lock_guard lock{databases_mutex};
// FIXME when loading metadata storage may not know UUIDs of it's dependencies, because they are not loaded yet,
// so UUID of `from` is not used here. (same for remove, get and update)
view_dependencies[{from.getDatabaseName(), from.getTableName()}].insert(where);
}
void DatabaseCatalog::removeDependency(const StorageID & from, const StorageID & where)
{
std::lock_guard lock{databases_mutex};
view_dependencies[{from.getDatabaseName(), from.getTableName()}].erase(where);
}
Dependencies DatabaseCatalog::getDependencies(const StorageID & from) const
{
std::lock_guard lock{databases_mutex};
auto iter = view_dependencies.find({from.getDatabaseName(), from.getTableName()});
if (iter == view_dependencies.end())
return {};
return Dependencies(iter->second.begin(), iter->second.end());
}
void
DatabaseCatalog::updateDependency(const StorageID & old_from, const StorageID & old_where, const StorageID & new_from,
const StorageID & new_where)
{
std::lock_guard lock{databases_mutex};
if (!old_from.empty())
view_dependencies[{old_from.getDatabaseName(), old_from.getTableName()}].erase(old_where);
if (!new_from.empty())
view_dependencies[{new_from.getDatabaseName(), new_from.getTableName()}].insert(new_where);
}
DDLGuardPtr DatabaseCatalog::getDDLGuard(const String & database, const String & table)
{
std::unique_lock lock(ddl_guards_mutex);
/// TSA does not support unique_lock
auto db_guard_iter = TSA_SUPPRESS_WARNING_FOR_WRITE(ddl_guards).try_emplace(database).first;
DatabaseGuard & db_guard = db_guard_iter->second;
return std::make_unique<DDLGuard>(db_guard.first, db_guard.second, std::move(lock), table, database);
}
std::unique_lock<std::shared_mutex> DatabaseCatalog::getExclusiveDDLGuardForDatabase(const String & database)
{
DDLGuards::iterator db_guard_iter;
{
std::lock_guard lock(ddl_guards_mutex);
db_guard_iter = ddl_guards.try_emplace(database).first;
assert(db_guard_iter->second.first.contains(""));
}
DatabaseGuard & db_guard = db_guard_iter->second;
return std::unique_lock{db_guard.second};
}
bool DatabaseCatalog::isDictionaryExist(const StorageID & table_id) const
{
auto storage = tryGetTable(table_id, getContext());
bool storage_is_dictionary = storage && storage->isDictionary();
return storage_is_dictionary;
}
StoragePtr DatabaseCatalog::getTable(const StorageID & table_id, ContextPtr local_context) const
{
std::optional<Exception> exc;
auto res = getTableImpl(table_id, local_context, &exc);
if (!res.second)
throw Exception(*exc);
return res.second;
}
StoragePtr DatabaseCatalog::tryGetTable(const StorageID & table_id, ContextPtr local_context) const
{
return getTableImpl(table_id, local_context, nullptr).second;
}
DatabaseAndTable DatabaseCatalog::getDatabaseAndTable(const StorageID & table_id, ContextPtr local_context) const
{
std::optional<Exception> exc;
auto res = getTableImpl(table_id, local_context, &exc);
if (!res.second)
throw Exception(*exc);
return res;
}
DatabaseAndTable DatabaseCatalog::tryGetDatabaseAndTable(const StorageID & table_id, ContextPtr local_context) const
{
return getTableImpl(table_id, local_context, nullptr);
}
void DatabaseCatalog::loadMarkedAsDroppedTables()
{
assert(!cleanup_task);
/// /clickhouse_root/metadata_dropped/ contains files with metadata of tables,
/// which where marked as dropped by Atomic databases.
/// Data directories of such tables still exists in store/
/// and metadata still exists in ZooKeeper for ReplicatedMergeTree tables.
/// If server restarts before such tables was completely dropped,
/// we should load them and enqueue cleanup to remove data from store/ and metadata from ZooKeeper
std::map<String, StorageID> dropped_metadata;
String path = getContext()->getPath() + "metadata_dropped/";
if (!std::filesystem::exists(path))
{
return;
}
Poco::DirectoryIterator dir_end;
for (Poco::DirectoryIterator it(path); it != dir_end; ++it)
{
/// File name has the following format:
/// database_name.table_name.uuid.sql
/// Ignore unexpected files
if (!it.name().ends_with(".sql"))
continue;
/// Process .sql files with metadata of tables which were marked as dropped
StorageID dropped_id = StorageID::createEmpty();
size_t dot_pos = it.name().find('.');
if (dot_pos == std::string::npos)
continue;
dropped_id.database_name = unescapeForFileName(it.name().substr(0, dot_pos));
size_t prev_dot_pos = dot_pos;
dot_pos = it.name().find('.', prev_dot_pos + 1);
if (dot_pos == std::string::npos)
continue;
dropped_id.table_name = unescapeForFileName(it.name().substr(prev_dot_pos + 1, dot_pos - prev_dot_pos - 1));
prev_dot_pos = dot_pos;
dot_pos = it.name().find('.', prev_dot_pos + 1);
if (dot_pos == std::string::npos)
continue;
dropped_id.uuid = parse<UUID>(it.name().substr(prev_dot_pos + 1, dot_pos - prev_dot_pos - 1));
String full_path = path + it.name();
dropped_metadata.emplace(std::move(full_path), std::move(dropped_id));
}
LOG_INFO(log, "Found {} partially dropped tables. Will load them and retry removal.", dropped_metadata.size());
ThreadPool pool;
for (const auto & elem : dropped_metadata)
{
pool.scheduleOrThrowOnError([&]()
{
this->enqueueDroppedTableCleanup(elem.second, nullptr, elem.first);
});
}
pool.wait();
}
String DatabaseCatalog::getPathForDroppedMetadata(const StorageID & table_id) const
{
return getContext()->getPath() + "metadata_dropped/" +
escapeForFileName(table_id.getDatabaseName()) + "." +
escapeForFileName(table_id.getTableName()) + "." +
toString(table_id.uuid) + ".sql";
}
void DatabaseCatalog::enqueueDroppedTableCleanup(StorageID table_id, StoragePtr table, String dropped_metadata_path, bool ignore_delay)
{
assert(table_id.hasUUID());
assert(!table || table->getStorageID().uuid == table_id.uuid);
assert(dropped_metadata_path == getPathForDroppedMetadata(table_id));
/// Table was removed from database. Enqueue removal of its data from disk.
time_t drop_time;
if (table)
{
chassert(hasUUIDMapping(table_id.uuid));
drop_time = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
table->is_dropped = true;
}
else
{
/// Try load table from metadata to drop it correctly (e.g. remove metadata from zk or remove data from all volumes)
LOG_INFO(log, "Trying load partially dropped table {} from {}", table_id.getNameForLogs(), dropped_metadata_path);
ASTPtr ast = DatabaseOnDisk::parseQueryFromMetadata(
log, getContext(), dropped_metadata_path, /*throw_on_error*/ false, /*remove_empty*/ false);
auto * create = typeid_cast<ASTCreateQuery *>(ast.get());
assert(!create || create->uuid == table_id.uuid);
if (create)
{
String data_path = "store/" + getPathForUUID(table_id.uuid);
create->setDatabase(table_id.database_name);
create->setTable(table_id.table_name);
try
{
table = createTableFromAST(*create, table_id.getDatabaseName(), data_path, getContext(), false).second;
table->is_dropped = true;
}
catch (...)
{
tryLogCurrentException(log, "Cannot load partially dropped table " + table_id.getNameForLogs() +
" from: " + dropped_metadata_path +
". Parsed query: " + serializeAST(*create) +
". Will remove metadata and " + data_path +
". Garbage may be left in ZooKeeper.");
}
}
else
{
LOG_WARNING(log, "Cannot parse metadata of partially dropped table {} from {}. Will remove metadata file and data directory. Garbage may be left in /store directory and ZooKeeper.", table_id.getNameForLogs(), dropped_metadata_path);
}
addUUIDMapping(table_id.uuid);
drop_time = FS::getModificationTime(dropped_metadata_path);
}
std::lock_guard lock(tables_marked_dropped_mutex);
if (ignore_delay)
tables_marked_dropped.push_front({table_id, table, dropped_metadata_path, drop_time});
else
tables_marked_dropped.push_back({table_id, table, dropped_metadata_path, drop_time + drop_delay_sec});
tables_marked_dropped_ids.insert(table_id.uuid);
CurrentMetrics::add(CurrentMetrics::TablesToDropQueueSize, 1);
/// If list of dropped tables was empty, start a drop task.
/// If ignore_delay is set, schedule drop task as soon as possible.
if (drop_task && (tables_marked_dropped.size() == 1 || ignore_delay))
(*drop_task)->schedule();
}
void DatabaseCatalog::dropTableDataTask()
{
/// Background task that removes data of tables which were marked as dropped by Atomic databases.
/// Table can be removed when it's not used by queries and drop_delay_sec elapsed since it was marked as dropped.
bool need_reschedule = true;
/// Default reschedule time for the case when we are waiting for reference count to become 1.
size_t schedule_after_ms = reschedule_time_ms;
TableMarkedAsDropped table;
try
{
std::lock_guard lock(tables_marked_dropped_mutex);
assert(!tables_marked_dropped.empty());
time_t current_time = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
time_t min_drop_time = std::numeric_limits<time_t>::max();
size_t tables_in_use_count = 0;
auto it = std::find_if(tables_marked_dropped.begin(), tables_marked_dropped.end(), [&](const auto & elem)
{
bool not_in_use = !elem.table || elem.table.unique();
bool old_enough = elem.drop_time <= current_time;
min_drop_time = std::min(min_drop_time, elem.drop_time);
tables_in_use_count += !not_in_use;
return not_in_use && old_enough;
});
if (it != tables_marked_dropped.end())
{
table = std::move(*it);
LOG_INFO(log, "Have {} tables in drop queue ({} of them are in use), will try drop {}",
tables_marked_dropped.size(), tables_in_use_count, table.table_id.getNameForLogs());
tables_marked_dropped.erase(it);
/// Schedule the task as soon as possible, while there are suitable tables to drop.
schedule_after_ms = 0;
}
else if (current_time < min_drop_time)
{
/// We are waiting for drop_delay_sec to exceed, no sense to wakeup until min_drop_time.
/// If new table is added to the queue with ignore_delay flag, schedule() is called to wakeup the task earlier.
schedule_after_ms = (min_drop_time - current_time) * 1000;
LOG_TRACE(log, "Not found any suitable tables to drop, still have {} tables in drop queue ({} of them are in use). "
"Will check again after {} seconds", tables_marked_dropped.size(), tables_in_use_count, min_drop_time - current_time);
}
need_reschedule = !tables_marked_dropped.empty();
}
catch (...)
{
tryLogCurrentException(log, __PRETTY_FUNCTION__);
}
if (table.table_id)
{
try
{
dropTableFinally(table);
std::lock_guard lock(tables_marked_dropped_mutex);
[[maybe_unused]] auto removed = tables_marked_dropped_ids.erase(table.table_id.uuid);
assert(removed);
}
catch (...)
{
tryLogCurrentException(log, "Cannot drop table " + table.table_id.getNameForLogs() +
". Will retry later.");
{
table.drop_time = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now()) + drop_error_cooldown_sec;
std::lock_guard lock(tables_marked_dropped_mutex);
tables_marked_dropped.emplace_back(std::move(table));
/// If list of dropped tables was empty, schedule a task to retry deletion.
if (tables_marked_dropped.size() == 1)
{
need_reschedule = true;
schedule_after_ms = drop_error_cooldown_sec * 1000;
}
}
}
wait_table_finally_dropped.notify_all();
}
/// Do not schedule a task if there is no tables to drop
if (need_reschedule)
(*drop_task)->scheduleAfter(schedule_after_ms);
}
void DatabaseCatalog::dropTableFinally(const TableMarkedAsDropped & table)
{
if (table.table)
{
table.table->drop();
}
/// Even if table is not loaded, try remove its data from disk.
/// TODO remove data from all volumes
fs::path data_path = fs::path(getContext()->getPath()) / "store" / getPathForUUID(table.table_id.uuid);
if (fs::exists(data_path))
{
LOG_INFO(log, "Removing data directory {} of dropped table {}", data_path.string(), table.table_id.getNameForLogs());
fs::remove_all(data_path);
}
LOG_INFO(log, "Removing metadata {} of dropped table {}", table.metadata_path, table.table_id.getNameForLogs());
fs::remove(fs::path(table.metadata_path));
removeUUIDMappingFinally(table.table_id.uuid);
CurrentMetrics::sub(CurrentMetrics::TablesToDropQueueSize, 1);
}
String DatabaseCatalog::getPathForUUID(const UUID & uuid)
{
const size_t uuid_prefix_len = 3;
return toString(uuid).substr(0, uuid_prefix_len) + '/' + toString(uuid) + '/';
}
void DatabaseCatalog::waitTableFinallyDropped(const UUID & uuid)
{
if (uuid == UUIDHelpers::Nil)
return;
LOG_DEBUG(log, "Waiting for table {} to be finally dropped", toString(uuid));
std::unique_lock lock{tables_marked_dropped_mutex};
wait_table_finally_dropped.wait(lock, [&]() TSA_REQUIRES(tables_marked_dropped_mutex) -> bool
{
return !tables_marked_dropped_ids.contains(uuid);
});
}
void DatabaseCatalog::addLoadingDependencies(const QualifiedTableName & table, TableNamesSet && dependencies)
{
DependenciesInfos new_info;
for (const auto & dependency : dependencies)
new_info[dependency].dependent_database_objects.insert(table);
new_info[table].dependencies = std::move(dependencies);
addLoadingDependencies(new_info);
}
void DatabaseCatalog::addLoadingDependencies(const DependenciesInfos & new_infos)
{
std::lock_guard lock{databases_mutex};
mergeDependenciesGraphs(loading_dependencies, new_infos);
}
DependenciesInfo DatabaseCatalog::getLoadingDependenciesInfo(const StorageID & table_id) const
{
std::lock_guard lock{databases_mutex};
auto it = loading_dependencies.find(table_id.getQualifiedName());
if (it == loading_dependencies.end())
return {};
return it->second;
}
TableNamesSet DatabaseCatalog::tryRemoveLoadingDependencies(const StorageID & table_id, bool check_dependencies, bool is_drop_database)
{
QualifiedTableName removing_table = table_id.getQualifiedName();
std::lock_guard lock{databases_mutex};
return tryRemoveLoadingDependenciesUnlocked(removing_table, check_dependencies, is_drop_database);
}
TableNamesSet DatabaseCatalog::tryRemoveLoadingDependenciesUnlocked(const QualifiedTableName & removing_table, bool check_dependencies, bool is_drop_database)
{
auto it = loading_dependencies.find(removing_table);
if (it == loading_dependencies.end())
return {};
TableNamesSet & dependent = it->second.dependent_database_objects;
if (!dependent.empty())
{
if (check_dependencies && !is_drop_database)
throw Exception(ErrorCodes::HAVE_DEPENDENT_OBJECTS, "Cannot drop or rename {}, because some tables depend on it: {}",
removing_table, fmt::join(dependent, ", "));
/// For DROP DATABASE we should ignore dependent tables from the same database.
/// TODO unload tables in reverse topological order and remove this code
if (check_dependencies)
{
TableNames from_other_databases;
for (const auto & table : dependent)
if (table.database != removing_table.database)
from_other_databases.push_back(table);
if (!from_other_databases.empty())
throw Exception(ErrorCodes::HAVE_DEPENDENT_OBJECTS, "Cannot drop or rename {}, because some tables depend on it: {}",
removing_table, fmt::join(from_other_databases, ", "));
}
for (const auto & table : dependent)
{
[[maybe_unused]] bool removed = loading_dependencies[table].dependencies.erase(removing_table);
assert(removed);
}
dependent.clear();
}
TableNamesSet dependencies = it->second.dependencies;
for (const auto & table : dependencies)
{
[[maybe_unused]] bool removed = loading_dependencies[table].dependent_database_objects.erase(removing_table);
assert(removed);
}
loading_dependencies.erase(it);
return dependencies;
}
void DatabaseCatalog::checkTableCanBeRemovedOrRenamed(const StorageID & table_id) const
{
QualifiedTableName removing_table = table_id.getQualifiedName();
std::lock_guard lock{databases_mutex};
auto it = loading_dependencies.find(removing_table);
if (it == loading_dependencies.end())
return;
const TableNamesSet & dependent = it->second.dependent_database_objects;
if (!dependent.empty())
throw Exception(ErrorCodes::HAVE_DEPENDENT_OBJECTS, "Cannot drop or rename {}, because some tables depend on it: {}",
table_id.getNameForLogs(), fmt::join(dependent, ", "));
}
void DatabaseCatalog::updateLoadingDependencies(const StorageID & table_id, TableNamesSet && new_dependencies)
{
if (new_dependencies.empty())
return;
QualifiedTableName table_name = table_id.getQualifiedName();
std::lock_guard lock{databases_mutex};
auto it = loading_dependencies.find(table_name);
if (it == loading_dependencies.end())
it = loading_dependencies.emplace(table_name, DependenciesInfo{}).first;
auto & old_dependencies = it->second.dependencies;
for (const auto & dependency : old_dependencies)
if (!new_dependencies.contains(dependency))
loading_dependencies[dependency].dependent_database_objects.erase(table_name);
for (const auto & dependency : new_dependencies)
if (!old_dependencies.contains(dependency))
loading_dependencies[dependency].dependent_database_objects.insert(table_name);
old_dependencies = std::move(new_dependencies);
}
void DatabaseCatalog::cleanupStoreDirectoryTask()
{
fs::path store_path = fs::path(getContext()->getPath()) / "store";
size_t affected_dirs = 0;
for (const auto & prefix_dir : fs::directory_iterator{store_path})
{
String prefix = prefix_dir.path().filename();
bool expected_prefix_dir = prefix_dir.is_directory() &&
prefix.size() == 3 &&
isHexDigit(prefix[0]) &&
isHexDigit(prefix[1]) &&
isHexDigit(prefix[2]);
if (!expected_prefix_dir)
{
LOG_WARNING(log, "Found invalid directory {}, will try to remove it", prefix_dir.path().string());
affected_dirs += maybeRemoveDirectory(prefix_dir.path());
continue;
}
for (const auto & uuid_dir : fs::directory_iterator{prefix_dir.path()})
{
String uuid_str = uuid_dir.path().filename();
UUID uuid;
bool parsed = tryParse(uuid, uuid_str);
bool expected_dir = uuid_dir.is_directory() &&
parsed &&
uuid != UUIDHelpers::Nil &&
uuid_str.starts_with(prefix);
if (!expected_dir)
{
LOG_WARNING(log, "Found invalid directory {}, will try to remove it", uuid_dir.path().string());
affected_dirs += maybeRemoveDirectory(uuid_dir.path());
continue;
}
/// Order is important
if (!hasUUIDMapping(uuid))
{
/// We load uuids even for detached and permanently detached tables,
/// so it looks safe enough to remove directory if we don't have uuid mapping for it.
/// No table or database using this directory should concurrently appear,
/// because creation of new table would fail with "directory already exists".
affected_dirs += maybeRemoveDirectory(uuid_dir.path());
}
}
}
if (affected_dirs)
LOG_INFO(log, "Cleaned up {} directories from store/", affected_dirs);
(*cleanup_task)->scheduleAfter(unused_dir_cleanup_period_sec * 1000);
}
bool DatabaseCatalog::maybeRemoveDirectory(const fs::path & unused_dir)
{
/// "Safe" automatic removal of some directory.
/// At first we do not remove anything and only revoke all access right.
/// And remove only if nobody noticed it after, for example, one month.
struct stat st;
if (stat(unused_dir.string().c_str(), &st))
{
LOG_ERROR(log, "Failed to stat {}, errno: {}", unused_dir.string(), errno);
return false;
}
if (st.st_uid != geteuid())
{
/// Directory is not owned by clickhouse, it's weird, let's ignore it (chmod will likely fail anyway).
LOG_WARNING(log, "Found directory {} with unexpected owner (uid={})", unused_dir.string(), st.st_uid);
return false;
}
time_t max_modification_time = std::max(st.st_atime, std::max(st.st_mtime, st.st_ctime));
time_t current_time = time(nullptr);
if (st.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO))
{
if (current_time <= max_modification_time + unused_dir_hide_timeout_sec)
return false;
LOG_INFO(log, "Removing access rights for unused directory {} (will remove it when timeout exceed)", unused_dir.string());
/// Explicitly update modification time just in case
struct utimbuf tb;
tb.actime = current_time;
tb.modtime = current_time;
if (utime(unused_dir.string().c_str(), &tb) != 0)
LOG_ERROR(log, "Failed to utime {}, errno: {}", unused_dir.string(), errno);
/// Remove all access right
if (chmod(unused_dir.string().c_str(), 0))
LOG_ERROR(log, "Failed to chmod {}, errno: {}", unused_dir.string(), errno);
return true;
}
else
{
if (!unused_dir_rm_timeout_sec)
return false;
if (current_time <= max_modification_time + unused_dir_rm_timeout_sec)
return false;
LOG_INFO(log, "Removing unused directory {}", unused_dir.string());
/// We have to set these access rights to make recursive removal work
if (chmod(unused_dir.string().c_str(), S_IRWXU))
LOG_ERROR(log, "Failed to chmod {}, errno: {}", unused_dir.string(), errno);
fs::remove_all(unused_dir);
return true;
}
}
static void maybeUnlockUUID(UUID uuid)
{
if (uuid == UUIDHelpers::Nil)
return;
chassert(DatabaseCatalog::instance().hasUUIDMapping(uuid));
auto db_and_table = DatabaseCatalog::instance().tryGetByUUID(uuid);
if (!db_and_table.first && !db_and_table.second)
{
DatabaseCatalog::instance().removeUUIDMappingFinally(uuid);
return;
}
chassert(db_and_table.first || !db_and_table.second);
}
TemporaryLockForUUIDDirectory::TemporaryLockForUUIDDirectory(UUID uuid_)
: uuid(uuid_)
{
if (uuid != UUIDHelpers::Nil)
DatabaseCatalog::instance().addUUIDMapping(uuid);
}
TemporaryLockForUUIDDirectory::~TemporaryLockForUUIDDirectory()
{
maybeUnlockUUID(uuid);
}
TemporaryLockForUUIDDirectory::TemporaryLockForUUIDDirectory(TemporaryLockForUUIDDirectory && rhs) noexcept
: uuid(rhs.uuid)
{
rhs.uuid = UUIDHelpers::Nil;
}
TemporaryLockForUUIDDirectory & TemporaryLockForUUIDDirectory::operator = (TemporaryLockForUUIDDirectory && rhs) noexcept
{
maybeUnlockUUID(uuid);
uuid = rhs.uuid;
rhs.uuid = UUIDHelpers::Nil;
return *this;
}
DDLGuard::DDLGuard(Map & map_, std::shared_mutex & db_mutex_, std::unique_lock<std::mutex> guards_lock_, const String & elem, const String & database_name)
: map(map_), db_mutex(db_mutex_), guards_lock(std::move(guards_lock_))
{
it = map.emplace(elem, Entry{std::make_unique<std::mutex>(), 0}).first;
++it->second.counter;
guards_lock.unlock();
table_lock = std::unique_lock(*it->second.mutex);
is_database_guard = elem.empty();
if (!is_database_guard)
{
bool locked_database_for_read = db_mutex.try_lock_shared();
if (!locked_database_for_read)
{
releaseTableLock();
throw Exception(ErrorCodes::UNKNOWN_DATABASE, "Database {} is currently dropped or renamed", database_name);
}
}
}
void DDLGuard::releaseTableLock() noexcept
{
if (table_lock_removed)
return;
table_lock_removed = true;
guards_lock.lock();
UInt32 counter = --it->second.counter;
table_lock.unlock();
if (counter == 0)
map.erase(it);
guards_lock.unlock();
}
DDLGuard::~DDLGuard()
{
if (!is_database_guard)
db_mutex.unlock_shared();
releaseTableLock();
}
}
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