Class Database

src/jrd/Database.h:249–744

const ULONG DBB_shutdown_single		= 0x100L;	// Database is in single-user maintenance mode

class Database : public pool_alloc<type_dbb>
{
	// This class is a reference-counted container for all "global"
	// (shared among different dbb's) objects -- e.g. the lock manager.
	// The contained objects are created on demand (upon the first reference).
	// The container is destroyed by the last dbb going away and
	// it automatically destroys all the objects it holds.

	class GlobalObjectHolder : public Firebird::RefCounted, public Firebird::GlobalStorage
	{
		struct DbId;
		typedef Firebird::HashTable<DbId, Firebird::DEFAULT_HASH_SIZE,
			Firebird::string, DbId, DbId > DbIdHash;

		struct DbId : public DbIdHash::Entry, public Firebird::GlobalStorage, public Firebird::RefCounted
		{
			DbId(const Firebird::string& x, GlobalObjectHolder* h)
				: id(getPool(), x), holder(h)
			{}

			DbId* get()
			{
				return this;
			}

			bool isEqual(const Firebird::string& val) const
			{
				return val == id;
			}

			static const Firebird::string& generate(const DbId& item)
			{
				return item.id;
			}

			static FB_SIZE_T hash(const Firebird::string& value, FB_SIZE_T hashSize)
			{
				return Firebird::InternalHash::hash(value.length(),
													(const UCHAR*) value.c_str(),
													hashSize);
			}

			const Firebird::string id;
			GlobalObjectHolder* holder;
			// This mutex is working very tight with `g_mutex`, so use it carefully to avoid possible deadlocks.
			Firebird::Mutex shutdownMutex;
		};

		static Firebird::GlobalPtr<DbIdHash> g_hashTable;
		static Firebird::GlobalPtr<Firebird::Mutex> g_mutex;

	public:
		static GlobalObjectHolder* init(const Firebird::string& id,
										const Firebird::PathName& filename,
										Firebird::RefPtr<const Firebird::Config> config);

		int release() const override;