Class Database

  • All Implemented Interfaces:
    DatabaseConstants

    public final class Database
    extends java.lang.Object
    implements DatabaseConstants
    The representation of a single database in the system. A database is a set of schema, a set of tables and table definitions of tables in the schema, and a description of the schema.

    This class encapsulates the top level behaviour of a database. That is of creating itself, initializing itself, shutting itself down, deleting itself, creating/dropping a table, updating a table. It is not the responsibility of this class to handle table behaviour above this. Top level table behaviour is handled by DataTable through the DatabaseConnection interface.

    The Database object is also responsible for various database management functions such a creating, editing and removing users, triggers, functions and services.

    Author:
    Tobias Downer
    • Field Detail

      • SYSTEM_SCHEMA

        public static final java.lang.String SYSTEM_SCHEMA
        The name of the system schema that contains tables refering to system information.
        See Also:
        Constant Field Values
      • DEFAULT_SCHEMA

        public static final java.lang.String DEFAULT_SCHEMA
        The name of the default schema.
        See Also:
        Constant Field Values
      • JDBC_SCHEMA

        public static final java.lang.String JDBC_SCHEMA
        The name of the schema that contains JDBC helper tables.
        See Also:
        Constant Field Values
      • SYS_PASSWORD

        public static final TableName SYS_PASSWORD
        The password privs and grants table.
      • SYS_USERCONNECT

        public static final TableName SYS_USERCONNECT
      • SYS_USERPRIV

        public static final TableName SYS_USERPRIV
      • SYS_GRANTS

        public static final TableName SYS_GRANTS
      • SYS_SERVICE

        public static final TableName SYS_SERVICE
        The services table.
      • SYS_FUNCTIONFACTORY

        public static final TableName SYS_FUNCTIONFACTORY
        The function factory table.
      • SYS_FUNCTION

        public static final TableName SYS_FUNCTION
        The function table.
      • SYS_VIEW

        public static final TableName SYS_VIEW
        The view table.
      • SYS_LABEL

        public static final TableName SYS_LABEL
        The label table.
      • SYS_TABLE_COLUMNS

        public static final TableName SYS_TABLE_COLUMNS
        The system internally generated 'sUSRTableColumns' table.
      • SYS_TABLE_INFO

        public static final TableName SYS_TABLE_INFO
        The system internally generated 'sUSRTableInfo' table.
      • SYS_DATA_TRIGGER

        public static final TableName SYS_DATA_TRIGGER
        The system internally generated 'sUSRDataTrigger' table.
      • SYS_DB_STATISTICS

        public static final TableName SYS_DB_STATISTICS
        The system internally generated 'sUSRDatabaseStatistics' table.
      • OLD_TRIGGER_TABLE

        public static final TableName OLD_TRIGGER_TABLE
        The OLD table used inside a triggered procedure to represent a triggered row before the operation occurs.
      • NEW_TRIGGER_TABLE

        public static final TableName NEW_TRIGGER_TABLE
        The NEW table used inside a triggered procedure to represent a triggered row after the operation occurs.
      • LOCK_GROUP

        public static final java.lang.String LOCK_GROUP
        The name of the lock group. If a user belongs to this group the user account is locked and they are not allowed to log into the database.
        See Also:
        Constant Field Values
      • SECURE_GROUP

        public static final java.lang.String SECURE_GROUP
        THe name of the secure access group. If a user belongs to this group they are permitted to perform a number of priviledged operations such as shutting down the database, and adding and removing users.
        See Also:
        Constant Field Values
      • USER_MANAGER_GROUP

        public static final java.lang.String USER_MANAGER_GROUP
        The name of the user manager group. Users that belong in this group can create, alter and drop users from the system.
        See Also:
        Constant Field Values
      • SCHEMA_MANAGER_GROUP

        public static final java.lang.String SCHEMA_MANAGER_GROUP
        The name of the schema manager group. Users that belong in this group can create and drop schema from the system.
        See Also:
        Constant Field Values
      • INTERNAL_SECURE_USERNAME

        public static final java.lang.String INTERNAL_SECURE_USERNAME
        The username of the internal secure user. The internal secure user is only used for internal highly privileged operations. This user is given full privs to everything and is used to manage the system tables, for authentication, etc.
        See Also:
        Constant Field Values
    • Constructor Detail

      • Database

        public Database​(DatabaseSystem system,
                        java.lang.String name)
        The Constructor. This takes a directory path in which the database is stored.
    • Method Detail

      • getName

        public java.lang.String getName()
        Returns the name of this database.
      • isReadOnly

        public boolean isReadOnly()
        Returns true if this database is in read only mode.
      • getCommandsLog

        public Log getCommandsLog()
        Returns the log file where commands are recorded.
      • createNewConnection

        public DatabaseConnection createNewConnection​(User user,
                                                      DatabaseConnection.CallBack call_back)
        Returns a new DatabaseConnection instance that is used against this database.

        When a new connection is made on this database, this method is called to create a new DatabaseConnection instance for the connection. This connection handles all transactional queries and modifications to the database.

      • authenticateUser

        public User authenticateUser​(java.lang.String username,
                                     java.lang.String password,
                                     java.lang.String connection_string)
        Tries to authenticate a username/password against this database. If we fail to authenticate then a 'null' object is returned, otherwise a valid User object is returned. If a valid object is returned, the user will be logged into the engine via the UserManager object (in DatabaseSystem). The developer must ensure that 'close' is called before the object is disposed (logs out of the system).

        This method also returns null if a user exists but was denied access from the given host string. The given 'host_name' object is formatted in the database host connection encoding. This method checks all the values from the sUSRUserConnectPriv table for this user for the given protocol. It first checks if the user is specifically DENIED access from the given host. It then checks if the user is ALLOWED access from the given host. If a host is neither allowed or denied then it is denied.

      • userExists

        public boolean userExists​(DatabaseQueryContext context,
                                  java.lang.String username)
                           throws DatabaseException
        Returns true if a user exists in this database, otherwise returns false.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • createUser

        public void createUser​(DatabaseQueryContext context,
                               java.lang.String username,
                               java.lang.String password)
                        throws DatabaseException
        Creates and adds a new user to this database. The User object for the user is returned.

        If the user is already defined by the database then an error is generated.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • deleteAllUserGroups

        public void deleteAllUserGroups​(DatabaseQueryContext context,
                                        java.lang.String username)
                                 throws DatabaseException
        Deletes all the groups the user belongs to. This is intended for a user alter command for setting the groups a user belongs to.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • deleteUser

        public void deleteUser​(DatabaseQueryContext context,
                               java.lang.String username)
                        throws DatabaseException
        Deletes the user from the system. This also deletes all information associated with a user such as the groups they belong to. It does not delete the privs a user has set up.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • alterUserPassword

        public void alterUserPassword​(DatabaseQueryContext context,
                                      java.lang.String username,
                                      java.lang.String password)
                               throws DatabaseException
        Alters the password of the user but otherwise does not change any information about the user.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • userBelongsToGroup

        public boolean userBelongsToGroup​(DatabaseQueryContext context,
                                          java.lang.String username,
                                          java.lang.String group)
                                   throws DatabaseException
        Returns true if the given user belongs to the given group otherwise returns false.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • addUserToGroup

        public void addUserToGroup​(DatabaseQueryContext context,
                                   java.lang.String username,
                                   java.lang.String group)
                            throws DatabaseException
        Adds the user to the given group. This makes an entry in the sUSRUserPriv for this user and the given group. If the user already belongs to the group then no changes are made.

        It is important that any security checks for ensuring the grantee is allowed to give the user these privs are preformed before this method is called.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • setUserLock

        public void setUserLock​(DatabaseQueryContext context,
                                User user,
                                boolean lock_status)
                         throws DatabaseException
        Sets the lock status for the given user. If a user account if locked, it is rejected from logging in to the database.

        It is important that any security checks to determine if the process setting the user lock is allowed to do it is done before this method is called.

        NOTE: Assumes exclusive lock on DatabaseConnection.

        Throws:
        DatabaseException
      • grantHostAccessToUser

        public void grantHostAccessToUser​(DatabaseQueryContext context,
                                          java.lang.String user,
                                          java.lang.String protocol,
                                          java.lang.String host)
                                   throws DatabaseException
        Grants the given user access to connect to the database from the given host address. The 'protocol' string is the connecting protocol which can be either 'TCP' or 'Local'. The 'host' string is the actual host that is connecting. For example, if the protocol was TCP then the client host may be '127.0.0.1' for localhost.
        Throws:
        DatabaseException
      • canUserCreateAndDropUsers

        public boolean canUserCreateAndDropUsers​(DatabaseQueryContext context,
                                                 User user)
                                          throws DatabaseException
        Returns true if the user is permitted to create, alter and drop user information from the database, otherwise returns false. Only members of the 'secure access' group, or the 'user manager' group can do this.
        Throws:
        DatabaseException
      • canUserCreateAndDropSchema

        public boolean canUserCreateAndDropSchema​(DatabaseQueryContext context,
                                                  User user,
                                                  java.lang.String schema)
                                           throws DatabaseException
        Returns true if the user is permitted to create and drop schema's in the database, otherwise returns false. Only members of the 'secure access' group, or the 'schema manager' group can do this.
        Throws:
        DatabaseException
      • canUserShutDown

        public boolean canUserShutDown​(DatabaseQueryContext context,
                                       User user)
                                throws DatabaseException
        Returns true if the user can shut down the database server. A user can shut down the database if they are a member of the 'secure acces' group.
        Throws:
        DatabaseException
      • setupSystemFunctions

        public void setupSystemFunctions​(DatabaseConnection connection,
                                         java.lang.String admin_user)
                                  throws DatabaseException
        Sets all the standard functions and procedures available to engine. This creates an entry in the SYS_FUNCTION table for all the dynamic functions and procedures. This may not include the functions exposed though the FunctionFactory interface.
        Throws:
        DatabaseException
      • create

        public void create​(java.lang.String username,
                           java.lang.String password)
        Creates and sets up a new database to an initial empty state. The creation process involves creating all the system tables and views, adding an administrator user account, creating schema, and setting up the initial grant information for the administrator user.

        The 'username' and 'password' parameter given are set for the administrator account.

      • init

        public void init()
                  throws DatabaseException
        Initializes the database. This opens all the files that are required for the operation of the database. If it finds that the version of the data files are not a compatible version, this method throws an exception.

        NOTE: Perhaps a better name for this method is 'open'.

        Throws:
        DatabaseException
      • shutdown

        public void shutdown()
                      throws DatabaseException
        Cleanly shuts down the database. It is important that this method is called just before the system closes down.

        The main purpose of this method is to ensure any tables that are backed by files and in a 'safe' state and cleanly flushed to the file system.

        If 'delete_on_shutdown' is true, the database will delete itself from the file system when it shuts down.

        Throws:
        DatabaseException
      • exists

        public boolean exists()
        Returns true if the database exists. This must be called before 'init' and 'create'. It checks that the database files exist and we can boot into the database.
      • setDeleteOnShutdown

        public final void setDeleteOnShutdown​(boolean status)
        If the 'deleteOnShutdown' flag is set, the database will delete the database from the file system when it is shutdown.

        NOTE: Use with care - if this is set to true and the database is shutdown it will result in total loss of data.

      • isInitialized

        public boolean isInitialized()
        Returns true if the database is initialised.
      • liveCopyTo

        public void liveCopyTo​(java.io.File path)
                        throws java.io.IOException
        Copies all the persistent data in this database (the conglomerate) to the given destination path. This can copy information while the database is 'live'.
        Throws:
        java.io.IOException
      • convertToCurrent

        public boolean convertToCurrent​(java.io.PrintStream out,
                                        java.lang.String admin_username)
                                 throws java.io.IOException
        Functionality for converting and old database format to the existing format. This would typically be called from a convert tool program.

        Returns true if the convert was successful or false if it wasn't (error message is output to the PrintWriter).

        Throws:
        java.io.IOException
      • getDBProcedure

        public DatabaseProcedure getDBProcedure​(java.lang.String procedure_name,
                                                DatabaseConnection connection)
                                         throws DatabaseException
        Resolves a procedure name into a DBProcedure object. This is used for finding a server side script. It throws a DatabaseException if the procedure could not be resolved or there was an error retrieving it.

        ISSUE: Move this to DatabaseSystem?

        Throws:
        DatabaseException
      • getSystem

        public final DatabaseSystem getSystem()
        Returns the DatabaseSystem that this Database is from.
      • storeSystem

        public final com.mckoi.database.StoreSystem storeSystem()
        Returns the StoreSystem for this Database.
      • stats

        public final Stats stats()
        Convenience static for accessing the global Stats object. Perhaps this should be deprecated?
      • Debug

        public final DebugLogger Debug()
        Returns the DebugLogger implementation from the DatabaseSystem.
      • getTriggerManager

        public final com.mckoi.database.TriggerManager getTriggerManager()
        Returns the system trigger manager.
      • getUserManager

        public final UserManager getUserManager()
        Returns the system user manager.
      • createEvent

        public final java.lang.Object createEvent​(java.lang.Runnable runner)
        Creates an event for the database dispatcher.
      • postEvent

        public final void postEvent​(int time,
                                    java.lang.Object event)
        Posts an event on the database dispatcher.
      • getDataCellCache

        public final com.mckoi.database.DataCellCache getDataCellCache()
        Returns the system DataCellCache.
      • hasShutDown

        public final boolean hasShutDown()
        Returns true if the database has shut down.
      • startShutDownThread

        public final void startShutDownThread()
        Starts the shutdown thread which should contain delegates that shut the database and all its resources down. This method returns immediately.
      • waitUntilShutdown

        public final void waitUntilShutdown()
        Blocks until the database has shut down.
      • execute

        public final void execute​(User user,
                                  DatabaseConnection database,
                                  java.lang.Runnable runner)
        Executes database functions from the 'run' method of the given runnable instance on the first available worker thread. All database functions must go through a worker thread. If we ensure this, we can easily stop all database functions from executing if need be. Also, we only need to have a certain number of threads active at any one time rather than a unique thread for each connection.
      • registerShutDownDelegate

        public final void registerShutDownDelegate​(java.lang.Runnable delegate)
        Registers the delegate that is executed when the shutdown thread is activated.
      • setIsExecutingCommands

        public final void setIsExecutingCommands​(boolean status)
        Controls whether the database is allowed to execute commands or not. If this is set to true, then calls to 'execute' will be executed as soon as there is a free worker thread available. Otherwise no commands are executed until this is enabled.
      • getSingleRowTable

        public final Table getSingleRowTable()
        Returns a static table that has a single row but no columns. This table is useful for certain database operations.
      • finalize

        public void finalize()
                      throws java.lang.Throwable
        Overrides:
        finalize in class java.lang.Object
        Throws:
        java.lang.Throwable