session.java

hsql是很有名的嵌入式数据库

            table.removeRowFromStore(row);
        }

        return false;
    }

    /**
     *  Adds a single-row inssertion step to the transaction UNDO buffer.
     *
     * @param  table the table into which the row was inserted
     * @param  row the inserted row
     * @throws  HsqlException
     */
    boolean addTransactionInsert(Table table, Row row) throws HsqlException {

        if (!isAutoCommit || isNestedTransaction) {
            Transaction t = new Transaction(false, table, row, sessionSCN);

            transactionList.add(t);
            database.txManager.addTransaction(this, t);

            return true;
        } else {
            table.commitRowToStore(row);
        }

        return false;
    }

    /**
     *  Setter for the autocommit attribute.
     *
     * @param  autocommit the new value
     * @throws  HsqlException
     */
    public void setAutoCommit(boolean autocommit) {

        if (isClosed) {
            return;
        }

        synchronized (database) {
            if (autocommit != isAutoCommit) {
                commit();

                isAutoCommit = autocommit;

                try {
                    database.logger.writeToLog(this,
                                               getAutoCommitStatement());
                } catch (HsqlException e) {}
            }
        }
    }

    /**
     * Commits any uncommited transaction this Session may have open
     *
     * @throws  HsqlException
     */
    public void commit() {

        if (isClosed) {
            return;
        }

        synchronized (database) {
            if (!transactionList.isEmpty()) {
                try {
                    database.logger.writeCommitStatement(this);
                } catch (HsqlException e) {}
            }

            database.txManager.commit(this);
            clearIndexRoots();
        }
    }

    /**
     * Rolls back any uncommited transaction this Session may have open.
     *
     * @throws  HsqlException
     */
    public void rollback() {

        if (isClosed) {
            return;
        }

        synchronized (database) {
            if (transactionList.size() != 0) {
                try {
                    database.logger.writeToLog(this, Token.T_ROLLBACK);
                } catch (HsqlException e) {}
            }

            database.txManager.rollback(this);
            clearIndexRoots();
        }
    }

    /**
     * No-op in this implementation
     */
    public void resetSession() throws HsqlException {
        throw new HsqlException("", "", 0);
    }

    /**
     *  Implements a transaction SAVEPOINT. A new SAVEPOINT with the
     *  name of an existing one replaces the old SAVEPOINT.
     *
     * @param  name of the savepoint
     * @throws  HsqlException if there is no current transaction
     */
    void savepoint(String name) throws HsqlException {

        savepoints.remove(name);
        savepoints.add(name, ValuePool.getInt(transactionList.size()));

        try {
            database.logger.writeToLog(this, Token.T_SAVEPOINT + " " + name);
        } catch (HsqlException e) {}
    }

    /**
     *  Implements a partial transaction ROLLBACK.
     *
     * @param  name Name of savepoint that was marked before by savepoint()
     *      call
     * @throws  HsqlException
     */
    void rollbackToSavepoint(String name) throws HsqlException {

        if (isClosed) {
            return;
        }

        try {
            database.logger.writeToLog(this,
                                       Token.T_ROLLBACK + " " + Token.T_TO
                                       + " " + Token.T_SAVEPOINT + " "
                                       + name);
        } catch (HsqlException e) {}

        database.txManager.rollbackSavepoint(this, name);
    }

    /**
     * Implements release of named SAVEPOINT.
     *
     * @param  name Name of savepoint that was marked before by savepoint()
     *      call
     * @throws  HsqlException if name does not correspond to a savepoint
     */
    void releaseSavepoint(String name) throws HsqlException {

        // remove this and all later savepoints
        int index = savepoints.getIndex(name);

        Trace.check(index >= 0, Trace.SAVEPOINT_NOT_FOUND, name);

        while (savepoints.size() > index) {
            savepoints.remove(savepoints.size() - 1);
        }
    }

    /**
     * Starts a nested transaction.
     *
     * @throws  HsqlException
     */
    void beginNestedTransaction() throws HsqlException {

        if (isNestedTransaction) {
            Trace.doAssert(false, "beginNestedTransaction");
        }

        nestedOldTransIndex = transactionList.size();
        isNestedTransaction = true;
    }

    /**
     * @todo -- fredt 20050604 - if this method is called after an out of memory
     * error during update, the next block might throw out of memory too and as
     * a result inNestedTransaction remains true and no further update
     * is possible. The session must be closed at that point by the user
     * application.
     */

    /**
     * Ends a nested transaction.
     *
     * @param  rollback true to roll back or false to commit the nested transaction
     * @throws  HsqlException
     */
    void endNestedTransaction(boolean rollback) throws HsqlException {

        if (!isNestedTransaction) {
            Trace.doAssert(false, "endNestedTransaction");
        }

        if (rollback) {
            database.txManager.rollbackTransactions(this,
                    nestedOldTransIndex, true);
        }

        // reset after the rollback
        isNestedTransaction = false;

        if (isAutoCommit == true) {
            database.txManager.commit(this);
        }
    }

    /**
     * Setter for readonly attribute.
     *
     * @param  readonly the new value
     */
    public void setReadOnly(boolean readonly) throws HsqlException {

        if (!readonly && database.databaseReadOnly) {
            throw Trace.error(Trace.DATABASE_IS_READONLY);
        }

        isReadOnly = readonly;
    }

    /**
     *  Getter for readonly attribute.
     *
     * @return the current value
     */
    public boolean isReadOnly() {
        return isReadOnly;
    }

    /**
     *  Getter for nestedTransaction attribute.
     *
     * @return the current value
     */
    boolean isNestedTransaction() {
        return isNestedTransaction;
    }

    /**
     *  Getter for autoCommit attribute.
     *
     * @return the current value
     */
    public boolean isAutoCommit() {
        return isAutoCommit;
    }

    /**
     *  A switch to set scripting on the basis of type of statement executed.
     *  A method in DatabaseCommandInterpreter.java sets this value to false
     *  before other  methods are called to act on an SQL statement, which may
     *  set this to true. Afterwards the method reponsible for logging uses
     *  getScripting() to determine if logging is required for the executed
     *  statement. (fredt@users)
     *
     * @param  script The new scripting value
     */
    void setScripting(boolean script) {
        this.script = script;
    }

    /**
     * Getter for scripting attribute.
     *
     * @return  scripting for the last statement.
     */
    boolean getScripting() {
        return script;
    }

    public String getAutoCommitStatement() {
        return isAutoCommit ? "SET AUTOCOMMIT TRUE"
                            : "SET AUTOCOMMIT FALSE";
    }

    /**
     * Retrieves an internal Connection object equivalent to the one
     * that created this Session.
     *
     * @return  internal connection.
     */
    jdbcConnection getInternalConnection() throws HsqlException {

        if (intConnection == null) {
            intConnection = new jdbcConnection(this);
        }

        return intConnection;
    }

// boucherb@users 20020810 metadata 1.7.2
//----------------------------------------------------------------
    private final long connectTime = System.currentTimeMillis();

// more effecient for MetaData concerns than checkAdmin

    /**
     * Getter for admin attribute.
     *
     * @ return the current value
     */
    boolean isAdmin() {
        return user.isAdmin();
    }

    /**
     * Getter for connectTime attribute.
     *
     * @return the value
     */
    long getConnectTime() {
        return connectTime;
    }

    /**
     * Getter for transactionSise attribute.
     *
     * @return the current value
     */
    int getTransactionSize() {
        return transactionList.size();
    }

    /**
     * Retrieves whether the database object identifier by the dbobject
     * argument is accessible by the current Session User.
     *
     * @return true if so, else false
     */
    boolean isAccessible(Object dbobject) throws HsqlException {
        return user.isAccessible(dbobject);
    }

// boucherb@users 20030417 - patch 1.7.2 - compiled statement support
//-------------------------------------------------------------------
    DatabaseCommandInterpreter dbCommandInterpreter;
    CompiledStatementExecutor  compiledStatementExecutor;
    CompiledStatementManager   compiledStatementManager;

    private CompiledStatement sqlCompileStatement(String sql)
    throws HsqlException {

        parser.reset(sql);

        CompiledStatement cs;
        int               brackets = 0;
        String            token    = tokenizer.getString();
        int               cmd      = Token.get(token);

        switch (cmd) {

            case Token.OPENBRACKET : {
                brackets = Parser.parseOpenBrackets(tokenizer) + 1;

                tokenizer.getThis(Token.T_SELECT);
            }
            case Token.SELECT : {
                cs = parser.compileSelectStatement(brackets);

                break;
            }
            case Token.INSERT : {
                cs = parser.compileInsertStatement();

                break;
            }
            case Token.UPDATE : {
                cs = parser.compileUpdateStatement();

                break;
            }
            case Token.DELETE : {
                cs = parser.compileDeleteStatement();

                break;
            }
            case Token.CALL : {
                cs = parser.compileCallStatement();

                break;
            }
            default : {