| /** |
| * JDBM LICENSE v1.00 |
| * |
| * Redistribution and use of this software and associated documentation |
| * ("Software"), with or without modification, are permitted provided |
| * that the following conditions are met: |
| * |
| * 1. Redistributions of source code must retain copyright |
| * statements and notices. Redistributions must also contain a |
| * copy of this document. |
| * |
| * 2. 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. |
| * |
| * 3. The name "JDBM" must not be used to endorse or promote |
| * products derived from this Software without prior written |
| * permission of Cees de Groot. For written permission, |
| * please contact cg@cdegroot.com. |
| * |
| * 4. Products derived from this Software may not be called "JDBM" |
| * nor may "JDBM" appear in their names without prior written |
| * permission of Cees de Groot. |
| * |
| * 5. Due credit should be given to the JDBM Project |
| * (http://jdbm.sourceforge.net/). |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS |
| * ``AS IS'' AND ANY EXPRESSED 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 |
| * CEES DE GROOT OR ANY 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. |
| * |
| * Copyright 2000 (C) Cees de Groot. All Rights Reserved. |
| * Contributions are Copyright (C) 2000 by their associated contributors. |
| * |
| * $Id: RecordHeader.java,v 1.1 2000/05/06 00:00:31 boisvert Exp $ |
| */ |
| |
| package jdbm.recman; |
| |
| /** |
| * The data that comes at the start of a record of data. It stores |
| * both the current size and the avaliable size for the record - the latter |
| * can be bigger than the former, which allows the record to grow without |
| * needing to be moved and which allows the system to put small records |
| * in larger free spots. |
| */ |
| class RecordHeader { |
| // offsets |
| private static final short O_CURRENTSIZE = 0; // int currentSize |
| private static final short O_AVAILABLESIZE = Magic.SZ_INT; // int availableSize |
| static final int SIZE = O_AVAILABLESIZE + Magic.SZ_INT; |
| |
| // my block and the position within the block |
| private BlockIo block; |
| private short pos; |
| |
| /** |
| * Constructs a record header from the indicated data starting at |
| * the indicated position. |
| */ |
| RecordHeader(BlockIo block, short pos) { |
| this.block = block; |
| this.pos = pos; |
| if (pos > (RecordFile.BLOCK_SIZE - SIZE)) |
| throw new Error("Offset too large for record header (" |
| + block.getBlockId() + ":" |
| + pos + ")"); |
| } |
| |
| /** Returns the current size */ |
| int getCurrentSize() { |
| return block.readInt(pos + O_CURRENTSIZE); |
| } |
| |
| /** Sets the current size */ |
| void setCurrentSize(int value) { |
| block.writeInt(pos + O_CURRENTSIZE, value); |
| } |
| |
| /** Returns the available size */ |
| int getAvailableSize() { |
| return block.readInt(pos + O_AVAILABLESIZE); |
| } |
| |
| /** Sets the available size */ |
| void setAvailableSize(int value) { |
| block.writeInt(pos + O_AVAILABLESIZE, value); |
| } |
| |
| // overrides java.lang.Object |
| public String toString() { |
| return "RH(" + block.getBlockId() + ":" + pos |
| + ", avl=" + getAvailableSize() |
| + ", cur=" + getCurrentSize() |
| + ")"; |
| } |
| } |