| /* Copyright (c) 2001-2010, The HSQL Development Group |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are met: |
| * |
| * Redistributions of source code must retain the above copyright notice, this |
| * list of conditions and the following disclaimer. |
| * |
| * 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. |
| * |
| * Neither the name of the HSQL Development Group nor the names of its |
| * contributors may be used to endorse or promote products derived from this |
| * software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| * AND ANY EXPRESS 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 HSQL DEVELOPMENT GROUP, HSQLDB.ORG, |
| * OR 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. |
| */ |
| |
| |
| package org.hsqldb.persist; |
| |
| import org.hsqldb.lib.DoubleIntIndex; |
| |
| /** |
| * Maintains a list of free file blocks with fixed capacity.<p> |
| * |
| * @author Fred Toussi (fredt@users dot sourceforge.net) |
| * @version 1.8.0 |
| * @since 1.8.0 |
| */ |
| public class DataFileBlockManager { |
| |
| private DoubleIntIndex lookup; |
| private final int capacity; |
| private int midSize; |
| private final int scale; |
| private long releaseCount; |
| private long requestCount; |
| private long requestSize; |
| |
| // reporting vars |
| long lostFreeBlockSize; |
| boolean isModified; |
| |
| /** |
| * |
| */ |
| public DataFileBlockManager(int capacity, int scale, long lostSize) { |
| |
| lookup = new DoubleIntIndex(capacity, true); |
| |
| lookup.setValuesSearchTarget(); |
| |
| this.capacity = capacity; |
| this.scale = scale; |
| this.lostFreeBlockSize = lostSize; |
| this.midSize = 128; // arbitrary initial value |
| } |
| |
| /** |
| */ |
| void add(int pos, int rowSize) { |
| |
| isModified = true; |
| |
| if (capacity == 0) { |
| lostFreeBlockSize += rowSize; |
| |
| return; |
| } |
| |
| releaseCount++; |
| |
| // |
| if (lookup.size() == capacity) { |
| resetList(); |
| } |
| |
| lookup.add(pos, rowSize); |
| } |
| |
| /** |
| * Returns the position of a free block or 0. |
| */ |
| int get(int rowSize) { |
| |
| if (lookup.size() == 0) { |
| return -1; |
| } |
| |
| int index = lookup.findFirstGreaterEqualKeyIndex(rowSize); |
| |
| if (index == -1) { |
| return -1; |
| } |
| |
| // statistics for successful requests only - to be used later for midSize |
| requestCount++; |
| |
| requestSize += rowSize; |
| |
| int length = lookup.getValue(index); |
| int difference = length - rowSize; |
| int key = lookup.getKey(index); |
| |
| lookup.remove(index); |
| |
| if (difference >= midSize) { |
| int pos = key + (rowSize / scale); |
| |
| lookup.add(pos, difference); |
| } else { |
| lostFreeBlockSize += difference; |
| } |
| |
| return key; |
| } |
| |
| int size() { |
| return lookup.size(); |
| } |
| |
| long getLostBlocksSize() { |
| return lostFreeBlockSize; |
| } |
| |
| boolean isModified() { |
| return isModified; |
| } |
| |
| void clear() { |
| removeBlocks(lookup.size()); |
| } |
| |
| private void resetList() { |
| |
| if (requestCount != 0) { |
| midSize = (int) (requestSize / requestCount); |
| } |
| |
| int first = lookup.findFirstGreaterEqualSlotIndex(midSize); |
| |
| if (first < lookup.size() / 4) { |
| first = lookup.size() / 4; |
| } |
| |
| removeBlocks(first); |
| } |
| |
| private void removeBlocks(int blocks) { |
| |
| for (int i = 0; i < blocks; i++) { |
| lostFreeBlockSize += lookup.getValue(i); |
| } |
| |
| lookup.removeRange(0, blocks); |
| } |
| |
| private void checkIntegrity() throws NullPointerException {} |
| } |