| /** |
| * 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: FreeLogicalRowIdPageManager.java,v 1.1 2000/05/06 00:00:31 boisvert Exp $ |
| */ |
| |
| package jdbm.recman; |
| |
| import java.io.IOException; |
| |
| /** |
| * This class manages free Logical rowid pages and provides methods |
| * to free and allocate Logical rowids on a high level. |
| */ |
| final class FreeLogicalRowIdPageManager { |
| // our record file |
| private RecordFile file; |
| // our page manager |
| private PageManager pageman; |
| |
| /** |
| * Creates a new instance using the indicated record file and |
| * page manager. |
| */ |
| FreeLogicalRowIdPageManager(RecordFile file, |
| PageManager pageman) throws IOException { |
| this.file = file; |
| this.pageman = pageman; |
| } |
| |
| /** |
| * Returns a free Logical rowid, or |
| * null if nothing was found. |
| */ |
| Location get() throws IOException { |
| |
| // Loop through the free Logical rowid list until we find |
| // the first rowid. |
| Location retval = null; |
| PageCursor curs = new PageCursor(pageman, Magic.FREELOGIDS_PAGE); |
| while (curs.next() != 0) { |
| FreeLogicalRowIdPage fp = FreeLogicalRowIdPage |
| .getFreeLogicalRowIdPageView(file.get(curs.getCurrent())); |
| int slot = fp.getFirstAllocated(); |
| if (slot != -1) { |
| // got one! |
| retval = |
| new Location(fp.get(slot)); |
| fp.free(slot); |
| if (fp.getCount() == 0) { |
| // page became empty - free it |
| file.release(curs.getCurrent(), false); |
| pageman.free(Magic.FREELOGIDS_PAGE, curs.getCurrent()); |
| } |
| else |
| file.release(curs.getCurrent(), true); |
| |
| return retval; |
| } |
| else { |
| // no luck, go to next page |
| file.release(curs.getCurrent(), false); |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Puts the indicated rowid on the free list |
| */ |
| void put(Location rowid) |
| throws IOException { |
| |
| PhysicalRowId free = null; |
| PageCursor curs = new PageCursor(pageman, Magic.FREELOGIDS_PAGE); |
| long freePage = 0; |
| while (curs.next() != 0) { |
| freePage = curs.getCurrent(); |
| BlockIo curBlock = file.get(freePage); |
| FreeLogicalRowIdPage fp = FreeLogicalRowIdPage |
| .getFreeLogicalRowIdPageView(curBlock); |
| int slot = fp.getFirstFree(); |
| if (slot != -1) { |
| free = fp.alloc(slot); |
| break; |
| } |
| |
| file.release(curBlock); |
| } |
| if (free == null) { |
| // No more space on the free list, add a page. |
| freePage = pageman.allocate(Magic.FREELOGIDS_PAGE); |
| BlockIo curBlock = file.get(freePage); |
| FreeLogicalRowIdPage fp = |
| FreeLogicalRowIdPage.getFreeLogicalRowIdPageView(curBlock); |
| free = fp.alloc(0); |
| } |
| free.setBlock(rowid.getBlock()); |
| free.setOffset(rowid.getOffset()); |
| file.release(freePage, true); |
| } |
| } |