001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.fusesource.hawtdb.api; 018 019 import org.fusesource.hawtdb.internal.util.Ranges; 020 021 /** 022 * Handles allocation management of resources. Used for page allocations 023 * in a {@link Paged} resource. 024 * 025 * @author <a href="http://hiramchirino.com">Hiram Chirino</a> 026 */ 027 public interface Allocator { 028 029 /** 030 * Allocates a continuous number of items and returns the position of first item in the sequence. 031 */ 032 public int alloc(int count) throws OutOfSpaceException; 033 034 /** 035 * Frees a given number of items at a given position. 036 */ 037 public void free(int firstPage, int count); 038 039 /** 040 * Undoes a previous free method call. 041 * 042 * optional method. implementations my throw UnsupportedOperationException 043 * @throws UnsupportedOperationException may be thrown by some allocators. 044 */ 045 public void unfree(int firstPage, int count) throws UnsupportedOperationException; 046 047 /** 048 * Frees all previous allocations. 049 * 050 * optional method. implementations my throw UnsupportedOperationException 051 * @throws UnsupportedOperationException 052 */ 053 public void clear() throws UnsupportedOperationException; 054 055 /** 056 * @return the maximum number of pages that this allocator will allocate. 057 */ 058 public int getLimit(); 059 060 /** 061 * @param page 062 * @return true if the page has been allocated. 063 */ 064 public boolean isAllocated(int page); 065 066 /** 067 * 068 */ 069 public void setFreeRanges(Ranges freeList); 070 071 /** 072 * 073 */ 074 public Ranges getFreeRanges(); 075 }