1 /* 2 * Copyright 2010 The Apache Software Foundation 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, 15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 package org.apache.hadoop.hbase.regionserver; 21 22 import java.io.IOException; 23 24 /** 25 * A package protected interface for a store flushing. 26 * A store flusher carries the state required to prepare/flush/commit the 27 * store's cache. 28 */ 29 interface StoreFlusher { 30 31 /** 32 * Prepare for a store flush (create snapshot) 33 * 34 * Requires pausing writes. 35 * 36 * A very short operation. 37 */ 38 void prepare(); 39 40 /** 41 * Flush the cache (create the new store file) 42 * 43 * A length operation which doesn't require locking out any function 44 * of the store. 45 * 46 * @throws IOException in case the flush fails 47 */ 48 void flushCache() throws IOException; 49 50 /** 51 * Commit the flush - add the store file to the store and clear the 52 * memstore snapshot. 53 * 54 * Requires pausing scans. 55 * 56 * A very short operation 57 * 58 * @return 59 * @throws IOException 60 */ 61 boolean commit() throws IOException; 62 }