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 import org.apache.hadoop.hbase.monitoring.MonitoredTask; 25 26 /** 27 * A package protected interface for a store flushing. 28 * A store flusher carries the state required to prepare/flush/commit the 29 * store's cache. 30 */ 31 interface StoreFlusher { 32 33 /** 34 * Prepare for a store flush (create snapshot) 35 * 36 * Requires pausing writes. 37 * 38 * A very short operation. 39 */ 40 void prepare(); 41 42 /** 43 * Flush the cache (create the new store file) 44 * 45 * A length operation which doesn't require locking out any function 46 * of the store. 47 * 48 * @throws IOException in case the flush fails 49 */ 50 void flushCache(MonitoredTask status) throws IOException; 51 52 /** 53 * Commit the flush - add the store file to the store and clear the 54 * memstore snapshot. 55 * 56 * Requires pausing scans. 57 * 58 * A very short operation 59 * 60 * @return 61 * @throws IOException 62 */ 63 boolean commit(MonitoredTask status) throws IOException; 64 }