1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.hadoop.hbase.regionserver; 20 21 import java.io.IOException; 22 23 import org.apache.hadoop.classification.InterfaceAudience; 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 @InterfaceAudience.Private 32 interface StoreFlusher { 33 34 /** 35 * Prepare for a store flush (create snapshot) 36 * 37 * Requires pausing writes. 38 * 39 * A very short operation. 40 */ 41 void prepare(); 42 43 /** 44 * Flush the cache (create the new store file) 45 * 46 * A length operation which doesn't require locking out any function 47 * of the store. 48 * 49 * @throws IOException in case the flush fails 50 */ 51 void flushCache(MonitoredTask status) throws IOException; 52 53 /** 54 * Commit the flush - add the store file to the store and clear the 55 * memstore snapshot. 56 * 57 * Requires pausing scans. 58 * 59 * A very short operation 60 * 61 * @return 62 * @throws IOException 63 */ 64 boolean commit(MonitoredTask status) throws IOException; 65 }