1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache license, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the license for the specific language governing permissions and 15 * limitations under the license. 16 */ 17 18 package org.apache.logging.log4j.core.appender.db; 19 20 import java.io.Flushable; 21 import java.util.ArrayList; 22 23 import org.apache.logging.log4j.core.LogEvent; 24 import org.apache.logging.log4j.core.appender.AbstractManager; 25 import org.apache.logging.log4j.core.appender.ManagerFactory; 26 27 /** 28 * Manager that allows database appenders to have their configuration reloaded without losing events. 29 */ 30 public abstract class AbstractDatabaseManager extends AbstractManager implements Flushable { 31 private final ArrayList<LogEvent> buffer; 32 private final int bufferSize; 33 34 private boolean running = false; 35 36 /** 37 * Instantiates the base manager. 38 * 39 * @param name The manager name, which should include any configuration details that one might want to be able to 40 * reconfigure at runtime, such as database name, username, (hashed) password, etc. 41 * @param bufferSize The size of the log event buffer. 42 */ 43 protected AbstractDatabaseManager(final String name, final int bufferSize) { 44 super(name); 45 this.bufferSize = bufferSize; 46 this.buffer = new ArrayList<>(bufferSize + 1); 47 } 48 49 /** 50 * Implementations should implement this method to perform any proprietary startup operations. This method will 51 * never be called twice on the same instance. It is safe to throw any exceptions from this method. This method 52 * does not necessarily connect to the database, as it is generally unreliable to connect once and use the same 53 * connection for hours. 54 */ 55 protected abstract void startupInternal() throws Exception; 56 57 /** 58 * This method is called within the appender when the appender is started. If it has not already been called, it 59 * calls {@link #startupInternal()} and catches any exceptions it might throw. 60 */ 61 public final synchronized void startup() { 62 if (!this.isRunning()) { 63 try { 64 this.startupInternal(); 65 this.running = true; 66 } catch (final Exception e) { 67 logError("could not perform database startup operations", e); 68 } 69 } 70 } 71 72 /** 73 * Implementations should implement this method to perform any proprietary disconnection / shutdown operations. This 74 * method will never be called twice on the same instance, and it will only be called <em>after</em> 75 * {@link #startupInternal()}. It is safe to throw any exceptions from this method. This method does not 76 * necessarily disconnect from the database for the same reasons outlined in {@link #startupInternal()}. 77 */ 78 protected abstract void shutdownInternal() throws Exception; 79 80 /** 81 * This method is called from the {@link #release()} method when the appender is stopped or the appender's manager 82 * is replaced. If it has not already been called, it calls {@link #shutdownInternal()} and catches any exceptions 83 * it might throw. 84 */ 85 public final synchronized void shutdown() { 86 this.flush(); 87 if (this.isRunning()) { 88 try { 89 this.shutdownInternal(); 90 } catch (final Exception e) { 91 logWarn("caught exception while performing database shutdown operations", e); 92 } finally { 93 this.running = false; 94 } 95 } 96 } 97 98 /** 99 * Indicates whether the manager is currently connected {@link #startup()} has been called and {@link #shutdown()} 100 * has not been called). 101 * 102 * @return {@code true} if the manager is connected. 103 */ 104 public final boolean isRunning() { 105 return this.running; 106 } 107 108 /** 109 * Connects to the database and starts a transaction (if applicable). With buffering enabled, this is called when 110 * flushing the buffer begins, before the first call to {@link #writeInternal}. With buffering disabled, this is 111 * called immediately before every invocation of {@link #writeInternal}. 112 */ 113 protected abstract void connectAndStart(); 114 115 /** 116 * Performs the actual writing of the event in an implementation-specific way. This method is called immediately 117 * from {@link #write(LogEvent)} if buffering is off, or from {@link #flush()} if the buffer has reached its limit. 118 * 119 * @param event The event to write to the database. 120 */ 121 protected abstract void writeInternal(LogEvent event); 122 123 /** 124 * Commits any active transaction (if applicable) and disconnects from the database (returns the connection to the 125 * connection pool). With buffering enabled, this is called when flushing the buffer completes, after the last call 126 * to {@link #writeInternal}. With buffering disabled, this is called immediately after every invocation of 127 * {@link #writeInternal}. 128 */ 129 protected abstract void commitAndClose(); 130 131 /** 132 * This method is called automatically when the buffer size reaches its maximum or at the beginning of a call to 133 * {@link #shutdown()}. It can also be called manually to flush events to the database. 134 */ 135 @Override 136 public final synchronized void flush() { 137 if (this.isRunning() && this.buffer.size() > 0) { 138 this.connectAndStart(); 139 try { 140 for (final LogEvent event : this.buffer) { 141 this.writeInternal(event); 142 } 143 } finally { 144 this.commitAndClose(); 145 // not sure if this should be done when writing the events failed 146 this.buffer.clear(); 147 } 148 } 149 } 150 151 /** 152 * This method manages buffering and writing of events. 153 * 154 * @param event The event to write to the database. 155 */ 156 public final synchronized void write(final LogEvent event) { 157 if (this.bufferSize > 0) { 158 this.buffer.add(event); 159 if (this.buffer.size() >= this.bufferSize || event.isEndOfBatch()) { 160 this.flush(); 161 } 162 } else { 163 this.connectAndStart(); 164 try { 165 this.writeInternal(event); 166 } finally { 167 this.commitAndClose(); 168 } 169 } 170 } 171 172 @Override 173 public final void releaseSub() { 174 this.shutdown(); 175 } 176 177 @Override 178 public final String toString() { 179 return this.getName(); 180 } 181 182 /** 183 * Implementations should define their own getManager method and call this method from that to create or get 184 * existing managers. 185 * 186 * @param name The manager name, which should include any configuration details that one might want to be able to 187 * reconfigure at runtime, such as database name, username, (hashed) password, etc. 188 * @param data The concrete instance of {@link AbstractFactoryData} appropriate for the given manager. 189 * @param factory A factory instance for creating the appropriate manager. 190 * @param <M> The concrete manager type. 191 * @param <T> The concrete {@link AbstractFactoryData} type. 192 * @return a new or existing manager of the specified type and name. 193 */ 194 protected static <M extends AbstractDatabaseManager, T extends AbstractFactoryData> M getManager( 195 final String name, final T data, final ManagerFactory<M, T> factory 196 ) { 197 return AbstractManager.getManager(name, factory, data); 198 } 199 200 /** 201 * Implementations should extend this class for passing data between the getManager method and the manager factory 202 * class. 203 */ 204 protected abstract static class AbstractFactoryData { 205 private final int bufferSize; 206 207 /** 208 * Constructs the base factory data. 209 * 210 * @param bufferSize The size of the buffer. 211 */ 212 protected AbstractFactoryData(final int bufferSize) { 213 this.bufferSize = bufferSize; 214 } 215 216 /** 217 * Gets the buffer size. 218 * 219 * @return the buffer size. 220 */ 221 public int getBufferSize() { 222 return bufferSize; 223 } 224 } 225 }