Carmelo Cascone | 37d5dbf | 2016-04-18 15:15:48 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2016-present Open Networking Laboratory |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | /* |
| 18 | * Most of the code of this class was copied from: |
| 19 | * http://liveramp.com/engineering/reconnecting-thrift-client/ |
| 20 | */ |
| 21 | |
| 22 | package org.onosproject.bmv2.ctl; |
| 23 | |
| 24 | import com.google.common.collect.ImmutableSet; |
| 25 | import org.apache.thrift.TServiceClient; |
| 26 | import org.apache.thrift.transport.TTransport; |
| 27 | import org.apache.thrift.transport.TTransportException; |
| 28 | import org.slf4j.Logger; |
| 29 | import org.slf4j.LoggerFactory; |
| 30 | |
| 31 | import java.lang.reflect.InvocationHandler; |
| 32 | import java.lang.reflect.InvocationTargetException; |
| 33 | import java.lang.reflect.Method; |
| 34 | import java.lang.reflect.Proxy; |
| 35 | import java.util.Set; |
| 36 | |
| 37 | /** |
| 38 | * Thrift client wrapper that attempts a few reconnects before giving up a method call execution. It al provides |
| 39 | * synchronization between calls (automatically serialize multiple calls to the same client from different threads). |
| 40 | */ |
| 41 | public final class SafeThriftClient { |
| 42 | |
| 43 | private static final Logger LOG = LoggerFactory.getLogger(SafeThriftClient.class); |
| 44 | |
| 45 | /** |
| 46 | * List of causes which suggest a restart might fix things (defined as constants in {@link TTransportException}). |
| 47 | */ |
| 48 | private static final Set<Integer> RESTARTABLE_CAUSES = ImmutableSet.of(TTransportException.NOT_OPEN, |
| 49 | TTransportException.END_OF_FILE, |
| 50 | TTransportException.TIMED_OUT, |
| 51 | TTransportException.UNKNOWN); |
| 52 | |
| 53 | private SafeThriftClient() { |
| 54 | // ban constructor. |
| 55 | } |
| 56 | |
| 57 | /** |
| 58 | * Reflectively wraps an already existing Thrift client. |
| 59 | * |
| 60 | * @param baseClient the client to wrap |
| 61 | * @param clientInterface the interface that the client implements |
| 62 | * @param options options that control behavior of the reconnecting client |
| 63 | * @param <T> |
| 64 | * @param <C> |
| 65 | * @return |
| 66 | */ |
| 67 | public static <T extends TServiceClient, C> C wrap(T baseClient, Class<C> clientInterface, Options options) { |
| 68 | Object proxyObject = Proxy.newProxyInstance(clientInterface.getClassLoader(), |
| 69 | new Class<?>[]{clientInterface}, |
| 70 | new ReconnectingClientProxy<T>(baseClient, |
| 71 | options.getNumRetries(), |
| 72 | options.getTimeBetweenRetries())); |
| 73 | |
| 74 | return (C) proxyObject; |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * Reflectively wraps an already existing Thrift client. |
| 79 | * |
| 80 | * @param baseClient the client to wrap |
| 81 | * @param options options that control behavior of the reconnecting client |
| 82 | * @param <T> |
| 83 | * @param <C> |
| 84 | * @return |
| 85 | */ |
| 86 | public static <T extends TServiceClient, C> C wrap(T baseClient, Options options) { |
| 87 | Class<?>[] interfaces = baseClient.getClass().getInterfaces(); |
| 88 | |
| 89 | for (Class<?> iface : interfaces) { |
| 90 | if (iface.getSimpleName().equals("Iface") |
| 91 | && iface.getEnclosingClass().equals(baseClient.getClass().getEnclosingClass())) { |
| 92 | return (C) wrap(baseClient, iface, options); |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | throw new RuntimeException("Class needs to implement Iface directly. Use wrap(TServiceClient, Class) instead."); |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Reflectively wraps an already existing Thrift client. |
| 101 | * |
| 102 | * @param baseClient the client to wrap |
| 103 | * @param clientInterface the interface that the client implements |
| 104 | * @param <T> |
| 105 | * @param <C> |
| 106 | * @return |
| 107 | */ |
| 108 | public static <T extends TServiceClient, C> C wrap(T baseClient, Class<C> clientInterface) { |
| 109 | return wrap(baseClient, clientInterface, Options.defaults()); |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Reflectively wraps an already existing Thrift client. |
| 114 | * |
| 115 | * @param baseClient the client to wrap |
| 116 | * @param <T> |
| 117 | * @param <C> |
| 118 | * @return |
| 119 | */ |
| 120 | public static <T extends TServiceClient, C> C wrap(T baseClient) { |
| 121 | return wrap(baseClient, Options.defaults()); |
| 122 | } |
| 123 | |
| 124 | /** |
| 125 | * Reconnection options for {@link SafeThriftClient}. |
| 126 | */ |
| 127 | public static class Options { |
| 128 | private int numRetries; |
| 129 | private long timeBetweenRetries; |
| 130 | |
| 131 | /** |
| 132 | * Creates new options with the given parameters. |
| 133 | * |
| 134 | * @param numRetries the maximum number of times to try reconnecting before giving up and throwing an |
| 135 | * exception |
| 136 | * @param timeBetweenRetries the number of milliseconds to wait in between reconnection attempts. |
| 137 | */ |
| 138 | public Options(int numRetries, long timeBetweenRetries) { |
| 139 | this.numRetries = numRetries; |
| 140 | this.timeBetweenRetries = timeBetweenRetries; |
| 141 | } |
| 142 | |
| 143 | private static Options defaults() { |
| 144 | return new Options(5, 10000L); |
| 145 | } |
| 146 | |
| 147 | private int getNumRetries() { |
| 148 | return numRetries; |
| 149 | } |
| 150 | |
| 151 | private long getTimeBetweenRetries() { |
| 152 | return timeBetweenRetries; |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * Helper proxy class. Attempts to call method on proxy object wrapped in try/catch. If it fails, it attempts a |
| 158 | * reconnect and tries the method again. |
| 159 | * |
| 160 | * @param <T> |
| 161 | */ |
| 162 | private static class ReconnectingClientProxy<T extends TServiceClient> implements InvocationHandler { |
| 163 | private final T baseClient; |
| 164 | private final int maxRetries; |
| 165 | private final long timeBetweenRetries; |
| 166 | |
| 167 | public ReconnectingClientProxy(T baseClient, int maxRetries, long timeBetweenRetries) { |
| 168 | this.baseClient = baseClient; |
| 169 | this.maxRetries = maxRetries; |
| 170 | this.timeBetweenRetries = timeBetweenRetries; |
| 171 | } |
| 172 | |
| 173 | private static void reconnectOrThrowException(TTransport transport, int maxRetries, long timeBetweenRetries) |
| 174 | throws TTransportException { |
| 175 | int errors = 0; |
| 176 | transport.close(); |
| 177 | |
| 178 | while (errors < maxRetries) { |
| 179 | try { |
| 180 | LOG.debug("Attempting to reconnect..."); |
| 181 | transport.open(); |
| 182 | LOG.debug("Reconnection successful"); |
| 183 | break; |
| 184 | } catch (TTransportException e) { |
| 185 | LOG.error("Error while reconnecting:", e); |
| 186 | errors++; |
| 187 | |
| 188 | if (errors < maxRetries) { |
| 189 | try { |
| 190 | LOG.debug("Sleeping for {} milliseconds before retrying", timeBetweenRetries); |
| 191 | Thread.sleep(timeBetweenRetries); |
| 192 | } catch (InterruptedException e2) { |
| 193 | Thread.currentThread().interrupt(); |
| 194 | throw new RuntimeException(e); |
| 195 | } |
| 196 | } |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | if (errors >= maxRetries) { |
| 201 | throw new TTransportException("Failed to reconnect"); |
| 202 | } |
| 203 | } |
| 204 | |
| 205 | @Override |
| 206 | public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { |
| 207 | |
| 208 | // With Thrift clients must be instantiated for each different transport session, i.e. server instance. |
| 209 | // Hence, using baseClient as lock, only calls towards the same server will be synchronized. |
| 210 | |
| 211 | synchronized (baseClient) { |
| 212 | |
| 213 | LOG.debug("Invoking client method... > method={}, fromThread={}", |
| 214 | method.getName(), Thread.currentThread().getId()); |
| 215 | |
| 216 | Object result = null; |
| 217 | |
| 218 | try { |
| 219 | result = method.invoke(baseClient, args); |
| 220 | |
| 221 | } catch (InvocationTargetException e) { |
| 222 | if (e.getTargetException() instanceof TTransportException) { |
| 223 | TTransportException cause = (TTransportException) e.getTargetException(); |
| 224 | |
| 225 | if (RESTARTABLE_CAUSES.contains(cause.getType())) { |
| 226 | reconnectOrThrowException(baseClient.getInputProtocol().getTransport(), |
| 227 | maxRetries, |
| 228 | timeBetweenRetries); |
| 229 | result = method.invoke(baseClient, args); |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | if (result == null) { |
| 234 | LOG.debug("Exception while invoking client method: {} > method={}, fromThread={}", |
| 235 | e, method.getName(), Thread.currentThread().getId()); |
| 236 | throw e.getTargetException(); |
| 237 | } |
| 238 | } |
| 239 | |
| 240 | LOG.debug("Method invoke complete! > method={}, fromThread={}", |
| 241 | method.getName(), Thread.currentThread().getId()); |
| 242 | |
| 243 | return result; |
| 244 | } |
| 245 | } |
| 246 | } |
| 247 | } |