001/* 002 * Syncany, www.syncany.org 003 * Copyright (C) 2011-2016 Philipp C. Heckel <philipp.heckel@gmail.com> 004 * 005 * This program is free software: you can redistribute it and/or modify 006 * it under the terms of the GNU General Public License as published by 007 * the Free Software Foundation, either version 3 of the License, or 008 * (at your option) any later version. 009 * 010 * This program is distributed in the hope that it will be useful, 011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 013 * GNU General Public License for more details. 014 * 015 * You should have received a copy of the GNU General Public License 016 * along with this program. If not, see <http://www.gnu.org/licenses/>. 017 */ 018package org.syncany.plugins.transfer.features; 019 020import java.io.File; 021import java.lang.reflect.Constructor; 022import java.lang.reflect.InvocationTargetException; 023import java.util.Map; 024import java.util.logging.Level; 025import java.util.logging.Logger; 026 027import org.syncany.config.Config; 028import org.syncany.plugins.transfer.StorageException; 029import org.syncany.plugins.transfer.StorageTestResult; 030import org.syncany.plugins.transfer.TransferManager; 031import org.syncany.plugins.transfer.files.RemoteFile; 032import org.syncany.util.ReflectionUtil; 033 034/** 035 * <p>The ReadWriteConsistentFeatureTransferManager waits specific amount of time after 036 * {@link #upload(File, RemoteFile)} and {@link #move(RemoteFile, RemoteFile)} operations 037 * because some storage backends do no guarantee that a file immediately exists after 038 * creation. 039 * 040 * <p>It throttles existence check using a simple exponential method:<br> 041 * 042 * <code>throttle(n) = 3 ^ n * 100 ms</code>, with n being the current iteration 043 * 044 * @author Christian Roth (christian.roth@port17.de) 045 */ 046public class ReadAfterWriteConsistentFeatureTransferManager implements FeatureTransferManager { 047 private static final Logger logger = Logger.getLogger(ReadAfterWriteConsistentFeatureTransferManager.class.getSimpleName()); 048 049 private final TransferManager underlyingTransferManager; 050 private final Throttler throttler; 051 private final ReadAfterWriteConsistentFeatureExtension readAfterWriteConsistentFeatureExtension; 052 053 public ReadAfterWriteConsistentFeatureTransferManager(TransferManager originalTransferManager, TransferManager underlyingTransferManager, Config config, ReadAfterWriteConsistent readAfterWriteConsistentAnnotation) { 054 this.underlyingTransferManager = underlyingTransferManager; 055 this.throttler = new Throttler(readAfterWriteConsistentAnnotation.maxRetries(), readAfterWriteConsistentAnnotation.maxWaitTime()); 056 this.readAfterWriteConsistentFeatureExtension = getReadAfterWriteConsistentFeatureExtension(originalTransferManager, readAfterWriteConsistentAnnotation); 057 } 058 059 @SuppressWarnings("unchecked") 060 private ReadAfterWriteConsistentFeatureExtension getReadAfterWriteConsistentFeatureExtension(TransferManager originalTransferManager, ReadAfterWriteConsistent readAfterWriteConsistentAnnotation) { 061 Class<? extends TransferManager> originalTransferManagerClass = originalTransferManager.getClass(); 062 Class<ReadAfterWriteConsistentFeatureExtension> readAfterWriteConsistentFeatureExtensionClass = (Class<ReadAfterWriteConsistentFeatureExtension>) readAfterWriteConsistentAnnotation.extension(); 063 064 try { 065 Constructor<?> constructor = ReflectionUtil.getMatchingConstructorForClass(readAfterWriteConsistentFeatureExtensionClass, originalTransferManagerClass); 066 067 if (constructor != null) { 068 return (ReadAfterWriteConsistentFeatureExtension) constructor.newInstance(originalTransferManager); 069 } 070 071 return readAfterWriteConsistentFeatureExtensionClass.newInstance(); 072 } 073 catch (InvocationTargetException | InstantiationException | IllegalAccessException | NullPointerException e) { 074 throw new RuntimeException("Cannot instantiate ReadWriteConsistentFeatureExtension (perhaps " + readAfterWriteConsistentFeatureExtensionClass + " does not exist?)", e); 075 } 076 } 077 078 @Override 079 public void connect() throws StorageException { 080 underlyingTransferManager.connect(); 081 } 082 083 @Override 084 public void disconnect() throws StorageException { 085 underlyingTransferManager.disconnect(); 086 } 087 088 @Override 089 public void init(final boolean createIfRequired) throws StorageException { 090 underlyingTransferManager.init(createIfRequired); 091 } 092 093 @Override 094 public void download(final RemoteFile remoteFile, final File localFile) throws StorageException { 095 underlyingTransferManager.download(remoteFile, localFile); 096 } 097 098 @Override 099 public void move(final RemoteFile sourceFile, final RemoteFile targetFile) throws StorageException { 100 underlyingTransferManager.move(sourceFile, targetFile); 101 waitForFile(targetFile); 102 } 103 104 @Override 105 public void upload(final File localFile, final RemoteFile remoteFile) throws StorageException { 106 underlyingTransferManager.upload(localFile, remoteFile); 107 waitForFile(remoteFile); 108 } 109 110 @Override 111 public boolean delete(final RemoteFile remoteFile) throws StorageException { 112 return underlyingTransferManager.delete(remoteFile); 113 } 114 115 @Override 116 public <T extends RemoteFile> Map<String, T> list(final Class<T> remoteFileClass) throws StorageException { 117 return underlyingTransferManager.list(remoteFileClass); 118 } 119 120 @Override 121 public String getRemoteFilePath(Class<? extends RemoteFile> remoteFileClass) { 122 return underlyingTransferManager.getRemoteFilePath(remoteFileClass); 123 } 124 125 @Override 126 public StorageTestResult test(boolean testCreateTarget) { 127 return underlyingTransferManager.test(testCreateTarget); 128 } 129 130 @Override 131 public boolean testTargetExists() throws StorageException { 132 return underlyingTransferManager.testTargetExists(); 133 } 134 135 @Override 136 public boolean testTargetCanWrite() throws StorageException { 137 return underlyingTransferManager.testTargetCanWrite(); 138 } 139 140 @Override 141 public boolean testTargetCanCreate() throws StorageException { 142 return underlyingTransferManager.testTargetCanCreate(); 143 } 144 145 @Override 146 public boolean testRepoFileExists() throws StorageException { 147 return underlyingTransferManager.testRepoFileExists(); 148 } 149 150 private void waitForFile(RemoteFile remoteFile) throws StorageException { 151 while (true) { 152 if (readAfterWriteConsistentFeatureExtension.exists(remoteFile)) { 153 logger.log(Level.FINER, remoteFile + " exists on the remote side"); 154 throttler.reset(); 155 break; 156 } 157 158 try { 159 long waitForMs = throttler.next(); 160 logger.log(Level.FINER, "File not found on the remote side, perhaps its in transit, waiting " + waitForMs + "ms ..."); 161 Thread.sleep(waitForMs); 162 } 163 catch (InterruptedException e) { 164 throw new StorageException("Unable to wait anymore", e); 165 } 166 } 167 } 168 169 private class Throttler { 170 private final int maxRetries; 171 private final int maxWait; 172 private int currentIteration = 0; 173 174 public Throttler(int maxRetries, int maxWait) { 175 this.maxRetries = maxRetries; 176 this.maxWait = maxWait; 177 } 178 179 public long next() throws InterruptedException { 180 long waitFor = (long) Math.pow(3, currentIteration++) * 100; 181 182 if (waitFor > maxWait || currentIteration > maxRetries) { 183 throw new InterruptedException("Unable to wait anymore, because ending criteria reached"); 184 } 185 186 return waitFor; 187 } 188 189 public void reset() { 190 currentIteration = 0; 191 } 192 } 193}