1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.io;
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3 |
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4 | import java.io.File;
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5 | import java.io.IOException;
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6 | import java.nio.file.FileSystems;
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7 | import java.nio.file.Path;
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8 | import java.nio.file.StandardWatchEventKinds;
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9 | import java.nio.file.WatchEvent;
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10 | import java.nio.file.WatchEvent.Kind;
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11 | import java.nio.file.WatchKey;
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12 | import java.nio.file.WatchService;
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13 | import java.util.Collections;
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14 | import java.util.HashMap;
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15 | import java.util.Map;
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16 |
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17 | import org.openstreetmap.josm.Main;
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18 | import org.openstreetmap.josm.data.validation.OsmValidator;
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19 | import org.openstreetmap.josm.data.validation.tests.MapCSSTagChecker;
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20 | import org.openstreetmap.josm.gui.mappaint.MapPaintStyles.MapPaintStyleLoader;
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21 | import org.openstreetmap.josm.gui.mappaint.StyleSource;
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22 | import org.openstreetmap.josm.gui.mappaint.mapcss.parsergen.ParseException;
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23 | import org.openstreetmap.josm.gui.preferences.SourceEntry;
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24 | import org.openstreetmap.josm.tools.CheckParameterUtil;
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25 |
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26 | /**
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27 | * Background thread that monitors certain files and perform relevant actions when they change.
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28 | * @since 7185
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29 | */
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30 | public class FileWatcher {
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31 |
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32 | private WatchService watcher;
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33 | private Thread thread;
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34 |
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35 | private final Map<Path, StyleSource> styleMap = new HashMap<>();
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36 | private final Map<Path, SourceEntry> ruleMap = new HashMap<>();
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37 |
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38 | /**
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39 | * Constructs a new {@code FileWatcher}.
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40 | */
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41 | public FileWatcher() {
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42 | try {
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43 | watcher = FileSystems.getDefault().newWatchService();
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44 | thread = new Thread(new Runnable() {
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45 | @Override
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46 | public void run() {
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47 | processEvents();
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48 | }
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49 | }, "File Watcher");
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50 | } catch (IOException e) {
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51 | Main.error(e);
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52 | }
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53 | }
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54 |
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55 | /**
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56 | * Starts the File Watcher thread.
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57 | */
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58 | public final void start() {
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59 | if (!thread.isAlive()) {
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60 | thread.start();
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61 | }
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62 | }
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63 |
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64 | /**
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65 | * Registers a map paint style for local file changes, allowing dynamic reloading.
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66 | * @param style The style to watch
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67 | * @throws IllegalArgumentException if {@code style} is null or if it does not provide a local file
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68 | * @throws IllegalStateException if the watcher service failed to start
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69 | * @throws IOException if an I/O error occurs
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70 | */
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71 | public void registerStyleSource(StyleSource style) throws IOException {
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72 | register(style, styleMap);
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73 | }
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74 |
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75 | /**
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76 | * Registers a validator rule for local file changes, allowing dynamic reloading.
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77 | * @param rule The rule to watch
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78 | * @throws IllegalArgumentException if {@code rule} is null or if it does not provide a local file
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79 | * @throws IllegalStateException if the watcher service failed to start
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80 | * @throws IOException if an I/O error occurs
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81 | * @since 7276
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82 | */
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83 | public void registerValidatorRule(SourceEntry rule) throws IOException {
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84 | register(rule, ruleMap);
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85 | }
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86 |
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87 | private <T extends SourceEntry> void register(T obj, Map<Path, T> map) throws IOException {
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88 | CheckParameterUtil.ensureParameterNotNull(obj, "obj");
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89 | if (watcher == null) {
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90 | throw new IllegalStateException("File watcher is not available");
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91 | }
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92 | // Get local file, as this method is only called for local style sources
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93 | File file = new File(obj.url);
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94 | // Get parent directory as WatchService allows only to monitor directories, not single files
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95 | File dir = file.getParentFile();
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96 | if (dir == null) {
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97 | throw new IllegalArgumentException("Resource "+obj+" does not have a parent directory");
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98 | }
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99 | synchronized (this) {
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100 | // Register directory. Can be called several times for a same directory without problem
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101 | // (it returns the same key so it should not send events several times)
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102 | dir.toPath().register(watcher, StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_CREATE);
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103 | map.put(file.toPath(), obj);
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104 | }
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105 | }
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106 |
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107 | /**
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108 | * Process all events for the key queued to the watcher.
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109 | */
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110 | private void processEvents() {
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111 | if (Main.isDebugEnabled()) {
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112 | Main.debug("File watcher thread started");
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113 | }
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114 | while (true) {
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115 |
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116 | // wait for key to be signaled
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117 | WatchKey key;
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118 | try {
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119 | key = watcher.take();
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120 | } catch (InterruptedException x) {
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121 | return;
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122 | }
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123 |
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124 | for (WatchEvent<?> event: key.pollEvents()) {
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125 | Kind<?> kind = event.kind();
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126 |
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127 | if (StandardWatchEventKinds.OVERFLOW.equals(kind)) {
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128 | continue;
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129 | }
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130 |
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131 | // The filename is the context of the event.
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132 | @SuppressWarnings("unchecked")
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133 | WatchEvent<Path> ev = (WatchEvent<Path>) event;
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134 | Path filename = ev.context();
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135 | if (filename == null) {
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136 | continue;
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137 | }
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138 |
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139 | // Only way to get full path (http://stackoverflow.com/a/7802029/2257172)
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140 | Path fullPath = ((Path) key.watchable()).resolve(filename);
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141 |
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142 | synchronized (this) {
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143 | StyleSource style = styleMap.get(fullPath);
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144 | SourceEntry rule = ruleMap.get(fullPath);
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145 | if (style != null) {
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146 | Main.info("Map style "+style.getDisplayString()+" has been modified. Reloading style...");
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147 | Main.worker.submit(new MapPaintStyleLoader(Collections.singleton(style)));
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148 | } else if (rule != null) {
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149 | Main.info("Validator rule "+rule.getDisplayString()+" has been modified. Reloading rule...");
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150 | MapCSSTagChecker tagChecker = OsmValidator.getTest(MapCSSTagChecker.class);
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151 | if (tagChecker != null) {
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152 | try {
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153 | tagChecker.addMapCSS(rule.url);
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154 | } catch (IOException | ParseException e) {
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155 | Main.warn(e);
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156 | }
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157 | }
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158 | } else if (Main.isDebugEnabled()) {
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159 | Main.debug("Received "+kind.name()+" event for unregistered file: "+fullPath);
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160 | }
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161 | }
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162 | }
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163 |
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164 | // Reset the key -- this step is critical to receive
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165 | // further watch events. If the key is no longer valid, the directory
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166 | // is inaccessible so exit the loop.
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167 | if (!key.reset()) {
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168 | break;
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169 | }
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170 | }
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171 | }
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172 | }
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