001/*
002 *  Copyright 2001-2005 Stephen Colebourne
003 *
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package org.joda.time.tz;
017
018import java.io.DataInputStream;
019import java.io.File;
020import java.io.FileInputStream;
021import java.io.IOException;
022import java.io.InputStream;
023import java.lang.ref.SoftReference;
024import java.util.Map;
025import java.util.Set;
026import java.util.TreeMap;
027import java.util.TreeSet;
028
029import org.joda.time.DateTimeZone;
030
031/**
032 * ZoneInfoProvider loads compiled data files as generated by
033 * {@link ZoneInfoCompiler}.
034 * <p>
035 * ZoneInfoProvider is thread-safe and publicly immutable.
036 *
037 * @author Brian S O'Neill
038 * @since 1.0
039 */
040public class ZoneInfoProvider implements Provider {
041
042    /** The directory where the files are held. */
043    private final File iFileDir;
044    /** The resource path. */
045    private final String iResourcePath;
046    /** The class loader to use. */
047    private final ClassLoader iLoader;
048    /** Maps ids to strings or SoftReferences to DateTimeZones. */
049    private final Map iZoneInfoMap;
050
051    /**
052     * ZoneInfoProvider searches the given directory for compiled data files.
053     *
054     * @throws IOException if directory or map file cannot be read
055     */
056    public ZoneInfoProvider(File fileDir) throws IOException {
057        if (fileDir == null) {
058            throw new IllegalArgumentException("No file directory provided");
059        }
060        if (!fileDir.exists()) {
061            throw new IOException("File directory doesn't exist: " + fileDir);
062        }
063        if (!fileDir.isDirectory()) {
064            throw new IOException("File doesn't refer to a directory: " + fileDir);
065        }
066
067        iFileDir = fileDir;
068        iResourcePath = null;
069        iLoader = null;
070
071        iZoneInfoMap = loadZoneInfoMap(openResource("ZoneInfoMap"));
072    }
073
074    /**
075     * ZoneInfoProvider searches the given ClassLoader resource path for
076     * compiled data files. Resources are loaded from the ClassLoader that
077     * loaded this class.
078     *
079     * @throws IOException if directory or map file cannot be read
080     */
081    public ZoneInfoProvider(String resourcePath) throws IOException {
082        this(resourcePath, null, false);
083    }
084
085    /**
086     * ZoneInfoProvider searches the given ClassLoader resource path for
087     * compiled data files.
088     *
089     * @param loader ClassLoader to load compiled data files from. If null,
090     * use system ClassLoader.
091     * @throws IOException if directory or map file cannot be read
092     */
093    public ZoneInfoProvider(String resourcePath, ClassLoader loader)
094        throws IOException
095    {
096        this(resourcePath, loader, true);
097    }
098
099    /**
100     * @param favorSystemLoader when true, use the system class loader if
101     * loader null. When false, use the current class loader if loader is null.
102     */
103    private ZoneInfoProvider(String resourcePath,
104                             ClassLoader loader, boolean favorSystemLoader) 
105        throws IOException
106    {
107        if (resourcePath == null) {
108            throw new IllegalArgumentException("No resource path provided");
109        }
110        if (!resourcePath.endsWith("/")) {
111            resourcePath += '/';
112        }
113
114        iFileDir = null;
115        iResourcePath = resourcePath;
116
117        if (loader == null && !favorSystemLoader) {
118            loader = getClass().getClassLoader();
119        }
120
121        iLoader = loader;
122
123        iZoneInfoMap = loadZoneInfoMap(openResource("ZoneInfoMap"));
124    }
125
126    //-----------------------------------------------------------------------
127    /**
128     * If an error is thrown while loading zone data, uncaughtException is
129     * called to log the error and null is returned for this and all future
130     * requests.
131     * 
132     * @param id  the id to load
133     * @return the loaded zone
134     */
135    public synchronized DateTimeZone getZone(String id) {
136        if (id == null) {
137            return null;
138        }
139
140        Object obj = iZoneInfoMap.get(id);
141        if (obj == null) {
142            return null;
143        }
144
145        if (id.equals(obj)) {
146            // Load zone data for the first time.
147            return loadZoneData(id);
148        }
149
150        if (obj instanceof SoftReference) {
151            DateTimeZone tz = (DateTimeZone)((SoftReference)obj).get();
152            if (tz != null) {
153                return tz;
154            }
155            // Reference cleared; load data again.
156            return loadZoneData(id);
157        }
158
159        // If this point is reached, mapping must link to another.
160        return getZone((String)obj);
161    }
162
163    /**
164     * Gets a list of all the available zone ids.
165     * 
166     * @return the zone ids
167     */
168    public synchronized Set getAvailableIDs() {
169        // Return a copy of the keys rather than an umodifiable collection.
170        // This prevents ConcurrentModificationExceptions from being thrown by
171        // some JVMs if zones are opened while this set is iterated over.
172        return new TreeSet(iZoneInfoMap.keySet());
173    }
174
175    /**
176     * Called if an exception is thrown from getZone while loading zone data.
177     * 
178     * @param ex  the exception
179     */
180    protected void uncaughtException(Exception ex) {
181        Thread t = Thread.currentThread();
182        t.getThreadGroup().uncaughtException(t, ex);
183    }
184
185    /**
186     * Opens a resource from file or classpath.
187     * 
188     * @param name  the name to open
189     * @return the input stream
190     * @throws IOException if an error occurs
191     */
192    private InputStream openResource(String name) throws IOException {
193        InputStream in;
194        if (iFileDir != null) {
195            in = new FileInputStream(new File(iFileDir, name));
196        } else {
197            String path = iResourcePath.concat(name);
198            if (iLoader != null) {
199                in = iLoader.getResourceAsStream(path);
200            } else {
201                in = ClassLoader.getSystemResourceAsStream(path);
202            }
203            if (in == null) {
204                StringBuffer buf = new StringBuffer(40)
205                    .append("Resource not found: \"")
206                    .append(path)
207                    .append("\" ClassLoader: ")
208                    .append(iLoader != null ? iLoader.toString() : "system");
209                throw new IOException(buf.toString());
210            }
211        }
212        return in;
213    }
214
215    /**
216     * Loads the time zone data for one id.
217     * 
218     * @param id  the id to load
219     * @return the zone
220     */
221    private DateTimeZone loadZoneData(String id) {
222        InputStream in = null;
223        try {
224            in = openResource(id);
225            DateTimeZone tz = DateTimeZoneBuilder.readFrom(in, id);
226            iZoneInfoMap.put(id, new SoftReference(tz));
227            return tz;
228        } catch (IOException e) {
229            uncaughtException(e);
230            iZoneInfoMap.remove(id);
231            return null;
232        } finally {
233            try {
234                if (in != null) {
235                    in.close();
236                }
237            } catch (IOException e) {
238            }
239        }
240    }
241
242    //-----------------------------------------------------------------------
243    /**
244     * Loads the zone info map.
245     * 
246     * @param in  the input stream
247     * @return the map
248     */
249    private static Map loadZoneInfoMap(InputStream in) throws IOException {
250        Map map = new TreeMap(String.CASE_INSENSITIVE_ORDER);
251        DataInputStream din = new DataInputStream(in);
252        try {
253            readZoneInfoMap(din, map);
254        } finally {
255            try {
256                din.close();
257            } catch (IOException e) {
258            }
259        }
260        map.put("UTC", new SoftReference(DateTimeZone.UTC));
261        return map;
262    }
263
264    /**
265     * Reads the zone info map from file.
266     * 
267     * @param din  the input stream
268     * @param zimap  gets filled with string id to string id mappings
269     */
270    private static void readZoneInfoMap(DataInputStream din, Map zimap) throws IOException {
271        // Read the string pool.
272        int size = din.readUnsignedShort();
273        String[] pool = new String[size];
274        for (int i=0; i<size; i++) {
275            pool[i] = din.readUTF().intern();
276        }
277
278        // Read the mappings.
279        size = din.readUnsignedShort();
280        for (int i=0; i<size; i++) {
281            try {
282                zimap.put(pool[din.readUnsignedShort()], pool[din.readUnsignedShort()]);
283            } catch (ArrayIndexOutOfBoundsException e) {
284                throw new IOException("Corrupt zone info map");
285            }
286        }
287    }
288
289}