1 /*
2 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.util.prefs;
27
28 import java.util.HashMap;
29 import java.util.HashSet;
30 import java.util.Iterator;
31 import java.util.Timer;
32 import java.util.TimerTask;
33 import java.lang.ref.WeakReference;
34
35
36 /*
37 MacOSXPreferencesFile synchronization:
38
39 Everything is synchronized on MacOSXPreferencesFile.class. This prevents:
40 * simultaneous updates to cachedFiles or changedFiles
41 * simultaneous creation of two objects for the same name+user+host triplet
42 * simultaneous modifications to the same file
43 * modifications during syncWorld/flushWorld
44 * (in MacOSXPreferences.removeNodeSpi()) modification or sync during
45 multi-step node removal process
46 ... among other things.
47 */
48 /*
49 Timers. There are two timers that control synchronization of prefs data to
50 and from disk.
51
52 * Sync timer periodically calls syncWorld() to force external disk changes
53 (e.g. from another VM) into the memory cache. The sync timer runs even
54 if there are no outstanding local changes. The sync timer syncs all live
55 MacOSXPreferencesFile objects (the cachedFiles list).
56 The sync timer period is controlled by the java.util.prefs.syncInterval
57 property (same as FileSystemPreferences). By default there is *no*
58 sync timer (unlike FileSystemPreferences); it is only enabled if the
59 syncInterval property is set. The minimum interval is 5 seconds.
60
61 * Flush timer calls flushWorld() to force local changes to disk.
62 The flush timer is scheduled to fire some time after each pref change,
63 unless it's already scheduled to fire before that. syncWorld and
64 flushWorld will cancel any outstanding flush timer as unnecessary.
65 The flush timer flushes all changed files (the changedFiles list).
66 The time between pref write and flush timer call is controlled by the
67 java.util.prefs.flushDelay property (unlike FileSystemPreferences).
68 The default is 60 seconds and the minimum is 5 seconds.
69
70 The flush timer's behavior is required by the Java Preferences spec
71 ("changes will eventually propagate to the persistent backing store with
72 an implementation-dependent delay"). The sync timer is not required by
73 the spec (multiple VMs are only required to not corrupt the prefs), but
74 the periodic sync is implemented by FileSystemPreferences and may be
75 useful to some programs. The sync timer is disabled by default because
76 it's expensive and is usually not necessary.
77 */
78
79 class MacOSXPreferencesFile {
80
81 static {
82 java.security.AccessController.doPrivileged(new sun.security.action.LoadLibraryAction("osx"));
83 }
84
85 private class FlushTask extends TimerTask {
86 public void run() {
87 MacOSXPreferencesFile.flushWorld();
88 }
89 }
90
91 private class SyncTask extends TimerTask {
92 public void run() {
93 MacOSXPreferencesFile.syncWorld();
94 }
95 }
96
97 // Maps string -> weak reference to MacOSXPreferencesFile
98 private static HashMap cachedFiles = null;
99 // Files that may have unflushed changes
100 private static HashSet changedFiles = null;
101
102
103 // Timer and pending sync and flush tasks (which are both scheduled
104 // on the same timer)
105 private static Timer timer = null;
106 private static FlushTask flushTimerTask = null;
107 private static long flushDelay = -1; // in seconds (min 5, default 60)
108 private static long syncInterval = -1; // (min 5, default negative == off)
109
110 private String appName;
111 private long user;
112 private long host;
113
114 String name() { return appName; }
115 long user() { return user; }
116 long host() { return host; }
117
118 // private contructor - use factory method getFile() instead
119 private MacOSXPreferencesFile(String newName, long newUser, long newHost)
120 {
121 appName = newName;
122 user = newUser;
123 host = newHost;
124 }
125
126 // Factory method
127 // Always returns the same object for the given name+user+host
128 static synchronized MacOSXPreferencesFile
129 getFile(String newName, boolean isUser)
130 {
131 MacOSXPreferencesFile result = null;
132
133 if (cachedFiles == null) cachedFiles = new HashMap();
134
135 String hashkey =
136 newName + String.valueOf(isUser);
137 WeakReference hashvalue = (WeakReference)cachedFiles.get(hashkey);
138 if (hashvalue != null) {
139 result = (MacOSXPreferencesFile)hashvalue.get();
140 }
141 if (result == null) {
142 // Java user node == CF current user, any host
143 // Java system node == CF any user, current host
144 result = new MacOSXPreferencesFile(newName,
145 isUser ? cfCurrentUser : cfAnyUser,
146 isUser ? cfAnyHost : cfCurrentHost);
147 cachedFiles.put(hashkey, new WeakReference(result));
148 }
149
150 // Don't schedule this file for flushing until some nodes or
151 // keys are added to it.
152
153 // Do set up the sync timer if requested; sync timer affects reads
154 // as well as writes.
155 initSyncTimerIfNeeded();
156
157 return result;
158 }
159
160
161 // Write all prefs changes to disk and clear all cached prefs values
162 // (so the next read will read from disk).
163 static synchronized boolean syncWorld()
164 {
165 boolean ok = true;
166
167 if (cachedFiles != null && !cachedFiles.isEmpty()) {
168 Iterator iter = cachedFiles.values().iterator();
169 while (iter.hasNext()) {
170 WeakReference ref = (WeakReference)iter.next();
171 MacOSXPreferencesFile f = (MacOSXPreferencesFile)ref.get();
172 if (f != null) {
173 if (!f.synchronize()) ok = false;
174 } else {
175 iter.remove();
176 }
177 }
178 }
179
180 // Kill any pending flush
181 if (flushTimerTask != null) {
182 flushTimerTask.cancel();
183 flushTimerTask = null;
184 }
185
186 // Clear changed file list. The changed files were guaranteed to
187 // have been in the cached file list (because there was a strong
188 // reference from changedFiles.
189 if (changedFiles != null) changedFiles.clear();
190
191 return ok;
192 }
193
194
195 // Write all prefs changes to disk, but do not clear all cached prefs
196 // values. Also kills any scheduled flush task.
197 // There's no CFPreferencesFlush() (<rdar://problem/3049129>), so lots of cached prefs
198 // are cleared anyway.
199 static synchronized boolean flushWorld()
200 {
201 boolean ok = true;
202
203 if (changedFiles != null && !changedFiles.isEmpty()) {
204 Iterator iter = changedFiles.iterator();
205 while (iter.hasNext()) {
206 MacOSXPreferencesFile f = (MacOSXPreferencesFile)iter.next();
207 if (!f.synchronize()) ok = false;
208 }
209
210 changedFiles.clear();
211 }
212
213 if (flushTimerTask != null) {
214 flushTimerTask.cancel();
215 flushTimerTask = null;
216 }
217
218 return ok;
219 }
220
221 // Mark this prefs file as changed. The changes will be flushed in
222 // at most flushDelay() seconds.
223 // Must be called when synchronized on MacOSXPreferencesFile.class
224 private void markChanged()
225 {
226 // Add this file to the changed file list
227 if (changedFiles == null) changedFiles = new HashSet();
228 changedFiles.add(this);
229
230 // Schedule a new flush and a shutdown hook, if necessary
231 if (flushTimerTask == null) {
232 flushTimerTask = new FlushTask();
233 timer().schedule(flushTimerTask, flushDelay() * 1000);
234 }
235 }
236
237 // Return the flush delay, initializing from a property if necessary.
238 private static synchronized long flushDelay()
239 {
240 if (flushDelay == -1) {
241 try {
242 // flush delay >= 5, default 60
243 flushDelay = Math.max(5, Integer.parseInt(System.getProperty("java.util.prefs.flushDelay", "60")));
244 } catch (NumberFormatException e) {
245 flushDelay = 60;
246 }
247 }
248 return flushDelay;
249 }
250
251 // Initialize and run the sync timer, if the sync timer property is set
252 // and the sync timer hasn't already been started.
253 private static synchronized void initSyncTimerIfNeeded()
254 {
255 // syncInterval: -1 is uninitialized, other negative is off,
256 // positive is seconds between syncs (min 5).
257
258 if (syncInterval == -1) {
259 try {
260 syncInterval = Integer.parseInt(System.getProperty("java.util.prefs.syncInterval", "-2"));
261 if (syncInterval >= 0) {
262 // minimum of 5 seconds
263 syncInterval = Math.max(5, syncInterval);
264 } else {
265 syncInterval = -2; // default off
266 }
267 } catch (NumberFormatException e) {
268 syncInterval = -2; // bad property value - default off
269 }
270
271 if (syncInterval > 0) {
272 timer().schedule(new TimerTask() {
273 public void run() { MacOSXPreferencesFile.syncWorld();}
274 }, syncInterval * 1000, syncInterval * 1000);
275 } else {
276 // syncInterval property not set. No sync timer ever.
277 }
278 }
279 }
280
281 // Return the timer used for flush and sync, creating it if necessary.
282 private static synchronized Timer timer()
283 {
284 if (timer == null) {
285 timer = new Timer(true); // daemon
286 Thread flushThread = new Thread() {
287 public void run() {
288 flushWorld();
289 }
290 };
291 /* Set context class loader to null in order to avoid
292 * keeping a strong reference to an application classloader.
293 */
294 flushThread.setContextClassLoader(null);
295 Runtime.getRuntime().addShutdownHook(flushThread);
296 }
297 return timer;
298 }
299
300
301 // Node manipulation
302 boolean addNode(String path)
303 {
304 synchronized(MacOSXPreferencesFile.class) {
305 markChanged();
306 return addNode(path, appName, user, host);
307 }
308 }
309
310 void removeNode(String path)
311 {
312 synchronized(MacOSXPreferencesFile.class) {
313 markChanged();
314 removeNode(path, appName, user, host);
315 }
316 }
317
318 void addChildToNode(String path, String child)
319 {
320 synchronized(MacOSXPreferencesFile.class) {
321 markChanged();
322 addChildToNode(path, child+"/", appName, user, host);
323 }
324 }
325
326 void removeChildFromNode(String path, String child)
327 {
328 synchronized(MacOSXPreferencesFile.class) {
329 markChanged();
330 removeChildFromNode(path, child+"/", appName, user, host);
331 }
332 }
333
334
335 // Key manipulation
336 void addKeyToNode(String path, String key, String value)
337 {
338 synchronized(MacOSXPreferencesFile.class) {
339 markChanged();
340 addKeyToNode(path, key, value, appName, user, host);
341 }
342 }
343
344 void removeKeyFromNode(String path, String key)
345 {
346 synchronized(MacOSXPreferencesFile.class) {
347 markChanged();
348 removeKeyFromNode(path, key, appName, user, host);
349 }
350 }
351
352 String getKeyFromNode(String path, String key)
353 {
354 synchronized(MacOSXPreferencesFile.class) {
355 return getKeyFromNode(path, key, appName, user, host);
356 }
357 }
358
359
360 // Enumerators
361 String[] getChildrenForNode(String path)
362 {
363 synchronized(MacOSXPreferencesFile.class) {
364 return getChildrenForNode(path, appName, user, host);
365 }
366 }
367
368 String[] getKeysForNode(String path)
369 {
370 synchronized(MacOSXPreferencesFile.class) {
371 return getKeysForNode(path, appName, user, host);
372 }
373 }
374
375
376 // Synchronization
377 boolean synchronize()
378 {
379 synchronized(MacOSXPreferencesFile.class) {
380 return synchronize(appName, user, host);
381 }
382 }
383
384
385 // CF functions
386 // Must be called when synchronized on MacOSXPreferencesFile.class
387 private static final native boolean
388 addNode(String path, String name, long user, long host);
389 private static final native void
390 removeNode(String path, String name, long user, long host);
391 private static final native void
392 addChildToNode(String path, String child,
393 String name, long user, long host);
394 private static final native void
395 removeChildFromNode(String path, String child,
396 String name, long user, long host);
397 private static final native void
398 addKeyToNode(String path, String key, String value,
399 String name, long user, long host);
400 private static final native void
401 removeKeyFromNode(String path, String key,
402 String name, long user, long host);
403 private static final native String
404 getKeyFromNode(String path, String key,
405 String name, long user, long host);
406 private static final native String[]
407 getChildrenForNode(String path, String name, long user, long host);
408 private static final native String[]
409 getKeysForNode(String path, String name, long user, long host);
410 private static final native boolean
411 synchronize(String name, long user, long host);
412
413 // CFPreferences host and user values (CFStringRefs)
414 private static long cfCurrentUser = currentUser();
415 private static long cfAnyUser = anyUser();
416 private static long cfCurrentHost = currentHost();
417 private static long cfAnyHost = anyHost();
418
419 // CFPreferences constant accessors
420 private static final native long currentUser();
421 private static final native long anyUser();
422 private static final native long currentHost();
423 private static final native long anyHost();
424 }
425