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 // Sync only current user preferences
196 static synchronized boolean syncUser() {
197 boolean ok = true;
198 if (cachedFiles != null && !cachedFiles.isEmpty()) {
199 Iterator<WeakReference> iter = cachedFiles.values().iterator();
200 while (iter.hasNext()) {
201 WeakReference ref = iter.next();
202 MacOSXPreferencesFile f = (MacOSXPreferencesFile)ref.get();
203 if (f != null && f.user == cfCurrentUser) {
204 if (!f.synchronize()) {
205 ok = false;
206 }
207 } else {
208 iter.remove();
209 }
210 }
211 }
212 // Renove synchronized file from changed file list. The changed files were
213 // guaranteed to have been in the cached file list (because there was a strong
214 // reference from changedFiles.
215 if (changedFiles != null) {
216 Iterator<MacOSXPreferencesFile> iterChanged = changedFiles.iterator();
217 while (iterChanged.hasNext()) {
218 MacOSXPreferencesFile f = iterChanged.next();
219 if (f != null && f.user == cfCurrentUser)
220 iterChanged.remove();
221 }
222 }
223 return ok;
224 }
225
226
227
228
229 // Write all prefs changes to disk, but do not clear all cached prefs
230 // values. Also kills any scheduled flush task.
231 // There's no CFPreferencesFlush() (<rdar://problem/3049129>), so lots of cached prefs
232 // are cleared anyway.
233 static synchronized boolean flushWorld()
234 {
235 boolean ok = true;
236
237 if (changedFiles != null && !changedFiles.isEmpty()) {
238 Iterator iter = changedFiles.iterator();
239 while (iter.hasNext()) {
240 MacOSXPreferencesFile f = (MacOSXPreferencesFile)iter.next();
241 if (!f.synchronize()) ok = false;
242 }
243
244 changedFiles.clear();
245 }
246
247 if (flushTimerTask != null) {
248 flushTimerTask.cancel();
249 flushTimerTask = null;
250 }
251
252 return ok;
253 }
254
255 // Mark this prefs file as changed. The changes will be flushed in
256 // at most flushDelay() seconds.
257 // Must be called when synchronized on MacOSXPreferencesFile.class
258 private void markChanged()
259 {
260 // Add this file to the changed file list
261 if (changedFiles == null) changedFiles = new HashSet();
262 changedFiles.add(this);
263
264 // Schedule a new flush and a shutdown hook, if necessary
265 if (flushTimerTask == null) {
266 flushTimerTask = new FlushTask();
267 timer().schedule(flushTimerTask, flushDelay() * 1000);
268 }
269 }
270
271 // Return the flush delay, initializing from a property if necessary.
272 private static synchronized long flushDelay()
273 {
274 if (flushDelay == -1) {
275 try {
276 // flush delay >= 5, default 60
277 flushDelay = Math.max(5, Integer.parseInt(System.getProperty("java.util.prefs.flushDelay", "60")));
278 } catch (NumberFormatException e) {
279 flushDelay = 60;
280 }
281 }
282 return flushDelay;
283 }
284
285 // Initialize and run the sync timer, if the sync timer property is set
286 // and the sync timer hasn't already been started.
287 private static synchronized void initSyncTimerIfNeeded()
288 {
289 // syncInterval: -1 is uninitialized, other negative is off,
290 // positive is seconds between syncs (min 5).
291
292 if (syncInterval == -1) {
293 try {
294 syncInterval = Integer.parseInt(System.getProperty("java.util.prefs.syncInterval", "-2"));
295 if (syncInterval >= 0) {
296 // minimum of 5 seconds
297 syncInterval = Math.max(5, syncInterval);
298 } else {
299 syncInterval = -2; // default off
300 }
301 } catch (NumberFormatException e) {
302 syncInterval = -2; // bad property value - default off
303 }
304
305 if (syncInterval > 0) {
306 timer().schedule(new TimerTask() {
307 public void run() { MacOSXPreferencesFile.syncWorld();}
308 }, syncInterval * 1000, syncInterval * 1000);
309 } else {
310 // syncInterval property not set. No sync timer ever.
311 }
312 }
313 }
314
315 // Return the timer used for flush and sync, creating it if necessary.
316 private static synchronized Timer timer()
317 {
318 if (timer == null) {
319 timer = new Timer(true); // daemon
320 Thread flushThread = new Thread() {
321 public void run() {
322 flushWorld();
323 }
324 };
325 /* Set context class loader to null in order to avoid
326 * keeping a strong reference to an application classloader.
327 */
328 flushThread.setContextClassLoader(null);
329 Runtime.getRuntime().addShutdownHook(flushThread);
330 }
331 return timer;
332 }
333
334
335 // Node manipulation
336 boolean addNode(String path)
337 {
338 synchronized(MacOSXPreferencesFile.class) {
339 markChanged();
340 return addNode(path, appName, user, host);
341 }
342 }
343
344 void removeNode(String path)
345 {
346 synchronized(MacOSXPreferencesFile.class) {
347 markChanged();
348 removeNode(path, appName, user, host);
349 }
350 }
351
352 void addChildToNode(String path, String child)
353 {
354 synchronized(MacOSXPreferencesFile.class) {
355 markChanged();
356 addChildToNode(path, child+"/", appName, user, host);
357 }
358 }
359
360 void removeChildFromNode(String path, String child)
361 {
362 synchronized(MacOSXPreferencesFile.class) {
363 markChanged();
364 removeChildFromNode(path, child+"/", appName, user, host);
365 }
366 }
367
368
369 // Key manipulation
370 void addKeyToNode(String path, String key, String value)
371 {
372 synchronized(MacOSXPreferencesFile.class) {
373 markChanged();
374 addKeyToNode(path, key, value, appName, user, host);
375 }
376 }
377
378 void removeKeyFromNode(String path, String key)
379 {
380 synchronized(MacOSXPreferencesFile.class) {
381 markChanged();
382 removeKeyFromNode(path, key, appName, user, host);
383 }
384 }
385
386 String getKeyFromNode(String path, String key)
387 {
388 synchronized(MacOSXPreferencesFile.class) {
389 return getKeyFromNode(path, key, appName, user, host);
390 }
391 }
392
393
394 // Enumerators
395 String[] getChildrenForNode(String path)
396 {
397 synchronized(MacOSXPreferencesFile.class) {
398 return getChildrenForNode(path, appName, user, host);
399 }
400 }
401
402 String[] getKeysForNode(String path)
403 {
404 synchronized(MacOSXPreferencesFile.class) {
405 return getKeysForNode(path, appName, user, host);
406 }
407 }
408
409
410 // Synchronization
411 boolean synchronize()
412 {
413 synchronized(MacOSXPreferencesFile.class) {
414 return synchronize(appName, user, host);
415 }
416 }
417
418
419 // CF functions
420 // Must be called when synchronized on MacOSXPreferencesFile.class
421 private static final native boolean
422 addNode(String path, String name, long user, long host);
423 private static final native void
424 removeNode(String path, String name, long user, long host);
425 private static final native void
426 addChildToNode(String path, String child,
427 String name, long user, long host);
428 private static final native void
429 removeChildFromNode(String path, String child,
430 String name, long user, long host);
431 private static final native void
432 addKeyToNode(String path, String key, String value,
433 String name, long user, long host);
434 private static final native void
435 removeKeyFromNode(String path, String key,
436 String name, long user, long host);
437 private static final native String
438 getKeyFromNode(String path, String key,
439 String name, long user, long host);
440 private static final native String[]
441 getChildrenForNode(String path, String name, long user, long host);
442 private static final native String[]
443 getKeysForNode(String path, String name, long user, long host);
444 private static final native boolean
445 synchronize(String name, long user, long host);
446
447 // CFPreferences host and user values (CFStringRefs)
448 private static long cfCurrentUser = currentUser();
449 private static long cfAnyUser = anyUser();
450 private static long cfCurrentHost = currentHost();
451 private static long cfAnyHost = anyHost();
452
453 // CFPreferences constant accessors
454 private static final native long currentUser();
455 private static final native long anyUser();
456 private static final native long currentHost();
457 private static final native long anyHost();
458 }
459