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Improve safety of locking code.

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git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@14725 72102866-910b-0410-8b05-ffd578937521
This commit is contained in:
Richard Frith-Macdonald 2002-10-11 17:16:34 +00:00
parent 0a14d34103
commit 331d43ddda
2 changed files with 30 additions and 9 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2002-10-10 Richard Frith-Macdonald <rfm@gnu.org>
* Source/NSUserDefaults.m: ([-synchronize]) handle locking more
carefully ... avoid cpu intensive busy loops and give up after
a while.
2002-10-10 Richard Frith-Macdonald <rfm@gnu.org>
* Source/NSLog.m: Added GSPrintf()

33
Source/NSUserDefaults.m
View file

@ -1198,6 +1198,7 @@ static NSString *pathForUser(NSString *user)
NSFileManager *mgr = [NSFileManager defaultManager];
NSMutableDictionary *newDict;
NSDictionary *attr;
NSDate *started = [NSDate date];
unsigned long desired;
unsigned long attributes;
@ -1206,18 +1207,32 @@ static NSString *pathForUser(NSString *user)
while ([_fileLock tryLock] == NO)
{
CREATE_AUTORELEASE_POOL(arp);
NSDate *when, *lockDate;
NSDate *when;
NSDate *lockDate;
lockDate = [_fileLock lockDate];
/* If the lock has already been released, lockDate will be nil. If
so, just try again. */
if (!lockDate)
{
RELEASE(arp);
continue;
}
when = [NSDate dateWithTimeIntervalSinceNow: 0.1];
if ([when timeIntervalSinceDate: lockDate] > 5.0)
/*
* In case we have tried and failed to break the lock,
* we give up after a while ... 16 seconds should give
* us three lock breaks if we do them at 5 second
* intervals.
*/
if ([when timeIntervalSinceDate: started] > 16.0)
{
NSLog(@"Failed to lock user defaults database even after "
@"breaking old locks!");
[_lock unlock];
return NO;
}
/*
* If lockDate is nil, we should be able to lock again ... but we
* wait a little anyway ... so that in the case of a locking
* problem we do an idle wait rather than a busy one.
*/
if (lockDate != nil && [when timeIntervalSinceDate: lockDate] > 5.0)
{
[_fileLock breakLock];
}