catching exceptions help needed.

In article ,
Santa Claus wrote:

> Re: Detecting low disk space
> FROM : Fritz Anderson
> DATE : Fri Apr 09 17:48:19 2004
>
> NSDictionary * dict = [[NSFileManager defaultManager]
> fileSystemAttributesAtPath: @"/"];
> unsigned freeSpace = [[dict objectForKey:
> NSFileSystemFreeSize]
> unsignedIntValue];
>
> This will give you the free disk space on the startup volume. I can't
> vouch for whether it is wise (or possible) to take up all the free
> space.
>
>
> now to test it out...

This won't save you. No matter how hard you try to check free disk space, other
apps can fill it up while you aren't looking, and when they do, you will still
need to handle an exception.

The only robust way to handle running out of disk space is to cope with the
error when it happens; it may be helpful, but it is never sufficient, to try to
avoid running into the error in the first place.

hth

Ben

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 >> Stay informed about: catching exceptions help needed. 

In article ,
Ben Artin wrote:

> In article ,
> Santa Claus wrote:
>
> > Re: Detecting low disk space
> > FROM : Fritz Anderson
> > DATE : Fri Apr 09 17:48:19 2004
> >
> > NSDictionary * dict = [[NSFileManager defaultManager]
> > fileSystemAttributesAtPath: @"/"];
> > unsigned freeSpace = [[dict objectForKey:
> > NSFileSystemFreeSize]
> > unsignedIntValue];
> >
> > This will give you the free disk space on the startup volume. I can't
> > vouch for whether it is wise (or possible) to take up all the free
> > space.
> >
> >
> > now to test it out...
>
> This won't save you. No matter how hard you try to check free disk space,
> other
> apps can fill it up while you aren't looking, and when they do, you will
> still
> need to handle an exception.
>
> The only robust way to handle running out of disk space is to cope with the
> error when it happens; it may be helpful, but it is never sufficient, to try
> to
> avoid running into the error in the first place.

agreed, this brings me to the other point. how do i trap the
exception? is it with the notification manager or exception manager?
the exception manager appears to be intended to send exceptions not
receive them.

oh, i wish for the good old days of simply checking the ioresult and
determining what it was and acting on it that way. write a file, disk
gets full and it doesn't write and then sends back an error to the
method that called it and that method can handle it directly instead of
indirectly.
 >> Stay informed about: catching exceptions help needed. 

In article ,
Santa Claus wrote:

> agreed, this brings me to the other point. how do i trap the
> exception? is it with the notification manager or exception manager?
> the exception manager appears to be intended to send exceptions not
> receive them.
>
> oh, i wish for the good old days of simply checking the ioresult and
> determining what it was and acting on it that way. write a file, disk
> gets full and it doesn't write and then sends back an error to the
> method that called it and that method can handle it directly instead of
> indirectly.

ok, i found out why i can't find any references to the exception
manager, it wasn't included in my project frameworks. i added that and
then found out a whole bunch of things and got it to trap the error.

when i return the BOOL of NO, it continues to crash the program. when i
return YES, it doesn't crash the program but doesn't resume the thread
where it left off either. yes, i know i need to actually TEST for the
proper exception to handle it properly but this is a short and dirty
test to see what's supposed to happen.

- (BOOL)exceptionHandler: (NSExceptionHandler *) sender
shouldHandleException: (NSException *) exception
mask: (unsigned int) aMask;
{
NSLog(@"ignore the above exception, it's being handled.");
NSLog(@"exception sender = %@", sender);
NSLog(@"exception = %@", exception);
NSLog(@"exception mask = %ld", aMask);

// these things i added to try to close the thread properly since it
didn't close properly with just the return.
[self echotext: [NSMutableString stringWithString: @"done with zeroize
function\n"]];
[mapWindowPool release];

return YES;
}


NSExceptionHandler *handler = [NSExceptionHandler
defaultExceptionHandler];
[handler setExceptionHandlingMask: NSHandleUncaughtExceptionMask];
[handler setDelegate: self];
 >> Stay informed about: catching exceptions help needed. 

In article ,
Santa Claus wrote:

> it took a bit to remember the web site that has all of it but this is
> what cocoabuilder.com had to say
>
> Re: Detecting low disk space
> FROM : Fritz Anderson
> DATE : Fri Apr 09 17:48:19 2004
>
> NSDictionary * dict = [[NSFileManager defaultManager]
> fileSystemAttributesAtPath: @"/"];
> unsigned freeSpace = [[dict objectForKey:
> NSFileSystemFreeSize]
> unsignedIntValue];
>
> This will give you the free disk space on the startup volume. I can't
> vouch for whether it is wise (or possible) to take up all the free
> space.
>
>
> now to test it out...

NO! the free space can easily overflow a 32-bit unsigned. Use the correct
type:

long long freespace =
[[dict objectForKey: NSFileSystemFreeSize] longLongValue];
 >> Stay informed about: catching exceptions help needed. 

In article ,
Santa Claus wrote:

> i would appreciate some assistance in one of two things.
>
> 1) determine free space on a local volume
> 2) catch and handle an exception caused by the following:
>
> 2008-02-24 15:04:48.721 Avalon[26929] An uncaught exception was raised
> 2008-02-24 15:04:48.721 Avalon[26929] *** -[NSConcreteFileHandle
> writeData:]: No space left on device
> 2008-02-24 15:04:48.721 Avalon[26929] *** Uncaught exception:
> <NSFileHandleOperationException> *** -[NSConcreteFileHandle writeData:]:
> No space left on device
> Feb 24 15:04:50 nameserver crashdump[26931]: Avalon crashed
> Feb 24 15:04:50 nameserver crashdump[26931]: crash report written to:
> /Library/Logs/CrashReporter/Avalon.crash.log
>
> i checked apple's site and no help there, nothing that points to
> "errors" or "exceptions" that make any sense to me. i'm not trying to
> get the NSString of the "no space left on volume", i'm trying to ignore
> that message (it's handled within my code anyway) or get the drive space
> available so i can eliminate the possibility of it coming up.

@try {
[myFile writeData:myData];
} @catch(NSException *except) {
// <-- if we get here, the exception occurred.
NSLog(@"%@ %@\n", [except name], [except reason]);
}
 >> Stay informed about: catching exceptions help needed.