Re: Create an exclusive lock on an IFS file?

On 03-Nov-2014 10:16 -0600, David Gibbs wrote:

Folks:

Any suggestions on how to create an exclusive lock on an IFS file?

I need to ensure a process, running on a PC, is the only one running
at a time ... to do this I want to create a lock on a known IFS file.

Currently I'm looking at using this code to make the lock.

IFSRandomAccessFile lockFile = new IFSRandomAccessFile(as400, LOCKFILE, "rw");

IFSKey lockKey = lockFile.lock(0L, 10L);

If the lock operation on the lockFile thows an ExtendedIOException,
I know I can't get the lock.

Are there any better approaches?

I would think more appropriate, including the optional fourth argument [int shareOption] for the open request, using the value of SHARE_NONE; i.e. preventing an open by any other process\thread irrespective that other thread properly implementing the keyed-locking scheme.? I have never used the IFSKey class, but I infer that is the equivalent of a Space Location Lock (SLL) for which all accesses must be participants in the scheme, else anyone not participating might not /see/ the lock and be allowed to operate against [access] the file and data.?

Also, I am unsure of the default for the optional fifth argument [int existenceOption] for the open request, but possibly the value OPEN_OR_FAIL is desirable if the semaphore is implemented as a "lock on *a known* IFS file" [emphasis mine].?