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Title "INN::Utils::Shlock 3pm" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
INN::Utils::Shlock - Wrapper around the shlock program Header "DESCRIPTION" This Perl module wraps the shlock\|(1) program so that it can easily be used. Calling shlock is more portable than using flock\|(2) and its corresponding Perl function because this function does not work as expected on all existing systems.

See the shlock\|(1) documentation for more information.

Using INN::Utils::Shlock is straight-forward:

.Vb 2 use lib \*(Aq<pathnews>/lib/perl\*(Aq; use INN::Utils::Shlock; \& my $lockfile = "myprogram.LOCK"; \& # Acquire a lock. INN::Utils::Shlock::lock($lockfile); \& # Do whatever you want. The lock prevents concurrent accesses. \& # Unlock. INN::Utils::Shlock::unlock($lockfile); .Ve

These two functions return 1 on success, 0 on failure. For example, the success of (un)locking can be checked as:

.Vb 1 INN::Utils::Shlock::lock($lockfile) or die "cannot create lock file"; .Ve

or:

.Vb 3 if (! INN::Utils::Shlock::lock($lockfile, 4)) { die "giving up after 4 unsuccessful attempts to create lock file"; } .Ve

Instead of calling \*(C`unlock(\f(CIlockfile)\*(C', the \*(C`releaselocks()\*(C' function can be called. It removes any leftover locks, which is useful when several different locks are used. Another possible use is to call it in an \s-1END\s0 code block:

.Vb 4 END { # In case we bail out, while holding a lock. INN::Utils::Shlock::releaselocks(); } .Ve

Header "INTERFACE" Item "lock(lockfile)" Tries to create a lock file named lockfile. .Sp This function returns 1 on success, 0 on failure. Item "lock(lockfile, tries)" Tries to create a lock file named lockfile. If it fails, locking attempts are repeated once every 2 seconds for at most tries times (including the first unsuccessful attempt). .Sp This function returns 1 on success, 0 on failure. Item "lock(lockfile, tries, delay)" Tries to create a lock file named lockfile. If it fails, locking attempts are repeated once every delay seconds for at most tries times (including the first unsuccessful attempt). .Sp Note that \*(C`lock(\f(CIlockfile)\*(C' is equivalent to \*(C`lock(\f(CIlockfile, 1, 2)\*(C'. .Sp This function returns 1 on success, 0 on failure. Item "releaselocks()" Removes all the lock files previously created by calling the \*(C`lock(\f(CIlockfile)\*(C' function. .Sp This function returns the number of removed lock files. Item "unlock(lockfile)" Removes the file named lockfile. .Sp This function returns 1 on success, 0 on failure. Header "HISTORY" Documentation written by Julien Elie for InterNetNews.

\f(CW$Id: Shlock.pm.in 9408 2012-05-28 18:42:29Z iulius $

Header "SEE ALSO" \fBperl\|(1), shlock\|(1).