Note: This class is not available with the PO_NO_THREAD_CLASSES parse option.

AutoWriteLock objects, when used along with a RWLock object, allow Qore programmers to safely acquire and release a write lock, even if exceptions are thrown or return statements are executed in the block where the AutoWriteLock object is created. AutoWriteLock objects are helper objects that acquire a write lock for the lifetime of the AutoWriteLock object. For this reason, it is only appropriate to assign an AutoWriteLock object to a local variable, so when the local variable goes out of scope, the AutoWriteLock object will be deleted and the write lock will be automatically released.

For example:

our RWLock $rwl();

sub check_error($error) {
    # note that the write lock is acquired in the AutoWriteLock constructor, and
    # the write lock will be released as soon as the block is exited below.
    # (with either the throw statement or the return statement)
    my AutoWriteLock $arl($rwl);
    if ($error)
        throw "ERROR", "sorry, an error happened";

    return "OK";
}