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

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

For example:

our RWLock $rwl();

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

    return "OK";
}