In the
FRR example, which follows this procedure,
the FRR performs the following tasks:
- Tests the init_complete flag to determine if the updating_resource
and latch_token variables are initialized.
- Tests the updating_resource flag. If the flag is "on", the
latch is definitely held and the FRR can repair the resource associated
with the currently obtained latch. This is how the FRR knows if the
resource is serialized.
- Tests the latch_token to see if it is a non-zero value. If so,
the FRR assumes that the program might have obtained the latch; therefore,
the FRR should call Latch_Release with the ISGLREL_COND (value of
1) option to ensure the latch is no longer held. ISGLREL_COND (value
of 1) indicates that the latch manager should return control to the
requestor with a return code instead of issuing an abend if the latch
is not held.