tcl.unlock-item Verb: Access/TCL

tcl.unlock-item

Command tcl.unlock-item Verb: Access/TCL
Applicable release versions: AP
Category TCL (746)
Description clears item locks that have not cleared through usual system operation.

Item locks are set by Pick/BASIC "read" statements and other mechanisms.

Item locks provide a means of assuring data reliability by preventing two processes from attempting to update the same item at the same time.

The "read" statements (in Pick/BASIC) that have a "locking" form set "item" locks only while working with an item. This means that two processes can access items in the same group, provided they do not attempt to update the same item. This is in contrast to early Pick systems, which only set group locks on "read" statements.

A "locked" clause in "read" statements allows a graceful means of dealing with the situation of attempting to access a locked item. The program can take a special case and indicate to the operator that they should "try again later."

When a process attempts to access an item that is locked, the screen simply freezes and starts "beeping". Usually, there is only a brief wait until the item is unlocked, at which time the terminal stops beeping and is granted access to the item.

Other times, however, the locking system does not unlock the item for whatever reason (aborts, programming errors, logoffs, bad karma, etc.). It is in cases such as this, and only in these cases, that this verb should be used.
Syntax unlock-item file.reference {item.list*} {(options}
Options start.port.number{-end.port.number} Used only when fid(s) specified in options string. The fid is implied as a decimal number unless it is preceeded by a period, where it is then considered to be a hexadecimal reference.

i Suppresses "item 'x' released" message.
Example
list-locks (i
Item Locks      PIB# Lvl Hash  Item-id    Filename
29198  (00720E)  33  2   2D52  33109      cx
29003  (00714B)   7  1   2C8E  32914      cx
234034 (039232)  86  0   1923  record2    doc
179222 (02BC16)  25  0   248A  74845480   entity
234034 (039232)  89  0   404B  accounts   doc
169528 (029638)  35  1   6432  110462     entity
71998  (01193E)  12  0   7250  8462       action
79366  (013606)  79  0   04A4  kr         tcl-stack

This displays the current item locks.

unlock-item action 8462
[454] Item '8462' unlocked.

This unlocks the item shown.
Purpose
Related tcl.list-lock-queue
basic.readv
tcl.list-lockq
basic.release
basic.matread
tcl.clear-locks
tcl.what
tcl.clear-basic-locks
basic.lock
tcl.unlock-group
locking.scheme
tcl.list-locks_rp