[Cyan]<Tioga2>Base>TiogaLocksPrivateImpl.mesa!1

TiogaLocksPrivateImpl.mesa Edited by Paxton on October 11, 1982 10:27 am

DIRECTORY

TiogaLocks,

TiogaLocksPrivate,

TiogaNode,

NodeProps;

TiogaLocksPrivateImpl: CEDAR MONITOR

IMPORTS NodeProps

EXPORTS TiogaLocksPrivate = BEGIN OPEN TiogaLocks, TiogaLocksPrivate;

lastRoot: TiogaNode.RefBranchNode;

lastLock: LockRef;

GetLock: PUBLIC ENTRY PROC [root: TiogaNode.RefBranchNode] RETURNS [lock: LockRef] = {

ENABLE UNWIND => NULL;

IF root = NIL THEN RETURN [NIL];

IF root = lastRoot THEN RETURN [lastLock];

lastRoot ← root;

lock ← lastLock ← NARROW[NodeProps.GetProp[root, $DocumentLock]];

IF lastLock # NIL THEN RETURN;

lock ← lastLock ← NEW[LockRecord];

NodeProps.PutProp[root, $DocumentLock, lock];

};

NodeProps.Register[$DocumentLock, NodeProps.NullRead, NodeProps.NullWrite, NodeProps.NullCopy];

Don't copy document lock or big trouble.

END..