-- AlpineVolume.mesa
-- Last edited by
--   Kolling on March 9, 1983 11:08 am
--   MBrown on March 1, 1983 4:13 pm

-- This is an interim interface.  We expect it to evolve in the direction of: control of
--volume group locking, controlling the online/offline status of volume groups, etc.


DIRECTORY
  AlpineEnvironment;

AlpineVolume: DEFINITIONS =
  BEGIN

  Conversation: TYPE = AlpineEnvironment.Conversation;
  LockOption: TYPE = AlpineEnvironment.LockOption;
  TransID: TYPE = AlpineEnvironment.TransID;
  nullTransID: TransID = AlpineEnvironment.nullTransID;
  VolumeID: TYPE = AlpineEnvironment.VolumeID;
  VolumeGroupID: TYPE = AlpineEnvironment.VolumeGroupID;
  nullVolumeGroupID: VolumeGroupID = AlpineEnvironment.nullVolumeGroupID;

  GetNextGroup: PROC [
    conversation: Conversation, transID: TransID _ nullTransID,
    previousGroup: VolumeGroupID _ nullVolumeGroupID,
    lock: LockOption _ [none, wait]]
    RETURNS [volumeGroupID: VolumeGroupID];
    -- ! Unknown {volumeGroupID};
    -- Stateless enumerator for the on-line volume groups of this Alpine instance.
    -- previousGroup = nullVolumeGroupID starts an enumeration, and
    -- volumeGroupID = nullVolumeGroupID is returned at the end of an enumeration.

    -- For now, the transID and lock parms are ignored.  The proposed usage is as follows:
    -- If transID # nullTransID and lock.mode # none then sets the specified lock on the
    -- returned volume group.  Setting a read lock guarantees that the volume group
    -- will remain on-line for the remainder of the transaction.  Setting a write lock
    -- excludes all other access to the volume group for the remainder of the transaction
    -- (including opening files on the volume group); this requires the caller to be
    -- an asserted AlpineWheel.

  GetGroup: PROC [
    conversation: Conversation, transID: TransID _ nullTransID,
    volumeGroupID: VolumeGroupID, lock: LockOption _ [none, wait]]
    RETURNS [volumes: LIST OF VolumeID];
    -- ! Unknown {volumeGroupID};
    -- Returns the list of volumes belonging to the specified volumeGroup.
    -- Locking is as for GetNextGroup.
    
  GetEnclosingGroup: PROC [
    conversation: Conversation, transID: TransID _ nullTransID,
    volumeID: VolumeID, lock: LockOption _ [none, wait]]
    RETURNS [volumeGroupID: VolumeGroupID];
    -- ! Unknown {volumeID};
    -- Returns the VolumeGroupID of the volume group containing the specified
    -- volume.
    -- Locking is as for GetNextGroup.



  AccessFailed: ERROR [missingAccess: AlpineEnvironment.NeededAccess];
  
  Unknown: ERROR [what: AlpineEnvironment.UnknownType];
  
  StaticallyInvalid: ERROR;
  
  
  

END.