class B2IRowLocking3 extends java.lang.Object implements BTreeLockingPolicy
Holds read and write locks until end of transaction. Obtains previous key locks to protect from phantom reads.
Modifier and Type | Field and Description |
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protected ConglomerateController |
base_cc
The container id of the base container for this index.
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protected OpenBTree |
open_btree
The OpenBtree to use if we have to lock anything in the btree vs.
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private Transaction |
rawtran
The transaction to associate lock requests with.
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Constructor and Description |
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B2IRowLocking3(Transaction rawtran,
int lock_level,
LockingPolicy locking_policy,
ConglomerateController base_cc,
OpenBTree open_btree)
Constructors for This class:
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Modifier and Type | Method and Description |
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protected boolean |
_lockScanRow(OpenBTree open_btree,
BTreeRowPosition pos,
boolean request_row_lock,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
boolean previous_key_lock,
boolean forUpdate,
int lock_operation)
Lock a row as part of doing the scan.
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boolean |
lockNonScanPreviousRow(LeafControlRow current_leaf,
int current_slot,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
OpenBTree open_btree,
int lock_operation,
int lock_duration)
Lock the row previous to the input row.
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boolean |
lockNonScanRow(BTree btree,
LeafControlRow current_leaf,
LeafControlRow aux_leaf,
DataValueDescriptor[] current_row,
int lock_operation)
Lock the in memory row.
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boolean |
lockNonScanRowOnPage(LeafControlRow current_leaf,
int current_slot,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
int lock_operation)
Lock the row at the given slot.
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private boolean |
lockPreviousToFirstKey(LeafControlRow current_leaf,
LeafControlRow aux_leaf,
int lock_operation,
int lock_duration)
Lock key previous to first key in btree.
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private boolean |
lockRowOnPage(LeafControlRow current_leaf,
LeafControlRow aux_leaf,
int current_slot,
BTreeRowPosition position,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
int lock_operation,
int lock_duration)
Lock a btree row (row is at given slot in page).
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boolean |
lockScanCommittedDeletedRow(OpenBTree open_btree,
LeafControlRow leaf,
DataValueDescriptor[] template,
FetchDescriptor lock_fetch_desc,
int slot_no)
Lock a btree row to determine if it is a committed deleted row.
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boolean |
lockScanRow(OpenBTree open_btree,
BTreeRowPosition pos,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
boolean previous_key_lock,
boolean forUpdate,
int lock_operation)
Lock a row as part of doing the scan.
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private boolean |
searchLeftAndLockPreviousKey(LeafControlRow current_leaf,
FetchDescriptor lock_fetch_desc,
DataValueDescriptor[] lock_template,
RowLocation lock_row_loc,
OpenBTree open_btree,
int lock_operation,
int lock_duration)
move left in btree and lock previous key.
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void |
unlockScanRecordAfterRead(BTreeRowPosition pos,
boolean forUpdate)
Release read lock on a row.
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protected ConglomerateController base_cc
protected OpenBTree open_btree
private Transaction rawtran
B2IRowLocking3(Transaction rawtran, int lock_level, LockingPolicy locking_policy, ConglomerateController base_cc, OpenBTree open_btree)
private boolean lockPreviousToFirstKey(LeafControlRow current_leaf, LeafControlRow aux_leaf, int lock_operation, int lock_duration) throws StandardException
In the previous key locking protocol repeatable read and phantom protection is guaranteed by locking a range of keys in the btree. The range is defined by the key previous to the first key you look at and all subsequent keys you look at. The first key in the index is a special case, as there are no keys previous to it. In that case a special key is declared the "previous key" to the first key in the btree and is locked instead.
In this implementation that first key is defined to be in the base container, page ContainerHandle.FIRST_PAGE_NUMBER, record id PREVIOUS_KEY_HANDLE.
Note that the previous key is the same for all indexes on a given conglomerate. It seemed better for all locks on a base table to have the same containerid, rather than having some locks generated from a btree have a containerid from base table and some having a containerid from the btree. If this turns out to be a problem we could either have 2 different containerid's, be more creative with the record id, or even add more to the lock key.
aux_leaf
- If non-null, this leaf is unlatched if the
routine has to wait on the lock.lock_operation
- Whether to lock exclusive or share.lock_duration
- For what duration should the lock be held,
if INSTANT_DURATION, then the routine will
guarantee that lock was acquired while holding
the latch, but then immediately release the
lock. If COMMIT_DURATION or MANUAL_DURATION
then the lock be held when routine returns
successfully.StandardException
- Standard exception policy.private boolean lockRowOnPage(LeafControlRow current_leaf, LeafControlRow aux_leaf, int current_slot, BTreeRowPosition position, FetchDescriptor lock_fetch_desc, DataValueDescriptor[] lock_template, RowLocation lock_row_loc, int lock_operation, int lock_duration) throws StandardException
Lock the row at the given slot in the page. Meant to be used if caller only has the slot on the page to be locked, and has not read the row yet. This routine fetches the row location field from the page, and then locks that rowlocation in the base container.
Lock a btree row, enforcing the standard lock/latch protocol. On return the row is locked. Return status indicates if the lock was waited for, which will mean a latch was dropped while waiting. In general a false status means that the caller will either have to research the tree unless some protocol has been implemented that insures that the row will not have moved while the latch was dropped.
This routine request a row lock NOWAIT on the in-memory row "current_row.". If the lock is granted the routine will return true. If the lock cannot be granted NOWAIT, then the routine will release the latch on "current_leaf" and "aux_leaf" (if aux_leaf is non-null), and then it will request a WAIT lock on the row.
current_leaf
- Latched current leaf where "current" key is.aux_leaf
- If non-null, this leaf is unlatched if the
routine has to wait on the lock.current_slot
- Slot of row to lock.lock_fetch_desc
- Descriptor for fetching just the RowLocation,
used for locking.position
- The position to lock if the lock is requested
while performing a scan, null otherwise.lock_operation
- Whether lock is for key prev to insert or not.lock_duration
- For what duration should the lock be held,
if INSTANT_DURATION, then the routine will
guarantee that lock was acquired while holding
the latch, but then immediately release the
lock. If COMMIT_DURATION or MANUAL_DURATION
then the lock be held when routine returns
successfully.StandardException
- Standard exception policy.private boolean searchLeftAndLockPreviousKey(LeafControlRow current_leaf, FetchDescriptor lock_fetch_desc, DataValueDescriptor[] lock_template, RowLocation lock_row_loc, OpenBTree open_btree, int lock_operation, int lock_duration) throws StandardException
Enter routine with "current_leaf" latched. This routine implements the left travel ladder locking protocol to search the leaf pages from right to left for the previous key to 1st key on current_leaf. There are 2 cases: 1) the previous page has keys, in which case the last key on that page is locked, other wise search continues on the next page to the left. 2) there are no keys on the current page and there is no page to the left. In this case the special "leftmost key" lock is gotten by calling lockPreviousToFirstKey(). Left laddar locking is used if all latches can be obtained immediately with NOWAIT. This means that current latch is held while asking for left latch NOWAIT, and if left latch is granted then subsequently current latch can be released. If this protocol is followed and all latches are granted then caller is guaranteed that the correct previous key has been locked and current_page latch remains. The NOWAIT protocol is used to avoid latch/latch deadlocks. The overall protocol is that one never holds a latch while waiting on another unless the direction of travel is down and to the right.
If along the search a latch has to be waited on then latches are released and a wait is performed, and "false" status is returned to caller. In this case the routine can no longer be sure of it's current position and may have to retry the whole operation.
StandardException
- Standard exception policy.protected boolean _lockScanRow(OpenBTree open_btree, BTreeRowPosition pos, boolean request_row_lock, FetchDescriptor lock_fetch_desc, DataValueDescriptor[] lock_template, RowLocation lock_row_loc, boolean previous_key_lock, boolean forUpdate, int lock_operation) throws StandardException
Lock the row at the given slot (or the previous row if slot is 0).
If this routine returns true all locks were acquired while maintaining the latch on leaf. If this routine returns false, locks may or may not have been acquired, and the routine should be called again after the client has researched the tree to reget the latch on the appropriate page.
open_btree
- The open_btree to associate latches with -
used if routine has to scan backward.pos
- The position of the row to lock.request_row_lock
- Whether to request the row lock, should
only be requested once per page in the scan.lock_fetch_desc
- The fetch descriptor to use to fetch the
row location for the lock request.lock_template
- A scratch area to use to read in rows.previous_key_lock
- Is this a previous key lock call?forUpdate
- Is the scan for update or for read only.StandardException
- Standard exception policy.public boolean lockScanCommittedDeletedRow(OpenBTree open_btree, LeafControlRow leaf, DataValueDescriptor[] template, FetchDescriptor lock_fetch_desc, int slot_no) throws StandardException
lockScanCommittedDeletedRow
in interface BTreeLockingPolicy
open_btree
- The conglomerate we are locking.leaf
- The leaf page with the row to lock.template
- Empty full template row, to read row into.slot_no
- The slot of row on "current_leaf"StandardException
- Standard exception policy.BTreeLockingPolicy.lockScanCommittedDeletedRow(org.apache.derby.impl.store.access.btree.OpenBTree, org.apache.derby.impl.store.access.btree.LeafControlRow, org.apache.derby.iapi.types.DataValueDescriptor[], org.apache.derby.iapi.store.raw.FetchDescriptor, int)
public boolean lockScanRow(OpenBTree open_btree, BTreeRowPosition pos, FetchDescriptor lock_fetch_desc, DataValueDescriptor[] lock_template, RowLocation lock_row_loc, boolean previous_key_lock, boolean forUpdate, int lock_operation) throws StandardException
Lock the row at the given slot (or the previous row if slot is 0).
If this routine returns true all locks were acquired while maintaining the latch on leaf. If this routine returns false, locks may or may not have been acquired, and the routine should be called again after the client has researched the tree to reget the latch on the appropriate page.
lockScanRow
in interface BTreeLockingPolicy
open_btree
- The open_btree to associate latches with -
used if routine has to scan backward.pos
- The position of the row to lock.lock_template
- A scratch area to use to read in rows.previous_key_lock
- Is this a previous key lock call?forUpdate
- Is the scan for update or for read only.lock_operation
- For what operation are we requesting the lock,
this should be one of the following 4 options:
LOCK_READ [read lock],
(LOCK_INS | LOCK_UPD) [ lock for insert],
(LOCK_INSERT_PREVKEY | LOCK_UPD) [lock for
previous key to insert],
(LOCK_UPD) [lock for delete or replace]StandardException
- Standard exception policy.public void unlockScanRecordAfterRead(BTreeRowPosition pos, boolean forUpdate) throws StandardException
unlockScanRecordAfterRead
in interface BTreeLockingPolicy
pos
- Data structure that defines the current position
in the scan to be unlocked.forUpdate
- Is the scan for update or for read only.StandardException
- Standard exception policy.public boolean lockNonScanPreviousRow(LeafControlRow current_leaf, int current_slot, FetchDescriptor lock_fetch_desc, DataValueDescriptor[] lock_template, RowLocation lock_row_loc, OpenBTree open_btree, int lock_operation, int lock_duration) throws StandardException
See BTreeLockingPolicy.lockNonScanPreviousRow
lockNonScanPreviousRow
in interface BTreeLockingPolicy
current_leaf
- Latched current leaf where "current" key is.current_slot
- The slot of row on "current_leaf"lock_template
- Empty full template row, to read row into.open_btree
- The open_btree to associate latches with -
used if routine has to scan backward.lock_operation
- For what operation are we requesting the lock,
this should be one of the following 4 options:
LOCK_READ [read lock],
(LOCK_INS | LOCK_UPD) [ lock for insert],
(LOCK_INSERT_PREVKEY | LOCK_UPD) [lock for
previous key to insert],
(LOCK_UPD) [lock for delete or replace]lock_duration
- For what duration should the lock be held,
if INSTANT_DURATION, then the routine will
guarantee that lock was acquired while holding
the latch, but then immediately release the
lock. If COMMIT_DURATION or MANUAL_DURATION
then the lock be held when routine returns
successfully.StandardException
- Standard exception policy.public boolean lockNonScanRow(BTree btree, LeafControlRow current_leaf, LeafControlRow aux_leaf, DataValueDescriptor[] current_row, int lock_operation) throws StandardException
See BTree.lockRow() for more info.
lockNonScanRow
in interface BTreeLockingPolicy
btree
- The conglomerate we are locking.current_leaf
- If non-null, this leaf is unlatched if the
routine has to wait on the lock.aux_leaf
- If non-null, this leaf is unlatched if the
routine has to wait on the lock.current_row
- In memory, objectified "current" row.lock_operation
- For what operation are we requesting the lock,
this should be one of the following 4 options:
LOCK_READ [read lock],
(LOCK_INS | LOCK_UPD) [ lock for insert],
(LOCK_INSERT_PREVKEY | LOCK_UPD) [lock for
previous key to insert],
(LOCK_UPD) [lock for delete or replace]StandardException
- Standard exception policy.public boolean lockNonScanRowOnPage(LeafControlRow current_leaf, int current_slot, FetchDescriptor lock_fetch_desc, DataValueDescriptor[] lock_template, RowLocation lock_row_loc, int lock_operation) throws StandardException
BTreeLockingPolicy
If this routine returns true all locks were acquired while maintaining the latch on leaf. If this routine returns false, locks may or may not have been acquired, and the routine should be called again after the client has researched the tree to reget the latch on the appropriate page.
lockNonScanRowOnPage
in interface BTreeLockingPolicy
current_leaf
- The control row of the current leaf to lock.current_slot
- The slot position of the row to lock.lock_template
- A scratch area to use to read in rows.lock_operation
- For what operation are we requesting the lock,
this should be one of the following 4 options:
LOCK_READ [read lock],
(LOCK_INS | LOCK_UPD) [ lock for insert],
(LOCK_INSERT_PREVKEY | LOCK_UPD) [lock for
previous key to insert],
(LOCK_UPD) [lock for delete or replace]StandardException
- Standard exception policy.Apache Derby V10.13 Internals - Copyright © 2004,2016 The Apache Software Foundation. All Rights Reserved.