com.sleepycat.je.txn

Class ThinLockImpl

java.lang.Object

com.sleepycat.je.txn.LockInfo

com.sleepycat.je.txn.ThinLockImpl

All Implemented Interfaces:

Lock, java.lang.Cloneable

public class ThinLockImpl
extends LockInfo
implements Lock

Implements a lightweight Lock with no waiters and only a single Owner. If, during an operation (lock) more than one owner or waiter is required, then this will mutate to a LockImpl, perform the requested operation, and return the new LockImpl to the caller. public for Sizeof.

Field Summary

Fields inherited from class com.sleepycat.je.txn.LockInfo

locker, lockType

Constructor Summary

Constructors

Constructor and Description
ThinLockImpl() Create a Lock.

Method Summary

Methods

Modifier and Type	Method and Description
void	demote(Locker locker) Downgrade a write lock to a read lock.
void	flushWaiter(Locker locker, MemoryBudget mb, int lockTableIndex) Remove this locker from the waiter list.
LockType	getOwnedLockType(Locker locker) Returns the LockType if the given locker owns this lock, or null if the lock is not owned.
java.util.Set<LockInfo>	getOwnersClone() Get a new Set of the owners.
java.util.List<LockInfo>	getWaitersListClone() Get a list of waiters for debugging and error messages.
Locker	getWriteOwnerLocker() Return the locker that has a write ownership on this lock.
boolean	isOwnedWriteLock(Locker locker) Return true if locker is an owner of this Lock and this is a write lock.
boolean	isOwner(Locker locker, LockType lockType) Return true if locker is an owner of this Lock for lockType, false otherwise.
boolean	isThin()
boolean	isWaiter(Locker locker) Return true if locker is a waiter on this Lock.
LockAttemptResult	lock(LockType requestType, Locker locker, boolean nonBlockingRequest, boolean jumpAheadOfWaiters, MemoryBudget mb, int lockTableIndex) Attempts to acquire the lock and returns the LockGrantType.
int	nOwners()
int	nWaiters()
java.util.Set<Locker>	release(Locker locker, MemoryBudget mb, int lockTableIndex) Releases a lock and moves the next waiter(s) to the owners.
void	stealLock(Locker locker, MemoryBudget mb, int lockTableIndex) Removes all owners except for the given owner, and sets the Preempted property on the removed owners.
java.lang.String	toString() Debug dumper.

Methods inherited from class com.sleepycat.je.txn.LockInfo

clone, dump, getDeadlockStackTrace, getLocker, getLockType, setDeadlockStackTrace, setLocker, setLockType

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ThinLockImpl

public ThinLockImpl()

Create a Lock. Public for Sizeof.

Method Detail

getWaitersListClone

public java.util.List<LockInfo> getWaitersListClone()

Description copied from interface: Lock

Get a list of waiters for debugging and error messages.

Specified by:

getWaitersListClone in interface Lock

flushWaiter

public void flushWaiter(Locker locker,
               MemoryBudget mb,
               int lockTableIndex)

Description copied from interface: Lock

Remove this locker from the waiter list.

Specified by:

flushWaiter in interface Lock

getOwnersClone

public java.util.Set<LockInfo> getOwnersClone()

Description copied from interface: Lock

Get a new Set of the owners.

Specified by:

getOwnersClone in interface Lock

isOwner

public boolean isOwner(Locker locker,
              LockType lockType)

Description copied from interface: Lock

Return true if locker is an owner of this Lock for lockType, false otherwise. This method is only used by unit tests.

Specified by:

isOwner in interface Lock

isOwnedWriteLock

public boolean isOwnedWriteLock(Locker locker)

Description copied from interface: Lock

Return true if locker is an owner of this Lock and this is a write lock.

Specified by:

isOwnedWriteLock in interface Lock

getOwnedLockType

public LockType getOwnedLockType(Locker locker)

Description copied from interface: Lock

Returns the LockType if the given locker owns this lock, or null if the lock is not owned.

Specified by:

getOwnedLockType in interface Lock

isWaiter

public boolean isWaiter(Locker locker)

Description copied from interface: Lock

Return true if locker is a waiter on this Lock. This method is only used by unit tests.

Specified by:

isWaiter in interface Lock

nWaiters

public int nWaiters()

Specified by:

nWaiters in interface Lock

nOwners

public int nOwners()

Specified by:

nOwners in interface Lock

lock

public LockAttemptResult lock(LockType requestType,
                     Locker locker,
                     boolean nonBlockingRequest,
                     boolean jumpAheadOfWaiters,
                     MemoryBudget mb,
                     int lockTableIndex)
                       throws DatabaseException

Description copied from interface: Lock

Attempts to acquire the lock and returns the LockGrantType. Assumes we hold the lockTableLatch when entering this method.

Specified by:

lock in interface Lock

Throws:

DatabaseException

release

public java.util.Set<Locker> release(Locker locker,
                            MemoryBudget mb,
                            int lockTableIndex)

Description copied from interface: Lock

Releases a lock and moves the next waiter(s) to the owners.

Specified by:

release in interface Lock

Returns:

- null if we were not the owner, - a non-empty set if owners should be notified after releasing, - an empty set if no notification is required.

stealLock

public void stealLock(Locker locker,
             MemoryBudget mb,
             int lockTableIndex)

Description copied from interface: Lock

Removes all owners except for the given owner, and sets the Preempted property on the removed owners.

Specified by:

stealLock in interface Lock

demote

public void demote(Locker locker)

Description copied from interface: Lock

Downgrade a write lock to a read lock.

Specified by:

demote in interface Lock

getWriteOwnerLocker

public Locker getWriteOwnerLocker()

Description copied from interface: Lock

Return the locker that has a write ownership on this lock. If no write owner exists, return null.

Specified by:

getWriteOwnerLocker in interface Lock

isThin

public boolean isThin()

Specified by:

isThin in interface Lock

toString

public java.lang.String toString()

Description copied from interface: Lock

Debug dumper.

Specified by:

toString in interface Lock

Overrides:

toString in class LockInfo