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org.apache.derby.iapi.services.locks
Interface LockFactory
- All Superinterfaces:
- org.apache.derby.iapi.services.property.PropertySetCallback
- public interface LockFactory
- extends org.apache.derby.iapi.services.property.PropertySetCallback
Generic locking of objects. Enables deadlock detection.
MT - Mutable - Container Object - Thread Safe
| Method Summary | |
boolean |
anyoneBlocked()
Returns true if locks held by anyone are blocking anyone else |
boolean |
areLocksHeld(java.lang.Object compatabilitySpace)
Return true if locks are held in this compatability space. |
boolean |
areLocksHeld(java.lang.Object compatabilitySpace,
java.lang.Object group)
Return true if locks are held in this compatability space and this group. |
void |
clearLimit(java.lang.Object compatabilitySpace,
java.lang.Object group)
Clear a limit set by setLimit. |
boolean |
isLockHeld(java.lang.Object compatabilitySpace,
java.lang.Object group,
Lockable ref,
java.lang.Object qualifier)
Check to see if a specific lock is held. |
boolean |
latchObject(java.lang.Object compatabilitySpace,
Lockable ref,
java.lang.Object qualifier,
int timeout)
Latch an object. |
boolean |
lockObject(java.lang.Object group,
Lockable ref,
java.lang.Object qualifier,
int timeout,
Latch latch)
Lock an object within a compatability space and associate the lock with a group object, In addition a held latch is passed in. |
boolean |
lockObject(java.lang.Object compatabilitySpace,
java.lang.Object group,
Lockable ref,
java.lang.Object qualifier,
int timeout)
Lock an object within a compatability space and associate the lock with a group object, waits up to timeout milli-seconds for the object to become unlocked. |
java.util.Enumeration |
makeVirtualLockTable()
Make a virtual lock table for diagnostics. |
void |
setLimit(java.lang.Object compatabilitySpace,
java.lang.Object group,
int limit,
Limit callback)
Install a limit that is called when the size of the group exceeds the required limit. |
void |
transfer(java.lang.Object compatabilitySpace,
java.lang.Object oldGroup,
java.lang.Object newGroup)
Transfer a set of locks from one group to another. |
void |
unlatch(Latch heldLatch)
Unlatch an object. |
int |
unlock(java.lang.Object compatabilitySpace,
java.lang.Object group,
Lockable ref,
java.lang.Object qualifier)
Unlock a single lock on a single object held within this compatability space that was locked with the supplied qualifier. |
void |
unlockGroup(java.lang.Object compatabilitySpace,
java.lang.Object group)
Unlock all locks in a group. |
void |
unlockGroup(java.lang.Object compatabilitySpace,
java.lang.Object group,
org.apache.derby.iapi.util.Matchable key)
Unlock all locks on a group that match the passed in value. |
boolean |
zeroDurationlockObject(java.lang.Object compatabilitySpace,
Lockable ref,
java.lang.Object qualifier,
int timeout)
Lock an object with zero duration within a compatability space, waits up to timeout milli-seconds for the object to become unlocked. |
| Methods inherited from interface org.apache.derby.iapi.services.property.PropertySetCallback |
apply, init, map, validate |
| Method Detail |
lockObject
public boolean lockObject(java.lang.Object compatabilitySpace, java.lang.Object group, Lockable ref, java.lang.Object qualifier, int timeout) throws org.apache.derby.iapi.error.StandardException
- Lock an object within a compatability space
and associate the lock with a group object,
waits up to timeout milli-seconds for the object to become unlocked. A
timeout of 0 means do not wait for the lock to be unlocked.
Note the actual time waited is approximate.
A compatibility space in an space where lock requests are assumed to be compatabile and granted by the lock manager if the trio {compatabilitySpace, ref, qualifier} are equal (i.e. reference equality for qualifier, equals() method for compatabilitySpace and ref ). A typical reference to use for the compatability space is a reference to an object representing a transaction. Granted by the lock manager means that the Lockable object may or may not be queried to see if the request is compatible.
A compatability space is not assumed to be owned by a single thread.
lockObject
public boolean lockObject(java.lang.Object group, Lockable ref, java.lang.Object qualifier, int timeout, Latch latch) throws org.apache.derby.iapi.error.StandardException
- Lock an object within a compatability space
and associate the lock with a group object,
In addition a held latch is passed in. If the lock
cannot be granted immediately, the latch will be released
and relatched after the lock is obtained. If the lock can be granted
immediately the latch is not released.
The compatability space of the request is defined by the compatability space of the latch.
unlock
public int unlock(java.lang.Object compatabilitySpace, java.lang.Object group, Lockable ref, java.lang.Object qualifier)
- Unlock a single lock on a single object held within this compatability space
that was locked with the supplied qualifier.
unlockGroup
public void unlockGroup(java.lang.Object compatabilitySpace, java.lang.Object group)
- Unlock all locks in a group.
unlockGroup
public void unlockGroup(java.lang.Object compatabilitySpace, java.lang.Object group, org.apache.derby.iapi.util.Matchable key)
- Unlock all locks on a group that match the passed in value.
transfer
public void transfer(java.lang.Object compatabilitySpace, java.lang.Object oldGroup, java.lang.Object newGroup)
- Transfer a set of locks from one group to another.
anyoneBlocked
public boolean anyoneBlocked()
- Returns true if locks held by anyone are blocking anyone else
areLocksHeld
public boolean areLocksHeld(java.lang.Object compatabilitySpace, java.lang.Object group)
- Return true if locks are held in this compatability space and
this group.
areLocksHeld
public boolean areLocksHeld(java.lang.Object compatabilitySpace)
- Return true if locks are held in this compatability space.
latchObject
public boolean latchObject(java.lang.Object compatabilitySpace, Lockable ref, java.lang.Object qualifier, int timeout) throws org.apache.derby.iapi.error.StandardException
- Latch an object. A latch is a lock without a group.
This means that it must be released explicitly by the owner.
A latch is not released by any unlock methods, it must be
released by the unlatch method. A latch is assumed to only
be held by one locker at a time.
The first argument passed to lockEvent() is the Latch that is to be used in the unlatch() call. The firstArgument passed to unlockEvent() should be ignored.
unlatch
public void unlatch(Latch heldLatch)
- Unlatch an object.
zeroDurationlockObject
public boolean zeroDurationlockObject(java.lang.Object compatabilitySpace, Lockable ref, java.lang.Object qualifier, int timeout) throws org.apache.derby.iapi.error.StandardException
- Lock an object with zero duration within a compatability space,
waits up to timeout milli-seconds for the object to become unlocked. A
timeout of 0 means do not wait for the lock to be unlocked.
Note the actual time waited is approximate.
Zero duration means the lock is released as soon as it is obtained.
A compatibility space in an space where lock requests are assumed to be compatabile and granted by the lock manager if the trio {compatabilitySpace, ref, qualifier} are equal (i.e. reference equality for qualifier, equals() method for compatabilitySpace and ref ). A typical reference to use for the compatability space is a reference to an object representing a transaction. Granted by the lock manager means that the Lockable object may or may not be queried to see if the request is compatible.
A compatability space is not assumed to be owned by a single thread.
isLockHeld
public boolean isLockHeld(java.lang.Object compatabilitySpace, java.lang.Object group, Lockable ref, java.lang.Object qualifier)
- Check to see if a specific lock is held.
setLimit
public void setLimit(java.lang.Object compatabilitySpace, java.lang.Object group, int limit, Limit callback)
- Install a limit that is called when the size of the group exceeds
the required limit.
It is not guaranteed that the callback method (Limit.reached) is called as soon as the group size exceeds the given limit. If the callback method does not result in a decrease in the number of locks held then the lock factory implementation may delay calling the method again. E.g. with a limit of 500 and a reached() method that does nothing, may result in the call back method only being called when the group size reaches 550.
Only one limit may be in place for a group at any time.
clearLimit
public void clearLimit(java.lang.Object compatabilitySpace, java.lang.Object group)
- Clear a limit set by setLimit.
makeVirtualLockTable
public java.util.Enumeration makeVirtualLockTable()
- Make a virtual lock table for diagnostics.
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