Interface LockOwner
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- All Known Implementing Classes:
InternalXact
,UpdateLoader
,Xact
public interface LockOwner
Interface for classes that represent an owner of the locks within a compatibility space.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description boolean
isNestedOwner()
Return true if this is a nested owner, e.g., a nested user transaction.boolean
nestsUnder(LockOwner other)
Return true if this owner nests under another owner.boolean
noWait()
Tells whether lock requests should time out immediately if the lock cannot be granted at once, even ifC_LockFactory.TIMED_WAIT
was specified in the lock request.
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Method Detail
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noWait
boolean noWait()
Tells whether lock requests should time out immediately if the lock cannot be granted at once, even ifC_LockFactory.TIMED_WAIT
was specified in the lock request.Normally, this method should return
false
, but in some very special cases it could be appropriate to returntrue
. One example is when a stored prepared statement (SPS) is compiled and stored in a system table. In order to prevent exclusive locks in the system table from being held until the transaction that triggered the compilation is finished, the SPS will be compiled in a nested transaction that is committed and releases all locks upon completion. There is however a risk that the transaction that triggered the compilation is holding locks that the nested transaction needs, in which case the nested transaction will time out. The timeout will be detected by the calling code, and the operation will be retried in the parent transaction. To avoid long waits in the cases where the nested transaction runs into a lock conflict with its parent, the nested transaction'sLockOwner
instance could returntrue
and thereby making it possible to detect lock conflicts instantly.- Returns:
true
if timed waits should time out immediately,false
otherwise
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isNestedOwner
boolean isNestedOwner()
Return true if this is a nested owner, e.g., a nested user transaction.
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nestsUnder
boolean nestsUnder(LockOwner other)
Return true if this owner nests under another owner.
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