Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.iapi.services.locks.LockOwner

Method Summary

Modifier and Type	Method and Description
public boolean	Returns: true if this is a nested owner, e.g., a nested user transaction isNestedOwner() Return true if this is a nested owner, e.g., a nested user transaction.
public boolean	Returns: true if this owner nests under another owner nestsUnder(LockOwner The other lock owner other) Return true if this owner nests under another owner.
public boolean	Returns: `true` if timed waits should time out immediately, `false` otherwise noWait() Tells whether lock requests should time out immediately if the lock cannot be granted at once, even if `C_LockFactory.TIMED_WAIT` was specified in the lock request.

Method Detail

isNestedOwner	back to summary
public boolean isNestedOwner() Return true if this is a nested owner, e.g., a nested user transaction. Returns:boolean true if this is a nested owner, e.g., a nested user transaction

isNestedOwner

back to summary

public boolean isNestedOwner()

Return true if this is a nested owner, e.g., a nested user transaction.

Returns:boolean: true if this is a nested owner, e.g., a nested user transaction

nestsUnder	back to summary
public boolean nestsUnder(LockOwner other) Return true if this owner nests under another owner. Parameters other:LockOwner The other lock owner Returns:boolean true if this owner nests under another owner

nestsUnder

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public boolean nestsUnder(LockOwner other)

Return true if this owner nests under another owner.

Parameters

other:LockOwner: The other lock owner

Returns:boolean

true if this owner nests under another owner

noWait back to summary

noWait	back to summary
public boolean noWait() Tells whether lock requests should time out immediately if the lock cannot be granted at once, even if `C_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 return `true`. 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's `LockOwner` instance could return `true` and thereby making it possible to detect lock conflicts instantly. Returns:boolean `true` if timed waits should time out immediately, `false` otherwise

public boolean noWait()

Tells whether lock requests should time out immediately if the lock cannot be granted at once, even if C_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 return true. 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's LockOwner instance could return true and thereby making it possible to detect lock conflicts instantly.

Returns:boolean: true if timed waits should time out immediately, false otherwise

public Interface LockOwner

Method Summary

Method Detail