Class SkipLockedClaims

java.lang.Object

com.kingsrook.qqq.backend.core.jobs.store.SkipLockedClaims

public final class SkipLockedClaims
extends Object

Claims with SELECT ... FOR UPDATE SKIP LOCKED (spec section 2.13, item 5): in one short transaction, lock candidate rows other claimers have not locked, then claim them (the fenced conditional update still bumps leaseVersion) and commit. Competing pods skip each other's rows instead of racing for the same ones. Backends without it use conditional updates only.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	SkipLockedClaims.Claimer<T>	Claims the locked candidates inside the transaction.

Method Summary

Modifier and Type	Method	Description
static <T> T	claim(String tableName, QQueryFilter filter, SkipLockedClaims.Claimer<T> claimer)	Lock the filter's rows (skipping locked ones) and claim them, in one transaction (as the system user).
static boolean	isSupported(String tableName)	Whether the table's backend supports FOR UPDATE SKIP LOCKED.

Methods inherited from class java.lang.Object

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

Method Details

isSupported

public static boolean isSupported(String tableName)

Whether the table's backend supports FOR UPDATE SKIP LOCKED.

claim

public static <T> T claim(String tableName,
 QQueryFilter filter,
 SkipLockedClaims.Claimer<T> claimer)
                   throws QException

Lock the filter's rows (skipping locked ones) and claim them, in one transaction (as the system user).

Throws:

QException