Class CycleDetectingLockFactory.WithExplicitOrdering<E extends java.lang.Enum<E>>
- java.lang.Object
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- com.google.common.util.concurrent.CycleDetectingLockFactory
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- com.google.common.util.concurrent.CycleDetectingLockFactory.WithExplicitOrdering<E>
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- Type Parameters:
E
- The Enum type representing the explicit lock ordering.
- Enclosing class:
- CycleDetectingLockFactory
public static final class CycleDetectingLockFactory.WithExplicitOrdering<E extends java.lang.Enum<E>> extends CycleDetectingLockFactory
ACycleDetectingLockFactory.WithExplicitOrdering
provides the additional enforcement of an application-specified ordering of lock acquisitions. The application defines the allowed ordering with anEnum
whose values each correspond to a lock type. The order in which the values are declared dictates the allowed order of lock acquisition. In other words, locks corresponding to smaller values ofEnum.ordinal()
should only be acquired before locks with larger ordinals. Example:enum MyLockOrder { FIRST, SECOND, THIRD; } CycleDetectingLockFactory.WithExplicitOrdering<MyLockOrder> factory = CycleDetectingLockFactory.newInstanceWithExplicitOrdering(Policies.THROW); Lock lock1 = factory.newReentrantLock(MyLockOrder.FIRST); Lock lock2 = factory.newReentrantLock(MyLockOrder.SECOND); Lock lock3 = factory.newReentrantLock(MyLockOrder.THIRD); lock1.lock(); lock3.lock(); lock2.lock(); // will throw an IllegalStateException
As with all locks created by instances of
CycleDetectingLockFactory
explicitly ordered locks participate in general cycle detection with all other cycle detecting locks, and a lock's behavior when detecting a cyclic lock acquisition is defined by thePolicy
of the factory that created it.Note, however, that although multiple locks can be created for a given Enum value, whether it be through separate factory instances or through multiple calls to the same factory, attempting to acquire multiple locks with the same Enum value (within the same thread) will result in an IllegalStateException regardless of the factory's policy. For example:
CycleDetectingLockFactory.WithExplicitOrdering<MyLockOrder> factory1 = CycleDetectingLockFactory.newInstanceWithExplicitOrdering(...); CycleDetectingLockFactory.WithExplicitOrdering<MyLockOrder> factory2 = CycleDetectingLockFactory.newInstanceWithExplicitOrdering(...); Lock lockA = factory1.newReentrantLock(MyLockOrder.FIRST); Lock lockB = factory1.newReentrantLock(MyLockOrder.FIRST); Lock lockC = factory2.newReentrantLock(MyLockOrder.FIRST); lockA.lock(); lockB.lock(); // will throw an IllegalStateException lockC.lock(); // will throw an IllegalStateException lockA.lock(); // reentrant acquisition is okay
It is the responsibility of the application to ensure that multiple lock instances with the same rank are never acquired in the same thread.
- Since:
- 13.0
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Nested Class Summary
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Nested classes/interfaces inherited from class com.google.common.util.concurrent.CycleDetectingLockFactory
CycleDetectingLockFactory.Policies, CycleDetectingLockFactory.Policy, CycleDetectingLockFactory.PotentialDeadlockException, CycleDetectingLockFactory.WithExplicitOrdering<E extends java.lang.Enum<E>>
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.util.concurrent.locks.ReentrantLock
newReentrantLock(E rank)
Equivalent tonewReentrantLock(rank, false)
.java.util.concurrent.locks.ReentrantLock
newReentrantLock(E rank, boolean fair)
Creates aReentrantLock
with the given fairness policy and rank.java.util.concurrent.locks.ReentrantReadWriteLock
newReentrantReadWriteLock(E rank)
Equivalent tonewReentrantReadWriteLock(rank, false)
.java.util.concurrent.locks.ReentrantReadWriteLock
newReentrantReadWriteLock(E rank, boolean fair)
Creates aReentrantReadWriteLock
with the given fairness policy and rank.-
Methods inherited from class com.google.common.util.concurrent.CycleDetectingLockFactory
newInstance, newInstanceWithExplicitOrdering, newReentrantLock, newReentrantLock, newReentrantReadWriteLock, newReentrantReadWriteLock
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Method Detail
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newReentrantLock
public java.util.concurrent.locks.ReentrantLock newReentrantLock(E rank)
Equivalent tonewReentrantLock(rank, false)
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newReentrantLock
public java.util.concurrent.locks.ReentrantLock newReentrantLock(E rank, boolean fair)
Creates aReentrantLock
with the given fairness policy and rank. The values returned byEnum.getDeclaringClass()
andEnum.name()
are used to describe the lock in warning or exception output.- Throws:
java.lang.IllegalStateException
- If the factory has already created aLock
with the specified rank.
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newReentrantReadWriteLock
public java.util.concurrent.locks.ReentrantReadWriteLock newReentrantReadWriteLock(E rank)
Equivalent tonewReentrantReadWriteLock(rank, false)
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newReentrantReadWriteLock
public java.util.concurrent.locks.ReentrantReadWriteLock newReentrantReadWriteLock(E rank, boolean fair)
Creates aReentrantReadWriteLock
with the given fairness policy and rank. The values returned byEnum.getDeclaringClass()
andEnum.name()
are used to describe the lock in warning or exception output.- Throws:
java.lang.IllegalStateException
- If the factory has already created aLock
with the specified rank.
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