LockAndQueue (Apache HBase - Procedure 2.1.3 API)

java.lang.Object
- org.apache.hadoop.hbase.procedure2.LockAndQueue

所有已实现的接口:

LockStatus
```
@InterfaceAudience.Private
public class LockAndQueue
extends Object
implements LockStatus
```
Locking for mutual exclusion between procedures. Used only by procedure framework internally. LockAndQueue has two purposes:
1. Acquire/release exclusive/shared locks.
2. Maintains a list of procedures waiting on this lock. LockAndQueue extends ProcedureDeque class. Blocked Procedures are added to our super Deque. Using inheritance over composition to keep the Deque of waiting Procedures is unusual, but we do it this way because in certain cases, there will be millions of regions. This layout uses less memory.
NOT thread-safe. Needs external concurrency control: e.g. uses in MasterProcedureScheduler are guarded by schedLock().
There is no need of 'volatile' keyword for member variables because of memory synchronization guarantees of locks (see 'Memory Synchronization', http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/locks/Lock.html)
We do not implement Lock interface because we need exclusive and shared locking, and also because try-lock functions require procedure id.
We do not use ReentrantReadWriteLock directly because of its high memory overhead.

构造器概要

构造器
构造器和说明

LockAndQueue(Function<Long,Procedure<?>> procedureRetriever)

构造器
构造器和说明
`LockAndQueue(Function<Long,Procedure<?>> procedureRetriever)`

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`void`	`addLast(Procedure<?> proc)`
`Stream<Procedure>`	`filterWaitingQueue(Predicate<Procedure> predicate)`
`Procedure<?>`	`getExclusiveLockOwnerProcedure()` Get the procedure which holds the exclusive lock.
`int`	`getSharedLockCount()` Get the number of procedures which hold the shared lock.
`boolean`	`hasExclusiveLock()` Whether the exclusive lock has been held.
`boolean`	`hasLockAccess(Procedure<?> proc)` Return true if the procedure itself holds the exclusive lock, or any ancestors of the give procedure hold the exclusive lock.
`boolean`	`isWaitingQueueEmpty()`
`boolean`	`releaseExclusiveLock(Procedure<?> proc)`
`boolean`	`releaseSharedLock()`
`Procedure<?>`	`removeFirst()`
`String`	`toString()`
`boolean`	`tryExclusiveLock(Procedure<?> proc)`
`boolean`	`trySharedLock(Procedure<?> proc)`
`int`	`wakeWaitingProcedures(ProcedureScheduler scheduler)`

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

从接口继承的方法 org.apache.hadoop.hbase.procedure2.LockStatus
getExclusiveLockProcIdOwner, isLocked

- 构造器详细资料
  - LockAndQueue
```
public LockAndQueue(Function<Long,Procedure<?>> procedureRetriever)
```
- 方法详细资料
  - hasExclusiveLock
```
public boolean hasExclusiveLock()
```
    从接口复制的说明: LockStatus
    
    Whether the exclusive lock has been held.
    
    指定者:
    
    hasExclusiveLock 在接口中 LockStatus
  - hasLockAccess
```
public boolean hasLockAccess(Procedure<?> proc)
```
    从接口复制的说明: LockStatus
    
    Return true if the procedure itself holds the exclusive lock, or any ancestors of the give procedure hold the exclusive lock.
    
    指定者:
    
    hasLockAccess 在接口中 LockStatus
  - getExclusiveLockOwnerProcedure
```
public Procedure<?> getExclusiveLockOwnerProcedure()
```
    从接口复制的说明: LockStatus
    
    Get the procedure which holds the exclusive lock.
    
    指定者:
    
    getExclusiveLockOwnerProcedure 在接口中 LockStatus
  - getSharedLockCount
```
public int getSharedLockCount()
```
    从接口复制的说明: LockStatus
    
    Get the number of procedures which hold the shared lock.
    
    指定者:
    
    getSharedLockCount 在接口中 LockStatus
  - trySharedLock
```
public boolean trySharedLock(Procedure<?> proc)
```
    返回:
    
    whether we have succesfully acquired the shared lock.
  - releaseSharedLock
```
public boolean releaseSharedLock()
```
    返回:
    
    whether we should wake the procedures waiting on the lock here.
  - tryExclusiveLock
```
public boolean tryExclusiveLock(Procedure<?> proc)
```
  - releaseExclusiveLock
```
public boolean releaseExclusiveLock(Procedure<?> proc)
```
    返回:
    
    whether we should wake the procedures waiting on the lock here.
  - isWaitingQueueEmpty
```
public boolean isWaitingQueueEmpty()
```
  - removeFirst
```
public Procedure<?> removeFirst()
```
  - addLast
```
public void addLast(Procedure<?> proc)
```
  - wakeWaitingProcedures
```
public int wakeWaitingProcedures(ProcedureScheduler scheduler)
```
  - filterWaitingQueue
```
public Stream<Procedure> filterWaitingQueue(Predicate<Procedure> predicate)
```
  - toString
```
public String toString()
```
    覆盖:
    
    toString 在类中 Object

类 LockAndQueue

构造器概要

方法概要

从类继承的方法 java.lang.Object

从接口继承的方法 org.apache.hadoop.hbase.procedure2.LockStatus

构造器详细资料

LockAndQueue

方法详细资料

hasExclusiveLock

hasLockAccess

getExclusiveLockOwnerProcedure

getSharedLockCount

trySharedLock

releaseSharedLock

tryExclusiveLock

releaseExclusiveLock

isWaitingQueueEmpty

removeFirst

addLast

wakeWaitingProcedures

filterWaitingQueue

toString