ProcedureStore (Apache HBase 2.5.0 API)

All Known Implementing Classes:

NoopProcedureStore, ProcedureStoreBase, RegionProcedureStore, WALProcedureStore
```
@InterfaceAudience.Private
 @InterfaceStability.Evolving
public interface ProcedureStore
```
The ProcedureStore is used by the executor to persist the state of each procedure execution. This allows to resume the execution of pending/in-progress procedures in case of machine failure or service shutdown.
Notice that, the implementation must guarantee that the maxProcId when loading is the maximum one in the whole history, not only the current live procedures. This is very important as for executing remote procedures, we have some nonce checks at region server side to prevent executing non-idempotent operations more than once. If the procedure id could go back, then we may accidentally ignore some important operations such as region assign or unassign.
This may lead to some garbages so we provide a cleanup() method, the framework will call this method periodically and the store implementation could do some clean up works in this method.

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`ProcedureStore.ProcedureIterator` An Iterator over a collection of Procedure
`static interface`	`ProcedureStore.ProcedureLoader` Interface passed to the ProcedureStore.load() method to handle the store-load events.
`static interface`	`ProcedureStore.ProcedureStoreListener` Store listener interface.

Method Summary

All Methods Instance Methods Abstract Methods Default Methods Deprecated Methods
Modifier and Type	Method and Description
`default void`	`cleanup()` Will be called by the framework to give the store a chance to do some clean up works.
`void`	`delete(long procId)` The specified procId was removed from the executor, due to completion, abort or failure.
`void`	`delete(long[] procIds, int offset, int count)` The specified procIds were removed from the executor, due to completion, abort or failure.
`void`	`delete(Procedure<?> parentProc, long[] subProcIds)` The parent procedure completed.
`int`	`getNumThreads()` Returns the number of threads/slots passed to start()
`void`	`insert(Procedure<?>[] procs)` Serialize a set of new procedures.
`void`	`insert(Procedure<?> proc, Procedure<?>[] subprocs)` When a procedure is submitted to the executor insert(proc, null) will be called.
`boolean`	`isRunning()` Returns true if the store is running, otherwise false.
`void`	`load(ProcedureStore.ProcedureLoader loader)` Load the Procedures in the store.
`void`	`recoverLease()` Deprecated. since 2.3.0, will be removed in 4.0.0 along with `WALProcedureStore`. As now we will store the procedure data in a master local region, and master itself will deal with the lease recovery of the region.
`void`	`registerListener(ProcedureStore.ProcedureStoreListener listener)` Add the listener to the notification list.
`int`	`setRunningProcedureCount(int count)` Set the number of procedure running.
`void`	`start(int numThreads)` Start/Open the procedure store
`void`	`stop(boolean abort)` Stop/Close the procedure store
`boolean`	`unregisterListener(ProcedureStore.ProcedureStoreListener listener)` Remove the listener from the notification list.
`void`	`update(Procedure<?> proc)` The specified procedure was executed, and the new state should be written to the store.

- Method Detail
  - registerListener
```
void registerListener(ProcedureStore.ProcedureStoreListener listener)
```
    Add the listener to the notification list.
    
    Parameters:
    
    listener - The AssignmentListener to register
  - unregisterListener
```
boolean unregisterListener(ProcedureStore.ProcedureStoreListener listener)
```
    Remove the listener from the notification list.
    
    Parameters:
    
    listener - The AssignmentListener to unregister
    
    Returns:
    
    true if the listner was in the list and it was removed, otherwise false.
  - start
```
void start(int numThreads)
    throws IOException
```
    Start/Open the procedure store
    
    Parameters:
    
    numThreads - number of threads to be used by the procedure store
    
    Throws:
    
    IOException
  - stop
```
void stop(boolean abort)
```
    Stop/Close the procedure store
    
    Parameters:
    
    abort - true if the stop is an abort
  - isRunning
```
boolean isRunning()
```
    Returns true if the store is running, otherwise false.
  - getNumThreads
```
int getNumThreads()
```
    Returns the number of threads/slots passed to start()
  - setRunningProcedureCount
```
int setRunningProcedureCount(int count)
```
    Set the number of procedure running. This can be used, for example, by the store to know how long to wait before a sync.
    
    Returns:
    
    how many procedures are running (may not be same as count).
  - recoverLease
```
@Deprecated
void recoverLease()
                       throws IOException
```
    Deprecated. since 2.3.0, will be removed in 4.0.0 along with WALProcedureStore. As now we will store the procedure data in a master local region, and master itself will deal with the lease recovery of the region.
    
    Acquire the lease for the procedure store.
    
    Throws:
    
    IOException
  - load
```
void load(ProcedureStore.ProcedureLoader loader)
   throws IOException
```
    Load the Procedures in the store.
    
    Parameters:
    
    loader - the ProcedureLoader that will handle the store-load events
    
    Throws:
    
    IOException
  - insert
```
void insert(Procedure<?> proc,
            Procedure<?>[] subprocs)
```
    When a procedure is submitted to the executor insert(proc, null) will be called. 'proc' has a 'RUNNABLE' state and the initial information required to start up. When a procedure is executed and it returns children insert(proc, subprocs) will be called. 'proc' has a 'WAITING' state and an update state. 'subprocs' are the children in 'RUNNABLE' state with the initial information.
    
    Parameters:
    
    proc - the procedure to serialize and write to the store.
    
    subprocs - the newly created child of the proc.
  - insert
```
void insert(Procedure<?>[] procs)
```
    Serialize a set of new procedures. These procedures are freshly submitted to the executor and each procedure has a 'RUNNABLE' state and the initial information required to start up.
    
    Parameters:
    
    procs - the procedures to serialize and write to the store.
  - update
```
void update(Procedure<?> proc)
```
    The specified procedure was executed, and the new state should be written to the store.
    
    Parameters:
    
    proc - the procedure to serialize and write to the store.
  - delete
```
void delete(long procId)
```
    The specified procId was removed from the executor, due to completion, abort or failure. The store implementor should remove all the information about the specified procId.
    
    Parameters:
    
    procId - the ID of the procedure to remove.
  - delete
```
void delete(Procedure<?> parentProc,
            long[] subProcIds)
```
    The parent procedure completed. Update the state and mark all the child deleted.
    
    Parameters:
    
    parentProc - the parent procedure to serialize and write to the store.
    
    subProcIds - the IDs of the sub-procedure to remove.
  - delete
```
void delete(long[] procIds,
            int offset,
            int count)
```
    The specified procIds were removed from the executor, due to completion, abort or failure. The store implementor should remove all the information about the specified procIds.
    
    Parameters:
    
    procIds - the IDs of the procedures to remove.
    
    offset - the array offset from where to start to delete
    
    count - the number of IDs to delete
  - cleanup
```
default void cleanup()
```
    Will be called by the framework to give the store a chance to do some clean up works.
    Notice that this is for periodical clean up work, not for the clean up after close, if you want to close the store just call the stop(boolean) method above.

Interface ProcedureStore

Nested Class Summary

Method Summary

Method Detail

registerListener

unregisterListener

start

stop

isRunning

getNumThreads

setRunningProcedureCount

recoverLease

load

insert

insert

update

delete

delete

delete

cleanup