RegionMergeTransaction (Apache HBase 1.4.11 API)

All Known Implementing Classes:: RegionMergeTransactionImpl

@InterfaceAudience.LimitedPrivate(value="Coprocesssor")
@InterfaceStability.Evolving
public interface RegionMergeTransaction

Executes region merge as a "transaction". It is similar with SplitTransaction. Call prepare(RegionServerServices) to setup the transaction, execute(Server, RegionServerServices) to run the transaction and rollback(Server, RegionServerServices) to cleanup if execute fails.

Here is an example of how you would use this interface:

  RegionMergeTransactionFactory factory = new RegionMergeTransactionFactory(conf);
  RegionMergeTransaction mt = factory.create(parent, midKey)
    .registerTransactionListener(new TransactionListener() {
       public void transition(RegionMergeTransaction transaction,
         RegionMergeTransactionPhase from, RegionMergeTransactionPhase to) throws IOException {
         // ...
       }
       public void rollback(RegionMergeTransaction transaction,
         RegionMergeTransactionPhase from, RegionMergeTransactionPhase to) {
         // ...
       }
    });
  if (!mt.prepare()) return;
  try {
    mt.execute(server, services);
  } catch (IOException ioe) {
    try {
      mt.rollback(server, services);
      return;
    } catch (RuntimeException e) {
      // abort the server
    }
  }

A merge transaction is not thread safe. Callers must ensure a split is run by one thread only.

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`RegionMergeTransaction.JournalEntry` Split transaction journal entry
`static class`	`RegionMergeTransaction.RegionMergeTransactionPhase` Each enum is a step in the merge transaction.
`static interface`	`RegionMergeTransaction.TransactionListener` Split transaction listener

Method Summary

Methods
Modifier and Type	Method and Description
`Region`	`execute(Server server, RegionServerServices services)` Deprecated. use #execute(Server, RegionServerServices, User)
`Region`	`execute(Server server, RegionServerServices services, User user)` Run the transaction.
`List<RegionMergeTransaction.JournalEntry>`	`getJournal()` Get the journal for the transaction.
`HRegionInfo`	`getMergedRegionInfo()`
`RegionServerServices`	`getRegionServerServices()` Get the RegonServerServices of the server running the transaction or rollback
`Server`	`getServer()` Get the Server running the transaction or rollback
`boolean`	`prepare(RegionServerServices services)` Check merge inputs and prepare the transaction.
`RegionMergeTransaction`	`registerTransactionListener(RegionMergeTransaction.TransactionListener listener)` Register a listener for transaction preparation, execution, and possibly rollback phases.
`boolean`	`rollback(Server server, RegionServerServices services)` Deprecated. use #rollback(Server, RegionServerServices, User)
`boolean`	`rollback(Server server, RegionServerServices services, User user)` Roll back a failed transaction

- Method Detail
  - prepare
```
boolean prepare(RegionServerServices services)
                throws IOException
```
    Check merge inputs and prepare the transaction.
    
    Parameters:
    services -
    
    Returns:
    true if the regions are mergeable else false if they are not (e.g. its already closed, etc.).
    
    Throws:
    
    IOException
  - execute
```
@Deprecated
Region execute(Server server,
                        RegionServerServices services)
               throws IOException
```
    Deprecated. use #execute(Server, RegionServerServices, User)
    
    Run the transaction.
    
    Parameters:
    server - Hosting server instance. Can be null when testing
    services - Used to online/offline regions.
    
    Returns:
    merged region
    
    Throws:
    
    IOException - If thrown, transaction failed. Call rollback(Server, RegionServerServices)
    
    IOException
    See Also:
    rollback(Server, RegionServerServices)
  - execute
```
Region execute(Server server,
             RegionServerServices services,
             User user)
               throws IOException
```
    Run the transaction.
    
    Parameters:
    server - Hosting server instance. Can be null when testing
    services - Used to online/offline regions.
    user -
    
    Returns:
    merged region
    
    Throws:
    
    IOException - If thrown, transaction failed. Call rollback(Server, RegionServerServices)
    
    IOException
    See Also:
    rollback(Server, RegionServerServices, User)
  - rollback
```
@Deprecated
boolean rollback(Server server,
                          RegionServerServices services)
                 throws IOException
```
    Deprecated. use #rollback(Server, RegionServerServices, User)
    
    Roll back a failed transaction
    
    Parameters:
    server - Hosting server instance (May be null when testing).
    services - Services of regionserver, used to online regions.
    
    Returns:
    True if we successfully rolled back, false if we got to the point of no return and so now need to abort the server to minimize damage.
    
    Throws:
    
    IOException - If thrown, rollback failed. Take drastic action.
  - rollback
```
boolean rollback(Server server,
               RegionServerServices services,
               User user)
                 throws IOException
```
    Roll back a failed transaction
    
    Parameters:
    server - Hosting server instance (May be null when testing).
    services - Services of regionserver, used to online regions.
    user -
    
    Returns:
    True if we successfully rolled back, false if we got to the point of no return and so now need to abort the server to minimize damage.
    
    Throws:
    
    IOException - If thrown, rollback failed. Take drastic action.
  - registerTransactionListener
```
RegionMergeTransaction registerTransactionListener(RegionMergeTransaction.TransactionListener listener)
```
    Register a listener for transaction preparation, execution, and possibly rollback phases.
    A listener can abort a transaction by throwing an exception.
    
    Parameters:
    listener - the listener
    
    Returns:
    'this' for chaining
  - getMergedRegionInfo
```
HRegionInfo getMergedRegionInfo()
```
    Returns:
    merged region info
  - getJournal
```
List<RegionMergeTransaction.JournalEntry> getJournal()
```
    Get the journal for the transaction.
    Journal entries are an opaque type represented as JournalEntry. They can also provide useful debugging information via their toString method.
    
    Returns:
    the transaction journal
  - getServer
```
Server getServer()
```
    Get the Server running the transaction or rollback
    
    Returns:
    server instance
  - getRegionServerServices
```
RegionServerServices getRegionServerServices()
```
    Get the RegonServerServices of the server running the transaction or rollback
    
    Returns:
    region server services

Interface RegionMergeTransaction

Nested Class Summary

Method Summary

Method Detail

prepare

execute

execute

rollback

rollback

registerTransactionListener

getMergedRegionInfo

getJournal

getServer

getRegionServerServices