org.apache.hadoop.hbase.regionserver

Interface SplitTransaction

All Known Implementing Classes:

SplitTransactionImpl

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

Executes region split as a "transaction". Call prepare() 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:

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

A split 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	SplitTransaction.JournalEntry Split transaction journal entry
static class	SplitTransaction.SplitTransactionPhase Each enum is a step in the split transaction.
static interface	SplitTransaction.TransactionListener Split transaction listener

Method Summary

Methods

Modifier and Type	Method and Description
PairOfSameType<Region>	execute(Server server, RegionServerServices services) Deprecated. use #execute(Server, RegionServerServices, User)
PairOfSameType<Region>	execute(Server server, RegionServerServices services, User user) Run the transaction.
List<SplitTransaction.JournalEntry>	getJournal() Get the journal for the transaction.
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() Check split inputs and prepare the transaction.
SplitTransaction	registerTransactionListener(SplitTransaction.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()
                throws IOException

Check split inputs and prepare the transaction.

Returns:

true if the region is splittable else false if it is not (e.g. its already closed, etc.).

Throws:

IOException

execute

@Deprecated
PairOfSameType<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:

Regions created

Throws:

IOException - If thrown, transaction failed. Call rollback(Server, RegionServerServices)

IOException

See Also:

rollback(Server, RegionServerServices)

execute

PairOfSameType<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:

Regions created

Throws:

IOException - If thrown, transaction failed. Call rollback(Server, RegionServerServices)

IOException

See Also:

rollback(Server, RegionServerServices)

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 -

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 -

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

SplitTransaction registerTransactionListener(SplitTransaction.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

getJournal

List<SplitTransaction.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