org.apache.hadoop.hbase.regionserver

Class RegionMergeTransaction

java.lang.Object

org.apache.hadoop.hbase.regionserver.RegionMergeTransaction

@InterfaceAudience.Private
public class RegionMergeTransaction
extends Object

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 class:

  RegionMergeTransaction mt = new RegionMergeTransaction(this.conf, parent, midKey)
  if (!mt.prepare(services)) return;
  try {
    mt.execute(server, services);
  } catch (IOException ioe) {
    try {
      mt.rollback(server, services);
      return;
    } catch (RuntimeException e) {
      myAbortable.abort("Failed merge, abort");
    }
  }
 

This class is not thread safe. Caller needs ensure merge is run by one thread only.

Constructor Summary

Constructors

Constructor and Description
RegionMergeTransaction(HRegion a, HRegion b, boolean forcible) Constructor

Method Summary

Methods

Modifier and Type	Method and Description
Put	addLocation(Put p, ServerName sn, long openSeqNum)
HRegion	execute(Server server, RegionServerServices services) Run the transaction.
static HRegionInfo	getMergedRegionInfo(HRegionInfo a, HRegionInfo b) Get merged region info through the specified two regions
boolean	prepare(RegionServerServices services) Does checks on merge inputs.
void	prepareMutationsForMerge(HRegionInfo mergedRegion, HRegionInfo regionA, HRegionInfo regionB, ServerName serverName, List<Mutation> mutations)
boolean	rollback(Server server, RegionServerServices services)
HRegion	stepsAfterPONR(Server server, RegionServerServices services, HRegion mergedRegion)
HRegion	stepsBeforePONR(Server server, RegionServerServices services, boolean testing)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RegionMergeTransaction

public RegionMergeTransaction(HRegion a,
                      HRegion b,
                      boolean forcible)

Constructor

Parameters:

a - region a to merge

b - region b to merge

forcible - if false, we will only merge adjacent regions

Method Detail

prepare

public boolean prepare(RegionServerServices services)

Does checks on merge inputs.

Parameters:

services -

Returns:

true if the regions are mergeable else false if they are not (e.g. its already closed, etc.).

execute

public HRegion execute(Server server,
              RegionServerServices services)
                throws IOException

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)

stepsAfterPONR

public HRegion stepsAfterPONR(Server server,
                     RegionServerServices services,
                     HRegion mergedRegion)
                       throws IOException

Throws:

IOException

prepareMutationsForMerge

public void prepareMutationsForMerge(HRegionInfo mergedRegion,
                            HRegionInfo regionA,
                            HRegionInfo regionB,
                            ServerName serverName,
                            List<Mutation> mutations)
                              throws IOException

Throws:

IOException

addLocation

public Put addLocation(Put p,
              ServerName sn,
              long openSeqNum)

stepsBeforePONR

public HRegion stepsBeforePONR(Server server,
                      RegionServerServices services,
                      boolean testing)
                        throws IOException

Throws:

IOException

getMergedRegionInfo

public static HRegionInfo getMergedRegionInfo(HRegionInfo a,
                              HRegionInfo b)

Get merged region info through the specified two regions

Parameters:

a - merging region A

b - merging region B

Returns:

the merged region info

rollback

public boolean rollback(Server server,
               RegionServerServices services)
                 throws IOException

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.