Revision 561935

HADOOP-1528 HClient for multiple tables (phase 1)

Modified:

HConstants
static final Text[] COL_REGIONINFO_ARRAY = new Text [] {COL_REGIONINFO};
static final Text EMPTY_START_ROW = new Text();

HMaster
- don't process a region server exit message if the lease has timed
  out. Otherwise we end up with two pending server shutdown messages
  to process and chaos ensues.
- don't reassign the root region when the server's lease expires. The
  lease expiration handler will queue a PendingServerShutdown
  operation that must run before the root region is reassigned because
  the HLog of the dead server must be split before any regions served
  by the dead server are reassigned.
- added some additional debug level logging

HBaseClusterTestCase
- call HConnectionManager.deleteConnection(conf) in tearDown() so that
  multiple tests can be run from the same test class.

TestScanner2
- changes to make test compatible with the change from inner class
  HClient.RegionLocation to public class HRegionLocation

Leases
- cancelLease just returns if the lease is not found instead of
  throwing an IOException

New:

HConnection - an interface that describes the operations performed by
a connection implementation

HConnectionManager - manages connections for multiple HBase instances
and returns an object that implements HConnection from its static
method getConnection

HBaseAdmin - the HBase administrative methods refactored out of
HClient. Each HBaseAdmin object can control a single HBase
instance. To manipulate multiple instances, create multiple HBaseAdmin
objects. 

HTable - The data manipulation methods refactored out of HClient. Each
HTable object talks to a single table in a single HBase
instance. Create multiple HTable objects to use more than one table.

HRegionLocation - an inner class refactored out of HClient. Each
HRegionLocation has an HRegionInfo object and an HServerAddress
object.

HClient - totally re-implemented in terms of the new classes
above. HClient is now deprecated.