org.apache.cassandra.db
Class HintedHandOffManager

java.lang.Object
  org.apache.cassandra.db.HintedHandOffManager

public class HintedHandOffManager
extends java.lang.Object

For each endpoint for which we have hints, there is a row in the system hints CF. SuperColumns in that row are keys for which we have hinted data. Subcolumns names within that supercolumn are keyspace+CF, concatenated with SEPARATOR. Subcolumn values are always empty; instead, we store the row data "normally" in the application table it belongs in. When FailureDetector signals that a node that was down is back up, we read its hints row to see what rows we need to forward data for, then reach each row in its entirety and send it over. deliverHints is also exposed to JMX so it can be run manually if FD ever misses its cue somehow. HHM never deletes the row from Application tables; usually (but not for CL.ANY!) the row belongs on this node, as well. instead, we rely on cleanup compactions to remove data that doesn't belong. (Cleanup compactions may be started manually -- on a per node basis -- with "nodeprobe cleanup.") TODO this avoids our hint rows from growing excessively large by offloading the message data into application tables. But, this means that cleanup compactions will nuke HH data. Probably better would be to store the RowMutation messages in a HHData (non-super) CF, modifying the above to store a UUID value in the HH subcolumn value, which we use as a key to a [standard] HHData system CF that would contain the message bytes.

Field Summary

static java.lang.String	HINTS_CF
static HintedHandOffManager	instance

Constructor Summary

HintedHandOffManager()

Method Summary

static void	deleteHintsForEndPoint(java.net.InetAddress endpoint)
void	deliverHints(java.net.InetAddress to)
void	deliverHints(java.lang.String to)
static java.nio.ByteBuffer	makeCombinedName(java.lang.String tableName, java.lang.String columnFamily)
static void	renameHints(java.lang.String oldTable, java.lang.String newTable) called when a keyspace is dropped or rename.

Methods inherited from class java.lang.Object

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

Field Detail

instance

public static final HintedHandOffManager instance

HINTS_CF

public static final java.lang.String HINTS_CF

See Also:

Constant Field Values

Constructor Detail

HintedHandOffManager

public HintedHandOffManager()

Method Detail

deleteHintsForEndPoint

public static void deleteHintsForEndPoint(java.net.InetAddress endpoint)

makeCombinedName

public static java.nio.ByteBuffer makeCombinedName(java.lang.String tableName,
                                                   java.lang.String columnFamily)

renameHints

public static void renameHints(java.lang.String oldTable,
                               java.lang.String newTable)
                        throws java.io.IOException

called when a keyspace is dropped or rename. newTable==null in the case of a drop.

Throws:

java.io.IOException

deliverHints

public void deliverHints(java.net.InetAddress to)

deliverHints

public void deliverHints(java.lang.String to)
                  throws java.net.UnknownHostException

Throws:

java.net.UnknownHostException