DeadServer (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.master.DeadServer

```
@InterfaceAudience.Private
public class DeadServer
extends Object
```
Class to hold dead servers list and utility querying dead server list. On znode expiration, servers are added here.

Field Summary

Fields
Modifier and Type	Field and Description
`private Map<ServerName,Long>`	`deadServers` Set of known dead servers.
`private static org.apache.commons.logging.Log`	`LOG`
`private int`	`numProcessing` Number of dead servers currently being processed
`private boolean`	`processing` Whether a dead server is being processed currently.
`private static Comparator<Pair<ServerName,Long>>`	`ServerNameDeathDateComparator`

Constructor Summary

Constructors
Constructor and Description

DeadServer()

Constructors
Constructor and Description
`DeadServer()`

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`add(ServerName sn)` Adds the server to the dead server list if it's not there already.
`boolean`	`areDeadServersInProgress()` Checks if there are currently any dead servers being processed by the master.
`void`	`cleanAllPreviousInstances(ServerName newServerName)`
`boolean`	`cleanPreviousInstance(ServerName newServerName)` A dead server that comes back alive has a different start code.
`List<Pair<ServerName,Long>>`	`copyDeadServersSince(long ts)` Extract all the servers dead since a given time, and sort them.
`Set<ServerName>`	`copyServerNames()`
`void`	`finish(ServerName sn)`
`Date`	`getTimeOfDeath(ServerName deadServerName)` Get the time when a server died
`boolean`	`isDeadServer(ServerName serverName)`
`boolean`	`isEmpty()`
`void`	`notifyServer(ServerName sn)` Notify that we started processing this dead server.
`int`	`size()`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - LOG
```
private static final org.apache.commons.logging.Log LOG
```
  - deadServers
```
private final Map<ServerName,Long> deadServers
```
    Set of known dead servers. On znode expiration, servers are added here. This is needed in case of a network partitioning where the server's lease expires, but the server is still running. After the network is healed, and it's server logs are recovered, it will be told to call server startup because by then, its regions have probably been reassigned.
  - numProcessing
```
private int numProcessing
```
    Number of dead servers currently being processed
  - processing
```
private boolean processing
```
    Whether a dead server is being processed currently.
  - ServerNameDeathDateComparator
```
private static Comparator<Pair<ServerName,Long>> ServerNameDeathDateComparator
```
- Constructor Detail
  - DeadServer
```
public DeadServer()
```
- Method Detail
  - cleanPreviousInstance
```
public boolean cleanPreviousInstance(ServerName newServerName)
```
    A dead server that comes back alive has a different start code. The new start code should be greater than the old one, but we don't take this into account in this method.
    
    Parameters:
    newServerName - Servername as either host:port or host,port,startcode.
    
    Returns:
    true if this server was dead before and coming back alive again
  - isDeadServer
```
public boolean isDeadServer(ServerName serverName)
```
    Parameters:
    serverName - server name.
    
    Returns:
    true if this server is on the dead servers list false otherwise
  - areDeadServersInProgress
```
public boolean areDeadServersInProgress()
```
    Checks if there are currently any dead servers being processed by the master. Returns true if at least one region server is currently being processed as dead.
    
    Returns:
    true if any RS are being processed as dead
  - copyServerNames
```
public Set<ServerName> copyServerNames()
```
  - add
```
public void add(ServerName sn)
```
    Adds the server to the dead server list if it's not there already.
    
    Parameters:
    sn - the server name
  - notifyServer
```
public void notifyServer(ServerName sn)
```
    Notify that we started processing this dead server.
    
    Parameters:
    sn - ServerName for the dead server.
  - finish
```
public void finish(ServerName sn)
```
  - size
```
public int size()
```
  - isEmpty
```
public boolean isEmpty()
```
  - cleanAllPreviousInstances
```
public void cleanAllPreviousInstances(ServerName newServerName)
```
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - copyDeadServersSince
```
public List<Pair<ServerName,Long>> copyDeadServersSince(long ts)
```
    Extract all the servers dead since a given time, and sort them.
    
    Parameters:
    ts - the time, 0 for all
    
    Returns:
    a sorted array list, by death time, lowest values first.
  - getTimeOfDeath
```
public Date getTimeOfDeath(ServerName deadServerName)
```
    Get the time when a server died
    
    Parameters:
    deadServerName - the dead server name
    
    Returns:
    the date when the server died

Class DeadServer

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

deadServers

numProcessing

processing

ServerNameDeathDateComparator

Constructor Detail

DeadServer

Method Detail

cleanPreviousInstance

isDeadServer

areDeadServersInProgress

copyServerNames

add

notifyServer

finish

size

isEmpty

cleanAllPreviousInstances

toString

copyDeadServersSince

getTimeOfDeath