ServerState (mongodb-async-driver 1.2.2 API)

java.lang.Object
- com.allanbank.mongodb.connection.state.ServerState

```
public class ServerState
extends Object
```
Tracks the state of a single server. Currently two factors are tracked:
- Is the server available to receive writes (inserts/updates/deletes)?
- What is the exponential moving average for the server's reply latency.
ServerStates should generally be created and their writable state updated via a ClusterState.
API Warning:

This class is NOT part of the drivers API. This class may be mutated in incompatible ways between any two releases of the driver.

Copyright ©:

2011-2013, Allanbank Consulting, Inc., All Rights Reserved

Field Summary

Fields
Modifier and Type	Field and Description
`static double`	`DECAY_ALPHA` The decay rate for the exponential average for the latency.
`static double`	`DECAY_SAMPLES` The decay period (number of samples) for the average latency.
`static int`	`DEFAULT_PORT` The default MongoDB port.

Constructor Summary

Constructors
Constructor and Description

ServerState(InetSocketAddress server)
Creates a new ServerState.

Constructors
Constructor and Description
`ServerState(InetSocketAddress server)` Creates a new `ServerState`.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`addConnection(Connection connection)` Adds a `Connection` to the state making it available for reuse.
`double`	`getAverageLatency()` Returns the current average latency (in milliseconds) seen in issuing requests to the server.
`long`	`getConnectionGeneration()` Returns a generation value for the connection currently being held.
`String`	`getName()` Returns the normalized name of the server being tracked.
`double`	`getSecondsBehind()` Sets the last reported seconds behind the primary.
`InetSocketAddress`	`getServer()` Returns the address of the server being tracked.
`Document`	`getTags()` Returns the tags for the server.
`boolean`	`isWritable()` Returns true if the server can be written to, false otherwise.
`void`	`setAverageLatency(double latency)` Sets the average latency (in milliseconds) for requests to the server.
`void`	`setSecondsBehind(double secondsBehind)` Sets the last reported seconds behind the primary.
`void`	`setTags(Document tags)` Sets the tags for the server.
`Connection`	`takeConnection()` Returns a `Connection` to the server if one is available.
`String`	`toString()`
`void`	`updateAverageLatency(double latency)` Updates the average latency (in milliseconds) for the server.

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

- Field Detail
  - DECAY_ALPHA
```
public static final double DECAY_ALPHA
```
    The decay rate for the exponential average for the latency.
  - DECAY_SAMPLES
```
public static final double DECAY_SAMPLES
```
    The decay period (number of samples) for the average latency.
    
    See Also:
    Constant Field Values
  - DEFAULT_PORT
```
public static final int DEFAULT_PORT
```
    The default MongoDB port.
    
    See Also:
    Constant Field Values
- Constructor Detail
  - ServerState
```
public ServerState(InetSocketAddress server)
```
    Creates a new ServerState. Package private to force creation through the ClusterState.
    
    Parameters:
    server - The server being tracked.
- Method Detail
  - addConnection
```
public boolean addConnection(Connection connection)
```
    Adds a Connection to the state making it available for reuse.
    Only a limited number of connections will be held (currently 1). If the connection is not added to the state false is returned.
    
    Parameters:
    connection - A Connection to the server making it available to other to use.
    
    Returns:
    True if the connection has been added to the state, false otherwise.
  - getAverageLatency
```
public double getAverageLatency()
```
    Returns the current average latency (in milliseconds) seen in issuing requests to the server. If the latency returns Double.MAX_VALUE then we have no basis for determining the latency.
    
    Returns:
    The current average latency (in milliseconds) seen in issuing requests to the server.
  - getConnectionGeneration
```
public long getConnectionGeneration()
```
    Returns a generation value for the connection currently being held. This is incremented whenever a connection is set. This allows the ClusterPinger to test if the connections it is creating are getting used.
    
    Returns:
    The generation value for the connection currently being held.
  - getName
```
public String getName()
```
    Returns the normalized name of the server being tracked.
    
    Returns:
    The normalized name of the server being tracked.
  - getSecondsBehind
```
public double getSecondsBehind()
```
    Sets the last reported seconds behind the primary.
    
    Returns:
    The seconds behind the primary server.
  - getServer
```
public InetSocketAddress getServer()
```
    Returns the address of the server being tracked.
    
    Returns:
    The address of the server being tracked.
  - getTags
```
public Document getTags()
```
    Returns the tags for the server.
    
    Returns:
    The tags for the server.
  - isWritable
```
public boolean isWritable()
```
    Returns true if the server can be written to, false otherwise.
    If writable it might be a standalone server, the primary in a replica set, or a mongos in a sharded configuration. If not writable it is a secondary server in a replica set or we cannot or have not connected to the server yet.
    
    To modify the writable flag update the ClusterState via a ClusterState.markNotWritable(ServerState) or ClusterState.markWritable(ServerState) call.
    
    Returns:
    True if the server can be written to, false otherwise.
  - setAverageLatency
```
public void setAverageLatency(double latency)
```
    Sets the average latency (in milliseconds) for requests to the server. The initial latency should be set for the "discovery commmands" sent to the server.
    
    Parameters:
    latency - The latency (in milliseconds) for requests to the server.
  - setSecondsBehind
```
public void setSecondsBehind(double secondsBehind)
```
    Sets the last reported seconds behind the primary.
    
    Parameters:
    secondsBehind - The seconds behind the primary server.
  - setTags
```
public void setTags(Document tags)
```
    Sets the tags for the server.
    
    Parameters:
    tags - The tags for the server.
  - takeConnection
```
public Connection takeConnection()
```
    Returns a Connection to the server if one is available.
    
    Returns:
    A Connection to the server if one is available.
  - toString
```
public String toString()
```
    Overridden to to return a human readable version of the server state.
    
    Overrides:
    
    toString in class Object
  - updateAverageLatency
```
public void updateAverageLatency(double latency)
```
    Updates the average latency (in milliseconds) for the server.
    
    Parameters:
    latency - The latency seen sending a request and receiving a reply from the server.

Class ServerState

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DECAY_ALPHA

DECAY_SAMPLES

DEFAULT_PORT

Constructor Detail

ServerState

Method Detail

addConnection

getAverageLatency

getConnectionGeneration

getName

getSecondsBehind

getServer

getTags

isWritable

setAverageLatency

setSecondsBehind

setTags

takeConnection

toString

updateAverageLatency