com.allanbank.mongodb.connection.state

Class SecondsBehindCallback

java.lang.Object

com.allanbank.mongodb.connection.FutureCallback<Reply>

com.allanbank.mongodb.connection.state.SecondsBehindCallback

All Implemented Interfaces:

Callback<Reply>, Future<Reply>

public class SecondsBehindCallback
extends FutureCallback<Reply>

SecondsBehindCallback provides a special callback to measure the number of seconds a replica is behind the primary.

To account for idle servers we use the optime for each server and assign a value of zero to the "latest" optime and then subtract the remaining servers from that optime.

In the case of an exception the seconds behind is set to Integer.MAX_VALUE. The value is configurable as a long so in theory a user can ignore this case using a large MongoClientConfiguration.setMaxSecondaryLag(long) .

Lastly, the state of the server is also checked and the seconds behind is set to Double.MAX_VALUE if not in the primary (1) or secondary (2).

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 ©:

2012-2013, Allanbank Consulting, Inc., All Rights Reserved

Field Summary

Fields

Modifier and Type	Field and Description
static Class<DocumentElement>	DOCUMENT_TYPE The document element type.
static Class<NumericElement>	NUMERIC_TYPE The numeric element type.
static int	PRIMARY_STATE The value for a primary server's state.
static int	SECONDARY_STATE The value for a secondary (actively replicating) server's state.
static Class<TimestampElement>	TIMESTAMP_TYPE The timestamp element type.

Fields inherited from class com.allanbank.mongodb.connection.FutureCallback

CLASS

Constructor Summary

Constructors

Constructor and Description
SecondsBehindCallback(ServerState server) Creates a new SecondsBehindCallback.

Method Summary

Methods

Modifier and Type	Method and Description
void	callback(Reply result) Called when the MongoDB operation has completed with the result of the operation.
void	exception(Throwable error) Called when the operation fails due to an exception.

Methods inherited from class com.allanbank.mongodb.connection.FutureCallback

cancel, get, get, isCancelled, isDone

Methods inherited from class java.lang.Object

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

Field Detail

DOCUMENT_TYPE

public static final Class<DocumentElement> DOCUMENT_TYPE

The document element type.

NUMERIC_TYPE

public static final Class<NumericElement> NUMERIC_TYPE

The numeric element type.

PRIMARY_STATE

public static final int PRIMARY_STATE

The value for a primary server's state.

See Also:

Constant Field Values

SECONDARY_STATE

public static final int SECONDARY_STATE

The value for a secondary (actively replicating) server's state.

See Also:

Constant Field Values

TIMESTAMP_TYPE

public static final Class<TimestampElement> TIMESTAMP_TYPE

The timestamp element type.

Constructor Detail

SecondsBehindCallback

public SecondsBehindCallback(ServerState server)

Creates a new SecondsBehindCallback.

Parameters:

server - The server we are tracking the latency for.

Method Detail

callback

public void callback(Reply result)

Called when the MongoDB operation has completed with the result of the operation.

Sets the value for the future and triggers any pending FutureCallback.get() to return.

Overridden to update the server's latency based on the round trip reply time.

Specified by:

callback in interface Callback<Reply>

Overrides:

callback in class FutureCallback<Reply>

Parameters:

result - The result of the operation.

See Also:

Callback.callback(V)

exception

public void exception(Throwable error)

Called when the operation fails due to an exception.

Sets the exception for the future and triggers any pending FutureCallback.get() to throw a ExecutionException.

Overridden to mark the server as Integer.MAX_VALUE seconds behind the primary.

Specified by:

exception in interface Callback<Reply>

Overrides:

exception in class FutureCallback<Reply>

Parameters:

error - The thrown exception.

See Also:

Callback.exception(java.lang.Throwable)