com.yahoo.bullet.pubsub

Class PubSub

java.lang.Object

com.yahoo.bullet.pubsub.PubSub

Direct Known Subclasses:

RESTPubSub

public abstract class PubSub
extends Object

Notation: Partition is a unit of parallelism in the Pub/Sub queue. Implementations of PubSub should take in a BulletConfig and use the information to wire up and return Publishers and Subscribers.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PubSub.Context The context determines how the Publisher and Subscriber returned by PubSub behave.

Field Summary

Fields

Modifier and Type	Field and Description
protected BulletConfig	config
protected PubSub.Context	context

Constructor Summary

Constructors

Constructor and Description
PubSub(BulletConfig config) Instantiate a PubSub using parameters from BulletConfig.

Method Summary

Modifier and Type	Method and Description
static PubSub	from(BulletConfig config) Create a PubSub instance using the class specified in the config file.
abstract Publisher	getPublisher() Get a Publisher instance wired to write to all allocated partitions in the appropriate queue (See context).
abstract List<Publisher>	getPublishers(int n) Get a list of n Publisher instances with the allocated partitions in the appropriate queue (See context) split as evenly as possible among them.
<T> T	getRequiredConfig(Class<T> clazz, String name) A method to get a required configuration of a particular type.
abstract Subscriber	getSubscriber() Get a Subscriber instance wired to read from all allocated partitions in the appropriate queue (See context).
abstract List<Subscriber>	getSubscribers(int n) Get a list of n Subscriber instances with allocated partitions from the appropriate queue (See context) split as evenly as possible among them.
void	switchContext(PubSub.Context context, BulletConfig config) Use this method to switch the PubSub.Context to another one.

Methods inherited from class java.lang.Object

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

Field Detail

context

protected PubSub.Context context

config

protected BulletConfig config

Constructor Detail

PubSub

public PubSub(BulletConfig config)
       throws PubSubException

Instantiate a PubSub using parameters from BulletConfig.

Parameters:

config - A non-null BulletConfig containing all required PubSub parameters.

Throws:

PubSubException - if the context name is not present or cannot be parsed.

Method Detail

switchContext

public void switchContext(PubSub.Context context,
                          BulletConfig config)
                   throws PubSubException

Use this method to switch the PubSub.Context to another one.

Parameters:

context - A different context from the initial one.

config - The BulletConfig containing any new required PubSub parameters. This will be merged with the existing config. Can be null.

Throws:

PubSubException - if the context switch could not be done.

getPublisher

public abstract Publisher getPublisher()
                                throws PubSubException

Get a Publisher instance wired to write to all allocated partitions in the appropriate queue (See context).

Returns:

Publisher wired as required.

Throws:

PubSubException - if the Publisher could not be created.

getPublishers

public abstract List<Publisher> getPublishers(int n)
                                       throws PubSubException

Get a list of n Publisher instances with the allocated partitions in the appropriate queue (See context) split as evenly as possible among them.

Parameters:

n - The number of Publishers requested.

Returns:

The List of n Publishers wired as required.

Throws:

PubSubException - if Publishers could not be created.

getSubscriber

public abstract Subscriber getSubscriber()
                                  throws PubSubException

Get a Subscriber instance wired to read from all allocated partitions in the appropriate queue (See context).

Returns:

Subscriber wired as required.

Throws:

PubSubException - if the Subscriber could not be created.

getSubscribers

public abstract List<Subscriber> getSubscribers(int n)
                                         throws PubSubException

Get a list of n Subscriber instances with allocated partitions from the appropriate queue (See context) split as evenly as possible among them.

Parameters:

n - The number of Subscribers requested.

Returns:

The List of n Subscribers wired as required.

Throws:

PubSubException - if Subscribers could not be created.

from

public static PubSub from(BulletConfig config)
                   throws PubSubException

Create a PubSub instance using the class specified in the config file.

Parameters:

config - The non-null BulletConfig containing the class name and PubSub settings.

Returns:

an instance of specified class initialized with settings from the input file and defaults.

Throws:

PubSubException - if PubSub creation fails.

getRequiredConfig

public <T> T getRequiredConfig(Class<T> clazz,
                               String name)
                        throws PubSubException

A method to get a required configuration of a particular type.

Type Parameters:

T - The type to cast the configuration to. Inferred from clazz.

Parameters:

name - The name of the required configuration.

clazz - The class of the required configuration.

Returns:

The extracted configuration of type T.

Throws:

PubSubException - if the configuration is missing or cannot be cast to type T.