Package org.bluezoo.gumdrop.mqtt.broker

Class RetainedMessageStore

java.lang.Object

org.bluezoo.gumdrop.mqtt.broker.RetainedMessageStore

public class RetainedMessageStore
extends Object

In-memory store for MQTT retained messages.

Each topic holds at most one retained message. Publishing a retained message with an empty payload removes the retained message for that topic.

Thread-safe via ConcurrentHashMap.

Author:

Chris Burdess

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	RetainedMessageStore.RetainedMessage	An immutable retained message.

Constructor Summary

Constructors

Constructor	Description
RetainedMessageStore()

Method Summary

Modifier and Type	Method	Description
void	clear()	Removes all retained messages.
RetainedMessageStore.RetainedMessage	get(String topic)	Returns the retained message for the given topic, or null.
List<RetainedMessageStore.RetainedMessage>	match(String topicFilter)	Returns all retained messages matching the given topic filter.
void	set(String topic, MQTTMessageContent content, QoS qos)	Sets or removes a retained message for the given topic.
int	size()	Returns the number of retained messages.

Methods inherited from class java.lang.Object

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

Constructor Details

RetainedMessageStore

public RetainedMessageStore()

Method Details

set

public void set(String topic,
 MQTTMessageContent content,
 QoS qos)

Sets or removes a retained message for the given topic.

If the content is null or has zero size, the retained message for the topic is removed and any previously stored content is released. If a previous retained message exists for the topic, its content is released before the new one is stored.

Parameters:

topic - the topic name

content - the message content (null or empty to remove)

qos - the message QoS

get

public RetainedMessageStore.RetainedMessage get(String topic)

Returns the retained message for the given topic, or null.

match

public List<RetainedMessageStore.RetainedMessage> match(String topicFilter)

Returns all retained messages matching the given topic filter.

Parameters:

topicFilter - a topic filter (may contain + and # wildcards)

Returns:

matching retained messages

clear

public void clear()

Removes all retained messages.

size

public int size()

Returns the number of retained messages.