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130 lines
2.7 KiB
130 lines
2.7 KiB
package mightypork.utils.patterns.subscription;
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import java.util.Collection;
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import java.util.LinkedHashSet;
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import mightypork.utils.logging.Log;
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/**
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* An event bus, accommodating multiple {@link MessageChannel}s.
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*
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* @author MightyPork
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*/
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final public class MessageBus {
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private Collection<MessageChannel<?, ?>> channels = new LinkedHashSet<MessageChannel<?, ?>>();
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private Collection<Object> clients = new LinkedHashSet<Object>();
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private boolean warn_unsent = true;
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/**
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* Add a {@link MessageChannel} to this bus.<br>
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* If a channel of matching types is already added, it is returned instead.
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*
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* @param channel channel to be added
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* @return the channel that's now in the bus
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*/
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public MessageChannel<?, ?> addChannel(MessageChannel<?, ?> channel)
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{
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// if the channel already exists, return this instance instead.
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for (MessageChannel<?, ?> ch : channels) {
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if (ch.equals(channel)) {
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Log.w("Channel of type " + channel + " already registered.");
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return ch;
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}
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}
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channels.add(channel);
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return channel;
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}
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/**
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* Remove a {@link MessageChannel} from this bus
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*
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* @param channel true if channel was removed
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*/
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public void removeChannel(MessageChannel<?, ?> channel)
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{
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channels.remove(channel);
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}
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/**
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* Broadcast a message
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*
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* @param message message
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* @return true if message was accepted by at least one channel
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*/
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public boolean broadcast(Object message)
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{
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boolean sent = false;
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for (MessageChannel<?, ?> b : channels) {
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sent |= b.broadcast(message, clients);
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}
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if (!sent && warn_unsent) Log.w("Message not accepted by any channel: " + message);
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return sent;
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}
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/**
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* Connect a client to the bus. The client will be connected to all current
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* and future channels, until removed from the bus.
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*
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* @param client the client
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* @return true on success
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*/
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public boolean subscribe(Object client)
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{
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if (client == null) return false;
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clients.add(client);
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return true;
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}
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/**
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* Disconnect a client from the bus.
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*
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* @param client the client
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*/
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public void unsubscribe(Object client)
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{
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clients.remove(client);
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}
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/**
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* Enable logging of unsent messages
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*
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* @param enable
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*/
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public void enableLoggingUnsent(boolean enable)
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{
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this.warn_unsent = enable;
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}
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/**
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* Add a channel for given message and client type.
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*
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* @param messageClass message type
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* @param clientClass client type
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* @return the created channel instance
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*/
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public <F_MESSAGE extends Handleable<F_CLIENT>, F_CLIENT> MessageChannel<?, ?> createChannel(Class<F_MESSAGE> messageClass, Class<F_CLIENT> clientClass)
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{
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MessageChannel<F_MESSAGE, F_CLIENT> bc = new MessageChannel<F_MESSAGE, F_CLIENT>(messageClass, clientClass);
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return addChannel(bc);
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}
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}
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