Package com.google.genai.gaos.utils

Class EventStream<T>

java.lang.Object

com.google.genai.gaos.utils.EventStream<T>

Type Parameters:

T - the type that SSE data fields will be deserialized into

All Implemented Interfaces:

AutoCloseable, Iterable<T>

public final class EventStream<T>
extends Object
implements Iterable<T>, AutoCloseable

Provides a convenient way to consume Server-Sent Events (SSE) from a stream.

Each SSE message's data field is deserialized into the type T, allowing for easy processing of events as domain objects.

Event Consumption

Events can be consumed in multiple ways:

• Iteration: Use a for-each loop to process each event:

 try (EventStream<MyEvent> eventStream = new EventStream<>(...)) {
     for (MyEvent event : eventStream) {
         handleEvent(event);
     }
 }
 

• Stream API: Consume events as a Java Stream (must be closed after use):

 try (EventStream<MyEvent> eventStream = new EventStream<>(...);
      Stream<MyEvent> stream = eventStream.stream()) {
     stream.forEach(this::handleEvent);
 }
 

• Collect to List: Read all remaining events into a list:

 try (EventStream<MyEvent> eventStream = new EventStream<>(...)) {
     List<MyEvent> events = eventStream.toList();
 }
 

Events are lazily loaded from the underlying SSE stream. Consumption stops either when the stream ends or when an optional terminal message is encountered.

Important: This class implements AutoCloseable and must be used within a try-with-resources block to ensure that underlying streams are properly closed after consumption, preventing resource leaks.

Constructor Summary

Constructors

Constructor	Description
EventStream(InputStream in, com.fasterxml.jackson.core.type.TypeReference<T> typeReference, com.fasterxml.jackson.databind.ObjectMapper mapper, Optional<String> terminalMessage)
EventStream(InputStream in, com.fasterxml.jackson.core.type.TypeReference<T> typeReference, com.fasterxml.jackson.databind.ObjectMapper mapper, Optional<String> terminalMessage, boolean dataRequired)

Method Summary

Modifier and Type	Method	Description
void	close()
boolean	isClosed()
Iterator<T>	iterator()	Returns an Iterator of EventStream events, enabling iteration via for-each loops.
Optional<T>	next()	Returns the next message.
Stream<T>	stream()	Returns a Stream of events.
List<T>	toList()	Reads all events and returns them as a List.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Details

EventStream

public EventStream(InputStream in,
 com.fasterxml.jackson.core.type.TypeReference<T> typeReference,
 com.fasterxml.jackson.databind.ObjectMapper mapper,
 Optional<String> terminalMessage)

EventStream

public EventStream(InputStream in,
 com.fasterxml.jackson.core.type.TypeReference<T> typeReference,
 com.fasterxml.jackson.databind.ObjectMapper mapper,
 Optional<String> terminalMessage,
 boolean dataRequired)

Method Details

next

public Optional<T> next()
                 throws IOException

Returns the next message. If another message does not exist returns Optional.empty().

Returns:

the next message or Optional.empty() if no more messages

Throws:

IOException - when parsing the next message.

toList

public List<T> toList()

Reads all events and returns them as a List. This method calls close().

Returns:

list of events

iterator

public Iterator<T> iterator()

Returns an Iterator of EventStream events, enabling iteration via for-each loops.

Specified by:

iterator in interface Iterable<T>

Returns:

events iterator.

stream

public Stream<T> stream()

Returns a Stream of events. Must be closed after use!

Returns:

streamed events

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Throws:

IOException

isClosed

public boolean isClosed()