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Merged
kinyoklion merged 2 commits into from
Jan 21, 2026
Merged

feat: Add support for accessing response headers. #97

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9dbb899
feat: Add support for accessing response headers.
kinyoklion Jan 21, 2026
e8e81b3
Exceptions after initial connection will not be exceptions with headers.
kinyoklion Jan 21, 2026
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2 changes: 1 addition & 1 deletion build.gradle.kts
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,7 @@ dependencies {
api("com.launchdarkly:launchdarkly-logging:${Versions.launchdarklyLogging}")
api("com.squareup.okhttp3:okhttp:${Versions.okhttp}")
testImplementation("org.mockito:mockito-core:1.10.19")
testImplementation("com.launchdarkly:test-helpers:2.0.1")
testImplementation("com.launchdarkly:test-helpers:2.1.0")
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@kinyoklion kinyoklion Jan 21, 2026

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Resolves the dependency on nanohttpd.

testImplementation("com.google.guava:guava:32.0.1-jre")
testImplementation("junit:junit:4.12")
testImplementation("org.hamcrest:hamcrest-all:1.3")
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33 changes: 31 additions & 2 deletions src/main/java/com/launchdarkly/eventsource/ConnectStrategy.java
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Expand Up @@ -65,18 +65,34 @@ public static class Result {
private final InputStream inputStream;
private final URI origin;
private final Closeable closer;

private final ResponseHeaders headers;

/**
* Creates an instance.
*
*
* @param inputStream see {@link #getInputStream()}
* @param origin see {@link #getOrigin()}
* @param closer see {@link #getCloser()}
*/
public Result(InputStream inputStream, URI origin, Closeable closer) {
this(inputStream, origin, closer, null);
}

/**
* Creates an instance with response headers.
*
* @param inputStream see {@link #getInputStream()}
* @param origin see {@link #getOrigin()}
* @param closer see {@link #getCloser()}
* @param headers see {@link #getHeaders()}
*
* @since 4.2.0
*/
public Result(InputStream inputStream, URI origin, Closeable closer, ResponseHeaders headers) {
this.inputStream = inputStream;
this.origin = origin;
this.closer = closer;
this.headers = headers;
}

/**
Expand Down Expand Up @@ -118,6 +134,19 @@ public URI getOrigin() {
public Closeable getCloser() {
return closer;
}

/**
* Returns the response headers from the connection, or null if not available.
* <p>
* For HTTP connections, this contains the HTTP response headers. For other
* connection types, this may be null or may contain connection-specific metadata.
*
* @return the response headers, or null if not available
* @since 4.2.0
*/
public ResponseHeaders getHeaders() {
return headers;
}
}

/**
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12 changes: 8 additions & 4 deletions src/main/java/com/launchdarkly/eventsource/EventParser.java
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Expand Up @@ -50,6 +50,7 @@ final class EventParser {
private Set<String> expectFields;
private final LDLogger logger;
private final URI origin;
private final ResponseHeaders headers;

private BufferedLineParser lineParser;
private byte[] chunkData;
Expand Down Expand Up @@ -77,14 +78,16 @@ final class EventParser {
int readBufferSize,
boolean streamEventData,
Set<String> expectFields,
LDLogger logger
LDLogger logger,
ResponseHeaders headers
) {
this.lineParser = new BufferedLineParser(inputStream, readBufferSize);
this.origin = origin;
this.streamEventData = streamEventData;
this.expectFields = expectFields;
this.logger = logger;

this.headers = headers;

dataBuffer = new ByteArrayOutputStream(VALUE_BUFFER_INITIAL_CAPACITY);
}

Expand Down Expand Up @@ -159,7 +162,7 @@ private StreamEvent tryNextEvent() throws StreamException {
}

String dataString = utf8ByteArrayOutputStreamToString(dataBuffer);
MessageEvent message = new MessageEvent(eventName, dataString, lastEventId, origin);
MessageEvent message = new MessageEvent(eventName, dataString, lastEventId, origin, headers);
resetState();
logger.debug("Received message: {}", message);
return message;
Expand Down Expand Up @@ -193,7 +196,8 @@ private StreamEvent tryNextEvent() throws StreamException {
eventName,
new InputStreamReader(messageDataStream),
lastEventId,
origin
origin,
headers
);
logger.debug("Received message: {}", message);
return message;
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19 changes: 14 additions & 5 deletions src/main/java/com/launchdarkly/eventsource/EventSource.java
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Expand Up @@ -301,14 +301,19 @@ private FaultEvent tryStart(boolean canReturnFaultEvent) throws StreamException
if (applyErrorStrategy(exception) == ErrorStrategy.Action.CONTINUE) {
// The ErrorStrategy told us to CONTINUE rather than throwing an exception.
if (canReturnFaultEvent) {
return new FaultEvent(exception);
// Extract headers from exception if available
ResponseHeaders headers = null;
if (exception instanceof StreamHttpErrorException) {
headers = ((StreamHttpErrorException) exception).getHeaders();
}
return new FaultEvent(exception, headers);
}
// If canReturnFaultEvent is false, it means the caller explicitly called start(),
// in which case there's no way to return a FaultEvent so we just keep retrying
// transparently.
continue;
}
// The ErrorStrategy told us to THROW rather than CONTINUE.
// The ErrorStrategy told us to THROW rather than CONTINUE.
throw exception;
}

Expand All @@ -317,14 +322,16 @@ private FaultEvent tryStart(boolean canReturnFaultEvent) throws StreamException
origin = clientResult.getOrigin() == null ? client.getOrigin() : clientResult.getOrigin();
connectedTime = System.currentTimeMillis();
logger.debug("Connected to SSE stream");


ResponseHeaders headers = clientResult.getHeaders();
eventParser = new EventParser(
clientResult.getInputStream(),
clientResult.getOrigin(),
readBufferSize,
streamEventData,
expectFields,
logger
logger,
headers
);

readyState.set(ReadyState.OPEN);
Expand Down Expand Up @@ -624,7 +631,9 @@ private StreamEvent requireEvent() throws StreamException {
eventParser = null;
computeReconnectDelay();
if (applyErrorStrategy(e) == ErrorStrategy.Action.CONTINUE) {
return new FaultEvent(e);
// At this point we're handling errors from reading the stream (not initial connection),
// so we never have HTTP response headers available (headers is always null)
return new FaultEvent(e, null);
}
throw e;
}
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32 changes: 30 additions & 2 deletions src/main/java/com/launchdarkly/eventsource/FaultEvent.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,16 +20,30 @@
*/
public final class FaultEvent implements StreamEvent {
private final StreamException cause;

private final ResponseHeaders headers;

/**
* Creates an instance.
*
* @param cause the cause of the failure
*/
public FaultEvent(StreamException cause) {
this(cause, null);
}

/**
* Creates an instance with response headers.
*
* @param cause the cause of the failure
* @param headers the response headers if available (typically for HTTP errors), or null
*
* @since 4.2.0
*/
public FaultEvent(StreamException cause, ResponseHeaders headers) {
this.cause = cause;
this.headers = headers;
}

/**
* Returns a {@link StreamException} describing the cause of the failure.
*
Expand All @@ -38,6 +52,20 @@ public FaultEvent(StreamException cause) {
public StreamException getCause() {
return cause;
}

/**
* Returns the response headers if available, or null otherwise.
* <p>
* For HTTP error responses (when the cause is a {@link StreamHttpErrorException}),
* this typically contains the HTTP response headers from the failed request.
* For other types of failures (I/O errors, timeouts, etc.), this may be null.
*
* @return the response headers, or null if not available
* @since 4.2.0
*/
public ResponseHeaders getHeaders() {
return headers;
}

@Override
public boolean equals(Object o) {
Expand Down
15 changes: 9 additions & 6 deletions src/main/java/com/launchdarkly/eventsource/HttpConnectStrategy.java
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Expand Up @@ -443,29 +443,32 @@ class Client extends ConnectStrategy.Client { // package-private visibility for
@Override
public Result connect(String lastEventId) throws StreamException {
logger.debug("Attempting to connect to SSE stream at {}", uri);

Request request = createRequest(lastEventId);
Call call = httpClient.newCall(request);

Response response;
try {
response = call.execute();
} catch (IOException e) {
logger.info("Connection failed: {}", LogValues.exceptionSummary(e));
throw new StreamIOException(e);
}

if (!response.isSuccessful()) {
ResponseHeaders headers = ResponseHeadersImpl.fromOkHttpHeaders(response.headers());
response.close();
logger.info("Server returned HTTP error {}", response.code());
throw new StreamHttpErrorException(response.code());
throw new StreamHttpErrorException(response.code(), headers);
}


ResponseHeaders headers = ResponseHeadersImpl.fromOkHttpHeaders(response.headers());
ResponseBody responseBody = response.body();
return new Result(
responseBody.byteStream(),
uri,
new RequestCloser(call)
new RequestCloser(call),
headers
);
}

Expand Down
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