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fix: Reconnect the FDv2 stream after a restart that follows an earlier disconnect #233

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fix: Reconnect the FDv2 stream after a restart that follows an earlier disconnect #233

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19 changes: 13 additions & 6 deletions lib/sdk/server/src/main/java/com/launchdarkly/sdk/server/StreamingSynchronizerImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -367,15 +367,22 @@ private void interruptedWithException(Exception e, DataSourceStatusProvider.Erro
}

private boolean handleError(StreamException e) {
// Check if this was a deliberate shutdown/restart rather than an actual error
boolean streamFailed = !(e instanceof StreamClosedByCallerException);
recordStreamInit(streamFailed);

if (e instanceof StreamClosedByCallerException) {
// We closed it ourselves (shutdown was called or stream was deliberately restarted)
return false;
// The event source can send this fault after close() or after restartStream().
// Only close() stops the stream.
synchronized (closeLock) {
if (closed) {
recordStreamInit(false);
return false;
}
}
// restartStream() already queued a result and recorded the stream init.
// Continue to read events so that the event source connects again.
return true;
}

recordStreamInit(true);

if (e instanceof StreamHttpErrorException) {
int status = ((StreamHttpErrorException) e).getCode();
DataSourceStatusProvider.ErrorInfo errorInfo = DataSourceStatusProvider.ErrorInfo.fromHttpError(status);
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265 changes: 265 additions & 0 deletions lib/sdk/server/src/test/java/com/launchdarkly/sdk/server/StreamingSynchronizerImplTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1640,4 +1640,269 @@ public void errorAfterSuccessfulChangesetRecordsNewDiagnostic() throws Exception
}
}


@Test
public void goodbyeAfterEarlierDisconnectRestartsStream() throws Exception {
DiagnosticStore diagnosticStore = basicDiagnosticStore();

String serverIntent = makeEvent("server-intent", "{\"payloads\":[{\"id\":\"payload-1\",\"target\":100,\"intentCode\":\"xfer-full\",\"reason\":\"payload-missing\"}]}");
String payloadTransferred = makeEvent("payload-transferred", "{\"state\":\"(p:payload-1:100)\",\"version\":100}");
String goodbyeEvent = makeEvent("goodbye", "{\"reason\":\"service-unavailable\"}");

// First connection: changeset, then the server ends the response.
// Second connection: changeset + goodbye.
// Third connection: changeset.
try (HttpServer server = HttpServer.start(Handlers.sequential(
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred)),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.event(goodbyeEvent),
Handlers.SSE.leaveOpen()),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.leaveOpen())))) {

HttpProperties httpProperties = toHttpProperties(clientContext("sdk-key", baseConfig().build()).getHttp());
SelectorSource selectorSource = mockSelectorSource();

StreamingSynchronizerImpl synchronizer = new StreamingSynchronizerImpl(
httpProperties,
server.getUri(),
"/stream",
testLogger,
selectorSource,
null,
Duration.ofMillis(100),
Thread.NORM_PRIORITY,
diagnosticStore
);

FDv2SourceResult result1 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.CHANGE_SET, result1.getResultType());

// The server ended the first response
FDv2SourceResult result2 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.STATUS, result2.getResultType());
assertEquals(SourceSignal.INTERRUPTED, result2.getStatus().getState());
assertEquals(DataSourceStatusProvider.ErrorKind.NETWORK_ERROR, result2.getStatus().getErrorInfo().getKind());

FDv2SourceResult result3 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.CHANGE_SET, result3.getResultType());

FDv2SourceResult result4 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.STATUS, result4.getResultType());
assertEquals(SourceSignal.GOODBYE, result4.getStatus().getState());

// The synchronizer restarts the stream and gets the next changeset
FDv2SourceResult result5 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.CHANGE_SET, result5.getResultType());
assertEquals(3, server.getRecorder().count());

// One successful init for each connection that delivered a changeset
LDValue event = diagnosticStore.createEventAndReset(0, 0).getJsonValue();
LDValue streamInits = event.get("streamInits");
assertEquals(3, streamInits.size());
assertFalse(streamInits.get(0).get("failed").booleanValue());
assertFalse(streamInits.get(1).get("failed").booleanValue());
assertFalse(streamInits.get(2).get("failed").booleanValue());

synchronizer.close();
}
}

@Test
public void invalidDataAfterEarlierDisconnectRestartsStream() throws Exception {
DiagnosticStore diagnosticStore = basicDiagnosticStore();

String serverIntent = makeEvent("server-intent", "{\"payloads\":[{\"id\":\"payload-1\",\"target\":100,\"intentCode\":\"xfer-full\",\"reason\":\"payload-missing\"}]}");
String payloadTransferred = makeEvent("payload-transferred", "{\"state\":\"(p:payload-1:100)\",\"version\":100}");
String invalidPayload = makeEvent("payload-transferred", "{malformed json}");

// First connection: changeset, then the server ends the response.
// Second connection: invalid data.
// Third connection: changeset.
try (HttpServer server = HttpServer.start(Handlers.sequential(
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred)),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(invalidPayload),
Handlers.SSE.leaveOpen()),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.leaveOpen())))) {

HttpProperties httpProperties = toHttpProperties(clientContext("sdk-key", baseConfig().build()).getHttp());
SelectorSource selectorSource = mockSelectorSource();

StreamingSynchronizerImpl synchronizer = new StreamingSynchronizerImpl(
httpProperties,
server.getUri(),
"/stream",
testLogger,
selectorSource,
null,
Duration.ofMillis(100),
Thread.NORM_PRIORITY,
diagnosticStore
);

FDv2SourceResult result1 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.CHANGE_SET, result1.getResultType());

// The server ended the first response
FDv2SourceResult result2 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.STATUS, result2.getResultType());
assertEquals(SourceSignal.INTERRUPTED, result2.getStatus().getState());
assertEquals(DataSourceStatusProvider.ErrorKind.NETWORK_ERROR, result2.getStatus().getErrorInfo().getKind());

FDv2SourceResult result3 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.STATUS, result3.getResultType());
assertEquals(SourceSignal.INTERRUPTED, result3.getStatus().getState());
assertEquals(DataSourceStatusProvider.ErrorKind.INVALID_DATA, result3.getStatus().getErrorInfo().getKind());

// The synchronizer restarts the stream and gets the next changeset
FDv2SourceResult result4 = synchronizer.next().get(5, TimeUnit.SECONDS);
assertEquals(SourceResultType.CHANGE_SET, result4.getResultType());
assertEquals(3, server.getRecorder().count());

// The restart records the failed init. The reconnect does not record a second one.
LDValue event = diagnosticStore.createEventAndReset(0, 0).getJsonValue();
LDValue streamInits = event.get("streamInits");
assertEquals(3, streamInits.size());
assertFalse(streamInits.get(0).get("failed").booleanValue());
assertTrue(streamInits.get(1).get("failed").booleanValue());
assertFalse(streamInits.get(2).get("failed").booleanValue());

synchronizer.close();
}
}

@Test
public void closeDuringRestartAfterEarlierDisconnectDoesNotReconnect() throws Exception {
String serverIntent = makeEvent("server-intent", "{\"payloads\":[{\"id\":\"payload-1\",\"target\":100,\"intentCode\":\"xfer-full\",\"reason\":\"payload-missing\"}]}");
String payloadTransferred = makeEvent("payload-transferred", "{\"state\":\"(p:payload-1:100)\",\"version\":100}");
String goodbyeEvent = makeEvent("goodbye", "{\"reason\":\"service-unavailable\"}");

// First connection: changeset, then the server ends the response.
// Second connection: changeset + goodbye.
// Third connection: the synchronizer must not make this request.
try (HttpServer server = HttpServer.start(Handlers.sequential(
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred)),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.event(goodbyeEvent),
Handlers.SSE.leaveOpen()),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.leaveOpen())))) {

HttpProperties httpProperties = toHttpProperties(clientContext("sdk-key", baseConfig().build()).getHttp());
SelectorSource selectorSource = mockSelectorSource();

// With this initial delay, the reconnect after the goodbye waits at least 200 milliseconds.
StreamingSynchronizerImpl synchronizer = new StreamingSynchronizerImpl(
httpProperties,
server.getUri(),
"/stream",
testLogger,
selectorSource,
null,
Duration.ofMillis(200),
Thread.NORM_PRIORITY,
null
);

assertEquals(SourceResultType.CHANGE_SET, synchronizer.next().get(5, TimeUnit.SECONDS).getResultType());
assertEquals(SourceSignal.INTERRUPTED, synchronizer.next().get(5, TimeUnit.SECONDS).getStatus().getState());
assertEquals(SourceResultType.CHANGE_SET, synchronizer.next().get(5, TimeUnit.SECONDS).getResultType());
assertEquals(SourceSignal.GOODBYE, synchronizer.next().get(5, TimeUnit.SECONDS).getStatus().getState());

// Close the synchronizer while the restarted stream waits to reconnect
Thread.sleep(100);
synchronizer.close();

FDv2SourceResult result = synchronizer.next().get(1, TimeUnit.SECONDS);
assertEquals(SourceResultType.STATUS, result.getResultType());
assertEquals(SourceSignal.SHUTDOWN, result.getStatus().getState());

// Wait longer than the longest possible reconnect delay
Thread.sleep(1200);
assertEquals(2, server.getRecorder().count());
}
}

@Test
public void closeAfterEarlierDisconnectDoesNotReconnect() throws Exception {
String serverIntent = makeEvent("server-intent", "{\"payloads\":[{\"id\":\"payload-1\",\"target\":100,\"intentCode\":\"xfer-full\",\"reason\":\"payload-missing\"}]}");
String payloadTransferred = makeEvent("payload-transferred", "{\"state\":\"(p:payload-1:100)\",\"version\":100}");

// First connection: changeset, then the server ends the response.
// Second connection: changeset.
// Third connection: the synchronizer must not make this request.
try (HttpServer server = HttpServer.start(Handlers.sequential(
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred)),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.leaveOpen()),
Handlers.all(
Handlers.SSE.start(),
Handlers.SSE.event(serverIntent),
Handlers.SSE.event(payloadTransferred),
Handlers.SSE.leaveOpen())))) {

HttpProperties httpProperties = toHttpProperties(clientContext("sdk-key", baseConfig().build()).getHttp());
SelectorSource selectorSource = mockSelectorSource();

StreamingSynchronizerImpl synchronizer = new StreamingSynchronizerImpl(
httpProperties,
server.getUri(),
"/stream",
testLogger,
selectorSource,
null,
Duration.ofMillis(100),
Thread.NORM_PRIORITY,
null
);

assertEquals(SourceResultType.CHANGE_SET, synchronizer.next().get(5, TimeUnit.SECONDS).getResultType());
assertEquals(SourceSignal.INTERRUPTED, synchronizer.next().get(5, TimeUnit.SECONDS).getStatus().getState());
assertEquals(SourceResultType.CHANGE_SET, synchronizer.next().get(5, TimeUnit.SECONDS).getResultType());

synchronizer.close();

FDv2SourceResult result = synchronizer.next().get(1, TimeUnit.SECONDS);
assertEquals(SourceResultType.STATUS, result.getResultType());
assertEquals(SourceSignal.SHUTDOWN, result.getStatus().getState());

// Wait longer than the longest possible reconnect delay
Thread.sleep(1000);
assertEquals(2, server.getRecorder().count());
}
}
}
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