com.launchdarkly.sdk.server.StreamProcessor Maven / Gradle / Ivy
package com.launchdarkly.sdk.server;
import com.google.common.annotations.VisibleForTesting;
import com.google.gson.JsonElement;
import com.launchdarkly.eventsource.ConnectionErrorHandler;
import com.launchdarkly.eventsource.ConnectionErrorHandler.Action;
import com.launchdarkly.eventsource.EventHandler;
import com.launchdarkly.eventsource.EventSource;
import com.launchdarkly.eventsource.MessageEvent;
import com.launchdarkly.eventsource.UnsuccessfulResponseException;
import com.launchdarkly.sdk.server.DataModel.VersionedData;
import com.launchdarkly.sdk.server.interfaces.DataSource;
import com.launchdarkly.sdk.server.interfaces.DataSourceStatusProvider.ErrorInfo;
import com.launchdarkly.sdk.server.interfaces.DataSourceStatusProvider.ErrorKind;
import com.launchdarkly.sdk.server.interfaces.DataSourceStatusProvider.State;
import com.launchdarkly.sdk.server.interfaces.DataSourceUpdates;
import com.launchdarkly.sdk.server.interfaces.DataStoreStatusProvider;
import com.launchdarkly.sdk.server.interfaces.DataStoreTypes.DataKind;
import com.launchdarkly.sdk.server.interfaces.DataStoreTypes.FullDataSet;
import com.launchdarkly.sdk.server.interfaces.DataStoreTypes.ItemDescriptor;
import com.launchdarkly.sdk.server.interfaces.HttpConfiguration;
import com.launchdarkly.sdk.server.interfaces.SerializationException;
import org.slf4j.Logger;
import java.io.IOException;
import java.net.URI;
import java.time.Duration;
import java.time.Instant;
import java.util.AbstractMap;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import static com.launchdarkly.sdk.server.DataModel.ALL_DATA_KINDS;
import static com.launchdarkly.sdk.server.DataModel.SEGMENTS;
import static com.launchdarkly.sdk.server.Util.checkIfErrorIsRecoverableAndLog;
import static com.launchdarkly.sdk.server.Util.concatenateUriPath;
import static com.launchdarkly.sdk.server.Util.configureHttpClientBuilder;
import static com.launchdarkly.sdk.server.Util.getHeadersBuilderFor;
import static com.launchdarkly.sdk.server.Util.httpErrorDescription;
import okhttp3.Headers;
import okhttp3.OkHttpClient;
/**
* Implementation of the streaming data source, not including the lower-level SSE implementation which is in
* okhttp-eventsource.
*
* Error handling works as follows:
* 1. If any event is malformed, we must assume the stream is broken and we may have missed updates. Set the
* data source state to INTERRUPTED, with an error kind of INVALID_DATA, and restart the stream.
* 2. If we try to put updates into the data store and we get an error, we must assume something's wrong with the
* data store. We don't have to log this error because it is logged by DataSourceUpdatesImpl, which will also set
* our state to INTERRUPTED for us.
* 2a. If the data store supports status notifications (which all persistent stores normally do), then we can
* assume it has entered a failed state and will notify us once it is working again. If and when it recovers, then
* it will tell us whether we need to restart the stream (to ensure that we haven't missed any updates), or
* whether it has already persisted all of the stream updates we received during the outage.
* 2b. If the data store doesn't support status notifications (which is normally only true of the in-memory store)
* then we don't know the significance of the error, but we must assume that updates have been lost, so we'll
* restart the stream.
* 3. If we receive an unrecoverable error like HTTP 401, we close the stream and don't retry, and set the state
* to OFF. Any other HTTP error or network error causes a retry with backoff, with a state of INTERRUPTED.
* 4. We set the Future returned by start() to tell the client initialization logic that initialization has either
* succeeded (we got an initial payload and successfully stored it) or permanently failed (we got a 401, etc.).
* Otherwise, the client initialization method may time out but we will still be retrying in the background, and
* if we succeed then the client can detect that we're initialized now by calling our Initialized method.
*/
final class StreamProcessor implements DataSource {
private static final String STREAM_URI_PATH = "all";
private static final String PUT = "put";
private static final String PATCH = "patch";
private static final String DELETE = "delete";
private static final Logger logger = Loggers.DATA_SOURCE;
private static final Duration DEAD_CONNECTION_INTERVAL = Duration.ofSeconds(300);
private static final String ERROR_CONTEXT_MESSAGE = "in stream connection";
private static final String WILL_RETRY_MESSAGE = "will retry";
private final DataSourceUpdates dataSourceUpdates;
private final HttpConfiguration httpConfig;
private final Headers headers;
@VisibleForTesting final URI streamUri;
@VisibleForTesting final Duration initialReconnectDelay;
private final DiagnosticAccumulator diagnosticAccumulator;
private final EventSourceCreator eventSourceCreator;
private final int threadPriority;
private final DataStoreStatusProvider.StatusListener statusListener;
private volatile EventSource es;
private final AtomicBoolean initialized = new AtomicBoolean(false);
private volatile long esStarted = 0;
private volatile boolean lastStoreUpdateFailed = false;
ConnectionErrorHandler connectionErrorHandler = createDefaultConnectionErrorHandler(); // exposed for testing
static final class EventSourceParams {
final EventHandler handler;
final URI streamUri;
final Duration initialReconnectDelay;
final ConnectionErrorHandler errorHandler;
final Headers headers;
final HttpConfiguration httpConfig;
EventSourceParams(EventHandler handler, URI streamUri, Duration initialReconnectDelay,
ConnectionErrorHandler errorHandler, Headers headers, HttpConfiguration httpConfig) {
this.handler = handler;
this.streamUri = streamUri;
this.initialReconnectDelay = initialReconnectDelay;
this.errorHandler = errorHandler;
this.headers = headers;
this.httpConfig = httpConfig;
}
}
@FunctionalInterface
static interface EventSourceCreator {
EventSource createEventSource(EventSourceParams params);
}
StreamProcessor(
HttpConfiguration httpConfig,
DataSourceUpdates dataSourceUpdates,
EventSourceCreator eventSourceCreator,
int threadPriority,
DiagnosticAccumulator diagnosticAccumulator,
URI streamUri,
Duration initialReconnectDelay
) {
this.dataSourceUpdates = dataSourceUpdates;
this.httpConfig = httpConfig;
this.diagnosticAccumulator = diagnosticAccumulator;
this.eventSourceCreator = eventSourceCreator != null ? eventSourceCreator : this::defaultEventSourceCreator;
this.threadPriority = threadPriority;
this.streamUri = streamUri;
this.initialReconnectDelay = initialReconnectDelay;
this.headers = getHeadersBuilderFor(httpConfig)
.add("Accept", "text/event-stream")
.build();
if (dataSourceUpdates.getDataStoreStatusProvider() != null &&
dataSourceUpdates.getDataStoreStatusProvider().isStatusMonitoringEnabled()) {
this.statusListener = this::onStoreStatusChanged;
dataSourceUpdates.getDataStoreStatusProvider().addStatusListener(statusListener);
} else {
this.statusListener = null;
}
}
private void onStoreStatusChanged(DataStoreStatusProvider.Status newStatus) {
if (newStatus.isAvailable()) {
if (newStatus.isRefreshNeeded()) {
// The store has just transitioned from unavailable to available, and we can't guarantee that
// all of the latest data got cached, so let's restart the stream to refresh all the data.
EventSource stream = es;
if (stream != null) {
logger.warn("Restarting stream to refresh data after data store outage");
stream.restart();
}
}
}
}
private ConnectionErrorHandler createDefaultConnectionErrorHandler() {
return (Throwable t) -> {
recordStreamInit(true);
if (t instanceof UnsuccessfulResponseException) {
int status = ((UnsuccessfulResponseException)t).getCode();
ErrorInfo errorInfo = ErrorInfo.fromHttpError(status);
boolean recoverable = checkIfErrorIsRecoverableAndLog(logger, httpErrorDescription(status),
ERROR_CONTEXT_MESSAGE, status, WILL_RETRY_MESSAGE);
if (recoverable) {
dataSourceUpdates.updateStatus(State.INTERRUPTED, errorInfo);
esStarted = System.currentTimeMillis();
return Action.PROCEED;
} else {
dataSourceUpdates.updateStatus(State.OFF, errorInfo);
return Action.SHUTDOWN;
}
}
checkIfErrorIsRecoverableAndLog(logger, t.toString(), ERROR_CONTEXT_MESSAGE, 0, WILL_RETRY_MESSAGE);
ErrorInfo errorInfo = ErrorInfo.fromException(t instanceof IOException ? ErrorKind.NETWORK_ERROR : ErrorKind.UNKNOWN, t);
dataSourceUpdates.updateStatus(State.INTERRUPTED, errorInfo);
return Action.PROCEED;
};
}
@Override
public Future start() {
final CompletableFuture initFuture = new CompletableFuture<>();
ConnectionErrorHandler wrappedConnectionErrorHandler = (Throwable t) -> {
Action result = connectionErrorHandler.onConnectionError(t);
if (result == Action.SHUTDOWN) {
initFuture.complete(null); // if client is initializing, make it stop waiting; has no effect if already inited
}
return result;
};
EventHandler handler = new StreamEventHandler(initFuture);
es = eventSourceCreator.createEventSource(new EventSourceParams(handler,
concatenateUriPath(streamUri, STREAM_URI_PATH),
initialReconnectDelay,
wrappedConnectionErrorHandler,
headers,
httpConfig));
esStarted = System.currentTimeMillis();
es.start();
return initFuture;
}
private void recordStreamInit(boolean failed) {
if (diagnosticAccumulator != null && esStarted != 0) {
diagnosticAccumulator.recordStreamInit(esStarted, System.currentTimeMillis() - esStarted, failed);
}
}
@Override
public void close() throws IOException {
logger.info("Closing LaunchDarkly StreamProcessor");
if (statusListener != null) {
dataSourceUpdates.getDataStoreStatusProvider().removeStatusListener(statusListener);
}
if (es != null) {
es.close();
}
dataSourceUpdates.updateStatus(State.OFF, null);
}
@Override
public boolean isInitialized() {
return initialized.get();
}
private class StreamEventHandler implements EventHandler {
private final CompletableFuture initFuture;
StreamEventHandler(CompletableFuture initFuture) {
this.initFuture = initFuture;
}
@Override
public void onOpen() throws Exception {
}
@Override
public void onClosed() throws Exception {
}
@Override
public void onMessage(String name, MessageEvent event) throws Exception {
try {
switch (name) {
case PUT:
handlePut(event.getData());
break;
case PATCH:
handlePatch(event.getData());
break;
case DELETE:
handleDelete(event.getData());
break;
default:
logger.warn("Unexpected event found in stream: " + name);
break;
}
lastStoreUpdateFailed = false;
dataSourceUpdates.updateStatus(State.VALID, null);
} catch (StreamInputException e) {
logger.error("LaunchDarkly service request failed or received invalid data: {}", e.toString());
logger.debug(e.toString(), e);
ErrorInfo errorInfo = new ErrorInfo(
e.getCause() instanceof IOException ? ErrorKind.NETWORK_ERROR : ErrorKind.INVALID_DATA,
0,
e.getCause() == null ? e.getMessage() : e.getCause().toString(),
Instant.now()
);
dataSourceUpdates.updateStatus(State.INTERRUPTED, errorInfo);
es.restart();
} catch (StreamStoreException e) {
// See item 2 in error handling comments at top of class
if (statusListener == null) {
if (!lastStoreUpdateFailed) {
logger.warn("Restarting stream to ensure that we have the latest data");
}
es.restart();
}
lastStoreUpdateFailed = true;
} catch (Exception e) {
logger.warn("Unexpected error from stream processor: {}", e.toString());
logger.debug(e.toString(), e);
}
}
private void handlePut(String eventData) throws StreamInputException, StreamStoreException {
recordStreamInit(false);
esStarted = 0;
PutData putData = parseStreamJson(PutData.class, eventData);
FullDataSet allData = putData.data.toFullDataSet();
if (!dataSourceUpdates.init(allData)) {
throw new StreamStoreException();
}
if (!initialized.getAndSet(true)) {
initFuture.complete(null);
logger.info("Initialized LaunchDarkly client.");
}
}
private void handlePatch(String eventData) throws StreamInputException, StreamStoreException {
PatchData data = parseStreamJson(PatchData.class, eventData);
Map.Entry kindAndKey = getKindAndKeyFromStreamApiPath(data.path);
if (kindAndKey == null) {
return;
}
DataKind kind = kindAndKey.getKey();
String key = kindAndKey.getValue();
VersionedData item = deserializeFromParsedJson(kind, data.data);
if (!dataSourceUpdates.upsert(kind, key, new ItemDescriptor(item.getVersion(), item))) {
throw new StreamStoreException();
}
}
private void handleDelete(String eventData) throws StreamInputException, StreamStoreException {
DeleteData data = parseStreamJson(DeleteData.class, eventData);
Map.Entry kindAndKey = getKindAndKeyFromStreamApiPath(data.path);
if (kindAndKey == null) {
return;
}
DataKind kind = kindAndKey.getKey();
String key = kindAndKey.getValue();
ItemDescriptor placeholder = new ItemDescriptor(data.version, null);
if (!dataSourceUpdates.upsert(kind, key, placeholder)) {
throw new StreamStoreException();
}
}
@Override
public void onComment(String comment) {
logger.debug("Received a heartbeat");
}
@Override
public void onError(Throwable throwable) {
logger.warn("Encountered EventSource error: {}", throwable.toString());
logger.debug(throwable.toString(), throwable);
}
}
private EventSource defaultEventSourceCreator(EventSourceParams params) {
EventSource.Builder builder = new EventSource.Builder(params.handler, params.streamUri)
.threadPriority(threadPriority)
.loggerBaseName(Loggers.DATA_SOURCE_LOGGER_NAME)
.clientBuilderActions(new EventSource.Builder.ClientConfigurer() {
public void configure(OkHttpClient.Builder builder) {
configureHttpClientBuilder(params.httpConfig, builder);
}
})
.connectionErrorHandler(params.errorHandler)
.headers(params.headers)
.reconnectTime(params.initialReconnectDelay)
.readTimeout(DEAD_CONNECTION_INTERVAL);
// Note that this is not the same read timeout that can be set in LDConfig. We default to a smaller one
// there because we don't expect long delays within any *non*-streaming response that the LD client gets.
// A read timeout on the stream will result in the connection being cycled, so we set this to be slightly
// more than the expected interval between heartbeat signals.
return builder.build();
}
private static Map.Entry getKindAndKeyFromStreamApiPath(String path) throws StreamInputException {
if (path == null) {
throw new StreamInputException("missing item path");
}
for (DataKind kind: ALL_DATA_KINDS) {
String prefix = (kind == SEGMENTS) ? "/segments/" : "/flags/";
if (path.startsWith(prefix)) {
return new AbstractMap.SimpleEntry(kind, path.substring(prefix.length()));
}
}
return null; // we don't recognize the path - the caller should ignore this event, just as we ignore unknown event types
}
private static T parseStreamJson(Class c, String json) throws StreamInputException {
try {
return JsonHelpers.deserialize(json, c);
} catch (SerializationException e) {
throw new StreamInputException(e);
}
}
private static VersionedData deserializeFromParsedJson(DataKind kind, JsonElement parsedJson)
throws StreamInputException {
try {
return JsonHelpers.deserializeFromParsedJson(kind, parsedJson);
} catch (SerializationException e) {
throw new StreamInputException(e);
}
}
// StreamInputException is either a JSON parsing error *or* a failure to query another endpoint
// (for indirect/put or indirect/patch); either way, it implies that we were unable to get valid data from LD services.
@SuppressWarnings("serial")
private static final class StreamInputException extends Exception {
public StreamInputException(String message) {
super(message);
}
public StreamInputException(Throwable cause) {
super(cause);
}
}
// This exception class indicates that the data store failed to persist an update.
@SuppressWarnings("serial")
private static final class StreamStoreException extends Exception {}
private static final class PutData {
FeatureRequestor.AllData data;
@SuppressWarnings("unused") // used by Gson
public PutData() { }
}
private static final class PatchData {
String path;
JsonElement data;
@SuppressWarnings("unused") // used by Gson
public PatchData() { }
}
private static final class DeleteData {
String path;
int version;
@SuppressWarnings("unused") // used by Gson
public DeleteData() { }
}
}
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