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RESTHeart MongoDB - MongoDB plugin
/*-
* ========================LICENSE_START=================================
* restheart-mongodb
* %%
* Copyright (C) 2014 - 2024 SoftInstigate
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see }
*/
public class ChangeStreamWorker implements Runnable {
private static final Logger LOGGER = LoggerFactory.getLogger(ChangeStreamWorker.class);
private final ChangeStreamWorkerKey key;
private final List resolvedStages;
private final String dbName;
private final String collName;
private final Set websocketSessions = Collections.synchronizedSet(new HashSet<>());
private Thread handlingVirtualThread = null;
public ChangeStreamWorker(ChangeStreamWorkerKey key, List resolvedStages, String dbName, String collName) {
super();
this.key = key;
this.resolvedStages = resolvedStages;
this.dbName = dbName;
this.collName = collName;
}
public ChangeStreamWorkerKey getKey() {
return this.key;
}
public String getDbName() {
return this.dbName;
}
public String getCollName() {
return this.collName;
}
public Thread handlingVirtualThread() {
return this.handlingVirtualThread;
}
@Override
public void run() {
if (Thread.currentThread().isVirtual()) {
this.handlingVirtualThread = Thread.currentThread();
}
LOGGER.debug("Change stream worker started {}", Thread.currentThread().getName());
try {
changeStreamEventsLoop();
} catch(Throwable t) {
if (t instanceof NoMoreWebSocketException) {
LOGGER.debug("Closing Change Stream Worker {} since it has no active WebSocket sessions", key);
} else {
LOGGER.error("Change Stream Worker {} died due to exception", key, t);
}
closeAllWebSocketSessions();
} finally {
ChangeStreamWorkers.getInstance().remove(key);
LOGGER.debug("Change stream worker ended");
}
}
/**
* executes the change stream events loop
*
* on MongoDB exceptions it reconnects to the change stream after 1 sec
*
**/
private void changeStreamEventsLoop() {
try {
_changeStreamEventsLoop();
} catch(MongoInterruptedException mie) {
close();
} catch(MongoException mqe) {
LOGGER.error("MongoDb error on ChangeStreamWorker {}, restarting a new worker", key, mqe);
try {
Thread.sleep(1_000);
} catch (InterruptedException ex) {
// nothing to do
} finally {
changeStreamEventsLoop();
}
}
}
private void _changeStreamEventsLoop() {
LOGGER.debug("Change Stream Worker {} started listening for change events", this.key);
final var changeStream = startChangeStream();
changeStream.forEach(changeEvent -> {
if (this.websocketSessions.isEmpty()) {
// this terminates the ChangeStreamWorker
LambdaUtils.throwsSneakyException(new NoMoreWebSocketException());
}
var msg = BsonUtils.toJson(getDocument(changeEvent), key.getJsonMode());
this.websocketSessions.stream().forEach(session -> ThreadsUtils.virtualThreadsExecutor().execute(() -> {
try {
this.send(session, msg);
LOGGER.trace("Change event sent to WebSocket session {}", session.getId());
} catch (Throwable t) {
LOGGER.error("Error sending change event to WebSocket session ", session.getId(), t);
}
}));
});
}
public Set websocketSessions() {
return this.websocketSessions;
}
private void send(WebSocketSession session, String message) {
WebSockets.sendText(message, session.getChannel(), new WebSocketCallback() {
@Override
public void complete(final WebSocketChannel channel, Void context) {
}
@Override
public void onError(final WebSocketChannel channel, Void context, Throwable throwable) {
// close WebSocket session
try {
session.close();
var sid = session.getId();
websocketSessions().removeIf(s -> s.getId().equals(sid));
} catch (IOException e) {
LOGGER.warn("Error closing WebSocket session {}", session.getId(), e);
}
}
});
}
/**
* removes the workers form the list of active workers and
* close all its websocket sesssions and interrupt the handling virtual thread
*
* on next change event, the thread will terminate since it has no active websocket sesssions
*/
void close() {
ChangeStreamWorkers.getInstance().remove(key);
closeAllWebSocketSessions();
if (this.handlingVirtualThread != null && !this.handlingVirtualThread.isInterrupted()) {
this.handlingVirtualThread.interrupt();
}
}
void closeAllWebSocketSessions() {
websocketSessions.stream()
.collect(Collectors.toSet())
.forEach(wsk -> {
try {
wsk.close();
websocketSessions.remove(wsk);
} catch(IOException ioe) {
LOGGER.warn("Error closing WebSocket session {}", wsk, ioe);
}
});
}
private static class NoMoreWebSocketException extends Exception {}
private ChangeStreamIterable startChangeStream() {
try {
return RHMongoClients.mclient()
.getDatabase(dbName)
.getCollection(collName)
.watch(resolvedStages)
.fullDocument(FullDocument.UPDATE_LOOKUP);
} catch(Throwable e) {
LOGGER.warn("Error trying to start the stream: " + e.getMessage());
throw e;
}
}
private BsonDocument getDocument(ChangeStreamDocument notification) {
var doc = new BsonDocument();
if (notification == null) {
return doc;
}
if (notification.getFullDocument() != null) {
try {
doc.put("fullDocument", BsonUtils.documentToBson((Document) notification.getFullDocument()));
} catch(ClassCastException cce) {
LOGGER.warn("change event fullDocument is not json {}", notification.getFullDocument());
doc.put("fullDocument", BsonNull.VALUE);
}
}
if (notification.getDocumentKey() != null) {
doc.put("documentKey", notification.getDocumentKey());
}
if (notification.getUpdateDescription() != null) {
var updateDescription = new BsonDocument();
var updatedFields = notification.getUpdateDescription().getUpdatedFields();
if (updatedFields != null) {
updateDescription.put("updatedFields", updatedFields);
} else {
updateDescription.put("updatedFields", BsonNull.VALUE);
}
var removedFields = notification.getUpdateDescription().getRemovedFields();
if (removedFields == null) {
updateDescription.put("updatedFields", new BsonArray());
} else {
var _removedFields = new BsonArray();
removedFields.forEach(rf -> _removedFields.add(new BsonString(rf)));
updateDescription.put("removedFields", _removedFields);
}
doc.put("updateDescription", updateDescription);
}
if (notification.getOperationType() != null) {
doc.put("operationType", new BsonString(notification.getOperationType().getValue()));
}
return doc;
}
}