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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 }
* @author Omar Trasatti {@literal }
*/
public class GetChangeStreamHandler extends PipelinedHandler {
private final String CONNECTION_HEADER_KEY = "connection";
private final String CONNECTION_HEADER_VALUE = "upgrade";
private final String UPGRADE_HEADER_KEY = "upgrade";
private final String UPGRADE_HEADER_VALUE = "websocket";
private static final Logger LOGGER = LoggerFactory.getLogger(GetChangeStreamHandler.class);
private static final HttpHandler WEBSOCKET_HANDLER = Handlers.websocket((exchange, channel) -> {
var csKey = new ChangeStreamWorkerKey(exchange);
var csw$ = ChangeStreamWorkers.getInstance().get(csKey);
if (csw$.isPresent()) {
var csw = csw$.get();
var wss = new WebSocketSession(channel, csw);
csw.websocketSessions().add(wss);
LOGGER.debug("New Change Stream WebSocket session, sessionkey={} for changeStreamKey={}", wss.getId(), csKey);
} else {
LOGGER.error("Cannot find Change Stream Worker changeStreamKey={}", csKey);
try {
channel.close();
} catch (IOException e) {
}
}
});
public static final AttachmentKey AVARS_ATTACHMENT_KEY = AttachmentKey.create(BsonDocument.class);
public static final AttachmentKey JSON_MODE_ATTACHMENT_KEY = AttachmentKey.create(JsonMode.class);
@Override
public void handleRequest(HttpServerExchange exchange) throws Exception {
var request = MongoRequest.of(exchange);
var response = MongoResponse.of(exchange);
if (request.isInError()) {
next(exchange);
return;
}
try {
if (isWebSocketHandshakeRequest(exchange)) {
exchange.putAttachment(JSON_MODE_ATTACHMENT_KEY, request.getJsonMode());
exchange.putAttachment(AVARS_ATTACHMENT_KEY, request.getAggregationVars());
initChangeStreamWorker(exchange);
WEBSOCKET_HANDLER.handleRequest(exchange);
} else {
response.setInError(HttpStatus.SC_BAD_REQUEST, "Change Stream requires WebSocket, no 'Upgrade' or 'Connection' request header found");
next(exchange);
}
} catch (QueryNotFoundException ex) {
response.setInError(HttpStatus.SC_NOT_FOUND, "Change Stream does not exist");
LOGGER.debug("Requested Change Stream {} does not exist", request.getUnmappedRequestUri());
next(exchange);
} catch (QueryVariableNotBoundException ex) {
response.setInError(HttpStatus.SC_BAD_REQUEST, ex.getMessage());
LOGGER.warn("Cannot open change stream, "
+ "the request does not specify the required variables "
+ "in the avars query paramter: {}",
ex.getMessage());
next(exchange);
} catch (IllegalStateException ise) {
if (ise.getMessage() != null && ise.getMessage().contains("transport does not support HTTP upgrade")) {
var error = "Cannot open change stream: the AJP listener does not support WebSocket";
LOGGER.warn(error);
response.setInError(HttpStatus.SC_INTERNAL_SERVER_ERROR, error);
}
} catch (Throwable t) {
LOGGER.error("Error handling the Change Stream request", t);
response.setInError(HttpStatus.SC_INTERNAL_SERVER_ERROR, t.getMessage());
}
}
private boolean isWebSocketHandshakeRequest(HttpServerExchange exchange) {
var chVals = exchange.getRequestHeaders().get(CONNECTION_HEADER_KEY);
var uhVals = exchange.getRequestHeaders().get(UPGRADE_HEADER_KEY);
return chVals != null && uhVals != null &&
Arrays.stream(chVals.toArray()).anyMatch(val -> val.toLowerCase().contains(CONNECTION_HEADER_VALUE)) &&
Arrays.stream(uhVals.toArray()).anyMatch(val -> val.toLowerCase().contains(UPGRADE_HEADER_VALUE));
}
private List getResolvedStagesAsList(MongoRequest request) throws InvalidMetadataException, QueryVariableNotBoundException, QueryNotFoundException {
var changesStreamOperation = request.getChangeStreamOperation();
var streams = ChangeStreamOperation.getFromJson(request.getCollectionProps());
var _query = streams
.stream()
.filter(q -> q.getUri().equals(changesStreamOperation))
.findFirst();
if (!_query.isPresent()) {
throw new QueryNotFoundException("Stream " + request.getUnmappedRequestUri() + " does not exist");
}
var pipeline = _query.get();
var resolvedStages = StagesInterpolator.interpolate(VAR_OPERATOR.$var, STAGE_OPERATOR.$ifvar, pipeline.getStages(), request.getAggregationVars());
return resolvedStages;
}
/**
* Initiate a `ChangeStreamWorker` thread to monitor change streams and relay updates to WebSocket clients.
*
* @param exchange
*
* @throws QueryVariableNotBoundException
* @throws QueryNotFoundException
* @throws InvalidMetadataException
*/
private synchronized void initChangeStreamWorker(HttpServerExchange exchange) throws QueryVariableNotBoundException, QueryNotFoundException, InvalidMetadataException {
var csKey = new ChangeStreamWorkerKey(exchange);
var request = MongoRequest.of(exchange);
var resolvedStages = getResolvedStagesAsList(request);
var existingChangeSreamWorker$ = ChangeStreamWorkers.getInstance().get(csKey);
if (existingChangeSreamWorker$.isEmpty()) {
var changeStreamWorker = (new ChangeStreamWorker(csKey,
resolvedStages,
request.getDBName(),
request.getCollectionName()));
ChangeStreamWorkers.getInstance().put(changeStreamWorker);
ThreadsUtils.virtualThreadsExecutor().execute(changeStreamWorker);
LOGGER.debug("Started Change Stream Worker, {}", csKey);
} else {
LOGGER.debug("Change Stream Worker already exists, {}", csKey);
}
}
}