spring-graphql WebSocketGraphQlTransport 源码
spring-graphql WebSocketGraphQlTransport 代码
文件路径：/spring-graphql/src/main/java/org/springframework/graphql/client/WebSocketGraphQlTransport.java
/*
* Copyright 2002-2022 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.graphql.client;
import java.net.URI;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import reactor.core.Scannable;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxSink;
import reactor.core.publisher.Mono;
import reactor.core.publisher.MonoSink;
import reactor.core.publisher.Sinks;
import org.springframework.graphql.GraphQlRequest;
import org.springframework.graphql.GraphQlResponse;
import org.springframework.graphql.ResponseError;
import org.springframework.graphql.server.support.GraphQlWebSocketMessage;
import org.springframework.graphql.server.support.GraphQlWebSocketMessageType;
import org.springframework.http.HttpHeaders;
import org.springframework.http.codec.CodecConfigurer;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.reactive.socket.CloseStatus;
import org.springframework.web.reactive.socket.WebSocketHandler;
import org.springframework.web.reactive.socket.WebSocketSession;
import org.springframework.web.reactive.socket.client.WebSocketClient;
/**
* {@link GraphQlTransport} for GraphQL over WebSocket via {@link WebSocketClient}.
*
* @author Rossen Stoyanchev
* @since 1.0.0
* @see <a href="https://github.com/enisdenjo/graphql-ws/blob/master/PROTOCOL.md">GraphQL over WebSocket protocol</a>
*/
final class WebSocketGraphQlTransport implements GraphQlTransport {
private static final Log logger = LogFactory.getLog(WebSocketGraphQlTransport.class);
private final URI url;
private final HttpHeaders headers = new HttpHeaders();
private final WebSocketClient webSocketClient;
private final GraphQlSessionHandler graphQlSessionHandler;
private final Mono<GraphQlSession> graphQlSessionMono;
WebSocketGraphQlTransport(
URI url, @Nullable HttpHeaders headers, WebSocketClient client, CodecConfigurer codecConfigurer,
WebSocketGraphQlClientInterceptor interceptor) {
Assert.notNull(url, "URI is required");
Assert.notNull(client, "WebSocketClient is required");
Assert.notNull(codecConfigurer, "CodecConfigurer is required");
Assert.notNull(interceptor, "WebSocketGraphQlClientInterceptor is required");
this.url = url;
this.headers.putAll(headers != null ? headers : HttpHeaders.EMPTY);
this.webSocketClient = client;
this.graphQlSessionHandler = new GraphQlSessionHandler(codecConfigurer, interceptor);
this.graphQlSessionMono = initGraphQlSession(this.url, this.headers, client, this.graphQlSessionHandler)
.cacheInvalidateWhen(GraphQlSession::notifyWhenClosed);
}
private static Mono<GraphQlSession> initGraphQlSession(
URI uri, HttpHeaders headers, WebSocketClient client, GraphQlSessionHandler handler) {
return Mono.defer(() -> {
if (handler.isStopped()) {
return Mono.error(new IllegalStateException("WebSocketGraphQlTransport has been stopped"));
}
client.execute(uri, headers, handler)
.subscribe(aVoid -> {}, handler::handleWebSocketSessionError, () -> {});
return handler.getGraphQlSession();
});
}
public URI getUrl() {
return this.url;
}
public HttpHeaders getHeaders() {
return this.headers;
}
public WebSocketClient getWebSocketClient() {
return this.webSocketClient;
}
public CodecConfigurer getCodecConfigurer() {
return this.graphQlSessionHandler.getCodecConfigurer();
}
/**
* Start the transport by connecting the WebSocket, sending the
* "connection_init" and waiting for the "connection_ack" message.
* @return {@code Mono} that completes when the WebSocket is connected and
* ready to begin sending GraphQL requests
*/
public Mono<Void> start() {
this.graphQlSessionHandler.setStopped(false);
return this.graphQlSessionMono.then();
}
/**
* Stop the transport by closing the WebSocket with
* {@link org.springframework.web.reactive.socket.CloseStatus#NORMAL} and
* terminating in-progress requests with an error signal.
* <p>New requests are rejected from the time of this call. If necessary,
* call {@link #start()} to allow requests again.
* @return {@code Mono} that completes when the underlying session is closed
*/
public Mono<Void> stop() {
this.graphQlSessionHandler.setStopped(true);
return this.graphQlSessionMono.flatMap(GraphQlSession::close).onErrorResume(ex -> Mono.empty());
}
@Override
public Mono<GraphQlResponse> execute(GraphQlRequest request) {
return this.graphQlSessionMono.flatMap(session -> session.execute(request));
}
@Override
public Flux<GraphQlResponse> executeSubscription(GraphQlRequest request) {
return this.graphQlSessionMono.flatMapMany(session -> session.executeSubscription(request));
}
/**
* Client {@code WebSocketHandler} for GraphQL that deals with WebSocket
* concerns such as encoding and decoding of messages, {@link GraphQlSession}
* initialization and lifecycle, as well the lifecycle of the WebSocket.
*
* <p>This handler is for use as a singleton, but expects only one shared
* connection at a time. This is managed at a higher level by caching and
* re-using the {@link #getGraphQlSession() GraphQlSession} until closed at
* which point a new connection can be started.
*/
private static class GraphQlSessionHandler implements WebSocketHandler {
private final CodecDelegate codecDelegate;
private final WebSocketGraphQlClientInterceptor interceptor;
private Sinks.One<GraphQlSession> graphQlSessionSink;
private final AtomicBoolean stopped = new AtomicBoolean();
GraphQlSessionHandler(CodecConfigurer codecConfigurer, WebSocketGraphQlClientInterceptor interceptor) {
this.codecDelegate = new CodecDelegate(codecConfigurer);
this.interceptor = interceptor;
this.graphQlSessionSink = Sinks.unsafe().one();
}
public CodecConfigurer getCodecConfigurer() {
return this.codecDelegate.getCodecConfigurer();
}
@Override
public List<String> getSubProtocols() {
return Collections.singletonList("graphql-transport-ws");
}
/**
* Return the {@link GraphQlSession} for sending requests.
* The {@code Mono} completes when the WebSocket session is connected and
* the "connection_init" and "connection_ack" messages are exchanged or
* returns an error if it fails for any reason.
*/
public Mono<GraphQlSession> getGraphQlSession() {
return this.graphQlSessionSink.asMono();
}
/**
* When the handler is marked "stopped", i.e. set to {@code true}, new
* requests are rejected. When set to {@code true} they are allowed.
*/
public void setStopped(boolean stopped) {
this.stopped.set(stopped);
}
/**
* Whether the handler is marked {@link #setStopped(boolean) "stopped"}.
*/
public boolean isStopped() {
return this.stopped.get();
}
@Override
public Mono<Void> handle(WebSocketSession session) {
Assert.state(sessionNotInitialized(),
"This handler supports only one session at a time, for shared use.");
GraphQlSession graphQlSession = new GraphQlSession(session);
registerCloseStatusHandling(graphQlSession, session);
Mono<GraphQlWebSocketMessage> connectionInitMono = this.interceptor.connectionInitPayload()
.defaultIfEmpty(Collections.emptyMap())
.map(GraphQlWebSocketMessage::connectionInit);
Mono<Void> sendCompletion =
session.send(connectionInitMono.concatWith(graphQlSession.getRequestFlux())
.map(message -> this.codecDelegate.encode(session, message)));
Mono<Void> receiveCompletion = session.receive()
.flatMap(webSocketMessage -> {
if (sessionNotInitialized()) {
try {
GraphQlWebSocketMessage message = this.codecDelegate.decode(webSocketMessage);
Assert.state(message.resolvedType() == GraphQlWebSocketMessageType.CONNECTION_ACK,
() -> "Unexpected message before connection_ack: " + message);
return this.interceptor.handleConnectionAck(message.getPayload())
.then(Mono.defer(() -> {
if (logger.isDebugEnabled()) {
logger.debug(graphQlSession + " initialized");
}
Sinks.EmitResult result = this.graphQlSessionSink.tryEmitValue(graphQlSession);
if (result.isFailure()) {
return Mono.error(new IllegalStateException(
"GraphQlSession initialized but could not be emitted: " + result));
}
return Mono.empty();
}));
}
catch (Throwable ex) {
this.graphQlSessionSink.tryEmitError(ex);
return Mono.error(ex);
}
}
else {
try {
GraphQlWebSocketMessage message = this.codecDelegate.decode(webSocketMessage);
switch (message.resolvedType()) {
case NEXT:
graphQlSession.handleNext(message);
break;
case PING:
graphQlSession.sendPong(null);
break;
case ERROR:
graphQlSession.handleError(message);
break;
case COMPLETE:
graphQlSession.handleComplete(message);
break;
default:
throw new IllegalStateException(
"Unexpected message type: '" + message.getType() + "'");
}
}
catch (Exception ex) {
if (logger.isErrorEnabled()) {
logger.error("Closing " + session + ": " + ex);
}
return session.close(new CloseStatus(4400, "Invalid message"));
}
}
return Mono.empty();
})
.then();
return Mono.zip(sendCompletion, receiveCompletion).then();
}
private boolean sessionNotInitialized() {
return !Boolean.TRUE.equals(this.graphQlSessionSink.scan(Scannable.Attr.TERMINATED));
}
private void registerCloseStatusHandling(GraphQlSession graphQlSession, WebSocketSession session) {
session.closeStatus()
.defaultIfEmpty(CloseStatus.NO_STATUS_CODE)
.doOnNext(closeStatus -> {
String closeStatusMessage = initCloseStatusMessage(closeStatus, null, graphQlSession);
if (logger.isDebugEnabled()) {
logger.debug(closeStatusMessage);
}
graphQlSession.terminateRequests(closeStatusMessage, closeStatus);
})
.doOnError(cause -> {
CloseStatus closeStatus = CloseStatus.NO_STATUS_CODE;
String closeStatusMessage = initCloseStatusMessage(closeStatus, cause, graphQlSession);
if (logger.isErrorEnabled()) {
logger.error(closeStatusMessage);
}
graphQlSession.terminateRequests(closeStatusMessage, closeStatus);
})
.doOnTerminate(() -> {
// Reset GraphQlSession sink to be ready to connect again
this.graphQlSessionSink = Sinks.unsafe().one();
})
.subscribe();
}
private String initCloseStatusMessage(CloseStatus status, @Nullable Throwable ex, GraphQlSession session) {
String reason = session + " disconnected";
if (isStopped()) {
reason = session + " was stopped";
}
else if (ex != null) {
reason += ", closeStatus() completed with error " + ex;
}
else if (!status.equals(CloseStatus.NO_STATUS_CODE)) {
reason += " with " + status;
}
else {
reason += " without a status";
}
return reason;
}
/**
* This must be called from code that calls the {@code WebSocketClient}
* when execution completes with an error, which includes connection and
* session handling issues, and handler is unaware of connection issues
* otherwise.
*
* <p>The exception is logged which may provide further information,
* beyond the CloseStatus, when closed locally due to handling completing
* with an error. The error is routed to subscribers of
* {@link #getGraphQlSession()} which is necessary for connection issues.
*/
public void handleWebSocketSessionError(Throwable ex) {
if (logger.isDebugEnabled()) {
logger.debug("Session handling error: " + ex.getMessage(), ex);
}
else if (logger.isErrorEnabled()) {
logger.error("Session handling error: " + ex.getMessage());
}
this.graphQlSessionSink.tryEmitError(ex);
}
}
/**
* Session that deals with GraphQL level concerns such as sending requests,
* handling and routing responses, managing the lifecycle of streams, and
* to allow higher level code to be notified of closing or to close the
* underlying WebSocket.
*/
private static class GraphQlSession {
private final DisposableConnection connection;
private final AtomicLong requestIndex = new AtomicLong();
private final RequestSink requestSink = new RequestSink();
private final Map<String, RequestState> requestStateMap = new ConcurrentHashMap<>();
GraphQlSession(WebSocketSession webSocketSession) {
this.connection = DisposableConnection.from(webSocketSession);
}
/**
* Return the {@code Flux} of GraphQL requests to send as WebSocket messages.
*/
public Flux<GraphQlWebSocketMessage> getRequestFlux() {
return this.requestSink.getRequestFlux();
}
// Outbound messages
public Mono<GraphQlResponse> execute(GraphQlRequest request) {
String id = String.valueOf(this.requestIndex.incrementAndGet());
return Mono.<GraphQlResponse>create(sink -> {
SingleResponseRequestState state = new SingleResponseRequestState(request, sink);
this.requestStateMap.put(id, state);
try {
GraphQlWebSocketMessage message = GraphQlWebSocketMessage.subscribe(id, request);
this.requestSink.sendRequest(message);
}
catch (Exception ex) {
this.requestStateMap.remove(id);
sink.error(ex);
}
}).doOnCancel(() -> this.requestStateMap.remove(id));
}
public Flux<GraphQlResponse> executeSubscription(GraphQlRequest request) {
String id = String.valueOf(this.requestIndex.incrementAndGet());
return Flux.<GraphQlResponse>create(sink -> {
SubscriptionRequestState state = new SubscriptionRequestState(request, sink);
this.requestStateMap.put(id, state);
try {
GraphQlWebSocketMessage message = GraphQlWebSocketMessage.subscribe(id, request);
this.requestSink.sendRequest(message);
}
catch (Exception ex) {
this.requestStateMap.remove(id);
sink.error(ex);
}
}).doOnCancel(() -> stopSubscription(id));
}
private void stopSubscription(String id) {
RequestState state = this.requestStateMap.remove(id);
if (state != null) {
try {
this.requestSink.sendRequest(GraphQlWebSocketMessage.complete(id));
}
catch (Exception ex) {
if (logger.isErrorEnabled()) {
logger.error("Closing " + this.connection.getDescription() +
" after failure to send 'complete' for subscription id='" + id + "'.");
}
// No other suitable status (like server error but there is none for client)
this.connection.close(CloseStatus.PROTOCOL_ERROR).subscribe();
}
}
}
public void sendPong(@Nullable Map<String, Object> payload) {
GraphQlWebSocketMessage message = GraphQlWebSocketMessage.pong(payload);
this.requestSink.sendRequest(message);
}
// Inbound messages
/**
* Handle a "next" message and route to its recipient.
*/
public void handleNext(GraphQlWebSocketMessage message) {
String id = message.getId();
RequestState requestState = this.requestStateMap.get(id);
if (requestState == null) {
if (logger.isDebugEnabled()) {
logger.debug("No receiver for: " + message);
}
return;
}
if (requestState instanceof SingleResponseRequestState) {
this.requestStateMap.remove(id);
}
Map<String, Object> payload = message.getPayload();
GraphQlResponse graphQlResponse = new ResponseMapGraphQlResponse(payload);
requestState.handleResponse(graphQlResponse);
}
/**
* Handle an "error" message, turning it into an {@link GraphQlResponse}
* for single responses, or signaling an error for streams.
*/
public void handleError(GraphQlWebSocketMessage message) {
String id = message.getId();
RequestState requestState = this.requestStateMap.remove(id);
if (requestState == null) {
if (logger.isDebugEnabled()) {
logger.debug("No receiver for: " + message);
}
return;
}
List<Map<String, Object>> errorList = message.getPayload();
GraphQlResponse response = new ResponseMapGraphQlResponse(Collections.singletonMap("errors", errorList));
if (requestState instanceof SingleResponseRequestState) {
requestState.handleResponse(response);
}
else {
List<ResponseError> errors = response.getErrors();
Exception ex = new SubscriptionErrorException(requestState.getRequest(), errors);
requestState.handlerError(ex);
}
}
/**
* Handle a "complete" message.
*/
public void handleComplete(GraphQlWebSocketMessage message) {
String id = message.getId();
RequestState requestState = this.requestStateMap.remove(id);
if (requestState == null) {
if (logger.isDebugEnabled()) {
logger.debug("No receiver for': " + message);
}
return;
}
requestState.handleCompletion();
}
/**
* Return a {@code Mono} that completes when the connection is closed
* for any reason.
*/
public Mono<Void> notifyWhenClosed() {
return this.connection.notifyWhenClosed();
}
/**
* Close the underlying connection.
*/
public Mono<Void> close() {
return this.connection.close(CloseStatus.GOING_AWAY);
}
/**
* Terminate and clean all in-progress requests with the given error.
*/
public void terminateRequests(String message, CloseStatus status) {
this.requestStateMap.values().forEach(info -> info.emitDisconnectError(message, status));
this.requestStateMap.clear();
}
@Override
public String toString() {
return "GraphQlSession over " + this.connection.getDescription();
}
}
/**
* Minimal abstraction to decouple the {@link GraphQlSession} from the
* underlying {@code WebSocketSession}.
*/
private interface DisposableConnection {
Mono<Void> close(CloseStatus status);
Mono<Void> notifyWhenClosed();
String getDescription();
static DisposableConnection from(WebSocketSession session) {
return new DisposableConnection() {
@Override
public Mono<Void> close(CloseStatus status) {
return session.close(status);
}
@Override
public Mono<Void> notifyWhenClosed() {
return session.closeStatus().then();
}
@Override
public String getDescription() {
return session.toString();
}
};
}
}
/**
* Holds the request {@code Flux} and associated {@link FluxSink}.
*/
private static class RequestSink {
@Nullable
private FluxSink<GraphQlWebSocketMessage> requestSink;
private final Flux<GraphQlWebSocketMessage> requestFlux = Flux.create(sink -> {
Assert.state(this.requestSink == null, "Expected single subscriber only for outbound messages");
this.requestSink = sink;
});
public Flux<GraphQlWebSocketMessage> getRequestFlux() {
return this.requestFlux;
}
public void sendRequest(GraphQlWebSocketMessage message) {
Assert.state(this.requestSink != null, "Unexpected request before Flux is subscribed to");
this.requestSink.next(message);
}
}
/**
* Base class, state container for any request type.
*/
private interface RequestState {
GraphQlRequest getRequest();
void handleResponse(GraphQlResponse response);
void handlerError(Throwable ex);
void handleCompletion();
default void emitDisconnectError(String message, CloseStatus closeStatus) {
emitDisconnectError(new WebSocketDisconnectedException(message, getRequest(), closeStatus));
}
void emitDisconnectError(WebSocketDisconnectedException ex);
}
/**
* State container for a request that emits a single response.
*/
private static class SingleResponseRequestState implements RequestState {
private final GraphQlRequest request;
private final MonoSink<GraphQlResponse> responseSink;
SingleResponseRequestState(GraphQlRequest request, MonoSink<GraphQlResponse> responseSink) {
this.request = request;
this.responseSink = responseSink;
}
@Override
public GraphQlRequest getRequest() {
return this.request;
}
@Override
public void handleResponse(GraphQlResponse response) {
this.responseSink.success(response);
}
@Override
public void handlerError(Throwable ex) {
this.responseSink.error(ex);
}
@Override
public void handleCompletion() {
this.responseSink.success();
}
@Override
public void emitDisconnectError(WebSocketDisconnectedException ex) {
handlerError(ex);
}
}
/**
* State container for a subscription request that emits a stream of responses.
*/
private static class SubscriptionRequestState implements RequestState {
private final GraphQlRequest request;
private final FluxSink<GraphQlResponse> responseSink;
SubscriptionRequestState(GraphQlRequest request, FluxSink<GraphQlResponse> responseSink) {
this.request = request;
this.responseSink = responseSink;
}
@Override
public GraphQlRequest getRequest() {
return request;
}
@Override
public void handleResponse(GraphQlResponse response) {
this.responseSink.next(response);
}
@Override
public void handlerError(Throwable ex) {
this.responseSink.error(ex);
}
@Override
public void handleCompletion() {
this.responseSink.complete();
}
@Override
public void emitDisconnectError(WebSocketDisconnectedException ex) {
handlerError(ex);
}
}
}
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