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Async boundary for Spring MVC reactive type streaming

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Issue: SPR-15365
This commit is contained in:
Rossen Stoyanchev
2017-04-04 10:12:02 -04:00
parent af6f688196
commit d9221fb87d
8 changed files with 156 additions and 37 deletions
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149
spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ReactiveTypeHandler.java
View File

@@ -19,7 +19,12 @@ import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Optional;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.reactivestreams.Publisher;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
@@ -27,6 +32,7 @@ import org.reactivestreams.Subscription;
import org.springframework.core.MethodParameter;
import org.springframework.core.ReactiveAdapter;
import org.springframework.core.ReactiveAdapterRegistry;
import org.springframework.core.task.TaskExecutor;
import org.springframework.http.MediaType;
import org.springframework.http.codec.ServerSentEvent;
import org.springframework.http.server.ServerHttpResponse;
@@ -60,18 +66,26 @@ import org.springframework.web.servlet.HandlerMapping;
*/
class ReactiveTypeHandler {
private static Log logger = LogFactory.getLog(ReactiveTypeHandler.class);
private static final MediaType JSON_TYPE = new MediaType("application", "*+json");
private final ReactiveAdapterRegistry reactiveRegistry;
private final TaskExecutor taskExecutor;
private final ContentNegotiationManager contentNegotiationManager;
ReactiveTypeHandler(ReactiveAdapterRegistry registry, ContentNegotiationManager manager) {
ReactiveTypeHandler(ReactiveAdapterRegistry registry, TaskExecutor executor,
ContentNegotiationManager manager) {
Assert.notNull(registry, "ReactiveAdapterRegistry is required");
Assert.notNull(executor, "TaskExecutor is required");
Assert.notNull(manager, "ContentNegotiationManager is required");
this.reactiveRegistry = registry;
this.taskExecutor = executor;
this.contentNegotiationManager = manager;
}
@@ -108,17 +122,17 @@ class ReactiveTypeHandler {
if (mediaTypes.stream().anyMatch(MediaType.TEXT_EVENT_STREAM::includes) ||
ServerSentEvent.class.isAssignableFrom(elementType)) {
SseEmitter emitter = new SseEmitter();
new SseEmitterSubscriber(emitter).connect(adapter, returnValue);
new SseEmitterSubscriber(emitter, this.taskExecutor).connect(adapter, returnValue);
return emitter;
}
if (mediaTypes.stream().anyMatch(MediaType.APPLICATION_STREAM_JSON::includes)) {
ResponseBodyEmitter emitter = getEmitter(MediaType.APPLICATION_STREAM_JSON);
new JsonEmitterSubscriber(emitter).connect(adapter, returnValue);
new JsonEmitterSubscriber(emitter, this.taskExecutor).connect(adapter, returnValue);
return emitter;
}
if (CharSequence.class.isAssignableFrom(elementType) && !jsonArrayOfStrings) {
ResponseBodyEmitter emitter = getEmitter(mediaType.orElse(MediaType.TEXT_PLAIN));
new TextEmitterSubscriber(emitter).connect(adapter, returnValue);
new TextEmitterSubscriber(emitter, this.taskExecutor).connect(adapter, returnValue);
return emitter;
}
}
@@ -161,13 +175,25 @@ class ReactiveTypeHandler {
private static abstract class AbstractEmitterSubscriber implements Subscriber<Object> {
private static final Object COMPLETE_SIGNAL = new Object();
private final ResponseBodyEmitter emitter;
private final TaskExecutor taskExecutor;
private Subscription subscription;
private final Queue<Object> queue = new ConcurrentLinkedQueue<>();
protected AbstractEmitterSubscriber(ResponseBodyEmitter emitter) {
private final AtomicBoolean executing = new AtomicBoolean(false);
private volatile boolean done;
protected AbstractEmitterSubscriber(ResponseBodyEmitter emitter, TaskExecutor executor) {
this.emitter = emitter;
this.taskExecutor = executor;
}
@@ -181,42 +207,113 @@ class ReactiveTypeHandler {
return this.emitter;
}
@Override
public void onSubscribe(Subscription subscription) {
public final void onSubscribe(Subscription subscription) {
this.subscription = subscription;
this.emitter.onTimeout(subscription::cancel);
if (logger.isDebugEnabled()) {
logger.debug("Subscribed to Publisher for " + this.emitter);
}
this.emitter.onTimeout(() -> {
if (logger.isDebugEnabled()) {
logger.debug("Connection timed out for " + this.emitter);
}
terminate();
this.emitter.complete();
});
subscription.request(1);
}
@Override
public void onNext(Object element) {
try {
send(element);
this.subscription.request(1);
public final void onNext(Object element) {
this.queue.offer(element);
trySchedule();
}
@Override
public final void onError(Throwable ex) {
this.queue.offer(ex);
trySchedule();
}
@Override
public final void onComplete() {
this.queue.offer(COMPLETE_SIGNAL);
trySchedule();
}
private void trySchedule() {
if (this.executing.compareAndSet(false, true)) {
try {
this.taskExecutor.execute(() -> {
try {
Object signal = this.queue.poll();
if (!this.done) {
handle(signal);
}
}
finally {
this.executing.set(false);
if(!this.queue.isEmpty())
trySchedule();
}
});
}
catch (Throwable ex) {
try {
terminate();
}
finally {
this.executing.set(false);
this.queue.clear();
}
}
}
catch (IOException ex) {
this.subscription.cancel();
}
private void handle(Object signal) {
if (signal instanceof Throwable) {
if (logger.isDebugEnabled()) {
logger.debug("Publisher error for " + this.emitter, (Throwable) signal);
}
this.done = true;
this.emitter.completeWithError((Throwable) signal);
}
else if (signal == COMPLETE_SIGNAL) {
if (logger.isDebugEnabled()) {
logger.debug("Publishing completed for " + this.emitter);
}
this.done = true;
this.emitter.complete();
}
else {
try {
send(signal);
this.subscription.request(1);
}
catch (final Throwable ex) {
if (logger.isDebugEnabled()) {
logger.debug("Send error for " + this.emitter, ex);
}
terminate();
}
}
}
protected abstract void send(Object element) throws IOException;
@Override
public void onError(Throwable ex) {
this.emitter.completeWithError(ex);
private void terminate() {
this.done = true;
this.subscription.cancel();
}
@Override
public void onComplete() {
this.emitter.complete();
}
}
private static class SseEmitterSubscriber extends AbstractEmitterSubscriber {
SseEmitterSubscriber(SseEmitter sseEmitter) {
super(sseEmitter);
SseEmitterSubscriber(SseEmitter sseEmitter, TaskExecutor executor) {
super(sseEmitter, executor);
}
@Override
@@ -243,8 +340,8 @@ class ReactiveTypeHandler {
private static class JsonEmitterSubscriber extends AbstractEmitterSubscriber {
JsonEmitterSubscriber(ResponseBodyEmitter emitter) {
super(emitter);
JsonEmitterSubscriber(ResponseBodyEmitter emitter, TaskExecutor executor) {
super(emitter, executor);
}
@Override
@@ -257,8 +354,8 @@ class ReactiveTypeHandler {
private static class TextEmitterSubscriber extends AbstractEmitterSubscriber {
TextEmitterSubscriber(ResponseBodyEmitter emitter) {
super(emitter);
TextEmitterSubscriber(ResponseBodyEmitter emitter, TaskExecutor executor) {
super(emitter, executor);
}
@Override

2
spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java
View File

@@ -683,7 +683,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
handlers.add(new ModelMethodProcessor());
handlers.add(new ViewMethodReturnValueHandler());
handlers.add(new ResponseBodyEmitterReturnValueHandler(getMessageConverters(),
this.reactiveRegistry, this.contentNegotiationManager));
this.reactiveRegistry, this.taskExecutor, this.contentNegotiationManager));
handlers.add(new StreamingResponseBodyReturnValueHandler());
handlers.add(new HttpEntityMethodProcessor(getMessageConverters(),
this.contentNegotiationManager, this.requestResponseBodyAdvice));

7
spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitter.java
View File

@@ -23,6 +23,7 @@ import java.util.Set;
import org.springframework.http.MediaType;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* A controller method return value type for asynchronous request processing
@@ -224,6 +225,12 @@ public class ResponseBodyEmitter {
}
@Override
public String toString() {
return "ResponseBodyEmitter@" + ObjectUtils.getIdentityHexString(this);
}
/**
* Handle sent objects and complete request processing.
*/

12
spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandler.java
View File

@@ -28,6 +28,7 @@ import org.apache.commons.logging.LogFactory;
import org.springframework.core.MethodParameter;
import org.springframework.core.ReactiveAdapterRegistry;
import org.springframework.core.ResolvableType;
import org.springframework.core.task.TaskExecutor;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
@@ -63,11 +64,12 @@ public class ResponseBodyEmitterReturnValueHandler implements HandlerMethodRetur
public ResponseBodyEmitterReturnValueHandler(List<HttpMessageConverter<?>> messageConverters,
ReactiveAdapterRegistry reactiveRegistry, ContentNegotiationManager manager) {
ReactiveAdapterRegistry reactiveRegistry, TaskExecutor executor,
ContentNegotiationManager manager) {
Assert.notEmpty(messageConverters, "HttpMessageConverter List must not be empty");
this.messageConverters = messageConverters;
this.reactiveHandler = new ReactiveTypeHandler(reactiveRegistry, manager);
this.reactiveHandler = new ReactiveTypeHandler(reactiveRegistry, executor, manager);
}
@@ -158,13 +160,13 @@ public class ResponseBodyEmitterReturnValueHandler implements HandlerMethodRetur
@SuppressWarnings("unchecked")
private <T> void sendInternal(T data, MediaType mediaType) throws IOException {
if (logger.isTraceEnabled()) {
logger.trace("Writing [" + data + "]");
}
for (HttpMessageConverter<?> converter : ResponseBodyEmitterReturnValueHandler.this.messageConverters) {
if (converter.canWrite(data.getClass(), mediaType)) {
((HttpMessageConverter<T>) converter).write(data, mediaType, this.outputMessage);
this.outputMessage.flush();
if (logger.isDebugEnabled()) {
logger.debug("Written [" + data + "] using [" + converter + "]");
}
return;
}
}

6
spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java
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@@ -25,6 +25,7 @@ import java.util.Set;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
/**
@@ -128,6 +129,11 @@ public class SseEmitter extends ResponseBodyEmitter {
}
}
@Override
public String toString() {
return "SseEmitter@" + ObjectUtils.getIdentityHexString(this);
}
public static SseEventBuilder event() {
return new SseEventBuilderImpl();