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Use StringDecoder to split SSE stream

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ServerSentEventHttpMessageReader had logic to split on new lines
and buffer until an empty new line (start of a new event). To account
for random data chunking, it later re-assembled the lines for each
event and split again on new lines. However bufferUntil was still
unreliable a chunk may contain nothing but a newline, which doesn't
necessarily mean an empty newline in the overall SSE stream.

This commit simplifies the above by delegating the splitting of the
stream along newlines to StringDecoder.

Issue: SPR-16744
This commit is contained in:
Rossen Stoyanchev
2018-04-19 11:29:12 -04:00
parent 30c98c8a1c
commit da98ff72d2
2 changed files with 62 additions and 95 deletions
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93
spring-web/src/main/java/org/springframework/http/codec/ServerSentEventHttpMessageReader.java
View File

@@ -16,15 +16,11 @@
package org.springframework.http.codec; package org.springframework.http.codec;
import java.nio.CharBuffer;
import java.nio.charset.StandardCharsets; import java.nio.charset.StandardCharsets;
import java.time.Duration; import java.time.Duration;
import java.util.ArrayList;
import java.util.Collections; import java.util.Collections;
import java.util.List; import java.util.List;
import java.util.Map; import java.util.Map;
import java.util.function.IntPredicate;
import java.util.stream.Collectors;
import reactor.core.publisher.Flux; import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono; import reactor.core.publisher.Mono;
@@ -35,7 +31,6 @@ import org.springframework.core.codec.Decoder;
import org.springframework.core.codec.StringDecoder; import org.springframework.core.codec.StringDecoder;
import org.springframework.core.io.buffer.DataBuffer; import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory; import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.DefaultDataBufferFactory; import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.MediaType; import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpInputMessage; import org.springframework.http.ReactiveHttpInputMessage;
@@ -51,12 +46,12 @@ import org.springframework.lang.Nullable;
*/ */
public class ServerSentEventHttpMessageReader implements HttpMessageReader<Object> { public class ServerSentEventHttpMessageReader implements HttpMessageReader<Object> {
private static final IntPredicate NEWLINE_DELIMITER = b -> b == '\n' || b == '\r';
private static final DataBufferFactory bufferFactory = new DefaultDataBufferFactory(); private static final DataBufferFactory bufferFactory = new DefaultDataBufferFactory();
private static final StringDecoder stringDecoder = StringDecoder.textPlainOnly(); private static final StringDecoder stringDecoder = StringDecoder.textPlainOnly();
private static final ResolvableType STRING_TYPE = ResolvableType.forClass(String.class);
@Nullable @Nullable
private final Decoder<?> decoder; private final Decoder<?> decoder;
@@ -110,77 +105,53 @@ public class ServerSentEventHttpMessageReader implements HttpMessageReader<Objec
boolean shouldWrap = isServerSentEvent(elementType); boolean shouldWrap = isServerSentEvent(elementType);
ResolvableType valueType = (shouldWrap ? elementType.getGeneric(0) : elementType); ResolvableType valueType = (shouldWrap ? elementType.getGeneric(0) : elementType);
return Flux.from(message.getBody()) return stringDecoder.decode(message.getBody(), STRING_TYPE, null, Collections.emptyMap())
.concatMap(ServerSentEventHttpMessageReader::splitOnNewline) .bufferUntil(line -> line.equals(""))
.map(buffer -> { .concatMap(lines -> buildEvent(lines, valueType, shouldWrap, hints));
CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer());
DataBufferUtils.release(buffer);
return charBuffer.toString();
})
.bufferUntil(line -> line.equals("\n"))
.concatMap(rawLines -> {
String[] lines = rawLines.stream().collect(Collectors.joining()).split("\\r?\\n");
return buildEvent(lines, valueType, hints)
.filter(event -> shouldWrap || event.data() != null)
.map(event -> shouldWrap ? event : event.data());
})
.cast(Object.class);
} }
private static Flux<DataBuffer> splitOnNewline(DataBuffer dataBuffer) { private Mono<?> buildEvent(List<String> lines, ResolvableType valueType, boolean shouldWrap,
List<DataBuffer> results = new ArrayList<>();
int startIdx = 0;
int endIdx;
final int limit = dataBuffer.readableByteCount();
do {
endIdx = dataBuffer.indexOf(NEWLINE_DELIMITER, startIdx);
int length = endIdx != -1 ? endIdx - startIdx + 1 : limit - startIdx;
DataBuffer token = dataBuffer.slice(startIdx, length);
results.add(DataBufferUtils.retain(token));
startIdx = endIdx + 1;
}
while (startIdx < limit && endIdx != -1);
DataBufferUtils.release(dataBuffer);
return Flux.fromIterable(results);
}
private Mono<ServerSentEvent<Object>> buildEvent(String[] lines, ResolvableType valueType,
Map<String, Object> hints) { Map<String, Object> hints) {
ServerSentEvent.Builder<Object> sseBuilder = ServerSentEvent.builder(); ServerSentEvent.Builder<Object> sseBuilder = shouldWrap ? ServerSentEvent.builder() : null;
StringBuilder data = null; StringBuilder data = null;
StringBuilder comment = null; StringBuilder comment = null;
for (String line : lines) { for (String line : lines) {
if (line.startsWith("id:")) { if (line.startsWith("data:")) {
sseBuilder.id(line.substring(3));
}
else if (line.startsWith("event:")) {
sseBuilder.event(line.substring(6));
}
else if (line.startsWith("data:")) {
data = (data != null ? data : new StringBuilder()); data = (data != null ? data : new StringBuilder());
data.append(line.substring(5)).append("\n"); data.append(line.substring(5)).append("\n");
} }
else if (line.startsWith("retry:")) { if (shouldWrap) {
sseBuilder.retry(Duration.ofMillis(Long.valueOf(line.substring(6)))); if (line.startsWith("id:")) {
} sseBuilder.id(line.substring(3));
else if (line.startsWith(":")) { }
comment = (comment != null ? comment : new StringBuilder()); else if (line.startsWith("event:")) {
comment.append(line.substring(1)).append("\n"); sseBuilder.event(line.substring(6));
}
else if (line.startsWith("retry:")) {
sseBuilder.retry(Duration.ofMillis(Long.valueOf(line.substring(6))));
}
else if (line.startsWith(":")) {
comment = (comment != null ? comment : new StringBuilder());
comment.append(line.substring(1)).append("\n");
}
} }
} }
if (comment != null) {
sseBuilder.comment(comment.toString().substring(0, comment.length() - 1)); Mono<?> decodedData = (data != null ? decodeData(data.toString(), valueType, hints) : Mono.empty());
}
if (data != null) { if (shouldWrap) {
return decodeData(data.toString(), valueType, hints).map(decodedData -> { if (comment != null) {
sseBuilder.data(decodedData); sseBuilder.comment(comment.toString().substring(0, comment.length() - 1));
}
return decodedData.map(o -> {
sseBuilder.data(o);
return sseBuilder.build(); return sseBuilder.build();
}); });
} }
else { else {
return Mono.just(sseBuilder.build()); return decodedData;
} }
} }

64
spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/SseIntegrationTests.java
View File

@@ -18,6 +18,7 @@ package org.springframework.web.reactive.result.method.annotation;
import java.time.Duration; import java.time.Duration;
import org.junit.Assume;
import org.junit.Before; import org.junit.Before;
import org.junit.Ignore; import org.junit.Ignore;
import org.junit.Test; import org.junit.Test;
@@ -32,8 +33,10 @@ import org.springframework.core.ParameterizedTypeReference;
import org.springframework.http.codec.ServerSentEvent; import org.springframework.http.codec.ServerSentEvent;
import org.springframework.http.server.reactive.AbstractHttpHandlerIntegrationTests; import org.springframework.http.server.reactive.AbstractHttpHandlerIntegrationTests;
import org.springframework.http.server.reactive.HttpHandler; import org.springframework.http.server.reactive.HttpHandler;
import org.springframework.http.server.reactive.bootstrap.JettyHttpServer;
import org.springframework.http.server.reactive.bootstrap.ReactorHttpServer; import org.springframework.http.server.reactive.bootstrap.ReactorHttpServer;
import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController; import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.reactive.DispatcherHandler; import org.springframework.web.reactive.DispatcherHandler;
import org.springframework.web.reactive.config.EnableWebFlux; import org.springframework.web.reactive.config.EnableWebFlux;
@@ -103,51 +106,42 @@ public class SseIntegrationTests extends AbstractHttpHandlerIntegrationTests {
@Test @Test
public void sseAsEvent() { public void sseAsEvent() {
Flux<ServerSentEvent<String>> result = this.webClient.get()
Assume.assumeTrue(server instanceof JettyHttpServer);
Flux<ServerSentEvent<Person>> result = this.webClient.get()
.uri("/event") .uri("/event")
.accept(TEXT_EVENT_STREAM) .accept(TEXT_EVENT_STREAM)
.retrieve() .retrieve()
.bodyToFlux(new ParameterizedTypeReference<ServerSentEvent<String>>() {}); .bodyToFlux(new ParameterizedTypeReference<ServerSentEvent<Person>>() {});
StepVerifier.create(result) verifyPersonEvents(result);
.consumeNextWith( event -> {
assertEquals("0", event.id());
assertEquals("foo", event.data());
assertEquals("bar", event.comment());
assertNull(event.event());
assertNull(event.retry());
})
.consumeNextWith( event -> {
assertEquals("1", event.id());
assertEquals("foo", event.data());
assertEquals("bar", event.comment());
assertNull(event.event());
assertNull(event.retry());
})
.thenCancel()
.verify(Duration.ofSeconds(5L));
} }
@Test @Test
public void sseAsEventWithoutAcceptHeader() { public void sseAsEventWithoutAcceptHeader() {
Flux<ServerSentEvent<String>> result = this.webClient.get() Flux<ServerSentEvent<Person>> result = this.webClient.get()
.uri("/event") .uri("/event")
.accept(TEXT_EVENT_STREAM) .accept(TEXT_EVENT_STREAM)
.retrieve() .retrieve()
.bodyToFlux(new ParameterizedTypeReference<ServerSentEvent<String>>() {}); .bodyToFlux(new ParameterizedTypeReference<ServerSentEvent<Person>>() {});
verifyPersonEvents(result);
}
private void verifyPersonEvents(Flux<ServerSentEvent<Person>> result) {
StepVerifier.create(result) StepVerifier.create(result)
.consumeNextWith( event -> { .consumeNextWith( event -> {
assertEquals("0", event.id()); assertEquals("0", event.id());
assertEquals("foo", event.data()); assertEquals(new Person("foo 0"), event.data());
assertEquals("bar", event.comment()); assertEquals("bar 0", event.comment());
assertNull(event.event()); assertNull(event.event());
assertNull(event.retry()); assertNull(event.retry());
}) })
.consumeNextWith( event -> { .consumeNextWith( event -> {
assertEquals("1", event.id()); assertEquals("1", event.id());
assertEquals("foo", event.data()); assertEquals(new Person("foo 1"), event.data());
assertEquals("bar", event.comment()); assertEquals("bar 1", event.comment());
assertNull(event.event()); assertNull(event.event());
assertNull(event.retry()); assertNull(event.retry());
}) })
@@ -180,6 +174,7 @@ public class SseIntegrationTests extends AbstractHttpHandlerIntegrationTests {
@RestController @RestController
@SuppressWarnings("unused") @SuppressWarnings("unused")
@RequestMapping("/sse")
static class SseController { static class SseController {
private static final Flux<Long> INTERVAL = interval(Duration.ofMillis(100), 50); private static final Flux<Long> INTERVAL = interval(Duration.ofMillis(100), 50);
@@ -187,25 +182,26 @@ public class SseIntegrationTests extends AbstractHttpHandlerIntegrationTests {
private MonoProcessor<Void> cancellation = MonoProcessor.create(); private MonoProcessor<Void> cancellation = MonoProcessor.create();
@GetMapping("/sse/string") @GetMapping("/string")
Flux<String> string() { Flux<String> string() {
return INTERVAL.map(l -> "foo " + l); return INTERVAL.map(l -> "foo " + l);
} }
@GetMapping("/sse/person") @GetMapping("/person")
Flux<Person> person() { Flux<Person> person() {
return INTERVAL.map(l -> new Person("foo " + l)); return INTERVAL.map(l -> new Person("foo " + l));
} }
@GetMapping("/sse/event") @GetMapping("/event")
Flux<ServerSentEvent<String>> sse() { Flux<ServerSentEvent<Person>> sse() {
return INTERVAL.map(l -> ServerSentEvent.builder("foo") return INTERVAL.take(2).map(l ->
.id(Long.toString(l)) ServerSentEvent.builder(new Person("foo " + l))
.comment("bar") .id(Long.toString(l))
.build()); .comment("bar " + l)
.build());
} }
@GetMapping("/sse/infinite") @GetMapping("/infinite")
Flux<String> infinite() { Flux<String> infinite() {
return Flux.just(0, 1).map(l -> "foo " + l) return Flux.just(0, 1).map(l -> "foo " + l)
.mergeWith(Flux.never()) .mergeWith(Flux.never())