Spring/spring-framework
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Use StringDecoder to split SSE stream

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

93
spring-web/src/main/java/org/springframework/http/codec/ServerSentEventHttpMessageReader.java
View File

@@ -16,15 +16,11 @@
package org.springframework.http.codec;
import java.nio.CharBuffer;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.function.IntPredicate;
import java.util.stream.Collectors;
import reactor.core.publisher.Flux;
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.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpInputMessage;
@@ -51,12 +46,12 @@ import org.springframework.lang.Nullable;
*/
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 StringDecoder stringDecoder = StringDecoder.textPlainOnly();
private static final ResolvableType STRING_TYPE = ResolvableType.forClass(String.class);
@Nullable
private final Decoder<?> decoder;
@@ -110,77 +105,53 @@ public class ServerSentEventHttpMessageReader implements HttpMessageReader<Objec
boolean shouldWrap = isServerSentEvent(elementType);
ResolvableType valueType = (shouldWrap ? elementType.getGeneric(0) : elementType);
return Flux.from(message.getBody())
.concatMap(ServerSentEventHttpMessageReader::splitOnNewline)
.map(buffer -> {
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);
return stringDecoder.decode(message.getBody(), STRING_TYPE, null, Collections.emptyMap())
.bufferUntil(line -> line.equals(""))
.concatMap(lines -> buildEvent(lines, valueType, shouldWrap, hints));
}
private static Flux<DataBuffer> splitOnNewline(DataBuffer dataBuffer) {
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,
private Mono<?> buildEvent(List<String> lines, ResolvableType valueType, boolean shouldWrap,
Map<String, Object> hints) {
ServerSentEvent.Builder<Object> sseBuilder = ServerSentEvent.builder();
ServerSentEvent.Builder<Object> sseBuilder = shouldWrap ? ServerSentEvent.builder() : null;
StringBuilder data = null;
StringBuilder comment = null;
for (String line : lines) {
if (line.startsWith("id:")) {
sseBuilder.id(line.substring(3));
}
else if (line.startsWith("event:")) {
sseBuilder.event(line.substring(6));
}
else if (line.startsWith("data:")) {
if (line.startsWith("data:")) {
data = (data != null ? data : new StringBuilder());
data.append(line.substring(5)).append("\n");
}
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 (shouldWrap) {
if (line.startsWith("id:")) {
sseBuilder.id(line.substring(3));
}
else if (line.startsWith("event:")) {
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));
}
if (data != null) {
return decodeData(data.toString(), valueType, hints).map(decodedData -> {
sseBuilder.data(decodedData);
Mono<?> decodedData = (data != null ? decodeData(data.toString(), valueType, hints) : Mono.empty());
if (shouldWrap) {
if (comment != null) {
sseBuilder.comment(comment.toString().substring(0, comment.length() - 1));
}
return decodedData.map(o -> {
sseBuilder.data(o);
return sseBuilder.build();
});
}
else {
return Mono.just(sseBuilder.build());
return decodedData;
}
}