reactor-netty中HttpClient对TcpClient的封装

2018-02-27 11:51:49来源:oschina作者:go4it人点击

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本文主要研究一下reactor-netty中HttpClient对TcpClien的封装


maven

io.projectreactor.ipc
reactor-netty
0.7.3.RELEASE

实例
HttpClient client = HttpClient.create();
Mono mono = client.get("http://baidu.com");
//NOTE reactor.ipc.netty.http.client.MonoHttpClientResponse
LOGGER.info("mono resp:{}",mono.getClass());
mono.subscribe();
HttpClient.request

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/http/client/HttpClient.java


/**
* Use the passed HTTP method to send to the given URL. When connection has been made,
* the passed handler is invoked and can be used to tune the request and
* write data to it.
*
* @param method the HTTP method to send
* @param url the target remote URL
* @param handler the {@link Function} to invoke on opened TCP connection
* @return a {@link Mono} of the {@link HttpServerResponse} ready to consume for
* response
*/
public Mono request(HttpMethod method,
String url,
Function<? super HttpClientRequest, ? extends Publisher> handler) {
if (method == null || url == null) {
throw new IllegalArgumentException("Method && url cannot be both null");
}
return new MonoHttpClientResponse(this, url, method, handler(handler, options));
}
Mono.subscribe

reactor-core-3.1.3.RELEASE-sources.jar!/reactor/core/publisher/Mono.java


/**
* Subscribe to this {@link Mono} and request unbounded demand.
*


* This version doesn't specify any consumption behavior for the events from the
* chain, especially no error handling, so other variants should usually be preferred.
*
*


*
*


*
* @return a new {@link Disposable} that can be used to cancel the underlying {@link Subscription}
*/
public final Disposable subscribe() {
if(this instanceof MonoProcessor){
MonoProcessor s = (MonoProcessor)this;
s.connect();
return s;
}
else{
return subscribeWith(new LambdaMonoSubscriber<>(null, null, null, null));
}
}


这里调用了subscribeWith,创建了一个LambdaMonoSubscriber



/**
* Subscribe the given {@link Subscriber} to this {@link Mono} and return said
* {@link Subscriber} (eg. a {@link MonoProcessor}).
*
* @param subscriber the {@link Subscriber} to subscribe with
* @param the reified type of the {@link Subscriber} for chaining
*
* @return the passed {@link Subscriber} after subscribing it to this {@link Mono}
*/
public final > E subscribeWith(E subscriber) {
subscribe(subscriber);
return subscriber;
}
public final void subscribe(Subscriber<? super T> actual) {
onLastAssembly(this).subscribe(Operators.toCoreSubscriber(actual));
}

这个onLastAssembly(this).subscribe调用的是子类的方法



MonoHttpClientResponse.subscribe

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/http/client/MonoHttpClientResponse.java


public void subscribe(final CoreSubscriber<? super HttpClientResponse> subscriber) {
ReconnectableBridge bridge = new ReconnectableBridge();
bridge.activeURI = startURI;
Mono.defer(() -> parent.client.newHandler(new HttpClientHandler(this, bridge),
parent.options.getRemoteAddress(bridge.activeURI),
HttpClientOptions.isSecure(bridge.activeURI),
bridge))
.retry(bridge)
.cast(HttpClientResponse.class)
.subscribe(subscriber);
}

这里使用Mono.defer又对client.newHandler包装了下,defer的英文原意是Defers the creation of the actual Publisher the Subscriber will be subscribed to.,也就是延迟publisher的创建




这里的subscriber便是Operators.toCoreSubscriber(lambdaMonoSubscriber)




可以看到这里调用了parent的client.newHandler,这里的parent便是HttpClient,里头的client是TcpClient




retry使用的是ReconnectableBridge,handler使用的是HttpClientHandler



MonoHttpClientResponse#ReconnectableBridge
static final class ReconnectableBridge
implements Predicate, Consumer {
volatile URIactiveURI;
volatile String[] redirectedFrom;
ReconnectableBridge() {
}
void redirect(String to) {
String[] redirectedFrom = this.redirectedFrom;
URI from = activeURI;
try {
activeURI = new URI(to);
}
catch (URISyntaxException e) {
throw Exceptions.propagate(e);
}
if (redirectedFrom == null) {
this.redirectedFrom = new String[]{from.toString()};
}
else {
String[] newRedirectedFrom = new String[redirectedFrom.length + 1];
System.arraycopy(redirectedFrom,
0,
newRedirectedFrom,
0,
redirectedFrom.length);
newRedirectedFrom[redirectedFrom.length] = from.toString();
this.redirectedFrom = newRedirectedFrom;
}
}
@Override
public void accept(Channel channel) {
String[] redirectedFrom = this.redirectedFrom;
if (redirectedFrom != null) {
channel.attr(HttpClientOperations.REDIRECT_ATTR_KEY)
.set(redirectedFrom);
}
}
@Override
public boolean test(Throwable throwable) {
if (throwable instanceof RedirectClientException) {
RedirectClientException re = (RedirectClientException) throwable;
redirect(re.location);
return true;
}
if (AbortedException.isConnectionReset(throwable)) {
redirect(activeURI.toString());
return true;
}
return false;
}
}

这里看好像是处理redirect的,并不是真正意义上的retry,比如retry多少次之类的



MonoHttpClientResponse#HttpClientHandler

reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/http/client/MonoHttpClientResponse.java


static final class HttpClientHandler
implements BiFunction> {
final MonoHttpClientResponse parent;
final ReconnectableBridgebridge;
HttpClientHandler(MonoHttpClientResponse parent, ReconnectableBridge bridge) {
this.bridge = bridge;
this.parent = parent;
}
@Override
public Publisher apply(NettyInbound in, NettyOutbound out) {
try {
URI uri = bridge.activeURI;
HttpClientOperations ch = (HttpClientOperations) in;
String host = uri.getHost();
int port = uri.getPort();
if (port != -1 && port != 80 && port != 443) {
host = host + ':' + port;
}
ch.getNettyRequest()
.setUri(uri.getRawPath() + (uri.getQuery() == null ? "" :
"?" + uri.getRawQuery()))
.setMethod(parent.method)
.setProtocolVersion(HttpVersion.HTTP_1_1)
.headers()
.add(HttpHeaderNames.HOST, host)
.add(HttpHeaderNames.ACCEPT, ALL);
if (parent.method == HttpMethod.GET
|| parent.method == HttpMethod.HEAD
|| parent.method == HttpMethod.DELETE) {
ch.chunkedTransfer(false);
}
if (parent.handler != null) {
return parent.handler.apply(ch);
}
else {
return ch.send();
}
}
catch (Throwable t) {
return Mono.error(t);
}
}
@Override
public String toString() {
return "HttpClientHandler{" + "startURI=" + bridge.activeURI + ", method=" + parent.method + ", handler=" + parent.handler + '}';
}
}

这里的handler可以看到netty的痕迹,最后是直接调用HttpClientOperations.send方法



reactor-netty-0.7.3.RELEASE-sources.jar!/reactor/ipc/netty/http/client/HttpClientOperations.java


public Mono send() {
if (markSentHeaderAndBody()) {
HttpMessage request = newFullEmptyBodyMessage();
return FutureMono.deferFuture(() -> channel().writeAndFlush(request));
}
else {
return Mono.empty();
}
}

最后调用netty的channel().writeAndFlush(request)将请求发送出去



小结

reactor-netty中的HttpClient对TcpClient进行了桥接,而TcpClient则是基于netty来实现。

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