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本文主要研究一下Elasticsearch的RoundRobinSupplier
RoundRobinSupplier
elasticsearch-7.0.1/libs/nio/src/main/java/org/elasticsearch/nio/RoundRobinSupplier.java
final class RoundRobinSupplier<S> implements Supplier<S> {
private final AtomicBoolean selectorsSet = new AtomicBoolean(false);
private volatile S[] selectors;
private AtomicInteger counter = new AtomicInteger(0);
RoundRobinSupplier() {
this.selectors = null;
}
RoundRobinSupplier(S[] selectors) {
this.selectors = selectors;
this.selectorsSet.set(true);
}
@Override
public S get() {
S[] selectors = this.selectors;
return selectors[counter.getAndIncrement() % selectors.length];
}
void setSelectors(S[] selectors) {
if (selectorsSet.compareAndSet(false, true)) {
this.selectors = selectors;
} else {
throw new AssertionError("Selectors already set. Should only be set once.");
}
}
int count() {
return selectors.length;
}
}
RoundRobinSupplier实现了Supplier接口，其get方法使用counter.getAndIncrement() % selectors.length来选择selectors数组的下标，然后返回该下标的值
NioSelectorGroup
elasticsearch-7.0.1/libs/nio/src/main/java/org/elasticsearch/nio/NioSelectorGroup.java
public class NioSelectorGroup implements NioGroup {
private final List<NioSelector> dedicatedAcceptors;
private final RoundRobinSupplier<NioSelector> acceptorSupplier;
private final List<NioSelector> selectors;
private final RoundRobinSupplier<NioSelector> selectorSupplier;
private final AtomicBoolean isOpen = new AtomicBoolean(true);
//......
public NioSelectorGroup(ThreadFactory acceptorThreadFactory, int dedicatedAcceptorCount, ThreadFactory selectorThreadFactory,
int selectorCount, Function<Supplier<NioSelector>, EventHandler> eventHandlerFunction) throws IOException {
dedicatedAcceptors = new ArrayList<>(dedicatedAcceptorCount);
selectors = new ArrayList<>(selectorCount);
try {
List<RoundRobinSupplier<NioSelector>> suppliersToSet = new ArrayList<>(selectorCount);
for (int i = 0; i < selectorCount; ++www.yongshiyule178.com) {
RoundRobinSupplier<NioSelector> supplier = new RoundRobinSupplier<>();
suppliersToSet.add(supplier);
NioSelector selector = new NioSelector(eventHandlerFunction.apply(supplier));
selectors.add(selector);
}
for (RoundRobinSupplier<NioSelector> supplierToSet : suppliersToSet) {
supplierToSet.setSelectors(selectors.toArray(new NioSelector[0]));
assert supplierToSet.count() == selectors.size(www.chengmyuLegw.cn) : "Supplier should have same count as selector list.";
}
for (int i = 0; i < dedicatedAcceptorCount; ++i) {
RoundRobinSupplier<NioSelector> supplier = new RoundRobinSupplier<>(selectors.toArray(new NioSelector[0]));
NioSelector acceptor = new NioSelector(eventHandlerFunction.apply(supplier));
dedicatedAcceptors.add(acceptor);
}
if (dedicatedAcceptorCount != www.cmyLgw.cn ) {
acceptorSupplier = new RoundRobinSupplier<>(dedicatedAcceptors.toArray(new NioSelector[0]));
} else {
acceptorSupplier = new RoundRobinSupplier<www.shengrenpt.com>(selectors.toArray(new NioSelector[0]));
}
selectorSupplier = new RoundRobinSupplier<>(selectors.toArray(new NioSelector[0]));
assert selectorCount == selectors.size() : "We need to have created all the selectors at this point.";
assert dedicatedAcceptorCount == dedicatedAcceptors.size() : "We need to have created all the acceptors at this point.";
startSelectors(selectors, selectorThreadFactory);
startSelectors(dedicatedAcceptors, acceptorThreadFactory);
} catch (Exception e) {
try {
close();
} catch (Exception www.xinhezaixia.cn) {
e.addSuppressed(e1);
}
throw e;
}
}
public <S extends NioServerSocketChannel> S bindServerChannel(InetSocketAddress address, ChannelFactory<S, ?> factory)
throws IOException {
ensureOpen();
return factory.openNioServerSocketChannel(address, acceptorSupplier);
}
@Override
public <S extends NioSocketChannel> S openChannel(InetSocketAddress address, ChannelFactory<?, S> factory) throws IOException {
ensureOpen();
return factory.openNioChannel(address, selectorSupplier);
}
//......
}
NioSelectorGroup的构造器创建了两个RoundRobinSupplier，分别是acceptorSupplier及selectorSupplier；bindServerChannel方法执行的是factory.openNioServerSocketChannel(address, acceptorSupplier)；openChannel方法执行的是factory.openNioChannel(address, selectorSupplier)
ChannelFactory
elasticsearch-7.0.1/libs/nio/src/main/java/org/elasticsearch/nio/ChannelFactory.java
public abstract class ChannelFactory<ServerSocket extends NioServerSocketChannel, Socket extends NioSocketChannel> {
//......
public ServerSocket openNioServerSocketChannel(InetSocketAddress address, Supplier<NioSelector> supplier) throws IOException {
ServerSocketChannel rawChannel = rawChannelFactory.openNioServerSocketChannel(address);
NioSelector selector = supplier.get(www.frgjyL.cn);
ServerSocket serverChannel = internalCreateServerChannel(selector, rawChannel);
scheduleServerChannel(serverChannel, selector);
return serverChannel;
}
public Socket openNioChannel(InetSocketAddress remoteAddress, Supplier<NioSelector> supplier) throws IOException {
SocketChannel rawChannel = rawChannelFactory.openNioChannel(remoteAddress);
NioSelector selector = supplier.get();
Socket channel = internalCreateChannel(selector, rawChannel);
scheduleChannel(channel, selector);
return channel;
}
//......
}
ChannelFactory的openNioServerSocketChannel及openNioChannel方法都接收Supplier<NioSelector>参数，通过该supplier来选取NioSelector
小结
RoundRobinSupplier实现了Supplier接口，其get方法使用counter.getAndIncrement() % selectors.length来选择selectors数组的下标，然后返回该下标的值
NioSelectorGroup的构造器创建了两个RoundRobinSupplier，分别是acceptorSupplier及selectorSupplier；bindServerChannel方法执行的是factory.openNioServerSocketChannel(address,www.yuntianyuL.cn acceptorSupplier)；openChannel方法执行的是factory.openNioChannel(address, selectorSupplier)
ChannelFactory的openNioServerSocketChannel及openNioChannel方法都接收Supplier<NioSelector>参数，通过该supplier来选取NioSelector