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本文主要研究一下 elasticsearch 的 SeedHostsResolver
ConfiguredHostsResolver
elasticsearch-7.0.0/server/src/main/java/org/elasticsearch/discovery/PeerFinder.java
public interface ConfiguredHostsResolver {
/**
* Attempt to resolve the configured unicast hosts list to a list of transport addresses.
*
* @param consumer Consumer for the resolved list. May not be called if an error occurs or if another resolution attempt is in
* progress.
*/
void resolveConfiguredHosts(Consumer<List<TransportAddress>> consumer);
}- ConfiguredHostsResolver 接口定义了 resolveConfiguredHosts 方法用于解析配置的 transport address 列表
SeedHostsResolver
elasticsearch-7.0.0/server/src/main/java/org/elasticsearch/discovery/SeedHostsResolver.java
public class SeedHostsResolver extends AbstractLifecycleComponent implements ConfiguredHostsResolver {
public static final Setting<Integer> LEGACY_DISCOVERY_ZEN_PING_UNICAST_CONCURRENT_CONNECTS_SETTING =
Setting.intSetting("discovery.zen.ping.unicast.concurrent_connects", 10, 0, Setting.Property.NodeScope,
Setting.Property.Deprecated);
public static final Setting<TimeValue> LEGACY_DISCOVERY_ZEN_PING_UNICAST_HOSTS_RESOLVE_TIMEOUT =
Setting.positiveTimeSetting("discovery.zen.ping.unicast.hosts.resolve_timeout", TimeValue.timeValueSeconds(5),
Setting.Property.NodeScope, Setting.Property.Deprecated);
public static final Setting<Integer> DISCOVERY_SEED_RESOLVER_MAX_CONCURRENT_RESOLVERS_SETTING =
Setting.intSetting("discovery.seed_resolver.max_concurrent_resolvers", 10, 0, Setting.Property.NodeScope);
public static final Setting<TimeValue> DISCOVERY_SEED_RESOLVER_TIMEOUT_SETTING =
Setting.positiveTimeSetting("discovery.seed_resolver.timeout", TimeValue.timeValueSeconds(5), Setting.Property.NodeScope);
private static final Logger logger = LogManager.getLogger(SeedHostsResolver.class);
private final Settings settings;
private final AtomicBoolean resolveInProgress = new AtomicBoolean();
private final TransportService transportService;
private final SeedHostsProvider hostsProvider;
private final SetOnce<ExecutorService> executorService = new SetOnce<>();
private final TimeValue resolveTimeout;
private final String nodeName;
private final int concurrentConnects;
public SeedHostsResolver(String nodeName, Settings settings, TransportService transportService,
SeedHostsProvider seedProvider) {
this.settings = settings;
this.nodeName = nodeName;
this.transportService = transportService;
this.hostsProvider = seedProvider;
resolveTimeout = getResolveTimeout(settings);
concurrentConnects = getMaxConcurrentResolvers(settings);
}
public static int getMaxConcurrentResolvers(Settings settings) {if (LEGACY_DISCOVERY_ZEN_PING_UNICAST_CONCURRENT_CONNECTS_SETTING.exists(settings)) {if (DISCOVERY_SEED_RESOLVER_MAX_CONCURRENT_RESOLVERS_SETTING.exists(settings)) {
throw new IllegalArgumentException("it is forbidden to set both ["
+ DISCOVERY_SEED_RESOLVER_MAX_CONCURRENT_RESOLVERS_SETTING.getKey() + "] and ["
+ LEGACY_DISCOVERY_ZEN_PING_UNICAST_CONCURRENT_CONNECTS_SETTING.getKey() + "]");
}
return LEGACY_DISCOVERY_ZEN_PING_UNICAST_CONCURRENT_CONNECTS_SETTING.get(settings);
}
return DISCOVERY_SEED_RESOLVER_MAX_CONCURRENT_RESOLVERS_SETTING.get(settings);
}
public static TimeValue getResolveTimeout(Settings settings) {if (LEGACY_DISCOVERY_ZEN_PING_UNICAST_HOSTS_RESOLVE_TIMEOUT.exists(settings)) {if (DISCOVERY_SEED_RESOLVER_TIMEOUT_SETTING.exists(settings)) {
throw new IllegalArgumentException("it is forbidden to set both ["
+ DISCOVERY_SEED_RESOLVER_TIMEOUT_SETTING.getKey() + "] and ["
+ LEGACY_DISCOVERY_ZEN_PING_UNICAST_HOSTS_RESOLVE_TIMEOUT.getKey() + "]");
}
return LEGACY_DISCOVERY_ZEN_PING_UNICAST_HOSTS_RESOLVE_TIMEOUT.get(settings);
}
return DISCOVERY_SEED_RESOLVER_TIMEOUT_SETTING.get(settings);
}
/**
* Resolves a list of hosts to a list of transport addresses. Each host is resolved into a transport address (or a collection of
* addresses if the number of ports is greater than one). Host lookups are done in parallel using specified executor service up
* to the specified resolve timeout.
*
* @param executorService the executor service used to parallelize hostname lookups
* @param logger logger used for logging messages regarding hostname lookups
* @param hosts the hosts to resolve
* @param limitPortCounts the number of ports to resolve (should be 1 for non-local transport)
* @param transportService the transport service
* @param resolveTimeout the timeout before returning from hostname lookups
* @return a list of resolved transport addresses
*/
public static List<TransportAddress> resolveHostsLists(
final ExecutorService executorService,
final Logger logger,
final List<String> hosts,
final int limitPortCounts,
final TransportService transportService,
final TimeValue resolveTimeout) {Objects.requireNonNull(executorService);
Objects.requireNonNull(logger);
Objects.requireNonNull(hosts);
Objects.requireNonNull(transportService);
Objects.requireNonNull(resolveTimeout);
if (resolveTimeout.nanos() < 0) {throw new IllegalArgumentException("resolve timeout must be non-negative but was [" + resolveTimeout + "]");
}
// create tasks to submit to the executor service; we will wait up to resolveTimeout for these tasks to complete
final List<Callable<TransportAddress[]>> callables =
hosts
.stream()
.map(hn -> (Callable<TransportAddress[]>) () -> transportService.addressesFromString(hn, limitPortCounts))
.collect(Collectors.toList());
final List<Future<TransportAddress[]>> futures;
try {futures = executorService.invokeAll(callables, resolveTimeout.nanos(), TimeUnit.NANOSECONDS);
} catch (InterruptedException e) {Thread.currentThread().interrupt();
return Collections.emptyList();}
final List<TransportAddress> transportAddresses = new ArrayList<>();
final Set<TransportAddress> localAddresses = new HashSet<>();
localAddresses.add(transportService.boundAddress().publishAddress());
localAddresses.addAll(Arrays.asList(transportService.boundAddress().boundAddresses()));
// ExecutorService#invokeAll guarantees that the futures are returned in the iteration order of the tasks so we can associate the
// hostname with the corresponding task by iterating together
final Iterator<String> it = hosts.iterator();
for (final Future<TransportAddress[]> future : futures) {final String hostname = it.next();
if (!future.isCancelled()) {assert future.isDone();
try {final TransportAddress[] addresses = future.get();
logger.trace("resolved host [{}] to {}", hostname, addresses);
for (int addressId = 0; addressId < addresses.length; addressId++) {final TransportAddress address = addresses[addressId];
// no point in pinging ourselves
if (localAddresses.contains(address) == false) {transportAddresses.add(address);
}
}
} catch (final ExecutionException e) {assert e.getCause() != null;
final String message = "failed to resolve host [" + hostname + "]";
logger.warn(message, e.getCause());
} catch (InterruptedException e) {Thread.currentThread().interrupt();
// ignore
}
} else {logger.warn("timed out after [{}] resolving host [{}]", resolveTimeout, hostname);
}
}
return Collections.unmodifiableList(transportAddresses);
}
@Override
protected void doStart() {logger.debug("using max_concurrent_resolvers [{}], resolver timeout [{}]", concurrentConnects, resolveTimeout);
final ThreadFactory threadFactory = EsExecutors.daemonThreadFactory(settings, "[unicast_configured_hosts_resolver]");
executorService.set(EsExecutors.newScaling(nodeName + "/" + "unicast_configured_hosts_resolver",
0, concurrentConnects, 60, TimeUnit.SECONDS, threadFactory, transportService.getThreadPool().getThreadContext()));
}
@Override
protected void doStop() {ThreadPool.terminate(executorService.get(), 10, TimeUnit.SECONDS);
}
@Override
protected void doClose() {}
@Override
public void resolveConfiguredHosts(Consumer<List<TransportAddress>> consumer) {if (lifecycle.started() == false) {logger.debug("resolveConfiguredHosts: lifecycle is {}, not proceeding", lifecycle);
return;
}
if (resolveInProgress.compareAndSet(false, true)) {transportService.getThreadPool().generic().execute(new AbstractRunnable() {
@Override
public void onFailure(Exception e) {logger.debug("failure when resolving unicast hosts list", e);
}
@Override
protected void doRun() {if (lifecycle.started() == false) {logger.debug("resolveConfiguredHosts.doRun: lifecycle is {}, not proceeding", lifecycle);
return;
}
List<TransportAddress> providedAddresses
= hostsProvider.getSeedAddresses((hosts, limitPortCounts)
-> resolveHostsLists(executorService.get(), logger, hosts, limitPortCounts,
transportService, resolveTimeout));
consumer.accept(providedAddresses);
}
@Override
public void onAfter() {resolveInProgress.set(false);
}
@Override
public String toString() {return "SeedHostsResolver resolving unicast hosts list";}
});
}
}
}- SeedHostsResolver 继承了 AbstractLifecycleComponent，同时实现了 ConfiguredHostsResolver 接口；它提供了 getMaxConcurrentResolvers、getResolveTimeout、resolveHostsLists(
使用线程池并发执行 transportService.addressesFromString) 这几个静态方法 - doStart 方法使用 EsExecutors.newScaling 创建了 EsThreadPoolExecutor；doStop 方法则使用 ThreadPool.terminate 来终止线程池
- resolveConfiguredHosts 方法首先将 resolveInProgress 从 false 设置为 true，之后通过 transportService.getThreadPool() 执行 hostsProvider.getSeedAddresses，执行完成则设置 resolveInProgress 为 false
小结
- ConfiguredHostsResolver 接口定义了 resolveConfiguredHosts 方法用于解析配置的 transport address 列表
- SeedHostsResolver 继承了 AbstractLifecycleComponent，同时实现了 ConfiguredHostsResolver 接口；它提供了 getMaxConcurrentResolvers、getResolveTimeout、resolveHostsLists(
使用线程池并发执行 transportService.addressesFromString) 这几个静态方法 - doStart 方法使用 EsExecutors.newScaling 创建了 EsThreadPoolExecutor；doStop 方法则使用 ThreadPool.terminate 来终止线程池；resolveConfiguredHosts 方法首先将 resolveInProgress 从 false 设置为 true，之后通过 transportService.getThreadPool() 执行 hostsProvider.getSeedAddresses，执行完成则设置 resolveInProgress 为 false
doc
- SeedHostsResolver