| /* |
| * Copyright 2015, Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package io.grpc.internal; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Preconditions; |
| |
| import io.grpc.Attributes; |
| import io.grpc.NameResolver; |
| import io.grpc.ResolvedServerInfo; |
| import io.grpc.ResolvedServerInfoGroup; |
| import io.grpc.Status; |
| import io.grpc.internal.SharedResourceHolder.Resource; |
| |
| import java.net.InetAddress; |
| import java.net.InetSocketAddress; |
| import java.net.URI; |
| import java.net.UnknownHostException; |
| import java.util.Collections; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.ScheduledFuture; |
| import java.util.concurrent.TimeUnit; |
| |
| import javax.annotation.Nullable; |
| import javax.annotation.concurrent.GuardedBy; |
| |
| /** |
| * A DNS-based {@link NameResolver}. |
| * |
| * @see DnsNameResolverFactory |
| */ |
| class DnsNameResolver extends NameResolver { |
| private final String authority; |
| private final String host; |
| private final int port; |
| private final Resource<ScheduledExecutorService> timerServiceResource; |
| private final Resource<ExecutorService> executorResource; |
| @GuardedBy("this") |
| private boolean shutdown; |
| @GuardedBy("this") |
| private ScheduledExecutorService timerService; |
| @GuardedBy("this") |
| private ExecutorService executor; |
| @GuardedBy("this") |
| private ScheduledFuture<?> resolutionTask; |
| @GuardedBy("this") |
| private boolean resolving; |
| @GuardedBy("this") |
| private Listener listener; |
| |
| DnsNameResolver(@Nullable String nsAuthority, String name, Attributes params, |
| Resource<ScheduledExecutorService> timerServiceResource, |
| Resource<ExecutorService> executorResource) { |
| // TODO: if a DNS server is provided as nsAuthority, use it. |
| // https://www.captechconsulting.com/blogs/accessing-the-dusty-corners-of-dns-with-java |
| |
| this.timerServiceResource = timerServiceResource; |
| this.executorResource = executorResource; |
| // Must prepend a "//" to the name when constructing a URI, otherwise it will be treated as an |
| // opaque URI, thus the authority and host of the resulted URI would be null. |
| URI nameUri = URI.create("//" + name); |
| authority = Preconditions.checkNotNull(nameUri.getAuthority(), |
| "nameUri (%s) doesn't have an authority", nameUri); |
| host = Preconditions.checkNotNull(nameUri.getHost(), "host"); |
| if (nameUri.getPort() == -1) { |
| Integer defaultPort = params.get(NameResolver.Factory.PARAMS_DEFAULT_PORT); |
| if (defaultPort != null) { |
| port = defaultPort; |
| } else { |
| throw new IllegalArgumentException( |
| "name '" + name + "' doesn't contain a port, and default port is not set in params"); |
| } |
| } else { |
| port = nameUri.getPort(); |
| } |
| } |
| |
| @Override |
| public final String getServiceAuthority() { |
| return authority; |
| } |
| |
| @Override |
| public final synchronized void start(Listener listener) { |
| Preconditions.checkState(this.listener == null, "already started"); |
| timerService = SharedResourceHolder.get(timerServiceResource); |
| executor = SharedResourceHolder.get(executorResource); |
| this.listener = Preconditions.checkNotNull(listener, "listener"); |
| resolve(); |
| } |
| |
| @Override |
| public final synchronized void refresh() { |
| Preconditions.checkState(listener != null, "not started"); |
| resolve(); |
| } |
| |
| private final Runnable resolutionRunnable = new Runnable() { |
| @Override |
| public void run() { |
| InetAddress[] inetAddrs; |
| Listener savedListener; |
| synchronized (DnsNameResolver.this) { |
| // If this task is started by refresh(), there might already be a scheduled task. |
| if (resolutionTask != null) { |
| resolutionTask.cancel(false); |
| resolutionTask = null; |
| } |
| if (shutdown) { |
| return; |
| } |
| savedListener = listener; |
| resolving = true; |
| } |
| try { |
| try { |
| inetAddrs = getAllByName(host); |
| } catch (UnknownHostException e) { |
| synchronized (DnsNameResolver.this) { |
| if (shutdown) { |
| return; |
| } |
| // Because timerService is the single-threaded GrpcUtil.TIMER_SERVICE in production, |
| // we need to delegate the blocking work to the executor |
| resolutionTask = |
| timerService.schedule(new LogExceptionRunnable(resolutionRunnableOnExecutor), |
| 1, TimeUnit.MINUTES); |
| } |
| savedListener.onError(Status.UNAVAILABLE.withCause(e)); |
| return; |
| } |
| ResolvedServerInfoGroup.Builder servers = ResolvedServerInfoGroup.builder(); |
| for (int i = 0; i < inetAddrs.length; i++) { |
| InetAddress inetAddr = inetAddrs[i]; |
| servers.add( |
| new ResolvedServerInfo(new InetSocketAddress(inetAddr, port), Attributes.EMPTY)); |
| } |
| savedListener.onUpdate(Collections.singletonList(servers.build()), Attributes.EMPTY); |
| } finally { |
| synchronized (DnsNameResolver.this) { |
| resolving = false; |
| } |
| } |
| } |
| }; |
| |
| private final Runnable resolutionRunnableOnExecutor = new Runnable() { |
| @Override |
| public void run() { |
| synchronized (DnsNameResolver.this) { |
| if (!shutdown) { |
| executor.execute(resolutionRunnable); |
| } |
| } |
| } |
| }; |
| |
| // To be mocked out in tests |
| @VisibleForTesting |
| InetAddress[] getAllByName(String host) throws UnknownHostException { |
| return InetAddress.getAllByName(host); |
| } |
| |
| @GuardedBy("this") |
| private void resolve() { |
| if (resolving || shutdown) { |
| return; |
| } |
| executor.execute(resolutionRunnable); |
| } |
| |
| @Override |
| public final synchronized void shutdown() { |
| if (shutdown) { |
| return; |
| } |
| shutdown = true; |
| if (resolutionTask != null) { |
| resolutionTask.cancel(false); |
| } |
| if (timerService != null) { |
| timerService = SharedResourceHolder.release(timerServiceResource, timerService); |
| } |
| if (executor != null) { |
| executor = SharedResourceHolder.release(executorResource, executor); |
| } |
| } |
| |
| final int getPort() { |
| return port; |
| } |
| } |