nl.topicus.jdbc.shaded.io.grpc.internal.DnsNameResolverProvider Maven / Gradle / Ivy

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JDBC Driver for Google Cloud Spanner
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/*
 * 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 nl.topicus.jdbc.shaded.io.grpc.internal;

import nl.topicus.jdbc.shaded.com.google.nl.topicus.jdbc.shaded.com.on.base.Preconditions;
import nl.topicus.jdbc.shaded.io.grpc.Attributes;
import nl.topicus.jdbc.shaded.io.grpc.NameResolverProvider;
import java.nl.topicus.jdbc.shaded.net.URI;

/**
 * A provider for {@link DnsNameResolver}.
 *
 * It resolves a target URI whose scheme is {@code "dns"}. The (optional) authority of the target
 * URI is reserved for the address of alternative DNS server (not implemented yet). The path of the
 * target URI, excluding the leading slash {@code '/'}, is treated as the host name and the optional
 * port to be resolved by DNS. Example target URIs:
 *
 * 

 *   {@code "dns:///foo.googleapis.nl.topicus.jdbc.shaded.com.8080"} (using default DNS)
 *   {@code "dns://8.8.8.8/foo.googleapis.nl.topicus.jdbc.shaded.com.8080"} (using alternative DNS (not implemented
 *   yet))
 *   {@code "dns:///foo.googleapis.nl.topicus.jdbc.shaded.com.} (without port)
 * 
 */
public final class DnsNameResolverProvider extends NameResolverProvider {

  private static final String SCHEME = "dns";

  @Override
  public DnsNameResolver newNameResolver(URI targetUri, Attributes params) {
    if (SCHEME.equals(targetUri.getScheme())) {
      String targetPath = Preconditions.checkNotNull(targetUri.getPath(), "targetPath");
      Preconditions.checkArgument(targetPath.startsWith("/"),
          "the path nl.topicus.jdbc.shaded.com.onent (%s) of the target (%s) must start with '/'", targetPath, targetUri);
      String name = targetPath.substring(1);
      return new DnsNameResolver(targetUri.getAuthority(), name, params, GrpcUtil.TIMER_SERVICE,
          GrpcUtil.SHARED_CHANNEL_EXECUTOR);
    } else {
      return null;
    }
  }

  @Override
  public String getDefaultScheme() {
    return SCHEME;
  }

  @Override
  protected boolean isAvailable() {
    return true;
  }

  @Override
  protected int priority() {
    return 5;
  }
}