| /* |
| * Copyright 2016, 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; |
| |
| import static io.grpc.ConnectivityState.SHUTDOWN; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| |
| import java.net.SocketAddress; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** |
| * A {@link LoadBalancer} that provides no load balancing mechanism over the |
| * addresses from the {@link NameResolver}. The channel's default behavior |
| * (currently pick-first) is used for all addresses found. |
| */ |
| @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1771") |
| public final class PickFirstBalancerFactory2 extends LoadBalancer2.Factory { |
| |
| private static final PickFirstBalancerFactory2 INSTANCE = new PickFirstBalancerFactory2(); |
| |
| private PickFirstBalancerFactory2() { |
| } |
| |
| public static PickFirstBalancerFactory2 getInstance() { |
| return INSTANCE; |
| } |
| |
| @Override |
| public LoadBalancer2 newLoadBalancer(LoadBalancer2.Helper helper) { |
| return new PickFirstBalancer(helper); |
| } |
| |
| @VisibleForTesting |
| static class PickFirstBalancer extends LoadBalancer2 { |
| private final Helper helper; |
| private Subchannel subchannel; |
| |
| public PickFirstBalancer(Helper helper) { |
| this.helper = helper; |
| } |
| |
| @Override |
| public void handleResolvedAddresses(List<ResolvedServerInfoGroup> servers, |
| Attributes attributes) { |
| // Flatten servers list received from name resolver into single address group. This means that |
| // as far as load balancer is concerned, there's virtually one single server with multiple |
| // addresses so the connection will be created only for the first address (pick first). |
| EquivalentAddressGroup newEag = |
| flattenResolvedServerInfoGroupsIntoEquivalentAddressGroup(servers); |
| if (subchannel == null || !newEag.equals(subchannel.getAddresses())) { |
| if (subchannel != null) { |
| subchannel.shutdown(); |
| } |
| |
| subchannel = helper.createSubchannel(newEag, Attributes.EMPTY); |
| helper.updatePicker(new Picker(PickResult.withSubchannel(subchannel))); |
| } |
| } |
| |
| @Override |
| public void handleNameResolutionError(Status error) { |
| if (subchannel != null) { |
| subchannel.shutdown(); |
| subchannel = null; |
| } |
| // NB(lukaszx0) Whether we should propagate the error unconditionally is arguable. It's fine |
| // for time being. |
| helper.updatePicker(new Picker(PickResult.withError(error))); |
| } |
| |
| @Override |
| public void handleSubchannelState(Subchannel subchannel, ConnectivityStateInfo stateInfo) { |
| ConnectivityState currentState = stateInfo.getState(); |
| if (subchannel != this.subchannel || currentState == SHUTDOWN) { |
| return; |
| } |
| |
| PickResult pickResult; |
| switch (currentState) { |
| case CONNECTING: |
| pickResult = PickResult.withNoResult(); |
| break; |
| case READY: |
| case IDLE: |
| pickResult = PickResult.withSubchannel(subchannel); |
| break; |
| case TRANSIENT_FAILURE: |
| pickResult = PickResult.withError(stateInfo.getStatus()); |
| break; |
| default: |
| throw new IllegalStateException(); |
| } |
| |
| helper.updatePicker(new Picker(pickResult)); |
| } |
| |
| @Override |
| public void shutdown() { |
| if (subchannel != null) { |
| subchannel.shutdown(); |
| } |
| } |
| |
| /** |
| * Flattens list of ResolvedServerInfoGroup objects into one EquivalentAddressGroup object. |
| */ |
| private static EquivalentAddressGroup flattenResolvedServerInfoGroupsIntoEquivalentAddressGroup( |
| List<ResolvedServerInfoGroup> groupList) { |
| List<SocketAddress> addrs = new ArrayList<SocketAddress>(); |
| for (ResolvedServerInfoGroup group : groupList) { |
| for (ResolvedServerInfo srv : group.getResolvedServerInfoList()) { |
| addrs.add(srv.getAddress()); |
| } |
| } |
| return new EquivalentAddressGroup(addrs); |
| } |
| |
| } |
| |
| /** |
| * No-op picker which doesn't add any custom picking logic. It just passes already known result |
| * received in constructor. |
| */ |
| @VisibleForTesting |
| static class Picker extends LoadBalancer2.SubchannelPicker { |
| private final LoadBalancer2.PickResult result; |
| |
| Picker(LoadBalancer2.PickResult result) { |
| this.result = result; |
| } |
| |
| @Override |
| public LoadBalancer2.PickResult pickSubchannel(Attributes affinity, Metadata headers) { |
| return result; |
| } |
| } |
| } |