#19383

Committed 31 Jul 2024 08:32PM UTC coverage: 84.448% (+0.001%) from 84.447%

Build # #19383

Build Type

push

github

Committed by

ejona86

Commit Message

xds: Stop extending RR in WRR

They share very little code, and we really don't want RoundRobinLb to be
public and non-final. Originally, WRR was expected to share much more
code with RR, and even delegated to RR at times. The delegation was
removed in 111ff60e. After dca89b25, most of the sharing has been moved
out into general-purpose tools that can be used by any LB policy.

FixedResultPicker now has equals to makes it as a EmptyPicker
replacement. RoundRobinLb still uses EmptyPicker because fixing its
tests is a larger change. OutlierDetectionLbTest was changed because
FixedResultPicker is used by PickFirstLeafLb, and now RoundRobinLb can
squelch some of its updates for ready pickers.

Run Details

33265 of 39391 relevant lines covered (84.45%)

0.84 hits per line

Source File
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88.33

/../util/src/main/java/io/grpc/util/RoundRobinLoadBalancer.java

/*
 * Copyright 2016 The gRPC Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.grpc.util;

import static com.google.common.base.Preconditions.checkArgument;
import static io.grpc.ConnectivityState.CONNECTING;
import static io.grpc.ConnectivityState.IDLE;
import static io.grpc.ConnectivityState.READY;
import static io.grpc.ConnectivityState.TRANSIENT_FAILURE;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
import com.google.common.base.Preconditions;
import io.grpc.ConnectivityState;
import io.grpc.EquivalentAddressGroup;
import io.grpc.LoadBalancer;
import io.grpc.NameResolver;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * A {@link LoadBalancer} that provides round-robin load-balancing over the {@link
 * EquivalentAddressGroup}s from the {@link NameResolver}.
 */
final class RoundRobinLoadBalancer extends MultiChildLoadBalancer {
  private final AtomicInteger sequence = new AtomicInteger(new Random().nextInt());
  private SubchannelPicker currentPicker = new EmptyPicker();

  public RoundRobinLoadBalancer(Helper helper) {
    super(helper);
  }

  /**
   * Updates picker with the list of active subchannels (state == READY).
   */
  @Override
  protected void updateOverallBalancingState() {
    List<ChildLbState> activeList = getReadyChildren();
    if (activeList.isEmpty()) {
      // No READY subchannels

      // RRLB will request connection immediately on subchannel IDLE.
      boolean isConnecting = false;
      for (ChildLbState childLbState : getChildLbStates()) {
        ConnectivityState state = childLbState.getCurrentState();
        if (state == CONNECTING || state == IDLE) {
          isConnecting = true;
          break;
        }
      }

      if (isConnecting) {
        updateBalancingState(CONNECTING, new EmptyPicker());
      } else {
        updateBalancingState(TRANSIENT_FAILURE, createReadyPicker(getChildLbStates()));
      }
    } else {
      updateBalancingState(READY, createReadyPicker(activeList));
    }
  }

  private void updateBalancingState(ConnectivityState state, SubchannelPicker picker) {
    if (state != currentConnectivityState || !picker.equals(currentPicker)) {
      getHelper().updateBalancingState(state, picker);
      currentConnectivityState = state;
      currentPicker = picker;
    }
  }

  private SubchannelPicker createReadyPicker(Collection<ChildLbState> children) {
    List<SubchannelPicker> pickerList = new ArrayList<>();
    for (ChildLbState child : children) {
      SubchannelPicker picker = child.getCurrentPicker();
      pickerList.add(picker);
    }

    return new ReadyPicker(pickerList, sequence);
  }

  @VisibleForTesting
  static class ReadyPicker extends SubchannelPicker {
    private final List<SubchannelPicker> subchannelPickers; // non-empty
    private final AtomicInteger index;
    private final int hashCode;

    public ReadyPicker(List<SubchannelPicker> list, AtomicInteger index) {
      checkArgument(!list.isEmpty(), "empty list");
      this.subchannelPickers = list;
      this.index = Preconditions.checkNotNull(index, "index");

      // Every created picker is checked for equality in updateBalancingState() at least once.
      // Pre-compute the hash so it can be checked cheaply. Using the hash in equals() makes it very
      // fast except when the pickers are (very likely) equal.
      //
      // For equality we treat children as a set; use hash code as defined by Set
      int sum = 0;
      for (SubchannelPicker picker : subchannelPickers) {
        sum += picker.hashCode();
      }
      this.hashCode = sum;
    }

    @Override
    public PickResult pickSubchannel(PickSubchannelArgs args) {
      return subchannelPickers.get(nextIndex()).pickSubchannel(args);
    }

    @Override
    public String toString() {
      return MoreObjects.toStringHelper(ReadyPicker.class)
          .add("subchannelPickers", subchannelPickers)
          .toString();
    }

    private int nextIndex() {
      int i = index.getAndIncrement() & Integer.MAX_VALUE;
      return i % subchannelPickers.size();
    }

    @VisibleForTesting
    List<SubchannelPicker> getSubchannelPickers() {
      return subchannelPickers;
    }

    @Override
    public int hashCode() {
      return hashCode;
    }

    @Override
    public boolean equals(Object o) {
      if (!(o instanceof ReadyPicker)) {
        return false;
      }
      ReadyPicker other = (ReadyPicker) o;
      if (other == this) {
        return true;
      }
      // the lists cannot contain duplicate subchannels
      return hashCode == other.hashCode
          && index == other.index
          && subchannelPickers.size() == other.subchannelPickers.size()
          && new HashSet<>(subchannelPickers).containsAll(other.subchannelPickers);
    }
  }

  @VisibleForTesting
  static final class EmptyPicker extends SubchannelPicker {
    @Override
    public PickResult pickSubchannel(PickSubchannelArgs args) {
      return PickResult.withNoResult();
    }

    @Override
    public int hashCode() {
      return getClass().hashCode();
    }

    @Override
    public boolean equals(Object o) {
      return o instanceof EmptyPicker;
    }
  }
}

1	/*
2	* Copyright 2016 The gRPC Authors
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16
17	package io.grpc.util;
18
19	import static com.google.common.base.Preconditions.checkArgument;
20	import static io.grpc.ConnectivityState.CONNECTING;
21	import static io.grpc.ConnectivityState.IDLE;
22	import static io.grpc.ConnectivityState.READY;
23	import static io.grpc.ConnectivityState.TRANSIENT_FAILURE;
24
25	import com.google.common.annotations.VisibleForTesting;
26	import com.google.common.base.MoreObjects;
27	import com.google.common.base.Preconditions;
28	import io.grpc.ConnectivityState;
29	import io.grpc.EquivalentAddressGroup;
30	import io.grpc.LoadBalancer;
31	import io.grpc.NameResolver;
32	import java.util.ArrayList;
33	import java.util.Collection;
34	import java.util.HashSet;
35	import java.util.List;
36	import java.util.Random;
37	import java.util.concurrent.atomic.AtomicInteger;
38
39	/**
40	* A {@link LoadBalancer} that provides round-robin load-balancing over the {@link
41	* EquivalentAddressGroup}s from the {@link NameResolver}.
42	*/
43	final class RoundRobinLoadBalancer extends MultiChildLoadBalancer {
44	private final AtomicInteger sequence = new AtomicInteger(new Random().nextInt());	1✔
45	private SubchannelPicker currentPicker = new EmptyPicker();	1✔
46
47	public RoundRobinLoadBalancer(Helper helper) {
48	super(helper);	1✔
49	}	1✔
50
51	/**
52	* Updates picker with the list of active subchannels (state == READY).
53	*/
54	@Override
55	protected void updateOverallBalancingState() {
56	List<ChildLbState> activeList = getReadyChildren();	1✔
57	if (activeList.isEmpty()) {	1✔
58	// No READY subchannels
59
60	// RRLB will request connection immediately on subchannel IDLE.
61	boolean isConnecting = false;	1✔
62	for (ChildLbState childLbState : getChildLbStates()) {	1✔
63	ConnectivityState state = childLbState.getCurrentState();	1✔
64	if (state == CONNECTING \|\| state == IDLE) {	1✔
65	isConnecting = true;	1✔
66	break;	1✔
67	}
68	}	1✔
69
70	if (isConnecting) {	1✔
71	updateBalancingState(CONNECTING, new EmptyPicker());	1✔
72	} else {
73	updateBalancingState(TRANSIENT_FAILURE, createReadyPicker(getChildLbStates()));	1✔
74	}
75	} else {	1✔
76	updateBalancingState(READY, createReadyPicker(activeList));	1✔
77	}
78	}	1✔
79
80	private void updateBalancingState(ConnectivityState state, SubchannelPicker picker) {
81	if (state != currentConnectivityState \|\| !picker.equals(currentPicker)) {	1✔
82	getHelper().updateBalancingState(state, picker);	1✔
83	currentConnectivityState = state;	1✔
84	currentPicker = picker;	1✔
85	}
86	}	1✔
87
88	private SubchannelPicker createReadyPicker(Collection<ChildLbState> children) {
89	List<SubchannelPicker> pickerList = new ArrayList<>();	1✔
90	for (ChildLbState child : children) {	1✔
91	SubchannelPicker picker = child.getCurrentPicker();	1✔
92	pickerList.add(picker);	1✔
93	}	1✔
94
95	return new ReadyPicker(pickerList, sequence);	1✔
96	}
97
98	@VisibleForTesting
99	static class ReadyPicker extends SubchannelPicker {
100	private final List<SubchannelPicker> subchannelPickers; // non-empty
101	private final AtomicInteger index;
102	private final int hashCode;
103
104	public ReadyPicker(List<SubchannelPicker> list, AtomicInteger index) {	1✔
105	checkArgument(!list.isEmpty(), "empty list");	1✔
106	this.subchannelPickers = list;	1✔
107	this.index = Preconditions.checkNotNull(index, "index");	1✔
108
109	// Every created picker is checked for equality in updateBalancingState() at least once.
110	// Pre-compute the hash so it can be checked cheaply. Using the hash in equals() makes it very
111	// fast except when the pickers are (very likely) equal.
112	//
113	// For equality we treat children as a set; use hash code as defined by Set
114	int sum = 0;	1✔
115	for (SubchannelPicker picker : subchannelPickers) {	1✔
116	sum += picker.hashCode();	1✔
117	}	1✔
118	this.hashCode = sum;	1✔
119	}	1✔
120
121	@Override
122	public PickResult pickSubchannel(PickSubchannelArgs args) {
123	return subchannelPickers.get(nextIndex()).pickSubchannel(args);	1✔
124	}
125
126	@Override
127	public String toString() {
128	return MoreObjects.toStringHelper(ReadyPicker.class)	×
129	.add("subchannelPickers", subchannelPickers)	×
130	.toString();	×
131	}
132
133	private int nextIndex() {
134	int i = index.getAndIncrement() & Integer.MAX_VALUE;	1✔
135	return i % subchannelPickers.size();	1✔
136	}
137
138	@VisibleForTesting
139	List<SubchannelPicker> getSubchannelPickers() {
140	return subchannelPickers;	1✔
141	}
142
143	@Override
144	public int hashCode() {
145	return hashCode;	×
146	}
147
148	@Override
149	public boolean equals(Object o) {
150	if (!(o instanceof ReadyPicker)) {	1✔
151	return false;	1✔
152	}
153	ReadyPicker other = (ReadyPicker) o;	1✔
154	if (other == this) {	1✔
155	return true;	×
156	}
157	// the lists cannot contain duplicate subchannels
158	return hashCode == other.hashCode	1✔
159	&& index == other.index
160	&& subchannelPickers.size() == other.subchannelPickers.size()	1✔
161	&& new HashSet<>(subchannelPickers).containsAll(other.subchannelPickers);	1✔
162	}
163	}
164
165	@VisibleForTesting
166	static final class EmptyPicker extends SubchannelPicker {	1✔
167	@Override
168	public PickResult pickSubchannel(PickSubchannelArgs args) {
169	return PickResult.withNoResult();	×
170	}
171
172	@Override
173	public int hashCode() {
174	return getClass().hashCode();	×
175	}
176
177	@Override
178	public boolean equals(Object o) {
179	return o instanceof EmptyPicker;	1✔
180	}
181	}
182	}

grpc / grpc-java / #19383

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