#19418

Committed 12 Aug 2024 10:40PM UTC coverage: 84.489% (+0.02%) from 84.469%

Build # #19418

Build Type

push

github

Committed by

ejona86

Commit Message

Remove implicit requestConnection() on IDLE from MultiChildLB

One LB no longer needs to extend ChildLbState and one has to start, so
it is a bit of a wash. There are more LBs that need the auto-request
logic, but if we have an API where subclasses override it without
calling super then we can't change the implementation in the future.
Adding behavior on top of a base class allows subclasses to call super,
which lets the base class change over time.

Run Details

33396 of 39527 relevant lines covered (84.49%)

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89.39

/../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);
  }

  @Override
  protected ChildLbState createChildLbState(Object key, Object policyConfig,
      SubchannelPicker initialPicker, ResolvedAddresses resolvedAddresses) {
    return new ChildLbState(key, pickFirstLbProvider, policyConfig, initialPicker) {
      @Override
      protected ChildLbStateHelper createChildHelper() {
        return new ChildLbStateHelper() {
          @Override
          public void updateBalancingState(ConnectivityState newState, SubchannelPicker newPicker) {
            super.updateBalancingState(newState, newPicker);
            if (!resolvingAddresses && newState == IDLE) {
              getLb().requestConnection();
            }
          }
        };
      }
    };
  }

  @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	@Override
99	protected ChildLbState createChildLbState(Object key, Object policyConfig,
100	SubchannelPicker initialPicker, ResolvedAddresses resolvedAddresses) {
101	return new ChildLbState(key, pickFirstLbProvider, policyConfig, initialPicker) {	1✔
102	@Override
103	protected ChildLbStateHelper createChildHelper() {
104	return new ChildLbStateHelper() {	1✔
105	@Override
106	public void updateBalancingState(ConnectivityState newState, SubchannelPicker newPicker) {
107	super.updateBalancingState(newState, newPicker);	1✔
108	if (!resolvingAddresses && newState == IDLE) {	1✔
109	getLb().requestConnection();	1✔
110	}
111	}	1✔
112	};
113	}
114	};
115	}
116
117	@VisibleForTesting
118	static class ReadyPicker extends SubchannelPicker {
119	private final List<SubchannelPicker> subchannelPickers; // non-empty
120	private final AtomicInteger index;
121	private final int hashCode;
122
123	public ReadyPicker(List<SubchannelPicker> list, AtomicInteger index) {	1✔
124	checkArgument(!list.isEmpty(), "empty list");	1✔
125	this.subchannelPickers = list;	1✔
126	this.index = Preconditions.checkNotNull(index, "index");	1✔
127
128	// Every created picker is checked for equality in updateBalancingState() at least once.
129	// Pre-compute the hash so it can be checked cheaply. Using the hash in equals() makes it very
130	// fast except when the pickers are (very likely) equal.
131	//
132	// For equality we treat children as a set; use hash code as defined by Set
133	int sum = 0;	1✔
134	for (SubchannelPicker picker : subchannelPickers) {	1✔
135	sum += picker.hashCode();	1✔
136	}	1✔
137	this.hashCode = sum;	1✔
138	}	1✔
139
140	@Override
141	public PickResult pickSubchannel(PickSubchannelArgs args) {
142	return subchannelPickers.get(nextIndex()).pickSubchannel(args);	1✔
143	}
144
145	@Override
146	public String toString() {
147	return MoreObjects.toStringHelper(ReadyPicker.class)	×
148	.add("subchannelPickers", subchannelPickers)	×
149	.toString();	×
150	}
151
152	private int nextIndex() {
153	int i = index.getAndIncrement() & Integer.MAX_VALUE;	1✔
154	return i % subchannelPickers.size();	1✔
155	}
156
157	@VisibleForTesting
158	List<SubchannelPicker> getSubchannelPickers() {
159	return subchannelPickers;	1✔
160	}
161
162	@Override
163	public int hashCode() {
164	return hashCode;	×
165	}
166
167	@Override
168	public boolean equals(Object o) {
169	if (!(o instanceof ReadyPicker)) {	1✔
170	return false;	1✔
171	}
172	ReadyPicker other = (ReadyPicker) o;	1✔
173	if (other == this) {	1✔
174	return true;	×
175	}
176	// the lists cannot contain duplicate subchannels
177	return hashCode == other.hashCode	1✔
178	&& index == other.index
179	&& subchannelPickers.size() == other.subchannelPickers.size()	1✔
180	&& new HashSet<>(subchannelPickers).containsAll(other.subchannelPickers);	1✔
181	}
182	}
183
184	@VisibleForTesting
185	static final class EmptyPicker extends SubchannelPicker {	1✔
186	@Override
187	public PickResult pickSubchannel(PickSubchannelArgs args) {
188	return PickResult.withNoResult();	×
189	}
190
191	@Override
192	public int hashCode() {
193	return getClass().hashCode();	×
194	}
195
196	@Override
197	public boolean equals(Object o) {
198	return o instanceof EmptyPicker;	1✔
199	}
200	}
201	}

grpc / grpc-java / #19418

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