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util: SocketAddress.toString() cannot be used for equality
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Some addresses are equal even though their toString is different
(InetSocketAddress ignores the hostname when it has an address). And
some addresses are not equal even though their toString might be the
same (AnonymousInProcessSocketAddress doesn't override toString()).

InetSocketAddress/InetAddress do not cache the toString() result. Thus,
even in the worst case that uses a HashSet, this should use less memory
than the earlier approach, as no strings are formatted. It probably also
significantly improves performance in the reasonably common case when an
Endpoint is created just for looking up a key, because the string
creation in the constructor isn't then amorized.
updateChildrenWithResolvedAddresses(), for example, creates n^2 Endpoint
objects for lookups.
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@ejona86
ejona86 committed Aug 9, 2024
1 parent 72a977b commit f866c80
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Showing 3 changed files with 54 additions and 50 deletions.
33 changes: 16 additions & 17 deletions util/src/main/java/io/grpc/util/MultiChildLoadBalancer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -37,10 +37,10 @@
import io.grpc.internal.PickFirstLoadBalancerProvider;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
Expand Down Expand Up @@ -494,25 +494,27 @@ protected Helper delegate() {

/**
* Endpoint is an optimization to quickly lookup and compare EquivalentAddressGroup address sets.
* Ignores the attributes, orders the addresses in a deterministic manner and converts each
* address into a string for easy comparison. Also caches the hashcode.
* Is used as a key for ChildLbState for most load balancers (ClusterManagerLB uses a String).
* It ignores the attributes. Is used as a key for ChildLbState for most load balancers
* (ClusterManagerLB uses a String).
*/
protected static class Endpoint {
final String[] addrs;
final Collection<SocketAddress> addrs;
final int hashCode;

public Endpoint(EquivalentAddressGroup eag) {
checkNotNull(eag, "eag");

addrs = new String[eag.getAddresses().size()];
int i = 0;
if (eag.getAddresses().size() < 10) {
addrs = eag.getAddresses();
} else {
// This is expected to be very unlikely in practice
addrs = new HashSet<>(eag.getAddresses());
}
int sum = 0;
for (SocketAddress address : eag.getAddresses()) {
addrs[i++] = address.toString();
sum += address.hashCode();
}
Arrays.sort(addrs);

hashCode = Arrays.hashCode(addrs);
hashCode = sum;
}

@Override
Expand All @@ -525,24 +527,21 @@ public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other == null) {
return false;
}

if (!(other instanceof Endpoint)) {
return false;
}
Endpoint o = (Endpoint) other;
if (o.hashCode != hashCode || o.addrs.length != addrs.length) {
if (o.hashCode != hashCode || o.addrs.size() != addrs.size()) {
return false;
}

return Arrays.equals(o.addrs, this.addrs);
return o.addrs.containsAll(addrs);
}

@Override
public String toString() {
return Arrays.toString(addrs);
return addrs.toString();
}
}

Expand Down
55 changes: 23 additions & 32 deletions util/src/test/java/io/grpc/util/MultiChildLoadBalancerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@
import static io.grpc.ConnectivityState.READY;
import static io.grpc.ConnectivityState.SHUTDOWN;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import static org.mockito.AdditionalAnswers.delegatesTo;
Expand All @@ -34,6 +33,7 @@
import static org.mockito.Mockito.verify;

import com.google.common.collect.Lists;
import com.google.common.testing.EqualsTester;
import io.grpc.Attributes;
import io.grpc.ConnectivityState;
import io.grpc.ConnectivityStateInfo;
Expand Down Expand Up @@ -244,37 +244,28 @@ public void testEndpoint_toString() {

@Test
public void testEndpoint_equals() {
assertEquals(
createEndpoint(Attributes.EMPTY, "addr1"),
createEndpoint(Attributes.EMPTY, "addr1"));

assertEquals(
createEndpoint(Attributes.EMPTY, "addr1", "addr2"),
createEndpoint(Attributes.EMPTY, "addr2", "addr1"));

assertEquals(
createEndpoint(Attributes.EMPTY, "addr1", "addr2"),
createEndpoint(affinity, "addr2", "addr1"));

assertEquals(
createEndpoint(Attributes.EMPTY, "addr1", "addr2").hashCode(),
createEndpoint(affinity, "addr2", "addr1").hashCode());

}

@Test
public void testEndpoint_notEquals() {
assertNotEquals(
createEndpoint(Attributes.EMPTY, "addr1", "addr2"),
createEndpoint(Attributes.EMPTY, "addr1", "addr3"));

assertNotEquals(
createEndpoint(Attributes.EMPTY, "addr1"),
createEndpoint(Attributes.EMPTY, "addr1", "addr2"));

assertNotEquals(
createEndpoint(Attributes.EMPTY, "addr1", "addr2"),
createEndpoint(Attributes.EMPTY, "addr1"));
new EqualsTester()
.addEqualityGroup(
createEndpoint(Attributes.EMPTY, "addr1"),
createEndpoint(Attributes.EMPTY, "addr1"))
.addEqualityGroup(
createEndpoint(Attributes.EMPTY, "addr1", "addr2"),
createEndpoint(Attributes.EMPTY, "addr2", "addr1"),
createEndpoint(affinity, "addr1", "addr2"))
.addEqualityGroup(
createEndpoint(Attributes.EMPTY, "addr1", "addr3"))
.addEqualityGroup(
createEndpoint(Attributes.EMPTY, "addr1", "addr2", "addr3", "addr4", "addr5", "addr6",
"addr7", "addr8", "addr9", "addr10"),
createEndpoint(Attributes.EMPTY, "addr2", "addr1", "addr3", "addr4", "addr5", "addr6",
"addr7", "addr8", "addr9", "addr10"))
.addEqualityGroup(
createEndpoint(Attributes.EMPTY, "addr1", "addr2", "addr3", "addr4", "addr5", "addr6",
"addr7", "addr8", "addr9", "addr11"))
.addEqualityGroup(
createEndpoint(Attributes.EMPTY, "addr1", "addr2", "addr3", "addr4", "addr5", "addr6",
"addr7", "addr8", "addr9", "addr10", "addr11"))
.testEquals();
}

private String addressesOnlyString(EquivalentAddressGroup eag) {