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Revert "core: pass Subchannel state updates to SubchannelStateListener rather than LoadBalancer (grpc#5503)" (grpc#5684)
This reverts commit 62b03fd. Effectively reverts its follow-up commits: dc218b6 405d8c3 44840fe
1 parent 1b6c131 commit f8d0868

21 files changed

Lines changed: 647 additions & 1243 deletions

‎api/src/main/java/io/grpc/LoadBalancer.java‎

Lines changed: 3 additions & 310 deletions
Original file line numberDiff line numberDiff line change
@@ -16,14 +16,12 @@
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package io.grpc;
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import static com.google.common.base.Preconditions.checkArgument;
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import static com.google.common.base.Preconditions.checkNotNull;
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import com.google.common.base.MoreObjects;
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import com.google.common.base.Objects;
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import com.google.common.base.Preconditions;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.List;
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import java.util.Map;
@@ -337,16 +335,9 @@ public boolean equals(Object obj) {
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* @param subchannel the involved Subchannel
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* @param stateInfo the new state
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* @since 1.2.0
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* @deprecated This method will be removed. Stop overriding it. Instead, pass {@link
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* SubchannelStateListener} to {@link Helper#createSubchannel(CreateSubchannelArgs)}
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* to receive Subchannel state updates
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*/
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@Deprecated
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public void handleSubchannelState(
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Subchannel subchannel, ConnectivityStateInfo stateInfo) {
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// Do nothing. If the implemetation doesn't implement this, it will get subchannel states from
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// the new API. We don't throw because there may be forwarding LoadBalancers still plumb this.
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}
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public abstract void handleSubchannelState(
340+
Subchannel subchannel, ConnectivityStateInfo stateInfo);
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/**
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* The channel asks the load-balancer to shutdown. No more callbacks will be called after this
@@ -660,243 +651,6 @@ public boolean equals(Object other) {
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}
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}
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/**
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* Arguments for {@link Helper#createSubchannel(CreateSubchannelArgs)}.
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*
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* @since 1.21.0
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*/
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@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1771")
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public static final class CreateSubchannelArgs {
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private final List<EquivalentAddressGroup> addrs;
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private final Attributes attrs;
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private final SubchannelStateListener stateListener;
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private final Object[][] customOptions;
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private CreateSubchannelArgs(
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List<EquivalentAddressGroup> addrs, Attributes attrs, Object[][] customOptions,
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SubchannelStateListener stateListener) {
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this.addrs = checkNotNull(addrs, "addresses are not set");
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this.attrs = checkNotNull(attrs, "attrs");
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this.customOptions = checkNotNull(customOptions, "customOptions");
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this.stateListener = checkNotNull(stateListener, "SubchannelStateListener is not set");
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}
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/**
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* Returns the addresses, which is an unmodifiable list.
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*/
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public List<EquivalentAddressGroup> getAddresses() {
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return addrs;
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}
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/**
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* Returns the attributes.
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*/
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public Attributes getAttributes() {
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return attrs;
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}
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/**
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* Get the value for a custom option or its inherent default.
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*
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* @param key Key identifying option
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*/
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@SuppressWarnings("unchecked")
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public <T> T getOption(Key<T> key) {
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Preconditions.checkNotNull(key, "key");
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for (int i = 0; i < customOptions.length; i++) {
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if (key.equals(customOptions[i][0])) {
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return (T) customOptions[i][1];
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}
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}
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return key.defaultValue;
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}
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/**
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* Returns the state listener.
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*/
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public SubchannelStateListener getStateListener() {
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return stateListener;
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}
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/**
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* Returns a builder with the same initial values as this object.
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*/
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public Builder toBuilder() {
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return newBuilder().setAddresses(addrs).setAttributes(attrs).setStateListener(stateListener)
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.copyCustomOptions(customOptions);
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}
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/**
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* Creates a new builder.
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*/
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public static Builder newBuilder() {
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return new Builder();
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}
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@Override
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public String toString() {
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return MoreObjects.toStringHelper(this)
739-
.add("addrs", addrs)
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.add("attrs", attrs)
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.add("listener", stateListener)
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.add("customOptions", Arrays.deepToString(customOptions))
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.toString();
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}
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@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1771")
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public static final class Builder {
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private List<EquivalentAddressGroup> addrs;
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private Attributes attrs = Attributes.EMPTY;
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private SubchannelStateListener stateListener;
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private Object[][] customOptions = new Object[0][2];
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Builder() {
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}
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private <T> Builder copyCustomOptions(Object[][] options) {
758-
customOptions = new Object[options.length][2];
759-
System.arraycopy(options, 0, customOptions, 0, options.length);
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return this;
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}
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/**
764-
* Add a custom option. Any existing value for the key is overwritten.
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*
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* <p>This is an <strong>optional</strong> property.
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*
768-
* @param key the option key
769-
* @param value the option value
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*/
771-
public <T> Builder addOption(Key<T> key, T value) {
772-
Preconditions.checkNotNull(key, "key");
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Preconditions.checkNotNull(value, "value");
774-
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int existingIdx = -1;
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for (int i = 0; i < customOptions.length; i++) {
777-
if (key.equals(customOptions[i][0])) {
778-
existingIdx = i;
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break;
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}
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}
782-
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if (existingIdx == -1) {
784-
Object[][] newCustomOptions = new Object[customOptions.length + 1][2];
785-
System.arraycopy(customOptions, 0, newCustomOptions, 0, customOptions.length);
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customOptions = newCustomOptions;
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existingIdx = customOptions.length - 1;
788-
}
789-
customOptions[existingIdx] = new Object[]{key, value};
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return this;
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}
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/**
794-
* The addresses to connect to. All addresses are considered equivalent and will be tried
795-
* in the order they are provided.
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*/
797-
public Builder setAddresses(EquivalentAddressGroup addrs) {
798-
this.addrs = Collections.singletonList(addrs);
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return this;
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}
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/**
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* The addresses to connect to. All addresses are considered equivalent and will
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* be tried in the order they are provided.
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*
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* <p>This is a <strong>required</strong> property.
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*
808-
* @throws IllegalArgumentException if {@code addrs} is empty
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*/
810-
public Builder setAddresses(List<EquivalentAddressGroup> addrs) {
811-
checkArgument(!addrs.isEmpty(), "addrs is empty");
812-
this.addrs = Collections.unmodifiableList(new ArrayList<>(addrs));
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return this;
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}
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/**
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* Attributes provided here will be included in {@link Subchannel#getAttributes}.
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*
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* <p>This is an <strong>optional</strong> property. Default is empty if not set.
820-
*/
821-
public Builder setAttributes(Attributes attrs) {
822-
this.attrs = checkNotNull(attrs, "attrs");
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return this;
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}
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826-
/**
827-
* Receives state changes of the created Subchannel. The listener is called from
828-
* the {@link Helper#getSynchronizationContext Synchronization Context}. It's safe to share
829-
* the listener among multiple Subchannels.
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*
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* <p>This is a <strong>required</strong> property.
832-
*/
833-
public Builder setStateListener(SubchannelStateListener listener) {
834-
this.stateListener = checkNotNull(listener, "listener");
835-
return this;
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}
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838-
/**
839-
* Creates a new args object.
840-
*/
841-
public CreateSubchannelArgs build() {
842-
return new CreateSubchannelArgs(addrs, attrs, customOptions, stateListener);
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}
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}
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/**
847-
* Key for a key-value pair. Uses reference equality.
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*/
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@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1771")
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public static final class Key<T> {
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private final String debugString;
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private final T defaultValue;
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private Key(String debugString, T defaultValue) {
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this.debugString = debugString;
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this.defaultValue = defaultValue;
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}
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/**
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* Factory method for creating instances of {@link Key}. The default value of the key is
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* {@code null}.
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*
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* @param debugString a debug string that describes this key.
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* @param <T> Key type
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* @return Key object
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*/
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public static <T> Key<T> create(String debugString) {
869-
Preconditions.checkNotNull(debugString, "debugString");
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return new Key<>(debugString, /*defaultValue=*/ null);
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}
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/**
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* Factory method for creating instances of {@link Key}.
875-
*
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* @param debugString a debug string that describes this key.
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* @param defaultValue default value to return when value for key not set
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* @param <T> Key type
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* @return Key object
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*/
881-
public static <T> Key<T> createWithDefault(String debugString, T defaultValue) {
882-
Preconditions.checkNotNull(debugString, "debugString");
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return new Key<>(debugString, defaultValue);
884-
}
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/**
887-
* Returns the user supplied default value for this key.
888-
*/
889-
public T getDefault() {
890-
return defaultValue;
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}
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@Override
894-
public String toString() {
895-
return debugString;
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}
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}
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}
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900654
/**
901655
* Provides essentials for LoadBalancer implementations.
902656
*
@@ -910,11 +664,7 @@ public abstract static class Helper {
910664
* EquivalentAddressGroup}.
911665
*
912666
* @since 1.2.0
913-
* @deprecated Use {@link #createSubchannel(CreateSubchannelArgs)} instead. Note the new API
914-
* must be called from {@link #getSynchronizationContext the Synchronization
915-
* Context}.
916667
*/
917-
@Deprecated
918668
public final Subchannel createSubchannel(EquivalentAddressGroup addrs, Attributes attrs) {
919669
checkNotNull(addrs, "addrs");
920670
return createSubchannel(Collections.singletonList(addrs), attrs);
@@ -935,35 +685,11 @@ public final Subchannel createSubchannel(EquivalentAddressGroup addrs, Attribute
935685
*
936686
* @throws IllegalArgumentException if {@code addrs} is empty
937687
* @since 1.14.0
938-
* @deprecated Use {@link #createSubchannel(CreateSubchannelArgs)} instead. Note the new API
939-
* must be called from {@link #getSynchronizationContext the Synchronization
940-
* Context}.
941688
*/
942-
@Deprecated
943689
public Subchannel createSubchannel(List<EquivalentAddressGroup> addrs, Attributes attrs) {
944690
throw new UnsupportedOperationException();
945691
}
946692

947-
/**
948-
* Creates a Subchannel, which is a logical connection to the given group of addresses which are
949-
* considered equivalent. The {@code attrs} are custom attributes associated with this
950-
* Subchannel, and can be accessed later through {@link Subchannel#getAttributes
951-
* Subchannel.getAttributes()}.
952-
*
953-
* <p>This method <strong>must be called from the {@link #getSynchronizationContext
954-
* Synchronization Context}</strong>, otherwise it may throw. This is to avoid the race between
955-
* the caller and {@link SubchannelStateListener#onSubchannelState}. See <a
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* href="https://github.com/grpc/grpc-java/issues/5015">#5015</a> for more discussions.
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*
958-
* <p>The LoadBalancer is responsible for closing unused Subchannels, and closing all
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* Subchannels within {@link #shutdown}.
960-
*
961-
* @since 1.21.0
962-
*/
963-
public Subchannel createSubchannel(CreateSubchannelArgs args) {
964-
throw new UnsupportedOperationException();
965-
}
966-
967693
/**
968694
* Equivalent to {@link #updateSubchannelAddresses(io.grpc.LoadBalancer.Subchannel, List)} with
969695
* the given single {@code EquivalentAddressGroup}.
@@ -1180,7 +906,7 @@ public abstract static class Subchannel {
1180906
*/
1181907
public final EquivalentAddressGroup getAddresses() {
1182908
List<EquivalentAddressGroup> groups = getAllAddresses();
1183-
Preconditions.checkState(groups.size() == 1, "%s does not have exactly one group", groups);
909+
Preconditions.checkState(groups.size() == 1, "Does not have exactly one group");
1184910
return groups.get(0);
1185911
}
1186912

@@ -1241,39 +967,6 @@ public ChannelLogger getChannelLogger() {
1241967
}
1242968
}
1243969

1244-
/**
1245-
* Receives state changes for one or more {@link Subchannel}s. All methods are run under {@link
1246-
* Helper#getSynchronizationContext}.
1247-
*
1248-
* @since 1.21.0
1249-
*/
1250-
public interface SubchannelStateListener {
1251-
1252-
/**
1253-
* Handles a state change on a Subchannel.
1254-
*
1255-
* <p>The initial state of a Subchannel is IDLE. You won't get a notification for the initial
1256-
* IDLE state.
1257-
*
1258-
* <p>If the new state is not SHUTDOWN, this method should create a new picker and call {@link
1259-
* Helper#updateBalancingState Helper.updateBalancingState()}. Failing to do so may result in
1260-
* unnecessary delays of RPCs. Please refer to {@link PickResult#withSubchannel
1261-
* PickResult.withSubchannel()}'s javadoc for more information.
1262-
*
1263-
* <p>SHUTDOWN can only happen in two cases. One is that LoadBalancer called {@link
1264-
* Subchannel#shutdown} earlier, thus it should have already discarded this Subchannel. The
1265-
* other is that Channel is doing a {@link ManagedChannel#shutdownNow forced shutdown} or has
1266-
* already terminated, thus there won't be further requests to LoadBalancer. Therefore,
1267-
* SHUTDOWN can be safely ignored.
1268-
*
1269-
* @param subchannel the involved Subchannel
1270-
* @param newState the new state
1271-
*
1272-
* @since 1.21.0
1273-
*/
1274-
void onSubchannelState(Subchannel subchannel, ConnectivityStateInfo newState);
1275-
}
1276-
1277970
/**
1278971
* Factory to create {@link LoadBalancer} instance.
1279972
*

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