core/src/main/java/io/grpc/ConnectivityStateInfo.java

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package io.grpc;

import com.google.common.base.Preconditions;

import io.grpc.Status;

/**
 * A tuple of a {@link ConnectivityState} and its associated {@link Status}.
 *
 * <p>If the state is {@code TRANSIENT_FAILURE}, the status is never {@code OK}.  For other states,
 * the status is always {@code OK}.
 */
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/1771")
public final class ConnectivityStateInfo {
  private final ConnectivityState state;
  private final Status status;

  /**
   * Returns an instance for a state that is not {@code TRANSIENT_FAILURE}.
   *
   * @throws IllegalArgumentException if {@code state} is {@code TRANSIENT_FAILURE}.
   */
  public static ConnectivityStateInfo forNonError(ConnectivityState state) {
    Preconditions.checkArgument(state != ConnectivityState.TRANSIENT_FAILURE,
        "state is TRANSIENT_ERROR. Use forError() instead");
    return new ConnectivityStateInfo(state, Status.OK);
  }

  /**
   * Returns an instance for {@code TRANSIENT_FAILURE}, associated with an error status.
   */
  public static ConnectivityStateInfo forTransientFailure(Status error) {
    Preconditions.checkArgument(!error.isOk(), "The error status must not be OK");
    return new ConnectivityStateInfo(ConnectivityState.TRANSIENT_FAILURE, error);
  }

  /**
   * Returns the state.
   */
  public ConnectivityState getState() {
    return state;
  }

  /**
   * Returns the status associated with the state.
   *
   * <p>If the state is {@code TRANSIENT_FAILURE}, the status is never {@code OK}.  For other
   * states, the status is always {@code OK}.
   */
  public Status getStatus() {
    return status;
  }

  @Override
  public boolean equals(Object other) {
    if (!(other instanceof ConnectivityStateInfo)) {
      return false;
    }
    ConnectivityStateInfo o = (ConnectivityStateInfo) other;
    return state.equals(o.state) && status.equals(o.status);
  }

  @Override
  public int hashCode() {
    return state.hashCode() ^ status.hashCode();
  }

  @Override
  public String toString() {
    if (status.isOk()) {
      return state.toString();
    }
    return state + "(" + status + ")";
  }

  private ConnectivityStateInfo(ConnectivityState state, Status status) {
    this.state = Preconditions.checkNotNull(state, "state is null");
    this.status = Preconditions.checkNotNull(status, "status is null");
  }
}