core/src/main/java/io/grpc/internal/TransportProvider.java

/*
 * Copyright 2019 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.internal;

import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;

/**
 * Provides transports for sending RPCs.
 */
@ThreadSafe
interface TransportProvider {
  /**
   * Returns a READY transport that will be used to create new streams.
   *
   * <p>Returns {@code null} if the state is not READY.  Will try to connect if state is IDLE.
   */
  @Nullable
  ClientTransport obtainActiveTransport();
}