io.grpc.ConnectivityState Maven / Gradle / Ivy
/*
* 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;
/**
* The connectivity states.
*
* @see
* more information
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/4359")
public enum ConnectivityState {
/**
* The channel is trying to establish a connection and is waiting to make progress on one of the
* steps involved in name resolution, TCP connection establishment or TLS handshake. This may be
* used as the initial state for channels upon creation.
*/
CONNECTING,
/**
* The channel has successfully established a connection all the way through TLS handshake (or
* equivalent) and all subsequent attempt to communicate have succeeded (or are pending without
* any known failure ).
*/
READY,
/**
* There has been some transient failure (such as a TCP 3-way handshake timing out or a socket
* error). Channels in this state will eventually switch to the CONNECTING state and try to
* establish a connection again. Since retries are done with exponential backoff, channels that
* fail to connect will start out spending very little time in this state but as the attempts
* fail repeatedly, the channel will spend increasingly large amounts of time in this state. For
* many non-fatal failures (e.g., TCP connection attempts timing out because the server is not
* yet available), the channel may spend increasingly large amounts of time in this state.
*/
TRANSIENT_FAILURE,
/**
* This is the state where the channel is not even trying to create a connection because of a
* lack of new or pending RPCs. New RPCs MAY be created in this state. Any attempt to start an
* RPC on the channel will push the channel out of this state to connecting. When there has been
* no RPC activity on a channel for a configurable IDLE_TIMEOUT, i.e., no new or pending (active)
* RPCs for this period, channels that are READY or CONNECTING switch to IDLE. Additionaly,
* channels that receive a GOAWAY when there are no active or pending RPCs should also switch to
* IDLE to avoid connection overload at servers that are attempting to shed connections.
*/
IDLE,
/**
* This channel has started shutting down. Any new RPCs should fail immediately. Pending RPCs
* may continue running till the application cancels them. Channels may enter this state either
* because the application explicitly requested a shutdown or if a non-recoverable error has
* happened during attempts to connect communicate . (As of 6/12/2015, there are no known errors
* (while connecting or communicating) that are classified as non-recoverable) Channels that
* enter this state never leave this state.
*/
SHUTDOWN
}