io.grpc

Class ManagedChannel

java.lang.Object

io.grpc.Channel

io.grpc.ManagedChannel

@ThreadSafe
public abstract class ManagedChannel
extends Channel

A Channel that provides lifecycle management.

Constructor Summary

Constructors

Constructor and Description
ManagedChannel()

Method Summary

Modifier and Type	Method and Description
abstract boolean	awaitTermination(long timeout, TimeUnit unit) Waits for the channel to become terminated, giving up if the timeout is reached.
void	enterIdle() Invoking this method moves the channel into the IDLE state and triggers tear-down of the channel's name resolver and load balancer, while still allowing on-going RPCs on the channel to continue.
ConnectivityState	getState(boolean requestConnection) Gets the current connectivity state.
abstract boolean	isShutdown() Returns whether the channel is shutdown.
abstract boolean	isTerminated() Returns whether the channel is terminated.
void	notifyWhenStateChanged(ConnectivityState source, Runnable callback) Registers a one-off callback that will be run if the connectivity state of the channel diverges from the given source, which is typically what has just been returned by getState(boolean).
void	resetConnectBackoff() For subchannels that are in TRANSIENT_FAILURE state, short-circuit the backoff timer and make them reconnect immediately.
abstract ManagedChannel	shutdown() Initiates an orderly shutdown in which preexisting calls continue but new calls are immediately cancelled.
abstract ManagedChannel	shutdownNow() Initiates a forceful shutdown in which preexisting and new calls are cancelled.

Methods inherited from class io.grpc.Channel

authority, newCall

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ManagedChannel

public ManagedChannel()

Method Detail

shutdown

public abstract ManagedChannel shutdown()

Initiates an orderly shutdown in which preexisting calls continue but new calls are immediately cancelled.

Returns:

this

Since:

1.0.0

isShutdown

public abstract boolean isShutdown()

Returns whether the channel is shutdown. Shutdown channels immediately cancel any new calls, but may still have some calls being processed.

Since:

1.0.0

See Also:

shutdown(), isTerminated()

isTerminated

public abstract boolean isTerminated()

Returns whether the channel is terminated. Terminated channels have no running calls and relevant resources released (like TCP connections).

Since:

1.0.0

See Also:

isShutdown()

shutdownNow

public abstract ManagedChannel shutdownNow()

Initiates a forceful shutdown in which preexisting and new calls are cancelled. Although forceful, the shutdown process is still not instantaneous; isTerminated() will likely return false immediately after this method returns.

Returns:

this

Since:

1.0.0

awaitTermination

public abstract boolean awaitTermination(long timeout,
                                         TimeUnit unit)
                                  throws InterruptedException

Waits for the channel to become terminated, giving up if the timeout is reached.

Returns:

whether the channel is terminated, as would be done by isTerminated().

Throws:

InterruptedException

Since:

1.0.0

getState

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/4359")
public ConnectivityState getState(boolean requestConnection)

Gets the current connectivity state. Note the result may soon become outdated.

Note that the core library did not provide an implementation of this method until v1.6.1.

Parameters:

requestConnection - if true, the channel will try to make a connection if it is currently IDLE

Throws:

UnsupportedOperationException - if not supported by implementation

Since:

1.1.0

notifyWhenStateChanged

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/4359")
public void notifyWhenStateChanged(ConnectivityState source,
                                                                                                           Runnable callback)

Registers a one-off callback that will be run if the connectivity state of the channel diverges from the given source, which is typically what has just been returned by getState(boolean). If the states are already different, the callback will be called immediately. The callback is run in the same executor that runs Call listeners.

There is an inherent race between the notification to callback and any call to getState(). There is a similar race between getState() and a call to notifyWhenStateChanged(). The state can change during those races, so there is not a way to see every state transition. "Transitions" to the same state are possible, because intermediate states may not have been observed. The API is only reliable in tracking the current state.

Note that the core library did not provide an implementation of this method until v1.6.1.

Parameters:

source - the assumed current state, typically just returned by getState(boolean)

callback - the one-off callback

Throws:

UnsupportedOperationException - if not supported by implementation

Since:

1.1.0

resetConnectBackoff

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/4056")
public void resetConnectBackoff()

For subchannels that are in TRANSIENT_FAILURE state, short-circuit the backoff timer and make them reconnect immediately. May also attempt to invoke NameResolver.refresh().

This is primarily intended for Android users, where the network may experience frequent temporary drops. Rather than waiting for gRPC's name resolution and reconnect timers to elapse before reconnecting, the app may use this method as a mechanism to notify gRPC that the network is now available and a reconnection attempt may occur immediately.

No-op if not supported by the implementation.

Since:

1.8.0

enterIdle

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/4056")
public void enterIdle()

Invoking this method moves the channel into the IDLE state and triggers tear-down of the channel's name resolver and load balancer, while still allowing on-going RPCs on the channel to continue. New RPCs on the channel will trigger creation of a new connection.

This is primarily intended for Android users when a device is transitioning from a cellular to a wifi connection. The OS will issue a notification that a new network (wifi) has been made the default, but for approximately 30 seconds the device will maintain both the cellular and wifi connections. Apps may invoke this method to ensure that new RPCs are created using the new default wifi network, rather than the soon-to-be-disconnected cellular network.

No-op if not supported by implementation.

Since:

1.11.0