grpc/src/core/ext/filters/client_channel/client_channel.h

/*
 *
 * Copyright 2015 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.
 *
 */

#ifndef GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_H
#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_H

#include <grpc/support/port_platform.h>

#include "src/core/ext/filters/client_channel/client_channel_channelz.h"
#include "src/core/ext/filters/client_channel/client_channel_factory.h"
#include "src/core/ext/filters/client_channel/resolver.h"
#include "src/core/lib/channel/channel_stack.h"

extern grpc_core::TraceFlag grpc_client_channel_trace;

// Channel arg key for server URI string.
#define GRPC_ARG_SERVER_URI "grpc.server_uri"

/* A client channel is a channel that begins disconnected, and can connect
   to some endpoint on demand. If that endpoint disconnects, it will be
   connected to again later.

   Calls on a disconnected client channel are queued until a connection is
   established. */

extern const grpc_channel_filter grpc_client_channel_filter;

grpc_connectivity_state grpc_client_channel_check_connectivity_state(
    grpc_channel_element* elem, int try_to_connect);

int grpc_client_channel_num_external_connectivity_watchers(
    grpc_channel_element* elem);

// Starts a one-time connectivity state watch.  When the channel's state
// becomes different from *state, sets *state to the new state and
// schedules on_complete.  The watcher_timer_init callback is invoked as
// soon as the watch is actually started (i.e., after hopping into the
// client channel combiner).  I/O will be serviced via pollent.
//
// This is intended to be used when starting a watch from outside of C-core
// via grpc_channel_watch_connectivity_state().  It should not be used
// by other callers.
void grpc_client_channel_watch_connectivity_state(
    grpc_channel_element* elem, grpc_polling_entity pollent,
    grpc_connectivity_state* state, grpc_closure* on_complete,
    grpc_closure* watcher_timer_init);

// Starts and stops a connectivity watch.  The watcher will be initially
// notified as soon as the state changes from initial_state and then on
// every subsequent state change until either the watch is stopped or
// it is notified that the state has changed to SHUTDOWN.
//
// This is intended to be used when starting watches from code inside of
// C-core (e.g., for a nested control plane channel for things like xds).
void grpc_client_channel_start_connectivity_watch(
    grpc_channel_element* elem, grpc_connectivity_state initial_state,
    grpc_core::OrphanablePtr<grpc_core::AsyncConnectivityStateWatcherInterface>
        watcher);
void grpc_client_channel_stop_connectivity_watch(
    grpc_channel_element* elem,
    grpc_core::AsyncConnectivityStateWatcherInterface* watcher);

/* Debug helper: pull the subchannel call from a call stack element */
grpc_core::RefCountedPtr<grpc_core::SubchannelCall>
grpc_client_channel_get_subchannel_call(grpc_call_element* elem);

#endif  // GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_CLIENT_CHANNEL_H