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/*
*
* 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_LB_POLICY_SUBCHANNEL_LIST_H
#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_SUBCHANNEL_LIST_H
#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
#include "src/core/ext/filters/client_channel/subchannel.h"
#include "src/core/lib/debug/trace.h"
#include "src/core/lib/transport/connectivity_state.h"
// TODO(roth): This code is intended to be shared between pick_first and
// round_robin. However, the interface needs more work to provide clean
// encapsulation. For example, the structs here have some fields that are
// only used in one of the two (e.g., the state counters in
// grpc_lb_subchannel_list and the prev_connectivity_state field in
// grpc_lb_subchannel_data are only used in round_robin, and the
// checking_subchannel field in grpc_lb_subchannel_list is only used by
// pick_first). Also, there is probably some code duplication between the
// connectivity state notification callback code in both pick_first and
// round_robin that could be refactored and moved here. In a future PR,
// need to clean this up.
#ifdef __cplusplus
extern "C" {
#endif
typedef struct grpc_lb_subchannel_list grpc_lb_subchannel_list;
typedef struct {
/** backpointer to owning subchannel list */
grpc_lb_subchannel_list* subchannel_list;
/** subchannel itself */
grpc_subchannel* subchannel;
grpc_connected_subchannel* connected_subchannel;
/** Is a connectivity notification pending? */
bool connectivity_notification_pending;
/** notification that connectivity has changed on subchannel */
grpc_closure connectivity_changed_closure;
/** previous and current connectivity states. Updated by \a
* \a connectivity_changed_closure based on
* \a pending_connectivity_state_unsafe. */
grpc_connectivity_state prev_connectivity_state;
grpc_connectivity_state curr_connectivity_state;
/** connectivity state to be updated by
* grpc_subchannel_notify_on_state_change(), not guarded by
* the combiner. To be copied to \a curr_connectivity_state by
* \a connectivity_changed_closure. */
grpc_connectivity_state pending_connectivity_state_unsafe;
/** the subchannel's target user data */
void* user_data;
/** vtable to operate over \a user_data */
const grpc_lb_user_data_vtable* user_data_vtable;
} grpc_lb_subchannel_data;
/// Unrefs the subchannel contained in sd.
void grpc_lb_subchannel_data_unref_subchannel(grpc_exec_ctx* exec_ctx,
grpc_lb_subchannel_data* sd,
const char* reason);
/// Starts watching the connectivity state of the subchannel.
/// The connectivity_changed_cb callback must invoke either
/// grpc_lb_subchannel_data_stop_connectivity_watch() or again call
/// grpc_lb_subchannel_data_start_connectivity_watch().
void grpc_lb_subchannel_data_start_connectivity_watch(
grpc_exec_ctx* exec_ctx, grpc_lb_subchannel_data* sd);
/// Stops watching the connectivity state of the subchannel.
void grpc_lb_subchannel_data_stop_connectivity_watch(
grpc_exec_ctx* exec_ctx, grpc_lb_subchannel_data* sd);
struct grpc_lb_subchannel_list {
/** backpointer to owning policy */
grpc_lb_policy* policy;
grpc_tracer_flag* tracer;
/** all our subchannels */
size_t num_subchannels;
grpc_lb_subchannel_data* subchannels;
/** Index into subchannels of the one we're currently checking.
* Used when connecting to subchannels serially instead of in parallel. */
// TODO(roth): When we have time, we can probably make this go away
// and compute the index dynamically by subtracting
// subchannel_list->subchannels from the subchannel_data pointer.
size_t checking_subchannel;
/** how many subchannels are in state READY */
size_t num_ready;
/** how many subchannels are in state TRANSIENT_FAILURE */
size_t num_transient_failures;
/** how many subchannels are in state SHUTDOWN */
size_t num_shutdown;
/** how many subchannels are in state IDLE */
size_t num_idle;
/** There will be one ref for each entry in subchannels for which there is a
* pending connectivity state watcher callback. */
gpr_refcount refcount;
/** Is this list shutting down? This may be true due to the shutdown of the
* policy itself or because a newer update has arrived while this one hadn't
* finished processing. */
bool shutting_down;
};
grpc_lb_subchannel_list* grpc_lb_subchannel_list_create(
grpc_exec_ctx* exec_ctx, grpc_lb_policy* p, grpc_tracer_flag* tracer,
const grpc_lb_addresses* addresses, const grpc_lb_policy_args* args,
grpc_iomgr_cb_func connectivity_changed_cb);
void grpc_lb_subchannel_list_ref(grpc_lb_subchannel_list* subchannel_list,
const char* reason);
void grpc_lb_subchannel_list_unref(grpc_exec_ctx* exec_ctx,
grpc_lb_subchannel_list* subchannel_list,
const char* reason);
/// Takes and releases refs needed for a connectivity notification.
/// This includes a ref to subchannel_list and a weak ref to the LB policy.
void grpc_lb_subchannel_list_ref_for_connectivity_watch(
grpc_lb_subchannel_list* subchannel_list, const char* reason);
void grpc_lb_subchannel_list_unref_for_connectivity_watch(
grpc_exec_ctx* exec_ctx, grpc_lb_subchannel_list* subchannel_list,
const char* reason);
/// Mark subchannel_list as discarded. Unsubscribes all its subchannels. The
/// connectivity state notification callback will ultimately unref it.
void grpc_lb_subchannel_list_shutdown_and_unref(
grpc_exec_ctx* exec_ctx, grpc_lb_subchannel_list* subchannel_list,
const char* reason);
#ifdef __cplusplus
}
#endif
#endif /* GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_LB_POLICY_SUBCHANNEL_LIST_H */
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