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|
/*
*
* Copyright 2015, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "src/core/ext/client_channel/client_channel.h"
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>
#include <grpc/support/sync.h>
#include <grpc/support/useful.h>
#include "src/core/ext/client_channel/lb_policy_registry.h"
#include "src/core/ext/client_channel/subchannel.h"
#include "src/core/lib/channel/channel_args.h"
#include "src/core/lib/channel/connected_channel.h"
#include "src/core/lib/channel/deadline_filter.h"
#include "src/core/lib/iomgr/iomgr.h"
#include "src/core/lib/iomgr/polling_entity.h"
#include "src/core/lib/profiling/timers.h"
#include "src/core/lib/support/string.h"
#include "src/core/lib/surface/channel.h"
#include "src/core/lib/transport/connectivity_state.h"
#include "src/core/lib/transport/metadata.h"
#include "src/core/lib/transport/metadata_batch.h"
#include "src/core/lib/transport/service_config.h"
#include "src/core/lib/transport/static_metadata.h"
/* Client channel implementation */
/*************************************************************************
* METHOD-CONFIG TABLE
*/
typedef enum {
WAIT_FOR_READY_UNSET,
WAIT_FOR_READY_FALSE,
WAIT_FOR_READY_TRUE
} wait_for_ready_value;
typedef struct method_parameters {
gpr_timespec timeout;
wait_for_ready_value wait_for_ready;
} method_parameters;
static void *method_parameters_copy(void *value) {
void *new_value = gpr_malloc(sizeof(method_parameters));
memcpy(new_value, value, sizeof(method_parameters));
return new_value;
}
static void method_parameters_free(grpc_exec_ctx *exec_ctx, void *p) {
gpr_free(p);
}
static const grpc_mdstr_hash_table_vtable method_parameters_vtable = {
method_parameters_free, method_parameters_copy};
static void *method_parameters_create_from_json(const grpc_json *json) {
wait_for_ready_value wait_for_ready = WAIT_FOR_READY_UNSET;
gpr_timespec timeout = {0, 0, GPR_TIMESPAN};
for (grpc_json *field = json->child; field != NULL; field = field->next) {
if (field->key == NULL) continue;
if (strcmp(field->key, "waitForReady") == 0) {
if (wait_for_ready != WAIT_FOR_READY_UNSET) return NULL; // Duplicate.
if (field->type != GRPC_JSON_TRUE && field->type != GRPC_JSON_FALSE) {
return NULL;
}
wait_for_ready = field->type == GRPC_JSON_TRUE ? WAIT_FOR_READY_TRUE
: WAIT_FOR_READY_FALSE;
} else if (strcmp(field->key, "timeout") == 0) {
if (timeout.tv_sec > 0 || timeout.tv_nsec > 0) return NULL; // Duplicate.
if (field->type != GRPC_JSON_STRING) return NULL;
size_t len = strlen(field->value);
if (field->value[len - 1] != 's') return NULL;
char *buf = gpr_strdup(field->value);
buf[len - 1] = '\0'; // Remove trailing 's'.
char *decimal_point = strchr(buf, '.');
if (decimal_point != NULL) {
*decimal_point = '\0';
timeout.tv_nsec = gpr_parse_nonnegative_int(decimal_point + 1);
if (timeout.tv_nsec == -1) {
gpr_free(buf);
return NULL;
}
// There should always be exactly 3, 6, or 9 fractional digits.
int multiplier = 1;
switch (strlen(decimal_point + 1)) {
case 9:
break;
case 6:
multiplier *= 1000;
break;
case 3:
multiplier *= 1000000;
break;
default: // Unsupported number of digits.
gpr_free(buf);
return NULL;
}
timeout.tv_nsec *= multiplier;
}
timeout.tv_sec = gpr_parse_nonnegative_int(buf);
if (timeout.tv_sec == -1) return NULL;
gpr_free(buf);
}
}
method_parameters *value = gpr_malloc(sizeof(method_parameters));
value->timeout = timeout;
value->wait_for_ready = wait_for_ready;
return value;
}
/*************************************************************************
* CHANNEL-WIDE FUNCTIONS
*/
typedef struct client_channel_channel_data {
/** resolver for this channel */
grpc_resolver *resolver;
/** have we started resolving this channel */
bool started_resolving;
/** client channel factory */
grpc_client_channel_factory *client_channel_factory;
/** mutex protecting all variables below in this data structure */
gpr_mu mu;
/** currently active load balancer */
char *lb_policy_name;
grpc_lb_policy *lb_policy;
/** service config in JSON form */
char *service_config_json;
/** maps method names to method_parameters structs */
grpc_mdstr_hash_table *method_params_table;
/** incoming resolver result - set by resolver.next() */
grpc_channel_args *resolver_result;
/** a list of closures that are all waiting for config to come in */
grpc_closure_list waiting_for_config_closures;
/** resolver callback */
grpc_closure on_resolver_result_changed;
/** connectivity state being tracked */
grpc_connectivity_state_tracker state_tracker;
/** when an lb_policy arrives, should we try to exit idle */
bool exit_idle_when_lb_policy_arrives;
/** owning stack */
grpc_channel_stack *owning_stack;
/** interested parties (owned) */
grpc_pollset_set *interested_parties;
} channel_data;
/** We create one watcher for each new lb_policy that is returned from a
resolver, to watch for state changes from the lb_policy. When a state
change is seen, we update the channel, and create a new watcher. */
typedef struct {
channel_data *chand;
grpc_closure on_changed;
grpc_connectivity_state state;
grpc_lb_policy *lb_policy;
} lb_policy_connectivity_watcher;
static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
grpc_lb_policy *lb_policy,
grpc_connectivity_state current_state);
static void set_channel_connectivity_state_locked(grpc_exec_ctx *exec_ctx,
channel_data *chand,
grpc_connectivity_state state,
grpc_error *error,
const char *reason) {
if ((state == GRPC_CHANNEL_TRANSIENT_FAILURE ||
state == GRPC_CHANNEL_SHUTDOWN) &&
chand->lb_policy != NULL) {
/* cancel picks with wait_for_ready=false */
grpc_lb_policy_cancel_picks(
exec_ctx, chand->lb_policy,
/* mask= */ GRPC_INITIAL_METADATA_WAIT_FOR_READY,
/* check= */ 0, GRPC_ERROR_REF(error));
}
grpc_connectivity_state_set(exec_ctx, &chand->state_tracker, state, error,
reason);
}
static void on_lb_policy_state_changed_locked(grpc_exec_ctx *exec_ctx,
lb_policy_connectivity_watcher *w,
grpc_error *error) {
grpc_connectivity_state publish_state = w->state;
/* check if the notification is for a stale policy */
if (w->lb_policy != w->chand->lb_policy) return;
if (publish_state == GRPC_CHANNEL_SHUTDOWN && w->chand->resolver != NULL) {
publish_state = GRPC_CHANNEL_TRANSIENT_FAILURE;
grpc_resolver_channel_saw_error(exec_ctx, w->chand->resolver);
GRPC_LB_POLICY_UNREF(exec_ctx, w->chand->lb_policy, "channel");
w->chand->lb_policy = NULL;
}
set_channel_connectivity_state_locked(exec_ctx, w->chand, publish_state,
GRPC_ERROR_REF(error), "lb_changed");
if (w->state != GRPC_CHANNEL_SHUTDOWN) {
watch_lb_policy(exec_ctx, w->chand, w->lb_policy, w->state);
}
}
static void on_lb_policy_state_changed(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
lb_policy_connectivity_watcher *w = arg;
gpr_mu_lock(&w->chand->mu);
on_lb_policy_state_changed_locked(exec_ctx, w, error);
gpr_mu_unlock(&w->chand->mu);
GRPC_CHANNEL_STACK_UNREF(exec_ctx, w->chand->owning_stack, "watch_lb_policy");
gpr_free(w);
}
static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
grpc_lb_policy *lb_policy,
grpc_connectivity_state current_state) {
lb_policy_connectivity_watcher *w = gpr_malloc(sizeof(*w));
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "watch_lb_policy");
w->chand = chand;
grpc_closure_init(&w->on_changed, on_lb_policy_state_changed, w);
w->state = current_state;
w->lb_policy = lb_policy;
grpc_lb_policy_notify_on_state_change(exec_ctx, lb_policy, &w->state,
&w->on_changed);
}
static void on_resolver_result_changed(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
channel_data *chand = arg;
char *lb_policy_name = NULL;
grpc_lb_policy *lb_policy = NULL;
grpc_lb_policy *old_lb_policy;
grpc_mdstr_hash_table *method_params_table = NULL;
grpc_connectivity_state state = GRPC_CHANNEL_TRANSIENT_FAILURE;
bool exit_idle = false;
grpc_error *state_error = GRPC_ERROR_CREATE("No load balancing policy");
char *service_config_json = NULL;
if (chand->resolver_result != NULL) {
// Find LB policy name.
const grpc_arg *channel_arg =
grpc_channel_args_find(chand->resolver_result, GRPC_ARG_LB_POLICY_NAME);
if (channel_arg != NULL) {
GPR_ASSERT(channel_arg->type == GRPC_ARG_STRING);
lb_policy_name = channel_arg->value.string;
}
// Special case: If all of the addresses are balancer addresses,
// assume that we should use the grpclb policy, regardless of what the
// resolver actually specified.
channel_arg =
grpc_channel_args_find(chand->resolver_result, GRPC_ARG_LB_ADDRESSES);
if (channel_arg != NULL) {
GPR_ASSERT(channel_arg->type == GRPC_ARG_POINTER);
grpc_lb_addresses *addresses = channel_arg->value.pointer.p;
bool found_backend_address = false;
for (size_t i = 0; i < addresses->num_addresses; ++i) {
if (!addresses->addresses[i].is_balancer) {
found_backend_address = true;
break;
}
}
if (!found_backend_address) {
if (lb_policy_name != NULL && strcmp(lb_policy_name, "grpclb") != 0) {
gpr_log(GPR_INFO,
"resolver requested LB policy %s but provided only balancer "
"addresses, no backend addresses -- forcing use of grpclb LB "
"policy",
lb_policy_name);
}
lb_policy_name = "grpclb";
}
}
// Use pick_first if nothing was specified and we didn't select grpclb
// above.
if (lb_policy_name == NULL) lb_policy_name = "pick_first";
// Instantiate LB policy.
grpc_lb_policy_args lb_policy_args;
lb_policy_args.args = chand->resolver_result;
lb_policy_args.client_channel_factory = chand->client_channel_factory;
lb_policy =
grpc_lb_policy_create(exec_ctx, lb_policy_name, &lb_policy_args);
if (lb_policy != NULL) {
GRPC_LB_POLICY_REF(lb_policy, "config_change");
GRPC_ERROR_UNREF(state_error);
state =
grpc_lb_policy_check_connectivity(exec_ctx, lb_policy, &state_error);
}
// Find service config.
channel_arg =
grpc_channel_args_find(chand->resolver_result, GRPC_ARG_SERVICE_CONFIG);
if (channel_arg != NULL) {
GPR_ASSERT(channel_arg->type == GRPC_ARG_STRING);
service_config_json = gpr_strdup(channel_arg->value.string);
grpc_service_config *service_config =
grpc_service_config_create(service_config_json);
if (service_config != NULL) {
method_params_table = grpc_service_config_create_method_config_table(
exec_ctx, service_config, method_parameters_create_from_json,
&method_parameters_vtable);
grpc_service_config_destroy(service_config);
}
}
// Before we clean up, save a copy of lb_policy_name, since it might
// be pointing to data inside chand->resolver_result.
// The copy will be saved in chand->lb_policy_name below.
lb_policy_name = gpr_strdup(lb_policy_name);
grpc_channel_args_destroy(exec_ctx, chand->resolver_result);
chand->resolver_result = NULL;
}
if (lb_policy != NULL) {
grpc_pollset_set_add_pollset_set(exec_ctx, lb_policy->interested_parties,
chand->interested_parties);
}
gpr_mu_lock(&chand->mu);
if (lb_policy_name != NULL) {
gpr_free(chand->lb_policy_name);
chand->lb_policy_name = lb_policy_name;
}
old_lb_policy = chand->lb_policy;
chand->lb_policy = lb_policy;
if (service_config_json != NULL) {
gpr_free(chand->service_config_json);
chand->service_config_json = service_config_json;
}
if (chand->method_params_table != NULL) {
grpc_mdstr_hash_table_unref(exec_ctx, chand->method_params_table);
}
chand->method_params_table = method_params_table;
if (lb_policy != NULL) {
grpc_exec_ctx_enqueue_list(exec_ctx, &chand->waiting_for_config_closures,
NULL);
} else if (chand->resolver == NULL /* disconnected */) {
grpc_closure_list_fail_all(
&chand->waiting_for_config_closures,
GRPC_ERROR_CREATE_REFERENCING("Channel disconnected", &error, 1));
grpc_exec_ctx_enqueue_list(exec_ctx, &chand->waiting_for_config_closures,
NULL);
}
if (lb_policy != NULL && chand->exit_idle_when_lb_policy_arrives) {
GRPC_LB_POLICY_REF(lb_policy, "exit_idle");
exit_idle = true;
chand->exit_idle_when_lb_policy_arrives = false;
}
if (error == GRPC_ERROR_NONE && chand->resolver) {
set_channel_connectivity_state_locked(
exec_ctx, chand, state, GRPC_ERROR_REF(state_error), "new_lb+resolver");
if (lb_policy != NULL) {
watch_lb_policy(exec_ctx, chand, lb_policy, state);
}
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
grpc_resolver_next(exec_ctx, chand->resolver, &chand->resolver_result,
&chand->on_resolver_result_changed);
gpr_mu_unlock(&chand->mu);
} else {
if (chand->resolver != NULL) {
grpc_resolver_shutdown(exec_ctx, chand->resolver);
GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
chand->resolver = NULL;
}
grpc_error *refs[] = {error, state_error};
set_channel_connectivity_state_locked(
exec_ctx, chand, GRPC_CHANNEL_SHUTDOWN,
GRPC_ERROR_CREATE_REFERENCING("Got config after disconnection", refs,
GPR_ARRAY_SIZE(refs)),
"resolver_gone");
gpr_mu_unlock(&chand->mu);
}
if (exit_idle) {
grpc_lb_policy_exit_idle(exec_ctx, lb_policy);
GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "exit_idle");
}
if (old_lb_policy != NULL) {
grpc_pollset_set_del_pollset_set(
exec_ctx, old_lb_policy->interested_parties, chand->interested_parties);
GRPC_LB_POLICY_UNREF(exec_ctx, old_lb_policy, "channel");
}
if (lb_policy != NULL) {
GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "config_change");
}
GRPC_CHANNEL_STACK_UNREF(exec_ctx, chand->owning_stack, "resolver");
GRPC_ERROR_UNREF(state_error);
}
static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
grpc_channel_element *elem,
grpc_transport_op *op) {
channel_data *chand = elem->channel_data;
grpc_exec_ctx_sched(exec_ctx, op->on_consumed, GRPC_ERROR_NONE, NULL);
GPR_ASSERT(op->set_accept_stream == false);
if (op->bind_pollset != NULL) {
grpc_pollset_set_add_pollset(exec_ctx, chand->interested_parties,
op->bind_pollset);
}
gpr_mu_lock(&chand->mu);
if (op->on_connectivity_state_change != NULL) {
grpc_connectivity_state_notify_on_state_change(
exec_ctx, &chand->state_tracker, op->connectivity_state,
op->on_connectivity_state_change);
op->on_connectivity_state_change = NULL;
op->connectivity_state = NULL;
}
if (op->send_ping != NULL) {
if (chand->lb_policy == NULL) {
grpc_exec_ctx_sched(exec_ctx, op->send_ping,
GRPC_ERROR_CREATE("Ping with no load balancing"),
NULL);
} else {
grpc_lb_policy_ping_one(exec_ctx, chand->lb_policy, op->send_ping);
op->bind_pollset = NULL;
}
op->send_ping = NULL;
}
if (op->disconnect_with_error != GRPC_ERROR_NONE) {
if (chand->resolver != NULL) {
set_channel_connectivity_state_locked(
exec_ctx, chand, GRPC_CHANNEL_SHUTDOWN,
GRPC_ERROR_REF(op->disconnect_with_error), "disconnect");
grpc_resolver_shutdown(exec_ctx, chand->resolver);
GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
chand->resolver = NULL;
if (!chand->started_resolving) {
grpc_closure_list_fail_all(&chand->waiting_for_config_closures,
GRPC_ERROR_REF(op->disconnect_with_error));
grpc_exec_ctx_enqueue_list(exec_ctx,
&chand->waiting_for_config_closures, NULL);
}
if (chand->lb_policy != NULL) {
grpc_pollset_set_del_pollset_set(exec_ctx,
chand->lb_policy->interested_parties,
chand->interested_parties);
GRPC_LB_POLICY_UNREF(exec_ctx, chand->lb_policy, "channel");
chand->lb_policy = NULL;
}
}
GRPC_ERROR_UNREF(op->disconnect_with_error);
}
gpr_mu_unlock(&chand->mu);
}
static void cc_get_channel_info(grpc_exec_ctx *exec_ctx,
grpc_channel_element *elem,
const grpc_channel_info *info) {
channel_data *chand = elem->channel_data;
gpr_mu_lock(&chand->mu);
if (info->lb_policy_name != NULL) {
*info->lb_policy_name = chand->lb_policy_name == NULL
? NULL
: gpr_strdup(chand->lb_policy_name);
}
if (info->service_config_json != NULL) {
*info->service_config_json = chand->service_config_json == NULL
? NULL
: gpr_strdup(chand->service_config_json);
}
gpr_mu_unlock(&chand->mu);
}
/* Constructor for channel_data */
static void cc_init_channel_elem(grpc_exec_ctx *exec_ctx,
grpc_channel_element *elem,
grpc_channel_element_args *args) {
channel_data *chand = elem->channel_data;
memset(chand, 0, sizeof(*chand));
GPR_ASSERT(args->is_last);
GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
gpr_mu_init(&chand->mu);
grpc_closure_init(&chand->on_resolver_result_changed,
on_resolver_result_changed, chand);
chand->owning_stack = args->channel_stack;
grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE,
"client_channel");
chand->interested_parties = grpc_pollset_set_create();
}
/* Destructor for channel_data */
static void cc_destroy_channel_elem(grpc_exec_ctx *exec_ctx,
grpc_channel_element *elem) {
channel_data *chand = elem->channel_data;
if (chand->resolver != NULL) {
grpc_resolver_shutdown(exec_ctx, chand->resolver);
GRPC_RESOLVER_UNREF(exec_ctx, chand->resolver, "channel");
}
if (chand->client_channel_factory != NULL) {
grpc_client_channel_factory_unref(exec_ctx, chand->client_channel_factory);
}
if (chand->lb_policy != NULL) {
grpc_pollset_set_del_pollset_set(exec_ctx,
chand->lb_policy->interested_parties,
chand->interested_parties);
GRPC_LB_POLICY_UNREF(exec_ctx, chand->lb_policy, "channel");
}
gpr_free(chand->lb_policy_name);
gpr_free(chand->service_config_json);
if (chand->method_params_table != NULL) {
grpc_mdstr_hash_table_unref(exec_ctx, chand->method_params_table);
}
grpc_connectivity_state_destroy(exec_ctx, &chand->state_tracker);
grpc_pollset_set_destroy(chand->interested_parties);
gpr_mu_destroy(&chand->mu);
}
/*************************************************************************
* PER-CALL FUNCTIONS
*/
#define GET_CALL(call_data) \
((grpc_subchannel_call *)(gpr_atm_acq_load(&(call_data)->subchannel_call)))
#define CANCELLED_CALL ((grpc_subchannel_call *)1)
typedef enum {
GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING,
GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL
} subchannel_creation_phase;
/** Call data. Holds a pointer to grpc_subchannel_call and the
associated machinery to create such a pointer.
Handles queueing of stream ops until a call object is ready, waiting
for initial metadata before trying to create a call object,
and handling cancellation gracefully. */
typedef struct client_channel_call_data {
// State for handling deadlines.
// The code in deadline_filter.c requires this to be the first field.
// TODO(roth): This is slightly sub-optimal in that grpc_deadline_state
// and this struct both independently store a pointer to the call
// stack and each has its own mutex. If/when we have time, find a way
// to avoid this without breaking the grpc_deadline_state abstraction.
grpc_deadline_state deadline_state;
grpc_mdstr *path; // Request path.
gpr_timespec call_start_time;
gpr_timespec deadline;
wait_for_ready_value wait_for_ready_from_service_config;
grpc_closure read_service_config;
grpc_error *cancel_error;
/** either 0 for no call, 1 for cancelled, or a pointer to a
grpc_subchannel_call */
gpr_atm subchannel_call;
gpr_mu mu;
subchannel_creation_phase creation_phase;
grpc_connected_subchannel *connected_subchannel;
grpc_polling_entity *pollent;
grpc_transport_stream_op **waiting_ops;
size_t waiting_ops_count;
size_t waiting_ops_capacity;
grpc_closure next_step;
grpc_call_stack *owning_call;
grpc_linked_mdelem lb_token_mdelem;
} call_data;
static void add_waiting_locked(call_data *calld, grpc_transport_stream_op *op) {
GPR_TIMER_BEGIN("add_waiting_locked", 0);
if (calld->waiting_ops_count == calld->waiting_ops_capacity) {
calld->waiting_ops_capacity = GPR_MAX(3, 2 * calld->waiting_ops_capacity);
calld->waiting_ops =
gpr_realloc(calld->waiting_ops,
calld->waiting_ops_capacity * sizeof(*calld->waiting_ops));
}
calld->waiting_ops[calld->waiting_ops_count++] = op;
GPR_TIMER_END("add_waiting_locked", 0);
}
static void fail_locked(grpc_exec_ctx *exec_ctx, call_data *calld,
grpc_error *error) {
size_t i;
for (i = 0; i < calld->waiting_ops_count; i++) {
grpc_transport_stream_op_finish_with_failure(
exec_ctx, calld->waiting_ops[i], GRPC_ERROR_REF(error));
}
calld->waiting_ops_count = 0;
GRPC_ERROR_UNREF(error);
}
typedef struct {
grpc_transport_stream_op **ops;
size_t nops;
grpc_subchannel_call *call;
} retry_ops_args;
static void retry_ops(grpc_exec_ctx *exec_ctx, void *args, grpc_error *error) {
retry_ops_args *a = args;
size_t i;
for (i = 0; i < a->nops; i++) {
grpc_subchannel_call_process_op(exec_ctx, a->call, a->ops[i]);
}
GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, a->call, "retry_ops");
gpr_free(a->ops);
gpr_free(a);
}
static void retry_waiting_locked(grpc_exec_ctx *exec_ctx, call_data *calld) {
if (calld->waiting_ops_count == 0) {
return;
}
retry_ops_args *a = gpr_malloc(sizeof(*a));
a->ops = calld->waiting_ops;
a->nops = calld->waiting_ops_count;
a->call = GET_CALL(calld);
if (a->call == CANCELLED_CALL) {
gpr_free(a);
fail_locked(exec_ctx, calld, GRPC_ERROR_CANCELLED);
return;
}
calld->waiting_ops = NULL;
calld->waiting_ops_count = 0;
calld->waiting_ops_capacity = 0;
GRPC_SUBCHANNEL_CALL_REF(a->call, "retry_ops");
grpc_exec_ctx_sched(exec_ctx, grpc_closure_create(retry_ops, a),
GRPC_ERROR_NONE, NULL);
}
static void subchannel_ready(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_call_element *elem = arg;
call_data *calld = elem->call_data;
channel_data *chand = elem->channel_data;
gpr_mu_lock(&calld->mu);
GPR_ASSERT(calld->creation_phase ==
GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL);
grpc_polling_entity_del_from_pollset_set(exec_ctx, calld->pollent,
chand->interested_parties);
calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
if (calld->connected_subchannel == NULL) {
gpr_atm_no_barrier_store(&calld->subchannel_call, 1);
fail_locked(exec_ctx, calld, GRPC_ERROR_CREATE_REFERENCING(
"Failed to create subchannel", &error, 1));
} else if (GET_CALL(calld) == CANCELLED_CALL) {
/* already cancelled before subchannel became ready */
fail_locked(exec_ctx, calld,
GRPC_ERROR_CREATE_REFERENCING(
"Cancelled before creating subchannel", &error, 1));
} else {
/* Create call on subchannel. */
grpc_subchannel_call *subchannel_call = NULL;
grpc_error *new_error = grpc_connected_subchannel_create_call(
exec_ctx, calld->connected_subchannel, calld->pollent, calld->path,
calld->call_start_time, calld->deadline, &subchannel_call);
if (new_error != GRPC_ERROR_NONE) {
new_error = grpc_error_add_child(new_error, error);
subchannel_call = CANCELLED_CALL;
fail_locked(exec_ctx, calld, new_error);
}
gpr_atm_rel_store(&calld->subchannel_call,
(gpr_atm)(uintptr_t)subchannel_call);
retry_waiting_locked(exec_ctx, calld);
}
gpr_mu_unlock(&calld->mu);
GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "pick_subchannel");
}
static char *cc_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
call_data *calld = elem->call_data;
grpc_subchannel_call *subchannel_call = GET_CALL(calld);
if (subchannel_call == NULL || subchannel_call == CANCELLED_CALL) {
return NULL;
} else {
return grpc_subchannel_call_get_peer(exec_ctx, subchannel_call);
}
}
typedef struct {
grpc_metadata_batch *initial_metadata;
uint32_t initial_metadata_flags;
grpc_connected_subchannel **connected_subchannel;
grpc_closure *on_ready;
grpc_call_element *elem;
grpc_closure closure;
} continue_picking_args;
/** Return true if subchannel is available immediately (in which case on_ready
should not be called), or false otherwise (in which case on_ready should be
called when the subchannel is available). */
static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
grpc_metadata_batch *initial_metadata,
uint32_t initial_metadata_flags,
grpc_connected_subchannel **connected_subchannel,
grpc_closure *on_ready, grpc_error *error);
static void continue_picking(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
continue_picking_args *cpa = arg;
if (cpa->connected_subchannel == NULL) {
/* cancelled, do nothing */
} else if (error != GRPC_ERROR_NONE) {
grpc_exec_ctx_sched(exec_ctx, cpa->on_ready, GRPC_ERROR_REF(error), NULL);
} else {
call_data *calld = cpa->elem->call_data;
gpr_mu_lock(&calld->mu);
if (pick_subchannel(exec_ctx, cpa->elem, cpa->initial_metadata,
cpa->initial_metadata_flags, cpa->connected_subchannel,
cpa->on_ready, GRPC_ERROR_NONE)) {
grpc_exec_ctx_sched(exec_ctx, cpa->on_ready, GRPC_ERROR_NONE, NULL);
}
gpr_mu_unlock(&calld->mu);
}
gpr_free(cpa);
}
static bool pick_subchannel(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
grpc_metadata_batch *initial_metadata,
uint32_t initial_metadata_flags,
grpc_connected_subchannel **connected_subchannel,
grpc_closure *on_ready, grpc_error *error) {
GPR_TIMER_BEGIN("pick_subchannel", 0);
channel_data *chand = elem->channel_data;
call_data *calld = elem->call_data;
continue_picking_args *cpa;
grpc_closure *closure;
GPR_ASSERT(connected_subchannel);
gpr_mu_lock(&chand->mu);
if (initial_metadata == NULL) {
if (chand->lb_policy != NULL) {
grpc_lb_policy_cancel_pick(exec_ctx, chand->lb_policy,
connected_subchannel, GRPC_ERROR_REF(error));
}
for (closure = chand->waiting_for_config_closures.head; closure != NULL;
closure = closure->next_data.next) {
cpa = closure->cb_arg;
if (cpa->connected_subchannel == connected_subchannel) {
cpa->connected_subchannel = NULL;
grpc_exec_ctx_sched(
exec_ctx, cpa->on_ready,
GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1), NULL);
}
}
gpr_mu_unlock(&chand->mu);
GPR_TIMER_END("pick_subchannel", 0);
GRPC_ERROR_UNREF(error);
return true;
}
GPR_ASSERT(error == GRPC_ERROR_NONE);
if (chand->lb_policy != NULL) {
grpc_lb_policy *lb_policy = chand->lb_policy;
GRPC_LB_POLICY_REF(lb_policy, "pick_subchannel");
gpr_mu_unlock(&chand->mu);
// If the application explicitly set wait_for_ready, use that.
// Otherwise, if the service config specified a value for this
// method, use that.
const bool wait_for_ready_set_from_api =
initial_metadata_flags &
GRPC_INITIAL_METADATA_WAIT_FOR_READY_EXPLICITLY_SET;
const bool wait_for_ready_set_from_service_config =
calld->wait_for_ready_from_service_config != WAIT_FOR_READY_UNSET;
if (!wait_for_ready_set_from_api &&
wait_for_ready_set_from_service_config) {
if (calld->wait_for_ready_from_service_config == WAIT_FOR_READY_TRUE) {
initial_metadata_flags |= GRPC_INITIAL_METADATA_WAIT_FOR_READY;
} else {
initial_metadata_flags &= ~GRPC_INITIAL_METADATA_WAIT_FOR_READY;
}
}
// TODO(dgq): make this deadline configurable somehow.
const grpc_lb_policy_pick_args inputs = {
initial_metadata, initial_metadata_flags, &calld->lb_token_mdelem,
gpr_inf_future(GPR_CLOCK_MONOTONIC)};
const bool result = grpc_lb_policy_pick(
exec_ctx, lb_policy, &inputs, connected_subchannel, NULL, on_ready);
GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "pick_subchannel");
GPR_TIMER_END("pick_subchannel", 0);
return result;
}
if (chand->resolver != NULL && !chand->started_resolving) {
chand->started_resolving = true;
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
grpc_resolver_next(exec_ctx, chand->resolver, &chand->resolver_result,
&chand->on_resolver_result_changed);
}
if (chand->resolver != NULL) {
cpa = gpr_malloc(sizeof(*cpa));
cpa->initial_metadata = initial_metadata;
cpa->initial_metadata_flags = initial_metadata_flags;
cpa->connected_subchannel = connected_subchannel;
cpa->on_ready = on_ready;
cpa->elem = elem;
grpc_closure_init(&cpa->closure, continue_picking, cpa);
grpc_closure_list_append(&chand->waiting_for_config_closures, &cpa->closure,
GRPC_ERROR_NONE);
} else {
grpc_exec_ctx_sched(exec_ctx, on_ready, GRPC_ERROR_CREATE("Disconnected"),
NULL);
}
gpr_mu_unlock(&chand->mu);
GPR_TIMER_END("pick_subchannel", 0);
return false;
}
// The logic here is fairly complicated, due to (a) the fact that we
// need to handle the case where we receive the send op before the
// initial metadata op, and (b) the need for efficiency, especially in
// the streaming case.
// TODO(ctiller): Explain this more thoroughly.
static void cc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem,
grpc_transport_stream_op *op) {
call_data *calld = elem->call_data;
channel_data *chand = elem->channel_data;
GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
grpc_deadline_state_client_start_transport_stream_op(exec_ctx, elem, op);
/* try to (atomically) get the call */
grpc_subchannel_call *call = GET_CALL(calld);
GPR_TIMER_BEGIN("cc_start_transport_stream_op", 0);
if (call == CANCELLED_CALL) {
grpc_transport_stream_op_finish_with_failure(
exec_ctx, op, GRPC_ERROR_REF(calld->cancel_error));
GPR_TIMER_END("cc_start_transport_stream_op", 0);
return;
}
if (call != NULL) {
grpc_subchannel_call_process_op(exec_ctx, call, op);
GPR_TIMER_END("cc_start_transport_stream_op", 0);
return;
}
/* we failed; lock and figure out what to do */
gpr_mu_lock(&calld->mu);
retry:
/* need to recheck that another thread hasn't set the call */
call = GET_CALL(calld);
if (call == CANCELLED_CALL) {
gpr_mu_unlock(&calld->mu);
grpc_transport_stream_op_finish_with_failure(
exec_ctx, op, GRPC_ERROR_REF(calld->cancel_error));
GPR_TIMER_END("cc_start_transport_stream_op", 0);
return;
}
if (call != NULL) {
gpr_mu_unlock(&calld->mu);
grpc_subchannel_call_process_op(exec_ctx, call, op);
GPR_TIMER_END("cc_start_transport_stream_op", 0);
return;
}
/* if this is a cancellation, then we can raise our cancelled flag */
if (op->cancel_error != GRPC_ERROR_NONE) {
if (!gpr_atm_rel_cas(&calld->subchannel_call, 0,
(gpr_atm)(uintptr_t)CANCELLED_CALL)) {
goto retry;
} else {
// Stash a copy of cancel_error in our call data, so that we can use
// it for subsequent operations. This ensures that if the call is
// cancelled before any ops are passed down (e.g., if the deadline
// is in the past when the call starts), we can return the right
// error to the caller when the first op does get passed down.
calld->cancel_error = GRPC_ERROR_REF(op->cancel_error);
switch (calld->creation_phase) {
case GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING:
fail_locked(exec_ctx, calld, GRPC_ERROR_REF(op->cancel_error));
break;
case GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL:
pick_subchannel(exec_ctx, elem, NULL, 0, &calld->connected_subchannel,
NULL, GRPC_ERROR_REF(op->cancel_error));
break;
}
gpr_mu_unlock(&calld->mu);
grpc_transport_stream_op_finish_with_failure(
exec_ctx, op, GRPC_ERROR_REF(op->cancel_error));
GPR_TIMER_END("cc_start_transport_stream_op", 0);
return;
}
}
/* if we don't have a subchannel, try to get one */
if (calld->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING &&
calld->connected_subchannel == NULL &&
op->send_initial_metadata != NULL) {
calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_PICKING_SUBCHANNEL;
grpc_closure_init(&calld->next_step, subchannel_ready, elem);
GRPC_CALL_STACK_REF(calld->owning_call, "pick_subchannel");
/* If a subchannel is not available immediately, the polling entity from
call_data should be provided to channel_data's interested_parties, so
that IO of the lb_policy and resolver could be done under it. */
if (pick_subchannel(exec_ctx, elem, op->send_initial_metadata,
op->send_initial_metadata_flags,
&calld->connected_subchannel, &calld->next_step,
GRPC_ERROR_NONE)) {
calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "pick_subchannel");
} else {
grpc_polling_entity_add_to_pollset_set(exec_ctx, calld->pollent,
chand->interested_parties);
}
}
/* if we've got a subchannel, then let's ask it to create a call */
if (calld->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING &&
calld->connected_subchannel != NULL) {
grpc_subchannel_call *subchannel_call = NULL;
grpc_error *error = grpc_connected_subchannel_create_call(
exec_ctx, calld->connected_subchannel, calld->pollent, calld->path,
calld->call_start_time, calld->deadline, &subchannel_call);
if (error != GRPC_ERROR_NONE) {
subchannel_call = CANCELLED_CALL;
fail_locked(exec_ctx, calld, GRPC_ERROR_REF(error));
grpc_transport_stream_op_finish_with_failure(exec_ctx, op, error);
}
gpr_atm_rel_store(&calld->subchannel_call,
(gpr_atm)(uintptr_t)subchannel_call);
retry_waiting_locked(exec_ctx, calld);
goto retry;
}
/* nothing to be done but wait */
add_waiting_locked(calld, op);
gpr_mu_unlock(&calld->mu);
GPR_TIMER_END("cc_start_transport_stream_op", 0);
}
// Gets data from the service config. Invoked when the resolver returns
// its initial result.
static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
grpc_call_element *elem = arg;
channel_data *chand = elem->channel_data;
call_data *calld = elem->call_data;
// If this is an error, there's no point in looking at the service config.
if (error == GRPC_ERROR_NONE) {
// Get the method config table from channel data.
gpr_mu_lock(&chand->mu);
grpc_mdstr_hash_table *method_params_table = NULL;
if (chand->method_params_table != NULL) {
method_params_table =
grpc_mdstr_hash_table_ref(chand->method_params_table);
}
gpr_mu_unlock(&chand->mu);
// If the method config table was present, use it.
if (method_params_table != NULL) {
const method_parameters *method_params = grpc_method_config_table_get(
exec_ctx, method_params_table, calld->path);
if (method_params != NULL) {
const bool have_method_timeout =
gpr_time_cmp(method_params->timeout, gpr_time_0(GPR_TIMESPAN)) != 0;
if (have_method_timeout ||
method_params->wait_for_ready != WAIT_FOR_READY_UNSET) {
gpr_mu_lock(&calld->mu);
if (have_method_timeout) {
const gpr_timespec per_method_deadline =
gpr_time_add(calld->call_start_time, method_params->timeout);
if (gpr_time_cmp(per_method_deadline, calld->deadline) < 0) {
calld->deadline = per_method_deadline;
// Reset deadline timer.
grpc_deadline_state_reset(exec_ctx, elem, calld->deadline);
}
}
if (method_params->wait_for_ready != WAIT_FOR_READY_UNSET) {
calld->wait_for_ready_from_service_config =
method_params->wait_for_ready;
}
gpr_mu_unlock(&calld->mu);
}
}
grpc_mdstr_hash_table_unref(exec_ctx, method_params_table);
}
}
GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call, "read_service_config");
}
/* Constructor for call_data */
static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem,
grpc_call_element_args *args) {
channel_data *chand = elem->channel_data;
call_data *calld = elem->call_data;
// Initialize data members.
grpc_deadline_state_init(exec_ctx, elem, args->call_stack);
calld->path = GRPC_MDSTR_REF(args->path);
calld->call_start_time = args->start_time;
calld->deadline = gpr_convert_clock_type(args->deadline, GPR_CLOCK_MONOTONIC);
calld->wait_for_ready_from_service_config = WAIT_FOR_READY_UNSET;
calld->cancel_error = GRPC_ERROR_NONE;
gpr_atm_rel_store(&calld->subchannel_call, 0);
gpr_mu_init(&calld->mu);
calld->connected_subchannel = NULL;
calld->waiting_ops = NULL;
calld->waiting_ops_count = 0;
calld->waiting_ops_capacity = 0;
calld->creation_phase = GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING;
calld->owning_call = args->call_stack;
calld->pollent = NULL;
// If the resolver has already returned results, then we can access
// the service config parameters immediately. Otherwise, we need to
// defer that work until the resolver returns an initial result.
// TODO(roth): This code is almost but not quite identical to the code
// in read_service_config() above. It would be nice to find a way to
// combine them, to avoid having to maintain it twice.
gpr_mu_lock(&chand->mu);
if (chand->lb_policy != NULL) {
// We already have a resolver result, so check for service config.
if (chand->method_params_table != NULL) {
grpc_mdstr_hash_table *method_params_table =
grpc_mdstr_hash_table_ref(chand->method_params_table);
gpr_mu_unlock(&chand->mu);
method_parameters *method_params = grpc_method_config_table_get(
exec_ctx, method_params_table, args->path);
if (method_params != NULL) {
if (gpr_time_cmp(method_params->timeout,
gpr_time_0(GPR_CLOCK_MONOTONIC)) != 0) {
gpr_timespec per_method_deadline =
gpr_time_add(calld->call_start_time, method_params->timeout);
calld->deadline = gpr_time_min(calld->deadline, per_method_deadline);
}
if (method_params->wait_for_ready != WAIT_FOR_READY_UNSET) {
calld->wait_for_ready_from_service_config =
method_params->wait_for_ready;
}
}
grpc_mdstr_hash_table_unref(exec_ctx, method_params_table);
} else {
gpr_mu_unlock(&chand->mu);
}
} else {
// We don't yet have a resolver result, so register a callback to
// get the service config data once the resolver returns.
// Take a reference to the call stack to be owned by the callback.
GRPC_CALL_STACK_REF(calld->owning_call, "read_service_config");
grpc_closure_init(&calld->read_service_config, read_service_config, elem);
grpc_closure_list_append(&chand->waiting_for_config_closures,
&calld->read_service_config, GRPC_ERROR_NONE);
gpr_mu_unlock(&chand->mu);
}
// Start the deadline timer with the current deadline value. If we
// do not yet have service config data, then the timer may be reset
// later.
grpc_deadline_state_start(exec_ctx, elem, calld->deadline);
return GRPC_ERROR_NONE;
}
/* Destructor for call_data */
static void cc_destroy_call_elem(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem,
const grpc_call_final_info *final_info,
void *and_free_memory) {
call_data *calld = elem->call_data;
grpc_deadline_state_destroy(exec_ctx, elem);
GRPC_MDSTR_UNREF(exec_ctx, calld->path);
GRPC_ERROR_UNREF(calld->cancel_error);
grpc_subchannel_call *call = GET_CALL(calld);
if (call != NULL && call != CANCELLED_CALL) {
GRPC_SUBCHANNEL_CALL_UNREF(exec_ctx, call, "client_channel_destroy_call");
}
GPR_ASSERT(calld->creation_phase == GRPC_SUBCHANNEL_CALL_HOLDER_NOT_CREATING);
gpr_mu_destroy(&calld->mu);
GPR_ASSERT(calld->waiting_ops_count == 0);
if (calld->connected_subchannel != NULL) {
GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, calld->connected_subchannel,
"picked");
}
gpr_free(calld->waiting_ops);
gpr_free(and_free_memory);
}
static void cc_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem,
grpc_polling_entity *pollent) {
call_data *calld = elem->call_data;
calld->pollent = pollent;
}
/*************************************************************************
* EXPORTED SYMBOLS
*/
const grpc_channel_filter grpc_client_channel_filter = {
cc_start_transport_stream_op,
cc_start_transport_op,
sizeof(call_data),
cc_init_call_elem,
cc_set_pollset_or_pollset_set,
cc_destroy_call_elem,
sizeof(channel_data),
cc_init_channel_elem,
cc_destroy_channel_elem,
cc_get_peer,
cc_get_channel_info,
"client-channel",
};
void grpc_client_channel_finish_initialization(
grpc_exec_ctx *exec_ctx, grpc_channel_stack *channel_stack,
grpc_resolver *resolver,
grpc_client_channel_factory *client_channel_factory) {
/* post construction initialization: set the transport setup pointer */
GPR_ASSERT(client_channel_factory != NULL);
grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
channel_data *chand = elem->channel_data;
gpr_mu_lock(&chand->mu);
GPR_ASSERT(!chand->resolver);
chand->resolver = resolver;
GRPC_RESOLVER_REF(resolver, "channel");
if (!grpc_closure_list_empty(chand->waiting_for_config_closures) ||
chand->exit_idle_when_lb_policy_arrives) {
chand->started_resolving = true;
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
grpc_resolver_next(exec_ctx, resolver, &chand->resolver_result,
&chand->on_resolver_result_changed);
}
chand->client_channel_factory = client_channel_factory;
grpc_client_channel_factory_ref(client_channel_factory);
gpr_mu_unlock(&chand->mu);
}
grpc_connectivity_state grpc_client_channel_check_connectivity_state(
grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, int try_to_connect) {
channel_data *chand = elem->channel_data;
grpc_connectivity_state out;
gpr_mu_lock(&chand->mu);
out = grpc_connectivity_state_check(&chand->state_tracker, NULL);
if (out == GRPC_CHANNEL_IDLE && try_to_connect) {
if (chand->lb_policy != NULL) {
grpc_lb_policy_exit_idle(exec_ctx, chand->lb_policy);
} else {
chand->exit_idle_when_lb_policy_arrives = true;
if (!chand->started_resolving && chand->resolver != NULL) {
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
chand->started_resolving = true;
grpc_resolver_next(exec_ctx, chand->resolver, &chand->resolver_result,
&chand->on_resolver_result_changed);
}
}
}
gpr_mu_unlock(&chand->mu);
return out;
}
typedef struct {
channel_data *chand;
grpc_pollset *pollset;
grpc_closure *on_complete;
grpc_closure my_closure;
} external_connectivity_watcher;
static void on_external_watch_complete(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
external_connectivity_watcher *w = arg;
grpc_closure *follow_up = w->on_complete;
grpc_pollset_set_del_pollset(exec_ctx, w->chand->interested_parties,
w->pollset);
GRPC_CHANNEL_STACK_UNREF(exec_ctx, w->chand->owning_stack,
"external_connectivity_watcher");
gpr_free(w);
follow_up->cb(exec_ctx, follow_up->cb_arg, error);
}
void grpc_client_channel_watch_connectivity_state(
grpc_exec_ctx *exec_ctx, grpc_channel_element *elem, grpc_pollset *pollset,
grpc_connectivity_state *state, grpc_closure *on_complete) {
channel_data *chand = elem->channel_data;
external_connectivity_watcher *w = gpr_malloc(sizeof(*w));
w->chand = chand;
w->pollset = pollset;
w->on_complete = on_complete;
grpc_pollset_set_add_pollset(exec_ctx, chand->interested_parties, pollset);
grpc_closure_init(&w->my_closure, on_external_watch_complete, w);
GRPC_CHANNEL_STACK_REF(w->chand->owning_stack,
"external_connectivity_watcher");
gpr_mu_lock(&chand->mu);
grpc_connectivity_state_notify_on_state_change(
exec_ctx, &chand->state_tracker, state, &w->my_closure);
gpr_mu_unlock(&chand->mu);
}
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