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grpc/src/core/channel/client_channel.c

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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/channel/client_channel.h"
#include <stdio.h>
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <grpc/support/useful.h>
#include "src/core/channel/channel_args.h"
#include "src/core/channel/connected_channel.h"
#include "src/core/channel/subchannel_call_holder.h"
#include "src/core/iomgr/iomgr.h"
#include "src/core/profiling/timers.h"
#include "src/core/support/string.h"
#include "src/core/surface/channel.h"
#include "src/core/transport/connectivity_state.h"
/* Client channel implementation */
typedef grpc_subchannel_call_holder call_data;
typedef struct client_channel_channel_data {
/** resolver for this channel */
grpc_resolver *resolver;
/** have we started resolving this channel */
int started_resolving;
/** mutex protecting client configuration, including all
variables below in this data structure */
gpr_mu mu_config;
/** currently active load balancer - guarded by mu_config */
grpc_lb_policy *lb_policy;
/** incoming configuration - set by resolver.next
guarded by mu_config */
grpc_client_config *incoming_configuration;
/** 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_config_changed;
/** connectivity state being tracked */
grpc_connectivity_state_tracker state_tracker;
/** when an lb_policy arrives, should we try to exit idle */
int exit_idle_when_lb_policy_arrives;
/** owning stack */
grpc_channel_stack *owning_stack;
} 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;
typedef struct {
grpc_closure closure;
grpc_call_element *elem;
} waiting_call;
static char *cc_get_peer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
return grpc_subchannel_call_holder_get_peer(exec_ctx, elem->call_data);
}
static void cc_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem,
grpc_transport_stream_op *op) {
GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
grpc_subchannel_call_holder_perform_op(exec_ctx, elem->call_data, op);
}
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 on_lb_policy_state_changed_locked(
grpc_exec_ctx *exec_ctx, lb_policy_connectivity_watcher *w) {
/* check if the notification is for a stale policy */
if (w->lb_policy != w->chand->lb_policy) return;
grpc_connectivity_state_set(exec_ctx, &w->chand->state_tracker, w->state,
"lb_changed");
if (w->state != GRPC_CHANNEL_FATAL_FAILURE) {
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,
int iomgr_success) {
lb_policy_connectivity_watcher *w = arg;
gpr_mu_lock(&w->chand->mu_config);
on_lb_policy_state_changed_locked(exec_ctx, w);
gpr_mu_unlock(&w->chand->mu_config);
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 cc_on_config_changed(grpc_exec_ctx *exec_ctx, void *arg,
int iomgr_success) {
channel_data *chand = arg;
grpc_lb_policy *lb_policy = NULL;
grpc_lb_policy *old_lb_policy;
grpc_resolver *old_resolver;
grpc_connectivity_state state = GRPC_CHANNEL_TRANSIENT_FAILURE;
int exit_idle = 0;
if (chand->incoming_configuration != NULL) {
lb_policy = grpc_client_config_get_lb_policy(chand->incoming_configuration);
if (lb_policy != NULL) {
GRPC_LB_POLICY_REF(lb_policy, "channel");
GRPC_LB_POLICY_REF(lb_policy, "config_change");
state = grpc_lb_policy_check_connectivity(exec_ctx, lb_policy);
}
grpc_client_config_unref(exec_ctx, chand->incoming_configuration);
}
chand->incoming_configuration = NULL;
gpr_mu_lock(&chand->mu_config);
old_lb_policy = chand->lb_policy;
chand->lb_policy = lb_policy;
if (lb_policy != NULL || chand->resolver == NULL /* disconnected */) {
grpc_exec_ctx_enqueue_list(exec_ctx, &chand->waiting_for_config_closures);
}
if (lb_policy != NULL && chand->exit_idle_when_lb_policy_arrives) {
GRPC_LB_POLICY_REF(lb_policy, "exit_idle");
exit_idle = 1;
chand->exit_idle_when_lb_policy_arrives = 0;
}
if (iomgr_success && chand->resolver) {
grpc_resolver *resolver = chand->resolver;
GRPC_RESOLVER_REF(resolver, "channel-next");
grpc_connectivity_state_set(exec_ctx, &chand->state_tracker, state,
"new_lb+resolver");
if (lb_policy != NULL) {
watch_lb_policy(exec_ctx, chand, lb_policy, state);
}
gpr_mu_unlock(&chand->mu_config);
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
grpc_resolver_next(exec_ctx, resolver, &chand->incoming_configuration,
&chand->on_config_changed);
GRPC_RESOLVER_UNREF(exec_ctx, resolver, "channel-next");
} else {
old_resolver = chand->resolver;
chand->resolver = NULL;
grpc_connectivity_state_set(exec_ctx, &chand->state_tracker,
GRPC_CHANNEL_FATAL_FAILURE, "resolver_gone");
gpr_mu_unlock(&chand->mu_config);
if (old_resolver != NULL) {
grpc_resolver_shutdown(exec_ctx, old_resolver);
GRPC_RESOLVER_UNREF(exec_ctx, old_resolver, "channel");
}
}
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_lb_policy_shutdown(exec_ctx, old_lb_policy);
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");
}
static void cc_start_transport_op(grpc_exec_ctx *exec_ctx,
grpc_channel_element *elem,
grpc_transport_op *op) {
grpc_lb_policy *lb_policy = NULL;
channel_data *chand = elem->channel_data;
grpc_resolver *destroy_resolver = NULL;
grpc_exec_ctx_enqueue(exec_ctx, op->on_consumed, 1);
GPR_ASSERT(op->set_accept_stream == NULL);
GPR_ASSERT(op->bind_pollset == NULL);
gpr_mu_lock(&chand->mu_config);
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;
}
lb_policy = chand->lb_policy;
if (lb_policy) {
GRPC_LB_POLICY_REF(lb_policy, "broadcast");
}
if (op->disconnect && chand->resolver != NULL) {
grpc_connectivity_state_set(exec_ctx, &chand->state_tracker,
GRPC_CHANNEL_FATAL_FAILURE, "disconnect");
destroy_resolver = chand->resolver;
chand->resolver = NULL;
if (chand->lb_policy != NULL) {
grpc_lb_policy_shutdown(exec_ctx, chand->lb_policy);
GRPC_LB_POLICY_UNREF(exec_ctx, chand->lb_policy, "channel");
chand->lb_policy = NULL;
}
}
gpr_mu_unlock(&chand->mu_config);
if (destroy_resolver) {
grpc_resolver_shutdown(exec_ctx, destroy_resolver);
GRPC_RESOLVER_UNREF(exec_ctx, destroy_resolver, "channel");
}
if (lb_policy) {
grpc_lb_policy_broadcast(exec_ctx, lb_policy, op);
GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "broadcast");
}
}
typedef struct {
grpc_metadata_batch *initial_metadata;
grpc_connected_subchannel **connected_subchannel;
grpc_closure *on_ready;
grpc_call_element *elem;
grpc_closure closure;
} continue_picking_args;
static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *arg,
grpc_metadata_batch *initial_metadata,
grpc_connected_subchannel **connected_subchannel,
grpc_closure *on_ready);
static void continue_picking(grpc_exec_ctx *exec_ctx, void *arg, int success) {
continue_picking_args *cpa = arg;
if (!success) {
grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, 0);
} else if (cpa->connected_subchannel == NULL) {
/* cancelled, do nothing */
} else if (cc_pick_subchannel(exec_ctx, cpa->elem, cpa->initial_metadata,
cpa->connected_subchannel, cpa->on_ready)) {
grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, 1);
}
gpr_free(cpa);
}
static int cc_pick_subchannel(grpc_exec_ctx *exec_ctx, void *elemp,
grpc_metadata_batch *initial_metadata,
grpc_connected_subchannel **connected_subchannel,
grpc_closure *on_ready) {
grpc_call_element *elem = elemp;
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_config);
if (initial_metadata == NULL) {
if (chand->lb_policy != NULL) {
grpc_lb_policy_cancel_pick(exec_ctx, chand->lb_policy,
connected_subchannel);
}
for (closure = chand->waiting_for_config_closures.head; closure != NULL;
closure = grpc_closure_next(closure)) {
cpa = closure->cb_arg;
if (cpa->connected_subchannel == connected_subchannel) {
cpa->connected_subchannel = NULL;
grpc_exec_ctx_enqueue(exec_ctx, cpa->on_ready, 0);
}
}
gpr_mu_unlock(&chand->mu_config);
return 1;
}
if (chand->lb_policy != NULL) {
int r =
grpc_lb_policy_pick(exec_ctx, chand->lb_policy, calld->pollset,
initial_metadata, connected_subchannel, on_ready);
gpr_mu_unlock(&chand->mu_config);
return r;
}
if (chand->resolver != NULL && !chand->started_resolving) {
chand->started_resolving = 1;
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
grpc_resolver_next(exec_ctx, chand->resolver,
&chand->incoming_configuration,
&chand->on_config_changed);
}
cpa = gpr_malloc(sizeof(*cpa));
cpa->initial_metadata = initial_metadata;
cpa->connected_subchannel = connected_subchannel;
cpa->on_ready = on_ready;
cpa->elem = elem;
grpc_closure_init(&cpa->closure, continue_picking, cpa);
grpc_closure_list_add(&chand->waiting_for_config_closures, &cpa->closure, 1);
gpr_mu_unlock(&chand->mu_config);
return 0;
}
/* Constructor for call_data */
static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
grpc_call_element_args *args) {
grpc_subchannel_call_holder_init(elem->call_data, cc_pick_subchannel, elem,
args->call_stack);
}
/* Destructor for call_data */
static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
grpc_call_element *elem) {
grpc_subchannel_call_holder_destroy(exec_ctx, elem->call_data);
}
/* Constructor for channel_data */
static void 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_config);
grpc_closure_init(&chand->on_config_changed, cc_on_config_changed, chand);
chand->owning_stack = args->channel_stack;
grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE,
"client_channel");
}
/* Destructor for channel_data */
static void 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->lb_policy != NULL) {
GRPC_LB_POLICY_UNREF(exec_ctx, chand->lb_policy, "channel");
}
grpc_connectivity_state_destroy(exec_ctx, &chand->state_tracker);
gpr_mu_destroy(&chand->mu_config);
}
static void cc_set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
grpc_pollset *pollset) {
call_data *calld = elem->call_data;
calld->pollset = pollset;
}
const grpc_channel_filter grpc_client_channel_filter = {
cc_start_transport_stream_op, cc_start_transport_op, sizeof(call_data),
init_call_elem, cc_set_pollset, destroy_call_elem, sizeof(channel_data),
init_channel_elem, destroy_channel_elem, cc_get_peer, "client-channel",
};
void grpc_client_channel_set_resolver(grpc_exec_ctx *exec_ctx,
grpc_channel_stack *channel_stack,
grpc_resolver *resolver) {
/* post construction initialization: set the transport setup pointer */
grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
channel_data *chand = elem->channel_data;
gpr_mu_lock(&chand->mu_config);
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 = 1;
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
grpc_resolver_next(exec_ctx, resolver, &chand->incoming_configuration,
&chand->on_config_changed);
}
gpr_mu_unlock(&chand->mu_config);
}
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_config);
out = grpc_connectivity_state_check(&chand->state_tracker);
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 = 1;
if (!chand->started_resolving && chand->resolver != NULL) {
GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
chand->started_resolving = 1;
grpc_resolver_next(exec_ctx, chand->resolver,
&chand->incoming_configuration,
&chand->on_config_changed);
}
}
}
gpr_mu_unlock(&chand->mu_config);
return out;
}
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;
gpr_mu_lock(&chand->mu_config);
grpc_connectivity_state_notify_on_state_change(
exec_ctx, &chand->state_tracker, state, on_complete);
gpr_mu_unlock(&chand->mu_config);
}