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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.
*
*/
/** Round Robin Policy.
*
* Before every pick, the \a get_next_ready_subchannel_index_locked function
* returns the p->subchannel_list->subchannels index for next subchannel,
* respecting the relative
* order of the addresses provided upon creation or updates. Note however that
* updates will start picking from the beginning of the updated list. */
#include <string.h>
#include <grpc/support/alloc.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/channel/channel_args.h"
#include "src/core/lib/debug/trace.h"
#include "src/core/lib/iomgr/combiner.h"
#include "src/core/lib/iomgr/sockaddr_utils.h"
#include "src/core/lib/transport/connectivity_state.h"
#include "src/core/lib/transport/static_metadata.h"
grpc_tracer_flag grpc_lb_round_robin_trace =
GRPC_TRACER_INITIALIZER(false, "round_robin");
/** List of entities waiting for a pick.
*
* Once a pick is available, \a target is updated and \a on_complete called. */
typedef struct pending_pick {
struct pending_pick *next;
/* output argument where to store the pick()ed user_data. It'll be NULL if no
* such data is present or there's an error (the definite test for errors is
* \a target being NULL). */
void **user_data;
/* bitmask passed to pick() and used for selective cancelling. See
* grpc_lb_policy_cancel_picks() */
uint32_t initial_metadata_flags;
/* output argument where to store the pick()ed connected subchannel, or NULL
* upon error. */
grpc_connected_subchannel **target;
/* to be invoked once the pick() has completed (regardless of success) */
grpc_closure *on_complete;
} pending_pick;
typedef struct rr_subchannel_list rr_subchannel_list;
typedef struct round_robin_lb_policy {
/** base policy: must be first */
grpc_lb_policy base;
rr_subchannel_list *subchannel_list;
/** have we started picking? */
bool started_picking;
/** are we shutting down? */
bool shutdown;
/** List of picks that are waiting on connectivity */
pending_pick *pending_picks;
/** our connectivity state tracker */
grpc_connectivity_state_tracker state_tracker;
/** Index into subchannels for last pick. */
size_t last_ready_subchannel_index;
/** Latest version of the subchannel list.
* Subchannel connectivity callbacks will only promote updated subchannel
* lists if they equal \a latest_pending_subchannel_list. In other words,
* racing callbacks that reference outdated subchannel lists won't perform any
* update. */
rr_subchannel_list *latest_pending_subchannel_list;
} round_robin_lb_policy;
typedef struct {
/** backpointer to owning subchannel list */
rr_subchannel_list *subchannel_list;
/** subchannel itself */
grpc_subchannel *subchannel;
/** notification that connectivity has changed on subchannel */
grpc_closure connectivity_changed_closure;
/** last observed connectivity. Not updated by
* \a grpc_subchannel_notify_on_state_change. Used to determine the previous
* state while processing the new state in \a rr_connectivity_changed */
grpc_connectivity_state prev_connectivity_state;
/** current connectivity state. Updated by \a
* grpc_subchannel_notify_on_state_change */
grpc_connectivity_state curr_connectivity_state;
/** connectivity state to be updated by the watcher, not guarded by
* the combiner. Will be moved to curr_connectivity_state inside of
* the combiner by rr_connectivity_changed_locked(). */
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;
} subchannel_data;
struct rr_subchannel_list {
/** backpointer to owning policy */
round_robin_lb_policy *policy;
/** all our subchannels */
size_t num_subchannels;
subchannel_data *subchannels;
/** 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;
};
static rr_subchannel_list *rr_subchannel_list_create(round_robin_lb_policy *p,
size_t num_subchannels) {
rr_subchannel_list *subchannel_list = gpr_zalloc(sizeof(*subchannel_list));
subchannel_list->policy = p;
subchannel_list->subchannels =
gpr_zalloc(sizeof(subchannel_data) * num_subchannels);
subchannel_list->num_subchannels = num_subchannels;
gpr_ref_init(&subchannel_list->refcount, 1);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_INFO, "[RR %p] Created subchannel list %p for %lu subchannels",
(void *)p, (void *)subchannel_list, (unsigned long)num_subchannels);
}
return subchannel_list;
}
static void rr_subchannel_list_destroy(grpc_exec_ctx *exec_ctx,
rr_subchannel_list *subchannel_list) {
GPR_ASSERT(subchannel_list->shutting_down);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_INFO, "[RR %p] Destroying subchannel_list %p",
(void *)subchannel_list->policy, (void *)subchannel_list);
}
for (size_t i = 0; i < subchannel_list->num_subchannels; i++) {
subchannel_data *sd = &subchannel_list->subchannels[i];
if (sd->subchannel != NULL) {
GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel,
"rr_subchannel_list_destroy");
}
sd->subchannel = NULL;
if (sd->user_data != NULL) {
GPR_ASSERT(sd->user_data_vtable != NULL);
sd->user_data_vtable->destroy(exec_ctx, sd->user_data);
sd->user_data = NULL;
}
}
gpr_free(subchannel_list->subchannels);
gpr_free(subchannel_list);
}
static void rr_subchannel_list_ref(rr_subchannel_list *subchannel_list,
const char *reason) {
gpr_ref_non_zero(&subchannel_list->refcount);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
const gpr_atm count = gpr_atm_acq_load(&subchannel_list->refcount.count);
gpr_log(GPR_INFO, "[RR %p] subchannel_list %p REF %lu->%lu (%s)",
(void *)subchannel_list->policy, (void *)subchannel_list,
(unsigned long)(count - 1), (unsigned long)count, reason);
}
}
static void rr_subchannel_list_unref(grpc_exec_ctx *exec_ctx,
rr_subchannel_list *subchannel_list,
const char *reason) {
const bool done = gpr_unref(&subchannel_list->refcount);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
const gpr_atm count = gpr_atm_acq_load(&subchannel_list->refcount.count);
gpr_log(GPR_INFO, "[RR %p] subchannel_list %p UNREF %lu->%lu (%s)",
(void *)subchannel_list->policy, (void *)subchannel_list,
(unsigned long)(count + 1), (unsigned long)count, reason);
}
if (done) {
rr_subchannel_list_destroy(exec_ctx, subchannel_list);
}
}
/** Mark \a subchannel_list as discarded. Unsubscribes all its subchannels. The
* watcher's callback will ultimately unref \a subchannel_list. */
static void rr_subchannel_list_shutdown_and_unref(
grpc_exec_ctx *exec_ctx, rr_subchannel_list *subchannel_list,
const char *reason) {
GPR_ASSERT(!subchannel_list->shutting_down);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG, "[RR %p] Shutting down subchannel_list %p (%s)",
(void *)subchannel_list->policy, (void *)subchannel_list, reason);
}
GPR_ASSERT(!subchannel_list->shutting_down);
subchannel_list->shutting_down = true;
for (size_t i = 0; i < subchannel_list->num_subchannels; i++) {
subchannel_data *sd = &subchannel_list->subchannels[i];
if (sd->subchannel != NULL) { // if subchannel isn't shutdown, unsubscribe.
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(
GPR_DEBUG,
"[RR %p] Unsubscribing from subchannel %p as part of shutting down "
"subchannel_list %p",
(void *)subchannel_list->policy, (void *)sd->subchannel,
(void *)subchannel_list);
}
grpc_subchannel_notify_on_state_change(exec_ctx, sd->subchannel, NULL,
NULL,
&sd->connectivity_changed_closure);
}
}
rr_subchannel_list_unref(exec_ctx, subchannel_list, reason);
}
/** Returns the index into p->subchannel_list->subchannels of the next
* subchannel in READY state, or p->subchannel_list->num_subchannels if no
* subchannel is READY.
*
* Note that this function does *not* update p->last_ready_subchannel_index.
* The caller must do that if it returns a pick. */
static size_t get_next_ready_subchannel_index_locked(
const round_robin_lb_policy *p) {
GPR_ASSERT(p->subchannel_list != NULL);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_INFO,
"[RR %p] getting next ready subchannel (out of %lu), "
"last_ready_subchannel_index=%lu",
(void *)p, (unsigned long)p->subchannel_list->num_subchannels,
(unsigned long)p->last_ready_subchannel_index);
}
for (size_t i = 0; i < p->subchannel_list->num_subchannels; ++i) {
const size_t index = (i + p->last_ready_subchannel_index + 1) %
p->subchannel_list->num_subchannels;
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(
GPR_DEBUG,
"[RR %p] checking subchannel %p, subchannel_list %p, index %lu: "
"state=%s",
(void *)p, (void *)p->subchannel_list->subchannels[index].subchannel,
(void *)p->subchannel_list, (unsigned long)index,
grpc_connectivity_state_name(
p->subchannel_list->subchannels[index].curr_connectivity_state));
}
if (p->subchannel_list->subchannels[index].curr_connectivity_state ==
GRPC_CHANNEL_READY) {
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG,
"[RR %p] found next ready subchannel (%p) at index %lu of "
"subchannel_list %p",
(void *)p,
(void *)p->subchannel_list->subchannels[index].subchannel,
(unsigned long)index, (void *)p->subchannel_list);
}
return index;
}
}
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG, "[RR %p] no subchannels in ready state", (void *)p);
}
return p->subchannel_list->num_subchannels;
}
// Sets p->last_ready_subchannel_index to last_ready_index.
static void update_last_ready_subchannel_index_locked(round_robin_lb_policy *p,
size_t last_ready_index) {
GPR_ASSERT(last_ready_index < p->subchannel_list->num_subchannels);
p->last_ready_subchannel_index = last_ready_index;
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(
GPR_DEBUG,
"[RR %p] setting last_ready_subchannel_index=%lu (SC %p, CSC %p)",
(void *)p, (unsigned long)last_ready_index,
(void *)p->subchannel_list->subchannels[last_ready_index].subchannel,
(void *)grpc_subchannel_get_connected_subchannel(
p->subchannel_list->subchannels[last_ready_index].subchannel));
}
}
static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG, "[RR %p] Destroying Round Robin policy at %p",
(void *)pol, (void *)pol);
}
grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker);
gpr_free(p);
}
static void rr_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG, "[RR %p] Shutting down Round Robin policy at %p",
(void *)pol, (void *)pol);
}
p->shutdown = true;
pending_pick *pp;
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = NULL;
GRPC_CLOSURE_SCHED(
exec_ctx, pp->on_complete,
GRPC_ERROR_CREATE_FROM_STATIC_STRING("Channel Shutdown"));
gpr_free(pp);
}
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, GRPC_CHANNEL_SHUTDOWN,
GRPC_ERROR_CREATE_FROM_STATIC_STRING("Channel Shutdown"), "rr_shutdown");
const bool latest_is_current =
p->subchannel_list == p->latest_pending_subchannel_list;
rr_subchannel_list_shutdown_and_unref(exec_ctx, p->subchannel_list,
"sl_shutdown_rr_shutdown");
p->subchannel_list = NULL;
if (!latest_is_current && p->latest_pending_subchannel_list != NULL &&
!p->latest_pending_subchannel_list->shutting_down) {
rr_subchannel_list_shutdown_and_unref(exec_ctx,
p->latest_pending_subchannel_list,
"sl_shutdown_pending_rr_shutdown");
p->latest_pending_subchannel_list = NULL;
}
}
static void rr_cancel_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
grpc_connected_subchannel **target,
grpc_error *error) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
pending_pick *pp = p->pending_picks;
p->pending_picks = NULL;
while (pp != NULL) {
pending_pick *next = pp->next;
if (pp->target == target) {
*target = NULL;
GRPC_CLOSURE_SCHED(exec_ctx, pp->on_complete,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"Pick cancelled", &error, 1));
gpr_free(pp);
} else {
pp->next = p->pending_picks;
p->pending_picks = pp;
}
pp = next;
}
GRPC_ERROR_UNREF(error);
}
static void rr_cancel_picks_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
uint32_t initial_metadata_flags_mask,
uint32_t initial_metadata_flags_eq,
grpc_error *error) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
pending_pick *pp = p->pending_picks;
p->pending_picks = NULL;
while (pp != NULL) {
pending_pick *next = pp->next;
if ((pp->initial_metadata_flags & initial_metadata_flags_mask) ==
initial_metadata_flags_eq) {
*pp->target = NULL;
GRPC_CLOSURE_SCHED(exec_ctx, pp->on_complete,
GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
"Pick cancelled", &error, 1));
gpr_free(pp);
} else {
pp->next = p->pending_picks;
p->pending_picks = pp;
}
pp = next;
}
GRPC_ERROR_UNREF(error);
}
static void start_picking_locked(grpc_exec_ctx *exec_ctx,
round_robin_lb_policy *p) {
p->started_picking = true;
for (size_t i = 0; i < p->subchannel_list->num_subchannels; i++) {
subchannel_data *sd = &p->subchannel_list->subchannels[i];
GRPC_LB_POLICY_WEAK_REF(&p->base, "start_picking_locked");
rr_subchannel_list_ref(sd->subchannel_list, "started_picking");
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->pending_connectivity_state_unsafe,
&sd->connectivity_changed_closure);
}
}
static void rr_exit_idle_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
if (!p->started_picking) {
start_picking_locked(exec_ctx, p);
}
}
static int rr_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
const grpc_lb_policy_pick_args *pick_args,
grpc_connected_subchannel **target,
grpc_call_context_element *context, void **user_data,
grpc_closure *on_complete) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_INFO, "[RR %p] Trying to pick", (void *)pol);
}
if (p->subchannel_list != NULL) {
const size_t next_ready_index = get_next_ready_subchannel_index_locked(p);
if (next_ready_index < p->subchannel_list->num_subchannels) {
/* readily available, report right away */
subchannel_data *sd = &p->subchannel_list->subchannels[next_ready_index];
*target = GRPC_CONNECTED_SUBCHANNEL_REF(
grpc_subchannel_get_connected_subchannel(sd->subchannel),
"rr_picked");
if (user_data != NULL) {
*user_data = sd->user_data;
}
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(
GPR_DEBUG,
"[RR %p] Picked target <-- Subchannel %p (connected %p) (sl %p, "
"index %lu)",
(void *)p, (void *)sd->subchannel, (void *)*target,
(void *)sd->subchannel_list, (unsigned long)next_ready_index);
}
/* only advance the last picked pointer if the selection was used */
update_last_ready_subchannel_index_locked(p, next_ready_index);
return 1;
}
}
/* no pick currently available. Save for later in list of pending picks */
if (!p->started_picking) {
start_picking_locked(exec_ctx, p);
}
pending_pick *pp = gpr_malloc(sizeof(*pp));
pp->next = p->pending_picks;
pp->target = target;
pp->on_complete = on_complete;
pp->initial_metadata_flags = pick_args->initial_metadata_flags;
pp->user_data = user_data;
p->pending_picks = pp;
return 0;
}
static void update_state_counters_locked(subchannel_data *sd) {
rr_subchannel_list *subchannel_list = sd->subchannel_list;
if (sd->prev_connectivity_state == GRPC_CHANNEL_READY) {
GPR_ASSERT(subchannel_list->num_ready > 0);
--subchannel_list->num_ready;
} else if (sd->prev_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
GPR_ASSERT(subchannel_list->num_transient_failures > 0);
--subchannel_list->num_transient_failures;
} else if (sd->prev_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
GPR_ASSERT(subchannel_list->num_shutdown > 0);
--subchannel_list->num_shutdown;
} else if (sd->prev_connectivity_state == GRPC_CHANNEL_IDLE) {
GPR_ASSERT(subchannel_list->num_idle > 0);
--subchannel_list->num_idle;
}
if (sd->curr_connectivity_state == GRPC_CHANNEL_READY) {
++subchannel_list->num_ready;
} else if (sd->curr_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
++subchannel_list->num_transient_failures;
} else if (sd->curr_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
++subchannel_list->num_shutdown;
} else if (sd->curr_connectivity_state == GRPC_CHANNEL_IDLE) {
++subchannel_list->num_idle;
}
}
/** Sets the policy's connectivity status based on that of the passed-in \a sd
* (the subchannel_data associted with the updated subchannel) and the
* subchannel list \a sd belongs to (sd->subchannel_list). \a error will only be
* used upon policy transition to TRANSIENT_FAILURE or SHUTDOWN. Returns the
* connectivity status set. */
static grpc_connectivity_state update_lb_connectivity_status_locked(
grpc_exec_ctx *exec_ctx, subchannel_data *sd, grpc_error *error) {
/* In priority order. The first rule to match terminates the search (ie, if we
* are on rule n, all previous rules were unfulfilled).
*
* 1) RULE: ANY subchannel is READY => policy is READY.
* CHECK: At least one subchannel is ready iff p->ready_list is NOT empty.
*
* 2) RULE: ANY subchannel is CONNECTING => policy is CONNECTING.
* CHECK: sd->curr_connectivity_state == CONNECTING.
*
* 3) RULE: ALL subchannels are SHUTDOWN => policy is SHUTDOWN.
* CHECK: p->subchannel_list->num_shutdown ==
* p->subchannel_list->num_subchannels.
*
* 4) RULE: ALL subchannels are TRANSIENT_FAILURE => policy is
* TRANSIENT_FAILURE.
* CHECK: p->num_transient_failures == p->subchannel_list->num_subchannels.
*
* 5) RULE: ALL subchannels are IDLE => policy is IDLE.
* CHECK: p->num_idle == p->subchannel_list->num_subchannels.
*/
grpc_connectivity_state new_state = sd->curr_connectivity_state;
rr_subchannel_list *subchannel_list = sd->subchannel_list;
round_robin_lb_policy *p = subchannel_list->policy;
if (subchannel_list->num_ready > 0) { /* 1) READY */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker, GRPC_CHANNEL_READY,
GRPC_ERROR_NONE, "rr_ready");
new_state = GRPC_CHANNEL_READY;
} else if (sd->curr_connectivity_state ==
GRPC_CHANNEL_CONNECTING) { /* 2) CONNECTING */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker,
GRPC_CHANNEL_CONNECTING, GRPC_ERROR_NONE,
"rr_connecting");
new_state = GRPC_CHANNEL_CONNECTING;
} else if (p->subchannel_list->num_shutdown ==
p->subchannel_list->num_subchannels) { /* 3) SHUTDOWN */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker,
GRPC_CHANNEL_SHUTDOWN, GRPC_ERROR_REF(error),
"rr_shutdown");
new_state = GRPC_CHANNEL_SHUTDOWN;
} else if (subchannel_list->num_transient_failures ==
p->subchannel_list->num_subchannels) { /* 4) TRANSIENT_FAILURE */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker,
GRPC_CHANNEL_TRANSIENT_FAILURE,
GRPC_ERROR_REF(error), "rr_transient_failure");
new_state = GRPC_CHANNEL_TRANSIENT_FAILURE;
} else if (subchannel_list->num_idle ==
p->subchannel_list->num_subchannels) { /* 5) IDLE */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker, GRPC_CHANNEL_IDLE,
GRPC_ERROR_NONE, "rr_idle");
new_state = GRPC_CHANNEL_IDLE;
}
GRPC_ERROR_UNREF(error);
return new_state;
}
static void rr_connectivity_changed_locked(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
subchannel_data *sd = arg;
round_robin_lb_policy *p = sd->subchannel_list->policy;
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(
GPR_DEBUG,
"[RR %p] connectivity changed for subchannel %p, subchannel_list %p: "
"prev_state=%s new_state=%s p->shutdown=%d "
"sd->subchannel_list->shutting_down=%d error=%s",
(void *)p, (void *)sd->subchannel, (void *)sd->subchannel_list,
grpc_connectivity_state_name(sd->prev_connectivity_state),
grpc_connectivity_state_name(sd->pending_connectivity_state_unsafe),
p->shutdown, sd->subchannel_list->shutting_down,
grpc_error_string(error));
}
// If the policy is shutting down, unref and return.
if (p->shutdown) {
rr_subchannel_list_unref(exec_ctx, sd->subchannel_list,
"pol_shutdown+started_picking");
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "pol_shutdown");
return;
}
if (sd->subchannel_list->shutting_down && error == GRPC_ERROR_CANCELLED) {
// the subchannel list associated with sd has been discarded. This callback
// corresponds to the unsubscription. The unrefs correspond to the picking
// ref (start_picking_locked or update_started_picking).
rr_subchannel_list_unref(exec_ctx, sd->subchannel_list,
"sl_shutdown+started_picking");
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "sl_shutdown+picking");
return;
}
// Dispose of outdated subchannel lists.
if (sd->subchannel_list != p->subchannel_list &&
sd->subchannel_list != p->latest_pending_subchannel_list) {
// sd belongs to an outdated subchannel_list: get rid of it.
rr_subchannel_list_shutdown_and_unref(exec_ctx, sd->subchannel_list,
"sl_outdated");
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "sl_outdated");
return;
}
// Now that we're inside the combiner, copy the pending connectivity
// state (which was set by the connectivity state watcher) to
// curr_connectivity_state, which is what we use inside of the combiner.
sd->curr_connectivity_state = sd->pending_connectivity_state_unsafe;
// Update state counters and determine new overall state.
update_state_counters_locked(sd);
sd->prev_connectivity_state = sd->curr_connectivity_state;
const grpc_connectivity_state new_policy_connectivity_state =
update_lb_connectivity_status_locked(exec_ctx, sd, GRPC_ERROR_REF(error));
// If the sd's new state is SHUTDOWN, unref the subchannel, and if the new
// policy's state is SHUTDOWN, clean up.
if (sd->curr_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "rr_subchannel_shutdown");
sd->subchannel = NULL;
if (sd->user_data != NULL) {
GPR_ASSERT(sd->user_data_vtable != NULL);
sd->user_data_vtable->destroy(exec_ctx, sd->user_data);
sd->user_data = NULL;
}
if (new_policy_connectivity_state == GRPC_CHANNEL_SHUTDOWN) {
// the policy is shutting down. Flush all the pending picks...
pending_pick *pp;
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = NULL;
GRPC_CLOSURE_SCHED(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
gpr_free(pp);
}
}
rr_subchannel_list_unref(exec_ctx, sd->subchannel_list,
"sd_shutdown+started_picking");
// unref the "rr_connectivity_update" weak ref from start_picking.
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base,
"rr_connectivity_sd_shutdown");
} else { // sd not in SHUTDOWN
if (sd->curr_connectivity_state == GRPC_CHANNEL_READY) {
if (sd->subchannel_list != p->subchannel_list) {
// promote sd->subchannel_list to p->subchannel_list.
// sd->subchannel_list must be equal to
// p->latest_pending_subchannel_list because we have already filtered
// for sds belonging to outdated subchannel lists.
GPR_ASSERT(sd->subchannel_list == p->latest_pending_subchannel_list);
GPR_ASSERT(!sd->subchannel_list->shutting_down);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
const unsigned long num_subchannels =
p->subchannel_list != NULL
? (unsigned long)p->subchannel_list->num_subchannels
: 0;
gpr_log(GPR_DEBUG,
"[RR %p] phasing out subchannel list %p (size %lu) in favor "
"of %p (size %lu)",
(void *)p, (void *)p->subchannel_list, num_subchannels,
(void *)sd->subchannel_list, num_subchannels);
}
if (p->subchannel_list != NULL) {
// dispose of the current subchannel_list
rr_subchannel_list_shutdown_and_unref(exec_ctx, p->subchannel_list,
"sl_phase_out_shutdown");
}
p->subchannel_list = p->latest_pending_subchannel_list;
p->latest_pending_subchannel_list = NULL;
}
/* at this point we know there's at least one suitable subchannel. Go
* ahead and pick one and notify the pending suitors in
* p->pending_picks. This preemtively replicates rr_pick()'s actions. */
const size_t next_ready_index = get_next_ready_subchannel_index_locked(p);
GPR_ASSERT(next_ready_index < p->subchannel_list->num_subchannels);
subchannel_data *selected =
&p->subchannel_list->subchannels[next_ready_index];
if (p->pending_picks != NULL) {
// if the selected subchannel is going to be used for the pending
// picks, update the last picked pointer
update_last_ready_subchannel_index_locked(p, next_ready_index);
}
pending_pick *pp;
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = GRPC_CONNECTED_SUBCHANNEL_REF(
grpc_subchannel_get_connected_subchannel(selected->subchannel),
"rr_picked");
if (pp->user_data != NULL) {
*pp->user_data = selected->user_data;
}
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG,
"[RR %p] Fulfilling pending pick. Target <-- subchannel %p "
"(subchannel_list %p, index %lu)",
(void *)p, (void *)selected->subchannel,
(void *)p->subchannel_list, (unsigned long)next_ready_index);
}
GRPC_CLOSURE_SCHED(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
gpr_free(pp);
}
}
/* renew notification: reuses the "rr_connectivity_update" weak ref on the
* policy as well as the sd->subchannel_list ref. */
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->pending_connectivity_state_unsafe,
&sd->connectivity_changed_closure);
}
}
static grpc_connectivity_state rr_check_connectivity_locked(
grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_error **error) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
return grpc_connectivity_state_get(&p->state_tracker, error);
}
static void rr_notify_on_state_change_locked(grpc_exec_ctx *exec_ctx,
grpc_lb_policy *pol,
grpc_connectivity_state *current,
grpc_closure *notify) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
grpc_connectivity_state_notify_on_state_change(exec_ctx, &p->state_tracker,
current, notify);
}
static void rr_ping_one_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
grpc_closure *closure) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
const size_t next_ready_index = get_next_ready_subchannel_index_locked(p);
if (next_ready_index < p->subchannel_list->num_subchannels) {
subchannel_data *selected =
&p->subchannel_list->subchannels[next_ready_index];
grpc_connected_subchannel *target = GRPC_CONNECTED_SUBCHANNEL_REF(
grpc_subchannel_get_connected_subchannel(selected->subchannel),
"rr_picked");
grpc_connected_subchannel_ping(exec_ctx, target, closure);
GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, target, "rr_picked");
} else {
GRPC_CLOSURE_SCHED(exec_ctx, closure, GRPC_ERROR_CREATE_FROM_STATIC_STRING(
"Round Robin not connected"));
}
}
static void rr_update_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
const grpc_lb_policy_args *args) {
round_robin_lb_policy *p = (round_robin_lb_policy *)policy;
/* Find the number of backend addresses. We ignore balancer addresses, since
* we don't know how to handle them. */
const grpc_arg *arg =
grpc_channel_args_find(args->args, GRPC_ARG_LB_ADDRESSES);
if (arg == NULL || arg->type != GRPC_ARG_POINTER) {
if (p->subchannel_list == NULL) {
// If we don't have a current subchannel list, go into TRANSIENT FAILURE.
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
GRPC_ERROR_CREATE_FROM_STATIC_STRING("Missing update in args"),
"rr_update_missing");
} else {
// otherwise, keep using the current subchannel list (ignore this update).
gpr_log(GPR_ERROR,
"[RR %p] No valid LB addresses channel arg for update, ignoring.",
(void *)p);
}
return;
}
grpc_lb_addresses *addresses = arg->value.pointer.p;
size_t num_addrs = 0;
for (size_t i = 0; i < addresses->num_addresses; i++) {
if (!addresses->addresses[i].is_balancer) ++num_addrs;
}
if (num_addrs == 0) {
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
GRPC_ERROR_CREATE_FROM_STATIC_STRING("Empty update"),
"rr_update_empty");
if (p->subchannel_list != NULL) {
rr_subchannel_list_shutdown_and_unref(exec_ctx, p->subchannel_list,
"sl_shutdown_empty_update");
p->subchannel_list = NULL;
}
return;
}
size_t subchannel_index = 0;
rr_subchannel_list *subchannel_list = rr_subchannel_list_create(p, num_addrs);
if (p->latest_pending_subchannel_list != NULL && p->started_picking) {
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG,
"[RR %p] Shutting down latest pending subchannel list %p, about "
"to be "
"replaced by newer latest %p",
(void *)p, (void *)p->latest_pending_subchannel_list,
(void *)subchannel_list);
}
rr_subchannel_list_shutdown_and_unref(
exec_ctx, p->latest_pending_subchannel_list, "sl_outdated_dont_smash");
}
p->latest_pending_subchannel_list = subchannel_list;
grpc_subchannel_args sc_args;
/* We need to remove the LB addresses in order to be able to compare the
* subchannel keys of subchannels from a different batch of addresses. */
static const char *keys_to_remove[] = {GRPC_ARG_SUBCHANNEL_ADDRESS,
GRPC_ARG_LB_ADDRESSES};
/* Create subchannels for addresses in the update. */
for (size_t i = 0; i < addresses->num_addresses; i++) {
/* Skip balancer addresses, since we only know how to handle backends. */
if (addresses->addresses[i].is_balancer) continue;
GPR_ASSERT(i < num_addrs);
memset(&sc_args, 0, sizeof(grpc_subchannel_args));
grpc_arg addr_arg =
grpc_create_subchannel_address_arg(&addresses->addresses[i].address);
grpc_channel_args *new_args = grpc_channel_args_copy_and_add_and_remove(
args->args, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), &addr_arg,
1);
gpr_free(addr_arg.value.string);
sc_args.args = new_args;
grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(
exec_ctx, args->client_channel_factory, &sc_args);
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
char *address_uri =
grpc_sockaddr_to_uri(&addresses->addresses[i].address);
gpr_log(
GPR_DEBUG,
"[RR %p] index %lu: Created subchannel %p for address uri %s into "
"subchannel_list %p",
(void *)p, (unsigned long)subchannel_index, (void *)subchannel,
address_uri, (void *)subchannel_list);
gpr_free(address_uri);
}
grpc_channel_args_destroy(exec_ctx, new_args);
subchannel_data *sd = &subchannel_list->subchannels[subchannel_index++];
sd->subchannel_list = subchannel_list;
sd->subchannel = subchannel;
GRPC_CLOSURE_INIT(&sd->connectivity_changed_closure,
rr_connectivity_changed_locked, sd,
grpc_combiner_scheduler(args->combiner));
/* use some sentinel value outside of the range of
* grpc_connectivity_state to signal an undefined previous state. We
* won't be referring to this value again and it'll be overwritten after
* the first call to rr_connectivity_changed_locked */
sd->prev_connectivity_state = GRPC_CHANNEL_INIT;
sd->curr_connectivity_state = GRPC_CHANNEL_IDLE;
sd->user_data_vtable = addresses->user_data_vtable;
if (sd->user_data_vtable != NULL) {
sd->user_data =
sd->user_data_vtable->copy(addresses->addresses[i].user_data);
}
if (p->started_picking) {
rr_subchannel_list_ref(sd->subchannel_list, "update_started_picking");
GRPC_LB_POLICY_WEAK_REF(&p->base, "rr_connectivity_update");
/* 2. Watch every new subchannel. A subchannel list becomes active the
* moment one of its subchannels is READY. At that moment, we swap
* p->subchannel_list for sd->subchannel_list, provided the subchannel
* list is still valid (ie, isn't shutting down) */
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->pending_connectivity_state_unsafe,
&sd->connectivity_changed_closure);
}
}
if (!p->started_picking) {
// The policy isn't picking yet. Save the update for later, disposing of
// previous version if any.
if (p->subchannel_list != NULL) {
rr_subchannel_list_shutdown_and_unref(exec_ctx, p->subchannel_list,
"rr_update_before_started_picking");
}
p->subchannel_list = subchannel_list;
p->latest_pending_subchannel_list = NULL;
}
}
static const grpc_lb_policy_vtable round_robin_lb_policy_vtable = {
rr_destroy,
rr_shutdown_locked,
rr_pick_locked,
rr_cancel_pick_locked,
rr_cancel_picks_locked,
rr_ping_one_locked,
rr_exit_idle_locked,
rr_check_connectivity_locked,
rr_notify_on_state_change_locked,
rr_update_locked};
static void round_robin_factory_ref(grpc_lb_policy_factory *factory) {}
static void round_robin_factory_unref(grpc_lb_policy_factory *factory) {}
static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
grpc_lb_policy_factory *factory,
grpc_lb_policy_args *args) {
GPR_ASSERT(args->client_channel_factory != NULL);
round_robin_lb_policy *p = gpr_zalloc(sizeof(*p));
rr_update_locked(exec_ctx, &p->base, args);
grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable, args->combiner);
grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE,
"round_robin");
if (GRPC_TRACER_ON(grpc_lb_round_robin_trace)) {
gpr_log(GPR_DEBUG, "[RR %p] Created with %lu subchannels", (void *)p,
(unsigned long)p->subchannel_list->num_subchannels);
}
return &p->base;
}
static const grpc_lb_policy_factory_vtable round_robin_factory_vtable = {
round_robin_factory_ref, round_robin_factory_unref, round_robin_create,
"round_robin"};
static grpc_lb_policy_factory round_robin_lb_policy_factory = {
&round_robin_factory_vtable};
static grpc_lb_policy_factory *round_robin_lb_factory_create() {
return &round_robin_lb_policy_factory;
}
/* Plugin registration */
void grpc_lb_policy_round_robin_init() {
grpc_register_lb_policy(round_robin_lb_factory_create());
grpc_register_tracer(&grpc_lb_round_robin_trace);
}
void grpc_lb_policy_round_robin_shutdown() {}
|