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Fixed wrong connectivity status updates for RR

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pull/8666/head
David Garcia Quintas 8 years ago
parent b32149461a
commit a9cf87d9e4
1 changed files with 193 additions and 117 deletions
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  1. 310
      src/core/ext/lb_policy/round_robin/round_robin.c

310
src/core/ext/lb_policy/round_robin/round_robin.c
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@ -59,6 +59,7 @@
* the subchannel by the caller.
*/
#include <limits.h>
#include <string.h>
#include <grpc/support/alloc.h>
@ -116,8 +117,13 @@ typedef struct {
grpc_closure connectivity_changed_closure;
/** this subchannels current position in subchannel->ready_list */
ready_list *ready_list_node;
/** last observed connectivity */
grpc_connectivity_state connectivity_state;
/** 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;
/** the subchannel's target user data */
void *user_data;
/** vtable to operate over \a user_data */
@ -127,6 +133,7 @@ typedef struct {
struct round_robin_lb_policy {
/** base policy: must be first */
grpc_lb_policy base;
gpr_mu mu;
/** total number of addresses received at creation time */
size_t num_addresses;
@ -135,8 +142,11 @@ struct round_robin_lb_policy {
size_t num_subchannels;
subchannel_data **subchannels;
/** mutex protecting remaining members */
gpr_mu mu;
/** how many subchannels are in TRANSIENT_FAILURE */
size_t num_transient_failures;
/** how many subchannels are IDLE */
size_t num_idle;
/** have we started picking? */
int started_picking;
/** are we shutting down? */
@ -258,6 +268,10 @@ static void remove_disconnected_sc_locked(round_robin_lb_policy *p,
gpr_free(node);
}
static bool is_ready_list_empty(round_robin_lb_policy *p) {
return p->ready_list.prev == NULL;
}
static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
ready_list *elem;
@ -268,7 +282,7 @@ static void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
for (size_t i = 0; i < p->num_subchannels; i++) {
subchannel_data *sd = p->subchannels[i];
GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "round_robin_destroy");
GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "rr_destroy");
if (sd->user_data != NULL) {
GPR_ASSERT(sd->user_data_vtable != NULL);
sd->user_data_vtable->destroy(sd->user_data);
@ -381,18 +395,18 @@ static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) {
size_t i;
p->started_picking = 1;
if (grpc_lb_round_robin_trace) {
gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%" PRIuPTR, (void *)p,
p->num_subchannels);
}
for (i = 0; i < p->num_subchannels; i++) {
subchannel_data *sd = p->subchannels[i];
sd->connectivity_state = GRPC_CHANNEL_IDLE;
/* 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 */
sd->prev_connectivity_state = INT_MAX;
sd->curr_connectivity_state = GRPC_CHANNEL_IDLE;
GRPC_LB_POLICY_WEAK_REF(&p->base, "rr_connectivity");
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->connectivity_state, &sd->connectivity_changed_closure);
GRPC_LB_POLICY_WEAK_REF(&p->base, "round_robin_connectivity");
&sd->curr_connectivity_state, &sd->connectivity_changed_closure);
}
}
@ -453,125 +467,182 @@ static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
}
}
static void update_state_counters(subchannel_data *sd) {
round_robin_lb_policy *p = sd->policy;
/* update p->num_transient_failures (resp. p->num_idle): if the previous
* state was TRANSIENT_FAILURE (resp. IDLE), decrement
* p->num_transient_failures (resp. p->num_idle). */
if (sd->prev_connectivity_state == GRPC_CHANNEL_TRANSIENT_FAILURE) {
GPR_ASSERT(p->num_transient_failures > 0);
--p->num_transient_failures;
} else if (sd->prev_connectivity_state == GRPC_CHANNEL_IDLE) {
GPR_ASSERT(p->num_idle > 0);
--p->num_idle;
}
}
/* sd is the subchannel_data associted with the updated subchannel.
* shutdown_error will only be used upon policy transition to TRANSIENT_FAILURE
* or SHUTDOWN */
static grpc_connectivity_state update_lb_connectivity_status(
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->num_subchannels = 0.
*
* 4) RULE: ALL subchannels are TRANSIENT_FAILURE => policy is
* TRANSIENT_FAILURE.
* CHECK: p->num_transient_failures == p->num_subchannels.
*
* 5) RULE: ALL subchannels are IDLE => policy is IDLE.
* CHECK: p->num_idle == p->num_subchannels.
*/
round_robin_lb_policy *p = sd->policy;
if (!is_ready_list_empty(p)) { /* 1) READY */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker, GRPC_CHANNEL_READY,
GRPC_ERROR_NONE, "rr_ready");
return 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");
return GRPC_CHANNEL_CONNECTING;
} else if (p->num_subchannels == 0) { /* 3) SHUTDOWN */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker,
GRPC_CHANNEL_SHUTDOWN, GRPC_ERROR_REF(error),
"rr_shutdown");
return GRPC_CHANNEL_SHUTDOWN;
} else if (p->num_transient_failures ==
p->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");
return GRPC_CHANNEL_TRANSIENT_FAILURE;
} else if (p->num_idle == p->num_subchannels) { /* 5) IDLE */
grpc_connectivity_state_set(exec_ctx, &p->state_tracker, GRPC_CHANNEL_IDLE,
GRPC_ERROR_NONE, "rr_idle");
return GRPC_CHANNEL_IDLE;
}
/* no change */
return sd->curr_connectivity_state;
}
static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
subchannel_data *sd = arg;
round_robin_lb_policy *p = sd->policy;
pending_pick *pp;
int unref = 0;
GRPC_ERROR_REF(error);
gpr_mu_lock(&p->mu);
if (p->shutdown) {
unref = 1;
} else {
switch (sd->connectivity_state) {
case GRPC_CHANNEL_READY:
grpc_connectivity_state_set(exec_ctx, &p->state_tracker,
GRPC_CHANNEL_READY, GRPC_ERROR_REF(error),
"connecting_ready");
/* add the newly connected subchannel to the list of connected ones.
* Note that it goes to the "end of the line". */
sd->ready_list_node = add_connected_sc_locked(p, sd);
/* 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. */
ready_list *selected = peek_next_connected_locked(p);
GPR_ASSERT(selected != NULL);
if (p->pending_picks != NULL) {
/* if the selected subchannel is going to be used for the pending
* picks, update the last picked pointer */
advance_last_picked_locked(p);
gpr_mu_unlock(&p->mu);
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "rr_connectivity");
GRPC_ERROR_UNREF(error);
return;
}
switch (sd->curr_connectivity_state) {
case GRPC_CHANNEL_READY:
/* add the newly connected subchannel to the list of connected ones.
* Note that it goes to the "end of the line". */
sd->ready_list_node = add_connected_sc_locked(p, sd);
/* 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. */
ready_list *selected = peek_next_connected_locked(p);
GPR_ASSERT(selected != NULL);
if (p->pending_picks != NULL) {
/* if the selected subchannel is going to be used for the pending
* picks, update the last picked pointer */
advance_last_picked_locked(p);
}
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_lb_round_robin_trace) {
gpr_log(GPR_DEBUG,
"[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)",
(void *)selected->subchannel, (void *)selected);
}
grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
gpr_free(pp);
}
/* renew notification: reuses the "rr_connectivity" weak ref */
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->curr_connectivity_state, &sd->connectivity_changed_closure);
update_lb_connectivity_status(exec_ctx, sd, error);
sd->prev_connectivity_state = sd->curr_connectivity_state;
break;
case GRPC_CHANNEL_IDLE:
++p->num_idle;
/* fallthrough */
case GRPC_CHANNEL_CONNECTING:
update_state_counters(sd);
/* renew notification: reuses the "rr_connectivity" weak ref */
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->curr_connectivity_state, &sd->connectivity_changed_closure);
update_lb_connectivity_status(exec_ctx, sd, error);
sd->prev_connectivity_state = sd->curr_connectivity_state;
break;
case GRPC_CHANNEL_TRANSIENT_FAILURE:
++p->num_transient_failures;
/* remove from ready list if still present */
if (sd->ready_list_node != NULL) {
remove_disconnected_sc_locked(p, sd->ready_list_node);
sd->ready_list_node = NULL;
}
/* renew notification: reuses the "rr_connectivity" weak ref */
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->curr_connectivity_state, &sd->connectivity_changed_closure);
update_lb_connectivity_status(exec_ctx, sd, error);
sd->prev_connectivity_state = sd->curr_connectivity_state;
break;
case GRPC_CHANNEL_SHUTDOWN:
update_state_counters(sd);
if (sd->ready_list_node != NULL) {
remove_disconnected_sc_locked(p, sd->ready_list_node);
sd->ready_list_node = NULL;
}
--p->num_subchannels;
GPR_SWAP(subchannel_data *, p->subchannels[sd->index],
p->subchannels[p->num_subchannels]);
GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "rr_subchannel_shutdown");
p->subchannels[sd->index]->index = sd->index;
if (update_lb_connectivity_status(exec_ctx, sd, error) ==
GRPC_CHANNEL_SHUTDOWN) {
/* the policy is shutting down. Flush all the pending picks... */
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = GRPC_CONNECTED_SUBCHANNEL_REF(
grpc_subchannel_get_connected_subchannel(selected->subchannel),
"picked");
if (pp->user_data != NULL) {
*pp->user_data = selected->user_data;
}
if (grpc_lb_round_robin_trace) {
gpr_log(GPR_DEBUG,
"[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)",
(void *)selected->subchannel, (void *)selected);
}
*pp->target = NULL;
grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
gpr_free(pp);
}
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->connectivity_state, &sd->connectivity_changed_closure);
break;
case GRPC_CHANNEL_CONNECTING:
case GRPC_CHANNEL_IDLE:
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, sd->connectivity_state,
GRPC_ERROR_REF(error), "connecting_changed");
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->connectivity_state, &sd->connectivity_changed_closure);
break;
case GRPC_CHANNEL_TRANSIENT_FAILURE:
/* renew state notification */
grpc_subchannel_notify_on_state_change(
exec_ctx, sd->subchannel, p->base.interested_parties,
&sd->connectivity_state, &sd->connectivity_changed_closure);
/* remove from ready list if still present */
if (sd->ready_list_node != NULL) {
remove_disconnected_sc_locked(p, sd->ready_list_node);
sd->ready_list_node = NULL;
}
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
GRPC_ERROR_REF(error), "connecting_transient_failure");
break;
case GRPC_CHANNEL_SHUTDOWN:
if (sd->ready_list_node != NULL) {
remove_disconnected_sc_locked(p, sd->ready_list_node);
sd->ready_list_node = NULL;
}
p->num_subchannels--;
GPR_SWAP(subchannel_data *, p->subchannels[sd->index],
p->subchannels[p->num_subchannels]);
GRPC_SUBCHANNEL_UNREF(exec_ctx, sd->subchannel, "round_robin");
p->subchannels[sd->index]->index = sd->index;
gpr_free(sd);
unref = 1;
if (p->num_subchannels == 0) {
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, GRPC_CHANNEL_SHUTDOWN,
GRPC_ERROR_CREATE_REFERENCING("Round Robin Channels Exhausted",
&error, 1),
"no_more_channels");
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = NULL;
grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE,
NULL);
gpr_free(pp);
}
} else {
grpc_connectivity_state_set(
exec_ctx, &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE,
GRPC_ERROR_REF(error), "subchannel_failed");
}
} /* switch */
} /* !unref */
gpr_mu_unlock(&p->mu);
if (unref) {
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "round_robin_connectivity");
}
gpr_free(sd);
/* unref the "rr_connectivity" weak ref from start_picking */
GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "rr_connectivity");
break;
}
gpr_mu_unlock(&p->mu);
GRPC_ERROR_UNREF(error);
}
@ -607,9 +678,9 @@ static void rr_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
gpr_mu_unlock(&p->mu);
target = GRPC_CONNECTED_SUBCHANNEL_REF(
grpc_subchannel_get_connected_subchannel(selected->subchannel),
"picked");
"rr_picked");
grpc_connected_subchannel_ping(exec_ctx, target, closure);
GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, target, "picked");
GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, target, "rr_picked");
} else {
gpr_mu_unlock(&p->mu);
grpc_exec_ctx_sched(exec_ctx, closure,
@ -705,6 +776,11 @@ static grpc_lb_policy *round_robin_create(grpc_exec_ctx *exec_ctx,
grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable);
grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE,
"round_robin");
if (grpc_lb_round_robin_trace) {
gpr_log(GPR_DEBUG, "Created RR policy at %p with %lu subchannels",
(void *)p, (unsigned long)p->num_subchannels);
}
gpr_mu_init(&p->mu);
return &p->base;
}

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