diff options
Diffstat (limited to 'src/core/ext/lb_policy/round_robin/round_robin.c')
| -rw-r--r-- | src/core/ext/lb_policy/round_robin/round_robin.c | 90 |
1 files changed, 60 insertions, 30 deletions
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c index 95305e9cdd..7bcf608ab9 100644 --- a/src/core/ext/lb_policy/round_robin/round_robin.c +++ b/src/core/ext/lb_policy/round_robin/round_robin.c @@ -31,6 +31,34 @@ * */ +/** Round Robin Policy. + * + * This policy keeps: + * - A circular list of ready (connected) subchannels, the *readylist*. An empty + * readylist consists solely of its root (dummy) node. + * - A pointer to the last element picked from the readylist, the *lastpick*. + * Initially set to point to the readylist's root. + * + * Behavior: + * - When a subchannel connects, it's *prepended* to the readylist's root node. + * Ie, if readylist = A <-> B <-> ROOT <-> C + * ^ ^ + * |____________________| + * and subchannel D becomes connected, the addition of D to the readylist + * results in readylist = A <-> B <-> D <-> ROOT <-> C + * ^ ^ + * |__________________________| + * - When a subchannel disconnects, it's removed from the readylist. If the + * subchannel being removed was the most recently picked, the *lastpick* + * pointer moves to the removed node's previous element. Note that if the + * readylist only had one element, this is still legal, as the lastpick would + * point to the dummy root node, for an empty readylist. + * - Upon picking, *lastpick* is updated to point to the returned (connected) + * subchannel. Note that it's possible that the selected subchannel becomes + * disconnected in the interim between the selection and the actual usage of + * the subchannel by the caller. + */ + #include <string.h> #include <grpc/support/alloc.h> @@ -48,7 +76,7 @@ int grpc_lb_round_robin_trace = 0; * Once a pick is available, \a target is updated and \a on_complete called. */ typedef struct pending_pick { struct pending_pick *next; - grpc_pollset *pollset; + grpc_polling_entity *pollent; uint32_t initial_metadata_flags; grpc_connected_subchannel **target; grpc_closure *on_complete; @@ -173,9 +201,7 @@ static void remove_disconnected_sc_locked(round_robin_lb_policy *p, return; } if (node == p->ready_list_last_pick) { - /* If removing the lastly picked node, reset the last pick pointer to the - * dummy root of the list */ - p->ready_list_last_pick = &p->ready_list; + p->ready_list_last_pick = p->ready_list_last_pick->prev; } /* removing last item */ @@ -239,12 +265,12 @@ static void rr_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { while ((pp = p->pending_picks)) { p->pending_picks = pp->next; *pp->target = NULL; - grpc_exec_ctx_push(exec_ctx, pp->on_complete, - GRPC_ERROR_CREATE("Channel Shutdown"), NULL); + grpc_exec_ctx_sched(exec_ctx, pp->on_complete, + GRPC_ERROR_CREATE("Channel Shutdown"), NULL); gpr_free(pp); } grpc_connectivity_state_set( - exec_ctx, &p->state_tracker, GRPC_CHANNEL_FATAL_FAILURE, + exec_ctx, &p->state_tracker, GRPC_CHANNEL_SHUTDOWN, GRPC_ERROR_CREATE("Channel Shutdown"), "shutdown"); for (i = 0; i < p->num_subchannels; i++) { subchannel_data *sd = p->subchannels[i]; @@ -264,10 +290,11 @@ static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, while (pp != NULL) { pending_pick *next = pp->next; if (pp->target == target) { - grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, - pp->pollset); + grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent, + p->base.interested_parties); *target = NULL; - grpc_exec_ctx_push(exec_ctx, pp->on_complete, GRPC_ERROR_CANCELLED, NULL); + grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_CANCELLED, + NULL); gpr_free(pp); } else { pp->next = p->pending_picks; @@ -290,10 +317,11 @@ static void rr_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, pending_pick *next = pp->next; if ((pp->initial_metadata_flags & initial_metadata_flags_mask) == initial_metadata_flags_eq) { - grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, - pp->pollset); + grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent, + p->base.interested_parties); *pp->target = NULL; - grpc_exec_ctx_push(exec_ctx, pp->on_complete, GRPC_ERROR_CANCELLED, NULL); + grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_CANCELLED, + NULL); gpr_free(pp); } else { pp->next = p->pending_picks; @@ -309,7 +337,7 @@ static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) { p->started_picking = 1; if (grpc_lb_round_robin_trace) { - gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%d", p, + gpr_log(GPR_DEBUG, "LB_POLICY: p=%p num_subchannels=%" PRIuPTR, p, p->num_subchannels); } @@ -333,7 +361,8 @@ static void rr_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { } static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, - grpc_pollset *pollset, grpc_metadata_batch *initial_metadata, + grpc_polling_entity *pollent, + grpc_metadata_batch *initial_metadata, uint32_t initial_metadata_flags, grpc_connected_subchannel **target, grpc_closure *on_complete) { @@ -346,8 +375,8 @@ static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, *target = grpc_subchannel_get_connected_subchannel(selected->subchannel); if (grpc_lb_round_robin_trace) { gpr_log(GPR_DEBUG, - "[RR PICK] TARGET <-- CONNECTED SUBCHANNEL %p (NODE %p)", - selected->subchannel, selected); + "[RR PICK] TARGET <-- CONNECTED SUBCHANNEL %p (NODE %p)", *target, + selected); } /* only advance the last picked pointer if the selection was used */ advance_last_picked_locked(p); @@ -356,10 +385,11 @@ static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, if (!p->started_picking) { start_picking(exec_ctx, p); } - grpc_pollset_set_add_pollset(exec_ctx, p->base.interested_parties, pollset); + grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent, + p->base.interested_parties); pp = gpr_malloc(sizeof(*pp)); pp->next = p->pending_picks; - pp->pollset = pollset; + pp->pollent = pollent; pp->target = target; pp->on_complete = on_complete; pp->initial_metadata_flags = initial_metadata_flags; @@ -410,9 +440,9 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg, "[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)", selected->subchannel, selected); } - grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, - pp->pollset); - grpc_exec_ctx_push(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL); + grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent, + p->base.interested_parties); + grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL); gpr_free(pp); } grpc_subchannel_notify_on_state_change( @@ -443,7 +473,7 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg, exec_ctx, &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE, GRPC_ERROR_REF(error), "connecting_transient_failure"); break; - case GRPC_CHANNEL_FATAL_FAILURE: + case GRPC_CHANNEL_SHUTDOWN: if (sd->ready_list_node != NULL) { remove_disconnected_sc_locked(p, sd->ready_list_node); sd->ready_list_node = NULL; @@ -459,15 +489,15 @@ static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg, unref = 1; if (p->num_subchannels == 0) { grpc_connectivity_state_set( - exec_ctx, &p->state_tracker, GRPC_CHANNEL_FATAL_FAILURE, + 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_push(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, - NULL); + grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, + NULL); gpr_free(pp); } } else { @@ -521,8 +551,8 @@ static void rr_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_connected_subchannel_ping(exec_ctx, target, closure); } else { gpr_mu_unlock(&p->mu); - grpc_exec_ctx_push(exec_ctx, closure, - GRPC_ERROR_CREATE("Round Robin not connected"), NULL); + grpc_exec_ctx_sched(exec_ctx, closure, + GRPC_ERROR_CREATE("Round Robin not connected"), NULL); } } @@ -535,7 +565,7 @@ 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 *create_round_robin(grpc_exec_ctx *exec_ctx, +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->addresses != NULL); @@ -591,7 +621,7 @@ static grpc_lb_policy *create_round_robin(grpc_exec_ctx *exec_ctx, } static const grpc_lb_policy_factory_vtable round_robin_factory_vtable = { - round_robin_factory_ref, round_robin_factory_unref, create_round_robin, + round_robin_factory_ref, round_robin_factory_unref, round_robin_create, "round_robin"}; static grpc_lb_policy_factory round_robin_lb_policy_factory = { |