| /* |
| * |
| * 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/ext/filters/client_channel/subchannel_index.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 = |
| (rr_subchannel_list *)gpr_zalloc(sizeof(*subchannel_list)); |
| subchannel_list->policy = p; |
| subchannel_list->subchannels = |
| (subchannel_data *)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); |
| grpc_subchannel_index_unref(); |
| 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; |
| GPR_ASSERT(!p->shutdown); |
| 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 = (pending_pick *)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"); |
| p->shutdown = true; |
| 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 = (subchannel_data *)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) { |
| char *reason = NULL; |
| if (sd->subchannel_list->shutting_down) { |
| reason = "sl_outdated_straggler"; |
| rr_subchannel_list_unref(exec_ctx, sd->subchannel_list, reason); |
| } else { |
| reason = "sl_outdated"; |
| rr_subchannel_list_shutdown_and_unref(exec_ctx, sd->subchannel_list, |
| reason); |
| } |
| GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, reason); |
| 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; |
| 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 = (grpc_lb_addresses *)arg->value.pointer.p; |
| rr_subchannel_list *subchannel_list = |
| rr_subchannel_list_create(p, addresses->num_addresses); |
| if (addresses->num_addresses == 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 = subchannel_list; // empty list |
| return; |
| } |
| size_t subchannel_index = 0; |
| 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++) { |
| // If there were any balancer, we would have chosen grpclb policy instead. |
| GPR_ASSERT(!addresses->addresses[i].is_balancer); |
| 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); |
| grpc_channel_args_destroy(exec_ctx, new_args); |
| grpc_error *error; |
| // Get the connectivity state of the subchannel. Already existing ones may |
| // be in a state other than INIT. |
| const grpc_connectivity_state subchannel_connectivity_state = |
| grpc_subchannel_check_connectivity(subchannel, &error); |
| if (error != GRPC_ERROR_NONE) { |
| // The subchannel is in error (e.g. shutting down). Ignore it. |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, subchannel, "new_sc_connectivity_error"); |
| GRPC_ERROR_UNREF(error); |
| continue; |
| } |
| 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. Connectivity state %s", |
| (void *)p, (unsigned long)subchannel_index, (void *)subchannel, |
| address_uri, (void *)subchannel_list, |
| grpc_connectivity_state_name(subchannel_connectivity_state)); |
| gpr_free(address_uri); |
| } |
| 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 = subchannel_connectivity_state; |
| 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 = (round_robin_lb_policy *)gpr_zalloc(sizeof(*p)); |
| grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable, args->combiner); |
| grpc_subchannel_index_ref(); |
| grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE, |
| "round_robin"); |
| rr_update_locked(exec_ctx, &p->base, args); |
| 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() {} |