| /* |
| * |
| * Copyright 2015, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #include "src/core/client_config/lb_policies/round_robin.h" |
| |
| #include <string.h> |
| |
| #include <grpc/support/alloc.h> |
| #include "src/core/transport/connectivity_state.h" |
| |
| int grpc_lb_round_robin_trace = 0; |
| |
| /** 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; |
| grpc_pollset *pollset; |
| grpc_subchannel **target; |
| grpc_closure *on_complete; |
| } pending_pick; |
| |
| /** List of subchannels in a connectivity READY state */ |
| typedef struct ready_list { |
| grpc_subchannel *subchannel; |
| struct ready_list *next; |
| struct ready_list *prev; |
| } ready_list; |
| |
| typedef struct { |
| size_t subchannel_idx; /**< Index over p->subchannels */ |
| void *p; /**< round_robin_lb_policy instance */ |
| } connectivity_changed_cb_arg; |
| |
| typedef struct { |
| /** base policy: must be first */ |
| grpc_lb_policy base; |
| |
| /** all our subchannels */ |
| grpc_subchannel **subchannels; |
| size_t num_subchannels; |
| |
| /** Callbacks, one per subchannel being watched, to be called when their |
| * respective connectivity changes */ |
| grpc_closure *connectivity_changed_cbs; |
| connectivity_changed_cb_arg *cb_args; |
| |
| /** mutex protecting remaining members */ |
| gpr_mu mu; |
| /** have we started picking? */ |
| int started_picking; |
| /** are we shutting down? */ |
| int shutdown; |
| /** Connectivity state of the subchannels being watched */ |
| grpc_connectivity_state *subchannel_connectivity; |
| /** List of picks that are waiting on connectivity */ |
| pending_pick *pending_picks; |
| |
| /** our connectivity state tracker */ |
| grpc_connectivity_state_tracker state_tracker; |
| |
| /** (Dummy) root of the doubly linked list containing READY subchannels */ |
| ready_list ready_list; |
| /** Last pick from the ready list. */ |
| ready_list *ready_list_last_pick; |
| |
| /** Subchannel index to ready_list node. |
| * |
| * Kept in order to remove nodes from the ready list associated with a |
| * subchannel */ |
| ready_list **subchannel_index_to_readylist_node; |
| } round_robin_lb_policy; |
| |
| /** Returns the next subchannel from the connected list or NULL if the list is |
| * empty. |
| * |
| * Note that this function does *not* advance p->ready_list_last_pick. Use \a |
| * advance_last_picked_locked() for that. */ |
| static ready_list *peek_next_connected_locked(const round_robin_lb_policy *p) { |
| ready_list *selected; |
| selected = p->ready_list_last_pick->next; |
| |
| while (selected != NULL) { |
| if (selected == &p->ready_list) { |
| GPR_ASSERT(selected->subchannel == NULL); |
| /* skip dummy root */ |
| selected = selected->next; |
| } else { |
| GPR_ASSERT(selected->subchannel != NULL); |
| return selected; |
| } |
| } |
| return NULL; |
| } |
| |
| /** Advance the \a ready_list picking head. */ |
| static void advance_last_picked_locked(round_robin_lb_policy *p) { |
| if (p->ready_list_last_pick->next != NULL) { /* non-empty list */ |
| p->ready_list_last_pick = p->ready_list_last_pick->next; |
| if (p->ready_list_last_pick == &p->ready_list) { |
| /* skip dummy root */ |
| p->ready_list_last_pick = p->ready_list_last_pick->next; |
| } |
| } else { /* should be an empty list */ |
| GPR_ASSERT(p->ready_list_last_pick == &p->ready_list); |
| } |
| |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, "[READYLIST] ADVANCED LAST PICK. NOW AT NODE %p (SC %p)", |
| p->ready_list_last_pick, p->ready_list_last_pick->subchannel); |
| } |
| } |
| |
| /** Prepends (relative to the root at p->ready_list) the connected subchannel \a |
| * csc to the list of ready subchannels. */ |
| static ready_list *add_connected_sc_locked(round_robin_lb_policy *p, |
| grpc_subchannel *csc) { |
| ready_list *new_elem = gpr_malloc(sizeof(ready_list)); |
| new_elem->subchannel = csc; |
| if (p->ready_list.prev == NULL) { |
| /* first element */ |
| new_elem->next = &p->ready_list; |
| new_elem->prev = &p->ready_list; |
| p->ready_list.next = new_elem; |
| p->ready_list.prev = new_elem; |
| } else { |
| new_elem->next = &p->ready_list; |
| new_elem->prev = p->ready_list.prev; |
| p->ready_list.prev->next = new_elem; |
| p->ready_list.prev = new_elem; |
| } |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, "[READYLIST] ADDING NODE %p (SC %p)", new_elem, csc); |
| } |
| return new_elem; |
| } |
| |
| /** Removes \a node from the list of connected subchannels */ |
| static void remove_disconnected_sc_locked(round_robin_lb_policy *p, |
| ready_list *node) { |
| if (node == NULL) { |
| 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; |
| } |
| |
| /* removing last item */ |
| if (node->next == &p->ready_list && node->prev == &p->ready_list) { |
| GPR_ASSERT(p->ready_list.next == node); |
| GPR_ASSERT(p->ready_list.prev == node); |
| p->ready_list.next = NULL; |
| p->ready_list.prev = NULL; |
| } else { |
| node->prev->next = node->next; |
| node->next->prev = node->prev; |
| } |
| |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, "[READYLIST] REMOVED NODE %p (SC %p)", node, |
| node->subchannel); |
| } |
| |
| node->next = NULL; |
| node->prev = NULL; |
| node->subchannel = NULL; |
| |
| gpr_free(node); |
| } |
| |
| static void del_interested_parties_locked(grpc_exec_ctx *exec_ctx, |
| round_robin_lb_policy *p, |
| const size_t subchannel_idx) { |
| pending_pick *pp; |
| for (pp = p->pending_picks; pp; pp = pp->next) { |
| grpc_subchannel_del_interested_party( |
| exec_ctx, p->subchannels[subchannel_idx], pp->pollset); |
| } |
| } |
| |
| void rr_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| size_t i; |
| ready_list *elem; |
| for (i = 0; i < p->num_subchannels; i++) { |
| del_interested_parties_locked(exec_ctx, p, i); |
| } |
| for (i = 0; i < p->num_subchannels; i++) { |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, p->subchannels[i], "round_robin"); |
| } |
| gpr_free(p->connectivity_changed_cbs); |
| gpr_free(p->subchannel_connectivity); |
| |
| grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker); |
| gpr_free(p->subchannels); |
| gpr_mu_destroy(&p->mu); |
| |
| elem = p->ready_list.next; |
| while (elem != NULL && elem != &p->ready_list) { |
| ready_list *tmp; |
| tmp = elem->next; |
| elem->next = NULL; |
| elem->prev = NULL; |
| elem->subchannel = NULL; |
| gpr_free(elem); |
| elem = tmp; |
| } |
| gpr_free(p->subchannel_index_to_readylist_node); |
| gpr_free(p->cb_args); |
| gpr_free(p); |
| } |
| |
| void rr_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| size_t i; |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| pending_pick *pp; |
| gpr_mu_lock(&p->mu); |
| |
| for (i = 0; i < p->num_subchannels; i++) { |
| del_interested_parties_locked(exec_ctx, p, i); |
| } |
| |
| p->shutdown = 1; |
| while ((pp = p->pending_picks)) { |
| p->pending_picks = pp->next; |
| *pp->target = NULL; |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, 0); |
| gpr_free(pp); |
| } |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_FATAL_FAILURE, "shutdown"); |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| grpc_subchannel **target) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| pending_pick *pp; |
| size_t i; |
| gpr_mu_lock(&p->mu); |
| pp = p->pending_picks; |
| p->pending_picks = NULL; |
| while (pp != NULL) { |
| pending_pick *next = pp->next; |
| if (pp->target == target) { |
| for (i = 0; i < p->num_subchannels; i++) { |
| grpc_subchannel_add_interested_party(exec_ctx, p->subchannels[i], |
| pp->pollset); |
| } |
| *target = NULL; |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, 0); |
| gpr_free(pp); |
| } else { |
| pp->next = p->pending_picks; |
| p->pending_picks = pp; |
| } |
| pp = next; |
| } |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) { |
| size_t i; |
| p->started_picking = 1; |
| |
| for (i = 0; i < p->num_subchannels; i++) { |
| p->subchannel_connectivity[i] = GRPC_CHANNEL_IDLE; |
| grpc_subchannel_notify_on_state_change(exec_ctx, p->subchannels[i], |
| &p->subchannel_connectivity[i], |
| &p->connectivity_changed_cbs[i]); |
| GRPC_LB_POLICY_REF(&p->base, "round_robin_connectivity"); |
| } |
| } |
| |
| void rr_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| gpr_mu_lock(&p->mu); |
| if (!p->started_picking) { |
| start_picking(exec_ctx, p); |
| } |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_pollset *pollset, |
| grpc_metadata_batch *initial_metadata, grpc_subchannel **target, |
| grpc_closure *on_complete) { |
| size_t i; |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| pending_pick *pp; |
| ready_list *selected; |
| gpr_mu_lock(&p->mu); |
| if ((selected = peek_next_connected_locked(p))) { |
| gpr_mu_unlock(&p->mu); |
| *target = selected->subchannel; |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, "[RR PICK] TARGET <-- SUBCHANNEL %p (NODE %p)", |
| selected->subchannel, selected); |
| } |
| /* only advance the last picked pointer if the selection was used */ |
| advance_last_picked_locked(p); |
| return 1; |
| } else { |
| if (!p->started_picking) { |
| start_picking(exec_ctx, p); |
| } |
| for (i = 0; i < p->num_subchannels; i++) { |
| grpc_subchannel_add_interested_party(exec_ctx, p->subchannels[i], |
| pollset); |
| } |
| pp = gpr_malloc(sizeof(*pp)); |
| pp->next = p->pending_picks; |
| pp->pollset = pollset; |
| pp->target = target; |
| pp->on_complete = on_complete; |
| p->pending_picks = pp; |
| gpr_mu_unlock(&p->mu); |
| return 0; |
| } |
| } |
| |
| static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg, |
| int iomgr_success) { |
| connectivity_changed_cb_arg *cb_arg = arg; |
| round_robin_lb_policy *p = cb_arg->p; |
| /* index over p->subchannels of this cb's subchannel */ |
| const size_t this_idx = cb_arg->subchannel_idx; |
| pending_pick *pp; |
| ready_list *selected; |
| |
| int unref = 0; |
| |
| /* connectivity state of this cb's subchannel */ |
| grpc_connectivity_state *this_connectivity; |
| |
| gpr_mu_lock(&p->mu); |
| |
| this_connectivity = &p->subchannel_connectivity[this_idx]; |
| |
| if (p->shutdown) { |
| unref = 1; |
| } else { |
| switch (*this_connectivity) { |
| case GRPC_CHANNEL_READY: |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_READY, "connecting_ready"); |
| /* add the newly connected subchannel to the list of connected ones. |
| * Note that it goes to the "end of the line". */ |
| p->subchannel_index_to_readylist_node[this_idx] = |
| add_connected_sc_locked(p, p->subchannels[this_idx]); |
| /* 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. */ |
| selected = peek_next_connected_locked(p); |
| 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 = selected->subchannel; |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, |
| "[RR CONN CHANGED] TARGET <-- SUBCHANNEL %p (NODE %p)", |
| selected->subchannel, selected); |
| } |
| grpc_subchannel_del_interested_party(exec_ctx, selected->subchannel, |
| pp->pollset); |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, 1); |
| gpr_free(pp); |
| } |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[this_idx], this_connectivity, |
| &p->connectivity_changed_cbs[this_idx]); |
| break; |
| case GRPC_CHANNEL_CONNECTING: |
| case GRPC_CHANNEL_IDLE: |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| *this_connectivity, "connecting_changed"); |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[this_idx], this_connectivity, |
| &p->connectivity_changed_cbs[this_idx]); |
| break; |
| case GRPC_CHANNEL_TRANSIENT_FAILURE: |
| del_interested_parties_locked(exec_ctx, p, this_idx); |
| /* renew state notification */ |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[this_idx], this_connectivity, |
| &p->connectivity_changed_cbs[this_idx]); |
| |
| /* remove from ready list if still present */ |
| if (p->subchannel_index_to_readylist_node[this_idx] != NULL) { |
| remove_disconnected_sc_locked( |
| p, p->subchannel_index_to_readylist_node[this_idx]); |
| p->subchannel_index_to_readylist_node[this_idx] = NULL; |
| } |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_TRANSIENT_FAILURE, |
| "connecting_transient_failure"); |
| break; |
| case GRPC_CHANNEL_FATAL_FAILURE: |
| del_interested_parties_locked(exec_ctx, p, this_idx); |
| if (p->subchannel_index_to_readylist_node[this_idx] != NULL) { |
| remove_disconnected_sc_locked( |
| p, p->subchannel_index_to_readylist_node[this_idx]); |
| p->subchannel_index_to_readylist_node[this_idx] = NULL; |
| } |
| |
| GPR_SWAP(grpc_subchannel *, p->subchannels[this_idx], |
| p->subchannels[p->num_subchannels - 1]); |
| p->num_subchannels--; |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, p->subchannels[p->num_subchannels], |
| "round_robin"); |
| |
| if (p->num_subchannels == 0) { |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_FATAL_FAILURE, |
| "no_more_channels"); |
| while ((pp = p->pending_picks)) { |
| p->pending_picks = pp->next; |
| *pp->target = NULL; |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, 1); |
| gpr_free(pp); |
| } |
| unref = 1; |
| } else { |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_TRANSIENT_FAILURE, |
| "subchannel_failed"); |
| } |
| } /* switch */ |
| } /* !unref */ |
| |
| gpr_mu_unlock(&p->mu); |
| |
| if (unref) { |
| GRPC_LB_POLICY_UNREF(exec_ctx, &p->base, "round_robin_connectivity"); |
| } |
| } |
| |
| static void rr_broadcast(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| grpc_transport_op *op) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| size_t i; |
| size_t n; |
| grpc_subchannel **subchannels; |
| |
| gpr_mu_lock(&p->mu); |
| n = p->num_subchannels; |
| subchannels = gpr_malloc(n * sizeof(*subchannels)); |
| for (i = 0; i < n; i++) { |
| subchannels[i] = p->subchannels[i]; |
| GRPC_SUBCHANNEL_REF(subchannels[i], "rr_broadcast"); |
| } |
| gpr_mu_unlock(&p->mu); |
| |
| for (i = 0; i < n; i++) { |
| grpc_subchannel_process_transport_op(exec_ctx, subchannels[i], op); |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, subchannels[i], "rr_broadcast"); |
| } |
| gpr_free(subchannels); |
| } |
| |
| static grpc_connectivity_state rr_check_connectivity(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *pol) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| grpc_connectivity_state st; |
| gpr_mu_lock(&p->mu); |
| st = grpc_connectivity_state_check(&p->state_tracker); |
| gpr_mu_unlock(&p->mu); |
| return st; |
| } |
| |
| static void rr_notify_on_state_change(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; |
| gpr_mu_lock(&p->mu); |
| grpc_connectivity_state_notify_on_state_change(exec_ctx, &p->state_tracker, |
| current, notify); |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| static const grpc_lb_policy_vtable round_robin_lb_policy_vtable = { |
| rr_destroy, rr_shutdown, rr_pick, rr_cancel_pick, rr_exit_idle, |
| rr_broadcast, rr_check_connectivity, rr_notify_on_state_change}; |
| |
| 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_lb_policy_factory *factory, |
| grpc_lb_policy_args *args) { |
| size_t i; |
| round_robin_lb_policy *p = gpr_malloc(sizeof(*p)); |
| GPR_ASSERT(args->num_subchannels > 0); |
| memset(p, 0, sizeof(*p)); |
| grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable); |
| p->subchannels = |
| gpr_malloc(sizeof(grpc_subchannel *) * args->num_subchannels); |
| p->num_subchannels = args->num_subchannels; |
| grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE, |
| "round_robin"); |
| memcpy(p->subchannels, args->subchannels, |
| sizeof(grpc_subchannel *) * args->num_subchannels); |
| |
| gpr_mu_init(&p->mu); |
| p->connectivity_changed_cbs = |
| gpr_malloc(sizeof(grpc_closure) * args->num_subchannels); |
| p->subchannel_connectivity = |
| gpr_malloc(sizeof(grpc_connectivity_state) * args->num_subchannels); |
| |
| p->cb_args = |
| gpr_malloc(sizeof(connectivity_changed_cb_arg) * args->num_subchannels); |
| for (i = 0; i < args->num_subchannels; i++) { |
| p->cb_args[i].subchannel_idx = i; |
| p->cb_args[i].p = p; |
| grpc_closure_init(&p->connectivity_changed_cbs[i], rr_connectivity_changed, |
| &p->cb_args[i]); |
| } |
| |
| /* The (dummy node) root of the ready list */ |
| p->ready_list.subchannel = NULL; |
| p->ready_list.prev = NULL; |
| p->ready_list.next = NULL; |
| p->ready_list_last_pick = &p->ready_list; |
| |
| p->subchannel_index_to_readylist_node = |
| gpr_malloc(sizeof(grpc_subchannel *) * args->num_subchannels); |
| memset(p->subchannel_index_to_readylist_node, 0, |
| sizeof(grpc_subchannel *) * args->num_subchannels); |
| return &p->base; |
| } |
| |
| static const grpc_lb_policy_factory_vtable round_robin_factory_vtable = { |
| round_robin_factory_ref, round_robin_factory_unref, create_round_robin, |
| "round_robin"}; |
| |
| static grpc_lb_policy_factory round_robin_lb_policy_factory = { |
| &round_robin_factory_vtable}; |
| |
| grpc_lb_policy_factory *grpc_round_robin_lb_factory_create() { |
| return &round_robin_lb_policy_factory; |
| } |