| /* |
| * |
| * 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. |
| * |
| */ |
| |
| /** 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> |
| |
| #include "src/core/ext/client_channel/lb_policy_registry.h" |
| #include "src/core/ext/client_channel/subchannel.h" |
| #include "src/core/lib/channel/channel_args.h" |
| #include "src/core/lib/debug/trace.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" |
| |
| typedef struct round_robin_lb_policy round_robin_lb_policy; |
| |
| 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; |
| |
| /* 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; |
| |
| /** List of subchannels in a connectivity READY state */ |
| typedef struct ready_list { |
| grpc_subchannel *subchannel; |
| /* references namesake entry in subchannel_data */ |
| void *user_data; |
| struct ready_list *next; |
| struct ready_list *prev; |
| } ready_list; |
| |
| typedef struct { |
| /** index within policy->subchannels */ |
| size_t index; |
| /** backpointer to owning policy */ |
| round_robin_lb_policy *policy; |
| /** subchannel itself */ |
| grpc_subchannel *subchannel; |
| /** notification that connectivity has changed on subchannel */ |
| grpc_closure connectivity_changed_closure; |
| /** this subchannels current position in subchannel->ready_list */ |
| ready_list *ready_list_node; |
| /** 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 */ |
| const grpc_lb_user_data_vtable *user_data_vtable; |
| } subchannel_data; |
| |
| 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; |
| |
| /** all our subchannels */ |
| size_t num_subchannels; |
| subchannel_data **subchannels; |
| |
| /** 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? */ |
| int shutdown; |
| /** 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; |
| }; |
| |
| /** 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, RR: %p] ADVANCED LAST PICK. NOW AT NODE %p (SC %p, " |
| "CSC %p)", |
| (void *)p, (void *)p->ready_list_last_pick, |
| (void *)p->ready_list_last_pick->subchannel, |
| (void *)grpc_subchannel_get_connected_subchannel( |
| 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, |
| subchannel_data *sd) { |
| ready_list *new_elem = gpr_malloc(sizeof(ready_list)); |
| memset(new_elem, 0, sizeof(ready_list)); |
| new_elem->subchannel = sd->subchannel; |
| new_elem->user_data = sd->user_data; |
| 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 (Conn. SC %p)", |
| (void *)new_elem, (void *)sd->subchannel); |
| } |
| 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) { |
| p->ready_list_last_pick = p->ready_list_last_pick->prev; |
| } |
| |
| /* 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)", (void *)node, |
| (void *)node->subchannel); |
| } |
| |
| node->next = NULL; |
| node->prev = NULL; |
| node->subchannel = NULL; |
| |
| 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; |
| |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, "Destroying Round Robin policy at %p", (void *)pol); |
| } |
| |
| for (size_t i = 0; i < p->num_subchannels; i++) { |
| subchannel_data *sd = p->subchannels[i]; |
| 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(exec_ctx, sd->user_data); |
| } |
| gpr_free(sd); |
| } |
| |
| 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); |
| } |
| |
| static void rr_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| pending_pick *pp; |
| size_t i; |
| |
| gpr_mu_lock(&p->mu); |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, "Shutting down Round Robin policy at %p", (void *)pol); |
| } |
| |
| p->shutdown = 1; |
| while ((pp = p->pending_picks)) { |
| p->pending_picks = pp->next; |
| *pp->target = NULL; |
| grpc_closure_sched(exec_ctx, pp->on_complete, |
| GRPC_ERROR_CREATE("Channel Shutdown")); |
| gpr_free(pp); |
| } |
| grpc_connectivity_state_set( |
| exec_ctx, &p->state_tracker, GRPC_CHANNEL_SHUTDOWN, |
| GRPC_ERROR_CREATE("Channel Shutdown"), "rr_shutdown"); |
| for (i = 0; i < p->num_subchannels; i++) { |
| subchannel_data *sd = p->subchannels[i]; |
| grpc_subchannel_notify_on_state_change(exec_ctx, sd->subchannel, NULL, NULL, |
| &sd->connectivity_changed_closure); |
| } |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| static void rr_cancel_pick(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; |
| 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) { |
| *target = NULL; |
| grpc_closure_sched( |
| exec_ctx, pp->on_complete, |
| GRPC_ERROR_CREATE_REFERENCING("Pick cancelled", &error, 1)); |
| gpr_free(pp); |
| } else { |
| pp->next = p->pending_picks; |
| p->pending_picks = pp; |
| } |
| pp = next; |
| } |
| gpr_mu_unlock(&p->mu); |
| GRPC_ERROR_UNREF(error); |
| } |
| |
| static void rr_cancel_picks(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; |
| gpr_mu_lock(&p->mu); |
| 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("Pick cancelled", &error, 1)); |
| gpr_free(pp); |
| } else { |
| pp->next = p->pending_picks; |
| p->pending_picks = pp; |
| } |
| pp = next; |
| } |
| gpr_mu_unlock(&p->mu); |
| GRPC_ERROR_UNREF(error); |
| } |
| |
| 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++) { |
| subchannel_data *sd = p->subchannels[i]; |
| /* 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 = GRPC_CHANNEL_INIT; |
| 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->curr_connectivity_state, &sd->connectivity_changed_closure); |
| } |
| } |
| |
| static 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); |
| } |
| |
| static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| const grpc_lb_policy_pick_args *pick_args, |
| grpc_connected_subchannel **target, void **user_data, |
| grpc_closure *on_complete) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| pending_pick *pp; |
| ready_list *selected; |
| gpr_mu_lock(&p->mu); |
| |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_INFO, "Round Robin %p trying to pick", (void *)pol); |
| } |
| |
| if ((selected = peek_next_connected_locked(p))) { |
| /* readily available, report right away */ |
| *target = GRPC_CONNECTED_SUBCHANNEL_REF( |
| grpc_subchannel_get_connected_subchannel(selected->subchannel), |
| "rr_picked"); |
| |
| if (user_data != NULL) { |
| *user_data = selected->user_data; |
| } |
| if (grpc_lb_round_robin_trace) { |
| gpr_log(GPR_DEBUG, |
| "[RR PICK] TARGET <-- CONNECTED SUBCHANNEL %p (NODE %p)", |
| (void *)*target, (void *)selected); |
| } |
| /* only advance the last picked pointer if the selection was used */ |
| advance_last_picked_locked(p); |
| gpr_mu_unlock(&p->mu); |
| return 1; |
| } else { |
| /* no pick currently available. Save for later in list of pending picks */ |
| if (!p->started_picking) { |
| start_picking(exec_ctx, p); |
| } |
| 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; |
| gpr_mu_unlock(&p->mu); |
| return 0; |
| } |
| } |
| |
| 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; |
| |
| GRPC_ERROR_REF(error); |
| gpr_mu_lock(&p->mu); |
| |
| if (p->shutdown) { |
| 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_INIT: |
| GPR_UNREACHABLE_CODE(return ); |
| 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_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE); |
| gpr_free(pp); |
| } |
| update_lb_connectivity_status(exec_ctx, sd, error); |
| sd->prev_connectivity_state = sd->curr_connectivity_state; |
| /* 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); |
| break; |
| case GRPC_CHANNEL_IDLE: |
| ++p->num_idle; |
| /* fallthrough */ |
| case GRPC_CHANNEL_CONNECTING: |
| update_state_counters(sd); |
| update_lb_connectivity_status(exec_ctx, sd, error); |
| sd->prev_connectivity_state = sd->curr_connectivity_state; |
| /* 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); |
| 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; |
| } |
| update_lb_connectivity_status(exec_ctx, sd, error); |
| sd->prev_connectivity_state = sd->curr_connectivity_state; |
| /* 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); |
| 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 = NULL; |
| grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE); |
| gpr_free(pp); |
| } |
| } |
| 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); |
| } |
| |
| static grpc_connectivity_state rr_check_connectivity(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *pol, |
| grpc_error **error) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| grpc_connectivity_state st; |
| gpr_mu_lock(&p->mu); |
| st = grpc_connectivity_state_get(&p->state_tracker, error); |
| 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 void rr_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| grpc_closure *closure) { |
| round_robin_lb_policy *p = (round_robin_lb_policy *)pol; |
| ready_list *selected; |
| grpc_connected_subchannel *target; |
| gpr_mu_lock(&p->mu); |
| if ((selected = peek_next_connected_locked(p))) { |
| gpr_mu_unlock(&p->mu); |
| 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 { |
| gpr_mu_unlock(&p->mu); |
| grpc_closure_sched(exec_ctx, closure, |
| GRPC_ERROR_CREATE("Round Robin not connected")); |
| } |
| } |
| |
| static const grpc_lb_policy_vtable round_robin_lb_policy_vtable = { |
| rr_destroy, rr_shutdown, rr_pick, |
| rr_cancel_pick, rr_cancel_picks, rr_ping_one, |
| rr_exit_idle, 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 *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); |
| |
| /* 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); |
| GPR_ASSERT(arg != NULL && arg->type == GRPC_ARG_POINTER); |
| 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) return NULL; |
| |
| round_robin_lb_policy *p = gpr_malloc(sizeof(*p)); |
| memset(p, 0, sizeof(*p)); |
| |
| p->num_addresses = num_addrs; |
| p->subchannels = gpr_malloc(sizeof(*p->subchannels) * num_addrs); |
| memset(p->subchannels, 0, sizeof(*p->subchannels) * num_addrs); |
| |
| grpc_subchannel_args sc_args; |
| size_t subchannel_idx = 0; |
| 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; |
| |
| 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(args->args, &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_lb_round_robin_trace) { |
| char *address_uri = |
| grpc_sockaddr_to_uri(&addresses->addresses[i].address); |
| gpr_log(GPR_DEBUG, "Created subchannel %p for address uri %s", |
| (void *)subchannel, address_uri); |
| gpr_free(address_uri); |
| } |
| grpc_channel_args_destroy(exec_ctx, new_args); |
| |
| if (subchannel != NULL) { |
| subchannel_data *sd = gpr_malloc(sizeof(*sd)); |
| memset(sd, 0, sizeof(*sd)); |
| p->subchannels[subchannel_idx] = sd; |
| sd->policy = p; |
| sd->index = subchannel_idx; |
| sd->subchannel = subchannel; |
| 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); |
| } |
| ++subchannel_idx; |
| grpc_closure_init(&sd->connectivity_changed_closure, |
| rr_connectivity_changed, sd, grpc_schedule_on_exec_ctx); |
| } |
| } |
| if (subchannel_idx == 0) { |
| /* couldn't create any subchannel. Bail out */ |
| gpr_free(p->subchannels); |
| gpr_free(p); |
| return NULL; |
| } |
| p->num_subchannels = subchannel_idx; |
| |
| /* 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; |
| |
| 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; |
| } |
| |
| 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("round_robin", &grpc_lb_round_robin_trace); |
| } |
| |
| void grpc_lb_policy_round_robin_shutdown() {} |