| /* |
| * |
| * Copyright 2015-2016, 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/lib/client_config/lb_policies/pick_first.h" |
| #include "src/core/lib/client_config/lb_policy_factory.h" |
| |
| #include <string.h> |
| |
| #include <grpc/support/alloc.h> |
| #include "src/core/lib/transport/connectivity_state.h" |
| |
| typedef struct pending_pick { |
| struct pending_pick *next; |
| grpc_pollset *pollset; |
| uint32_t initial_metadata_flags; |
| grpc_connected_subchannel **target; |
| grpc_closure *on_complete; |
| } pending_pick; |
| |
| typedef struct { |
| /** base policy: must be first */ |
| grpc_lb_policy base; |
| /** all our subchannels */ |
| grpc_subchannel **subchannels; |
| size_t num_subchannels; |
| |
| grpc_closure connectivity_changed; |
| |
| /** the selected channel (a grpc_connected_subchannel) */ |
| gpr_atm selected; |
| |
| /** mutex protecting remaining members */ |
| gpr_mu mu; |
| /** have we started picking? */ |
| int started_picking; |
| /** are we shut down? */ |
| int shutdown; |
| /** which subchannel are we watching? */ |
| size_t checking_subchannel; |
| /** what is the connectivity of that channel? */ |
| grpc_connectivity_state checking_connectivity; |
| /** list of picks that are waiting on connectivity */ |
| pending_pick *pending_picks; |
| |
| /** our connectivity state tracker */ |
| grpc_connectivity_state_tracker state_tracker; |
| } pick_first_lb_policy; |
| |
| #define GET_SELECTED(p) \ |
| ((grpc_connected_subchannel *)gpr_atm_acq_load(&(p)->selected)) |
| |
| void pf_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| pick_first_lb_policy *p = (pick_first_lb_policy *)pol; |
| grpc_connected_subchannel *selected = GET_SELECTED(p); |
| size_t i; |
| GPR_ASSERT(p->pending_picks == NULL); |
| for (i = 0; i < p->num_subchannels; i++) { |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, p->subchannels[i], "pick_first"); |
| } |
| if (selected != NULL) { |
| GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, selected, "picked_first"); |
| } |
| grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker); |
| gpr_free(p->subchannels); |
| gpr_mu_destroy(&p->mu); |
| gpr_free(p); |
| } |
| |
| void pf_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| pick_first_lb_policy *p = (pick_first_lb_policy *)pol; |
| pending_pick *pp; |
| grpc_connected_subchannel *selected; |
| gpr_mu_lock(&p->mu); |
| selected = GET_SELECTED(p); |
| p->shutdown = 1; |
| pp = p->pending_picks; |
| p->pending_picks = NULL; |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_FATAL_FAILURE, "shutdown"); |
| /* cancel subscription */ |
| if (selected != NULL) { |
| grpc_connected_subchannel_notify_on_state_change( |
| exec_ctx, selected, NULL, NULL, &p->connectivity_changed); |
| } else { |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[p->checking_subchannel], NULL, NULL, |
| &p->connectivity_changed); |
| } |
| gpr_mu_unlock(&p->mu); |
| while (pp != NULL) { |
| pending_pick *next = pp->next; |
| *pp->target = NULL; |
| grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, |
| pp->pollset); |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, true, NULL); |
| gpr_free(pp); |
| pp = next; |
| } |
| } |
| |
| static void pf_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| grpc_connected_subchannel **target) { |
| pick_first_lb_policy *p = (pick_first_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) { |
| grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, |
| pp->pollset); |
| *target = NULL; |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, false, NULL); |
| gpr_free(pp); |
| } else { |
| pp->next = p->pending_picks; |
| p->pending_picks = pp; |
| } |
| pp = next; |
| } |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| static void pf_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| uint32_t initial_metadata_flags_mask, |
| uint32_t initial_metadata_flags_eq) { |
| pick_first_lb_policy *p = (pick_first_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) { |
| grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, |
| pp->pollset); |
| *pp->target = NULL; |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, false, NULL); |
| 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, pick_first_lb_policy *p) { |
| p->started_picking = 1; |
| p->checking_subchannel = 0; |
| p->checking_connectivity = GRPC_CHANNEL_IDLE; |
| GRPC_LB_POLICY_WEAK_REF(&p->base, "pick_first_connectivity"); |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[p->checking_subchannel], |
| p->base.interested_parties, &p->checking_connectivity, |
| &p->connectivity_changed); |
| } |
| |
| void pf_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { |
| pick_first_lb_policy *p = (pick_first_lb_policy *)pol; |
| gpr_mu_lock(&p->mu); |
| if (!p->started_picking) { |
| start_picking(exec_ctx, p); |
| } |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_pollset *pollset, |
| grpc_metadata_batch *initial_metadata, |
| uint32_t initial_metadata_flags, grpc_connected_subchannel **target, |
| grpc_closure *on_complete) { |
| pick_first_lb_policy *p = (pick_first_lb_policy *)pol; |
| pending_pick *pp; |
| |
| /* Check atomically for a selected channel */ |
| grpc_connected_subchannel *selected = GET_SELECTED(p); |
| if (selected != NULL) { |
| *target = selected; |
| return 1; |
| } |
| |
| /* No subchannel selected yet, so acquire lock and then attempt again */ |
| gpr_mu_lock(&p->mu); |
| selected = GET_SELECTED(p); |
| if (selected) { |
| gpr_mu_unlock(&p->mu); |
| *target = selected; |
| return 1; |
| } else { |
| if (!p->started_picking) { |
| start_picking(exec_ctx, p); |
| } |
| grpc_pollset_set_add_pollset(exec_ctx, p->base.interested_parties, pollset); |
| pp = gpr_malloc(sizeof(*pp)); |
| pp->next = p->pending_picks; |
| pp->pollset = pollset; |
| pp->target = target; |
| pp->initial_metadata_flags = initial_metadata_flags; |
| pp->on_complete = on_complete; |
| p->pending_picks = pp; |
| gpr_mu_unlock(&p->mu); |
| return 0; |
| } |
| } |
| |
| static void destroy_subchannels(grpc_exec_ctx *exec_ctx, void *arg, |
| bool iomgr_success) { |
| pick_first_lb_policy *p = arg; |
| size_t i; |
| size_t num_subchannels = p->num_subchannels; |
| grpc_subchannel **subchannels; |
| |
| gpr_mu_lock(&p->mu); |
| subchannels = p->subchannels; |
| p->num_subchannels = 0; |
| p->subchannels = NULL; |
| gpr_mu_unlock(&p->mu); |
| GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "destroy_subchannels"); |
| |
| for (i = 0; i < num_subchannels; i++) { |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, subchannels[i], "pick_first"); |
| } |
| |
| gpr_free(subchannels); |
| } |
| |
| static void pf_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg, |
| bool iomgr_success) { |
| pick_first_lb_policy *p = arg; |
| grpc_subchannel *selected_subchannel; |
| pending_pick *pp; |
| grpc_connected_subchannel *selected; |
| |
| gpr_mu_lock(&p->mu); |
| |
| selected = GET_SELECTED(p); |
| |
| if (p->shutdown) { |
| gpr_mu_unlock(&p->mu); |
| GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "pick_first_connectivity"); |
| return; |
| } else if (selected != NULL) { |
| if (p->checking_connectivity == GRPC_CHANNEL_TRANSIENT_FAILURE) { |
| /* if the selected channel goes bad, we're done */ |
| p->checking_connectivity = GRPC_CHANNEL_FATAL_FAILURE; |
| } |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| p->checking_connectivity, "selected_changed"); |
| if (p->checking_connectivity != GRPC_CHANNEL_FATAL_FAILURE) { |
| grpc_connected_subchannel_notify_on_state_change( |
| exec_ctx, selected, p->base.interested_parties, |
| &p->checking_connectivity, &p->connectivity_changed); |
| } else { |
| GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "pick_first_connectivity"); |
| } |
| } else { |
| loop: |
| switch (p->checking_connectivity) { |
| case GRPC_CHANNEL_READY: |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_READY, "connecting_ready"); |
| selected_subchannel = p->subchannels[p->checking_subchannel]; |
| selected = |
| grpc_subchannel_get_connected_subchannel(selected_subchannel); |
| GPR_ASSERT(selected != NULL); |
| GRPC_CONNECTED_SUBCHANNEL_REF(selected, "picked_first"); |
| /* drop the pick list: we are connected now */ |
| GRPC_LB_POLICY_WEAK_REF(&p->base, "destroy_subchannels"); |
| gpr_atm_rel_store(&p->selected, (gpr_atm)selected); |
| grpc_exec_ctx_enqueue( |
| exec_ctx, grpc_closure_create(destroy_subchannels, p), true, NULL); |
| /* update any calls that were waiting for a pick */ |
| while ((pp = p->pending_picks)) { |
| p->pending_picks = pp->next; |
| *pp->target = selected; |
| grpc_pollset_set_del_pollset(exec_ctx, p->base.interested_parties, |
| pp->pollset); |
| grpc_exec_ctx_enqueue(exec_ctx, pp->on_complete, true, NULL); |
| gpr_free(pp); |
| } |
| grpc_connected_subchannel_notify_on_state_change( |
| exec_ctx, selected, p->base.interested_parties, |
| &p->checking_connectivity, &p->connectivity_changed); |
| break; |
| case GRPC_CHANNEL_TRANSIENT_FAILURE: |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_TRANSIENT_FAILURE, |
| "connecting_transient_failure"); |
| p->checking_subchannel = |
| (p->checking_subchannel + 1) % p->num_subchannels; |
| p->checking_connectivity = grpc_subchannel_check_connectivity( |
| p->subchannels[p->checking_subchannel]); |
| if (p->checking_connectivity == GRPC_CHANNEL_TRANSIENT_FAILURE) { |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[p->checking_subchannel], |
| p->base.interested_parties, &p->checking_connectivity, |
| &p->connectivity_changed); |
| } else { |
| goto loop; |
| } |
| break; |
| case GRPC_CHANNEL_CONNECTING: |
| case GRPC_CHANNEL_IDLE: |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_CONNECTING, |
| "connecting_changed"); |
| grpc_subchannel_notify_on_state_change( |
| exec_ctx, p->subchannels[p->checking_subchannel], |
| p->base.interested_parties, &p->checking_connectivity, |
| &p->connectivity_changed); |
| break; |
| case GRPC_CHANNEL_FATAL_FAILURE: |
| p->num_subchannels--; |
| GPR_SWAP(grpc_subchannel *, p->subchannels[p->checking_subchannel], |
| p->subchannels[p->num_subchannels]); |
| GRPC_SUBCHANNEL_UNREF(exec_ctx, p->subchannels[p->num_subchannels], |
| "pick_first"); |
| 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, true, NULL); |
| gpr_free(pp); |
| } |
| GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, |
| "pick_first_connectivity"); |
| } else { |
| grpc_connectivity_state_set(exec_ctx, &p->state_tracker, |
| GRPC_CHANNEL_TRANSIENT_FAILURE, |
| "subchannel_failed"); |
| p->checking_subchannel %= p->num_subchannels; |
| p->checking_connectivity = grpc_subchannel_check_connectivity( |
| p->subchannels[p->checking_subchannel]); |
| goto loop; |
| } |
| } |
| } |
| |
| gpr_mu_unlock(&p->mu); |
| } |
| |
| static grpc_connectivity_state pf_check_connectivity(grpc_exec_ctx *exec_ctx, |
| grpc_lb_policy *pol) { |
| pick_first_lb_policy *p = (pick_first_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; |
| } |
| |
| void pf_notify_on_state_change(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| grpc_connectivity_state *current, |
| grpc_closure *notify) { |
| pick_first_lb_policy *p = (pick_first_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); |
| } |
| |
| void pf_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, |
| grpc_closure *closure) { |
| pick_first_lb_policy *p = (pick_first_lb_policy *)pol; |
| grpc_connected_subchannel *selected = GET_SELECTED(p); |
| if (selected) { |
| grpc_connected_subchannel_ping(exec_ctx, selected, closure); |
| } else { |
| grpc_exec_ctx_enqueue(exec_ctx, closure, false, NULL); |
| } |
| } |
| |
| static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = { |
| pf_destroy, pf_shutdown, pf_pick, |
| pf_cancel_pick, pf_cancel_picks, pf_ping_one, |
| pf_exit_idle, pf_check_connectivity, pf_notify_on_state_change}; |
| |
| static void pick_first_factory_ref(grpc_lb_policy_factory *factory) {} |
| |
| static void pick_first_factory_unref(grpc_lb_policy_factory *factory) {} |
| |
| static grpc_lb_policy *create_pick_first(grpc_lb_policy_factory *factory, |
| grpc_lb_policy_args *args) { |
| if (args->num_subchannels == 0) return NULL; |
| pick_first_lb_policy *p = gpr_malloc(sizeof(*p)); |
| memset(p, 0, sizeof(*p)); |
| grpc_lb_policy_init(&p->base, &pick_first_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, |
| "pick_first"); |
| memcpy(p->subchannels, args->subchannels, |
| sizeof(grpc_subchannel *) * args->num_subchannels); |
| grpc_closure_init(&p->connectivity_changed, pf_connectivity_changed, p); |
| gpr_mu_init(&p->mu); |
| return &p->base; |
| } |
| |
| static const grpc_lb_policy_factory_vtable pick_first_factory_vtable = { |
| pick_first_factory_ref, pick_first_factory_unref, create_pick_first, |
| "pick_first"}; |
| |
| static grpc_lb_policy_factory pick_first_lb_policy_factory = { |
| &pick_first_factory_vtable}; |
| |
| grpc_lb_policy_factory *grpc_pick_first_lb_factory_create() { |
| return &pick_first_lb_policy_factory; |
| } |