diff options
Diffstat (limited to 'src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c')
| -rw-r--r-- | src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c new file mode 100644 index 0000000000..2b77cd39b8 --- /dev/null +++ b/src/core/ext/filters/client_channel/lb_policy/pick_first/pick_first.c @@ -0,0 +1,476 @@ +/* + * + * 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 <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/lib/channel/channel_args.h" +#include "src/core/lib/iomgr/combiner.h" +#include "src/core/lib/iomgr/sockaddr_utils.h" +#include "src/core/lib/transport/connectivity_state.h" + +typedef struct pending_pick { + struct pending_pick *next; + 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; + + /** remaining members are protected by the combiner */ + + /** the selected channel */ + grpc_connected_subchannel *selected; + + /** 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; + +static void pf_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + 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 (p->selected != NULL) { + GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, p->selected, "picked_first"); + } + grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker); + gpr_free(p->subchannels); + gpr_free(p); +} + +static void pf_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + pending_pick *pp; + p->shutdown = 1; + pp = p->pending_picks; + p->pending_picks = NULL; + grpc_connectivity_state_set( + exec_ctx, &p->state_tracker, GRPC_CHANNEL_SHUTDOWN, + GRPC_ERROR_CREATE_FROM_STATIC_STRING("Channel shutdown"), "shutdown"); + /* cancel subscription */ + if (p->selected != NULL) { + grpc_connected_subchannel_notify_on_state_change( + exec_ctx, p->selected, NULL, NULL, &p->connectivity_changed); + } else if (p->num_subchannels > 0) { + grpc_subchannel_notify_on_state_change( + exec_ctx, p->subchannels[p->checking_subchannel], NULL, NULL, + &p->connectivity_changed); + } + while (pp != NULL) { + pending_pick *next = pp->next; + *pp->target = NULL; + grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE); + gpr_free(pp); + pp = next; + } +} + +static void pf_cancel_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, + grpc_connected_subchannel **target, + grpc_error *error) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + pending_pick *pp; + 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 pf_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) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + pending_pick *pp; + 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_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(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); +} + +static void pf_exit_idle_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + if (!p->started_picking) { + start_picking(exec_ctx, p); + } +} + +static int pf_pick_locked(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) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + pending_pick *pp; + + /* Check atomically for a selected channel */ + if (p->selected != NULL) { + *target = GRPC_CONNECTED_SUBCHANNEL_REF(p->selected, "picked"); + return 1; + } + + /* No subchannel selected yet, so try again */ + if (!p->started_picking) { + start_picking(exec_ctx, p); + } + pp = gpr_malloc(sizeof(*pp)); + pp->next = p->pending_picks; + pp->target = target; + pp->initial_metadata_flags = pick_args->initial_metadata_flags; + pp->on_complete = on_complete; + p->pending_picks = pp; + return 0; +} + +static void destroy_subchannels_locked(grpc_exec_ctx *exec_ctx, + pick_first_lb_policy *p) { + size_t i; + size_t num_subchannels = p->num_subchannels; + grpc_subchannel **subchannels; + + subchannels = p->subchannels; + p->num_subchannels = 0; + p->subchannels = NULL; + 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_locked(grpc_exec_ctx *exec_ctx, void *arg, + grpc_error *error) { + pick_first_lb_policy *p = arg; + grpc_subchannel *selected_subchannel; + pending_pick *pp; + + GRPC_ERROR_REF(error); + + if (p->shutdown) { + GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "pick_first_connectivity"); + GRPC_ERROR_UNREF(error); + return; + } else if (p->selected != NULL) { + if (p->checking_connectivity == GRPC_CHANNEL_TRANSIENT_FAILURE) { + /* if the selected channel goes bad, we're done */ + p->checking_connectivity = GRPC_CHANNEL_SHUTDOWN; + } + grpc_connectivity_state_set(exec_ctx, &p->state_tracker, + p->checking_connectivity, GRPC_ERROR_REF(error), + "selected_changed"); + if (p->checking_connectivity != GRPC_CHANNEL_SHUTDOWN) { + grpc_connected_subchannel_notify_on_state_change( + exec_ctx, p->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_INIT: + GPR_UNREACHABLE_CODE(return ); + case GRPC_CHANNEL_READY: + grpc_connectivity_state_set(exec_ctx, &p->state_tracker, + GRPC_CHANNEL_READY, GRPC_ERROR_NONE, + "connecting_ready"); + selected_subchannel = p->subchannels[p->checking_subchannel]; + p->selected = GRPC_CONNECTED_SUBCHANNEL_REF( + grpc_subchannel_get_connected_subchannel(selected_subchannel), + "picked_first"); + /* drop the pick list: we are connected now */ + GRPC_LB_POLICY_WEAK_REF(&p->base, "destroy_subchannels"); + destroy_subchannels_locked(exec_ctx, p); + /* update any calls that were waiting for a pick */ + while ((pp = p->pending_picks)) { + p->pending_picks = pp->next; + *pp->target = GRPC_CONNECTED_SUBCHANNEL_REF(p->selected, "picked"); + grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE); + gpr_free(pp); + } + grpc_connected_subchannel_notify_on_state_change( + exec_ctx, p->selected, p->base.interested_parties, + &p->checking_connectivity, &p->connectivity_changed); + break; + case GRPC_CHANNEL_TRANSIENT_FAILURE: + p->checking_subchannel = + (p->checking_subchannel + 1) % p->num_subchannels; + if (p->checking_subchannel == 0) { + /* only trigger transient failure when we've tried all alternatives */ + grpc_connectivity_state_set( + exec_ctx, &p->state_tracker, GRPC_CHANNEL_TRANSIENT_FAILURE, + GRPC_ERROR_REF(error), "connecting_transient_failure"); + } + GRPC_ERROR_UNREF(error); + p->checking_connectivity = grpc_subchannel_check_connectivity( + p->subchannels[p->checking_subchannel], &error); + 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, + GRPC_ERROR_REF(error), "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_SHUTDOWN: + 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_SHUTDOWN, + GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING( + "Pick first exhausted channels", &error, 1), + "no_more_channels"); + 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); + } + 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, + GRPC_ERROR_REF(error), "subchannel_failed"); + p->checking_subchannel %= p->num_subchannels; + GRPC_ERROR_UNREF(error); + p->checking_connectivity = grpc_subchannel_check_connectivity( + p->subchannels[p->checking_subchannel], &error); + goto loop; + } + } + } + + GRPC_ERROR_UNREF(error); +} + +static grpc_connectivity_state pf_check_connectivity_locked( + grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_error **error) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + return grpc_connectivity_state_get(&p->state_tracker, error); +} + +static void pf_notify_on_state_change_locked(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; + grpc_connectivity_state_notify_on_state_change(exec_ctx, &p->state_tracker, + current, notify); +} + +static void pf_ping_one_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, + grpc_closure *closure) { + pick_first_lb_policy *p = (pick_first_lb_policy *)pol; + if (p->selected) { + grpc_connected_subchannel_ping(exec_ctx, p->selected, closure); + } else { + grpc_closure_sched(exec_ctx, closure, + GRPC_ERROR_CREATE_FROM_STATIC_STRING("Not connected")); + } +} + +static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = { + pf_destroy, + pf_shutdown_locked, + pf_pick_locked, + pf_cancel_pick_locked, + pf_cancel_picks_locked, + pf_ping_one_locked, + pf_exit_idle_locked, + pf_check_connectivity_locked, + pf_notify_on_state_change_locked}; + +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_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); + if (arg == NULL || arg->type != GRPC_ARG_POINTER) { + return NULL; + } + 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; + + pick_first_lb_policy *p = gpr_zalloc(sizeof(*p)); + + p->subchannels = gpr_zalloc(sizeof(grpc_subchannel *) * 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; + + if (addresses->addresses[i].user_data != NULL) { + gpr_log(GPR_ERROR, + "This LB policy doesn't support user data. It will be ignored"); + } + + static const char *keys_to_remove[] = {GRPC_ARG_SUBCHANNEL_ADDRESS}; + 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); + + if (subchannel != NULL) { + p->subchannels[subchannel_idx++] = subchannel; + } + } + if (subchannel_idx == 0) { + gpr_free(p->subchannels); + gpr_free(p); + return NULL; + } + p->num_subchannels = subchannel_idx; + + grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable, args->combiner); + grpc_closure_init(&p->connectivity_changed, pf_connectivity_changed_locked, p, + grpc_combiner_scheduler(args->combiner, false)); + 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}; + +static grpc_lb_policy_factory *pick_first_lb_factory_create() { + return &pick_first_lb_policy_factory; +} + +/* Plugin registration */ + +void grpc_lb_policy_pick_first_init() { + grpc_register_lb_policy(pick_first_lb_factory_create()); +} + +void grpc_lb_policy_pick_first_shutdown() {} |