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/*
*
* 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/client_config/lb_policy_registry.h"
#include "src/core/lib/transport/connectivity_state.h"
typedef struct pending_pick {
struct pending_pick *next;
grpc_polling_entity *pollent;
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))
static 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);
}
static 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_SHUTDOWN,
GRPC_ERROR_CREATE("Channel shutdown"), "shutdown");
/* cancel subscription */
if (selected != NULL) {
grpc_connected_subchannel_notify_on_state_change(
exec_ctx, 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);
}
gpr_mu_unlock(&p->mu);
while (pp != NULL) {
pending_pick *next = pp->next;
*pp->target = NULL;
grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
p->base.interested_parties);
grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, NULL);
gpr_free(pp);
pp = next;
}
}
static void pf_cancel_pick(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;
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_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
p->base.interested_parties);
*target = NULL;
grpc_exec_ctx_sched(
exec_ctx, pp->on_complete,
GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled", &error, 1), NULL);
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 pf_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) {
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_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
p->base.interested_parties);
grpc_exec_ctx_sched(exec_ctx, pp->on_complete,
GRPC_ERROR_CREATE_REFERENCING("Pick Cancelled",
&error, 1), NULL);
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, 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(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);
}
static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
grpc_polling_entity *pollent,
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_polling_entity_add_to_pollset_set(exec_ctx, pollent,
p->base.interested_parties);
pp = gpr_malloc(sizeof(*pp));
pp->next = p->pending_picks;
pp->pollent = pollent;
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,
grpc_error *error) {
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,
grpc_error *error) {
pick_first_lb_policy *p = arg;
grpc_subchannel *selected_subchannel;
pending_pick *pp;
grpc_connected_subchannel *selected;
GRPC_ERROR_REF(error);
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");
GRPC_ERROR_UNREF(error);
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_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, 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, GRPC_ERROR_NONE,
"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_sched(exec_ctx,
grpc_closure_create(destroy_subchannels, p),
GRPC_ERROR_NONE, NULL);
/* update any calls that were waiting for a pick */
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = selected;
grpc_polling_entity_del_from_pollset_set(exec_ctx, pp->pollent,
p->base.interested_parties);
grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE, 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:
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("Pick first exhausted channels",
&error, 1),
"no_more_channels");
while ((pp = p->pending_picks)) {
p->pending_picks = pp->next;
*pp->target = NULL;
grpc_exec_ctx_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE,
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,
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;
}
}
}
gpr_mu_unlock(&p->mu);
GRPC_ERROR_UNREF(error);
}
static grpc_connectivity_state pf_check_connectivity(grpc_exec_ctx *exec_ctx,
grpc_lb_policy *pol,
grpc_error **error) {
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, error);
gpr_mu_unlock(&p->mu);
return st;
}
static 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);
}
static 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_sched(exec_ctx, closure, GRPC_ERROR_CREATE("Not connected"),
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_exec_ctx *exec_ctx,
grpc_lb_policy_factory *factory,
grpc_lb_policy_args *args) {
GPR_ASSERT(args->addresses != NULL);
GPR_ASSERT(args->client_channel_factory != NULL);
if (args->addresses->naddrs == 0) return NULL;
pick_first_lb_policy *p = gpr_malloc(sizeof(*p));
memset(p, 0, sizeof(*p));
p->subchannels =
gpr_malloc(sizeof(grpc_subchannel *) * args->addresses->naddrs);
memset(p->subchannels, 0, sizeof(*p->subchannels) * args->addresses->naddrs);
grpc_subchannel_args sc_args;
size_t subchannel_idx = 0;
for (size_t i = 0; i < args->addresses->naddrs; i++) {
memset(&sc_args, 0, sizeof(grpc_subchannel_args));
sc_args.addr = (struct sockaddr *)(args->addresses->addrs[i].addr);
sc_args.addr_len = (size_t)args->addresses->addrs[i].len;
grpc_subchannel *subchannel = grpc_client_channel_factory_create_subchannel(
exec_ctx, args->client_channel_factory, &sc_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);
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};
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() {}
|