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Check in c_ares/dns_resolver.c

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pull/7704/head
Yuchen Zeng 9 years ago
parent 43b4bfd02b
commit 1e4c44bfe6
1 changed files with 347 additions and 0 deletions
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  1. 347
      src/core/ext/resolver/dns/c_ares/dns_resolver.c

347
src/core/ext/resolver/dns/c_ares/dns_resolver.c
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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 <grpc/support/port_platform.h>
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/host_port.h>
#include <grpc/support/string_util.h>
#include <ares.h>
#include "src/core/ext/client_config/lb_policy_registry.h"
#include "src/core/ext/client_config/resolver_registry.h"
#include "src/core/ext/resolver/dns/c_ares/grpc_ares_wrapper.h"
#include "src/core/lib/iomgr/resolve_address.h"
#include "src/core/lib/iomgr/timer.h"
#include "src/core/lib/support/backoff.h"
#include "src/core/lib/support/string.h"
#define BACKOFF_MULTIPLIER 1.6
#define BACKOFF_JITTER 0.2
#define BACKOFF_MIN_SECONDS 1
#define BACKOFF_MAX_SECONDS 120
typedef struct {
/** base class: must be first */
grpc_resolver base;
/** refcount */
gpr_refcount refs;
/** name to resolve */
char *name;
/** default port to use */
char *default_port;
/** subchannel factory */
grpc_client_channel_factory *client_channel_factory;
/** load balancing policy name */
char *lb_policy_name;
/** mutex guarding the rest of the state */
gpr_mu mu;
/** are we currently resolving? */
int resolving;
/** which version of resolved_config have we published? */
int published_version;
/** which version of resolved_config is current? */
int resolved_version;
/** pending next completion, or NULL */
grpc_closure *next_completion;
/** target config address for next completion */
grpc_client_config **target_config;
/** current (fully resolved) config */
grpc_client_config *resolved_config;
/** retry timer */
bool have_retry_timer;
grpc_timer retry_timer;
/** retry backoff state */
gpr_backoff backoff_state;
/** currently resolving addresses */
grpc_resolved_addresses *addresses;
grpc_ares_request *request;
grpc_polling_entity *pollent;
} dns_resolver;
static void dns_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
static void dns_start_resolving_locked(grpc_exec_ctx *exec_ctx,
dns_resolver *r);
static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
dns_resolver *r);
static void dns_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
static void dns_channel_saw_error(grpc_exec_ctx *exec_ctx, grpc_resolver *r);
static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *r,
grpc_polling_entity *pollent,
grpc_client_config **target_config,
grpc_closure *on_complete);
static const grpc_resolver_vtable dns_resolver_vtable = {
dns_destroy, dns_shutdown, dns_channel_saw_error, dns_next};
static void dns_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver) {
dns_resolver *r = (dns_resolver *)resolver;
gpr_mu_lock(&r->mu);
if (r->have_retry_timer) {
grpc_timer_cancel(exec_ctx, &r->retry_timer);
}
if (r->next_completion != NULL) {
*r->target_config = NULL;
grpc_exec_ctx_sched(exec_ctx, r->next_completion,
GRPC_ERROR_CREATE("Resolver Shutdown"), NULL);
r->next_completion = NULL;
}
gpr_mu_unlock(&r->mu);
}
static void dns_channel_saw_error(grpc_exec_ctx *exec_ctx,
grpc_resolver *resolver) {
dns_resolver *r = (dns_resolver *)resolver;
gpr_mu_lock(&r->mu);
if (!r->resolving) {
gpr_backoff_reset(&r->backoff_state);
dns_start_resolving_locked(exec_ctx, r);
}
gpr_mu_unlock(&r->mu);
}
static void dns_on_retry_timer(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
dns_resolver *r = arg;
gpr_mu_lock(&r->mu);
r->have_retry_timer = false;
if (error == GRPC_ERROR_NONE) {
if (!r->resolving) {
dns_start_resolving_locked(exec_ctx, r);
}
}
gpr_mu_unlock(&r->mu);
GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "retry-timer");
}
static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
grpc_error *error) {
gpr_log(GPR_ERROR, "dns_on_resolved");
dns_resolver *r = arg;
grpc_client_config *config = NULL;
grpc_lb_policy *lb_policy;
gpr_log(GPR_ERROR, "before mu");
gpr_mu_lock(&r->mu);
gpr_log(GPR_ERROR, "after mu");
GPR_ASSERT(r->resolving);
r->resolving = 0;
grpc_resolved_addresses *addresses = r->addresses;
if (addresses != NULL) {
gpr_log(GPR_ERROR, "addresses != NULL");
grpc_lb_policy_args lb_policy_args;
config = grpc_client_config_create();
memset(&lb_policy_args, 0, sizeof(lb_policy_args));
lb_policy_args.addresses = addresses;
lb_policy_args.client_channel_factory = r->client_channel_factory;
lb_policy =
grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
if (lb_policy != NULL) {
grpc_client_config_set_lb_policy(config, lb_policy);
GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "construction");
}
grpc_resolved_addresses_destroy(addresses);
} else {
gpr_log(GPR_ERROR, "addresses == NULL");
gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC);
gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
gpr_timespec timeout = gpr_time_sub(next_try, now);
const char *msg = grpc_error_string(error);
gpr_log(GPR_DEBUG, "dns resolution failed: %s", msg);
grpc_error_free_string(msg);
GPR_ASSERT(!r->have_retry_timer);
r->have_retry_timer = true;
GRPC_RESOLVER_REF(&r->base, "retry-timer");
if (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) <= 0) {
gpr_log(GPR_DEBUG, "retrying in %" PRId64 ".%09d seconds", timeout.tv_sec,
timeout.tv_nsec);
} else {
gpr_log(GPR_DEBUG, "retrying immediately");
}
grpc_timer_init(exec_ctx, &r->retry_timer, next_try, dns_on_retry_timer, r,
now);
}
if (r->resolved_config) {
grpc_client_config_unref(exec_ctx, r->resolved_config);
}
r->resolved_config = config;
r->resolved_version++;
dns_maybe_finish_next_locked(exec_ctx, r);
gpr_mu_unlock(&r->mu);
gpr_log(GPR_ERROR, "mu_unlock");
GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "dns-resolving");
gpr_log(GPR_ERROR, "after GRPC_RESOLVER_UNREF");
}
static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
grpc_polling_entity *pollent,
grpc_client_config **target_config,
grpc_closure *on_complete) {
dns_resolver *r = (dns_resolver *)resolver;
gpr_mu_lock(&r->mu);
GPR_ASSERT(!r->next_completion);
r->next_completion = on_complete;
r->target_config = target_config;
if (r->resolved_version == 0 && !r->resolving) {
gpr_backoff_reset(&r->backoff_state);
gpr_log(GPR_ERROR, "dns_start_resolving_locked");
GRPC_RESOLVER_REF(&r->base, "dns-resolving");
GPR_ASSERT(!r->resolving);
if (pollent) {
r->pollent = pollent;
grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent,
r->base.pollset_set);
}
r->resolving = 1;
r->addresses = NULL;
r->request = grpc_resolve_address_ares(
exec_ctx, r->name, r->default_port, r->base.pollset_set,
grpc_closure_create(dns_on_resolved, r), &r->addresses);
} else {
dns_maybe_finish_next_locked(exec_ctx, r);
}
gpr_mu_unlock(&r->mu);
}
static void dns_start_resolving_locked(grpc_exec_ctx *exec_ctx,
dns_resolver *r) {
gpr_log(GPR_ERROR, "dns_start_resolving_locked");
GRPC_RESOLVER_REF(&r->base, "dns-resolving");
GPR_ASSERT(!r->resolving);
r->resolving = 1;
r->addresses = NULL;
r->request = grpc_resolve_address_ares(
exec_ctx, r->name, r->default_port, r->base.pollset_set,
grpc_closure_create(dns_on_resolved, r), &r->addresses);
// grpc_resolve_address(exec_ctx, r->name, r->default_port,
// grpc_closure_create(dns_on_resolved, r), &r->addresses);
}
static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx,
dns_resolver *r) {
if (r->next_completion != NULL &&
r->resolved_version != r->published_version) {
*r->target_config = r->resolved_config;
if (r->resolved_config) {
grpc_client_config_ref(r->resolved_config);
}
grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL);
r->next_completion = NULL;
r->published_version = r->resolved_version;
}
}
static void dns_destroy(grpc_exec_ctx *exec_ctx, grpc_resolver *gr) {
dns_resolver *r = (dns_resolver *)gr;
gpr_mu_destroy(&r->mu);
if (r->resolved_config) {
grpc_client_config_unref(exec_ctx, r->resolved_config);
}
grpc_client_channel_factory_unref(exec_ctx, r->client_channel_factory);
gpr_free(r->name);
gpr_free(r->default_port);
gpr_free(r->lb_policy_name);
gpr_free(r);
}
static grpc_resolver *dns_create(grpc_resolver_args *args,
const char *default_port,
const char *lb_policy_name) {
dns_resolver *r;
const char *path = args->uri->path;
if (0 != strcmp(args->uri->authority, "")) {
gpr_log(GPR_ERROR, "authority based dns uri's not supported");
return NULL;
}
if (path[0] == '/') ++path;
r = gpr_malloc(sizeof(dns_resolver));
memset(r, 0, sizeof(*r));
gpr_ref_init(&r->refs, 1);
gpr_mu_init(&r->mu);
grpc_resolver_init(&r->base, &dns_resolver_vtable);
r->name = gpr_strdup(path);
r->default_port = gpr_strdup(default_port);
r->client_channel_factory = args->client_channel_factory;
gpr_backoff_init(&r->backoff_state, BACKOFF_MULTIPLIER, BACKOFF_JITTER,
BACKOFF_MIN_SECONDS * 1000, BACKOFF_MAX_SECONDS * 1000);
grpc_client_channel_factory_ref(r->client_channel_factory);
r->lb_policy_name = gpr_strdup(lb_policy_name);
grpc_ares_init();
return &r->base;
}
/*
* FACTORY
*/
static void dns_factory_ref(grpc_resolver_factory *factory) {}
static void dns_factory_unref(grpc_resolver_factory *factory) {}
static grpc_resolver *dns_factory_create_resolver(
grpc_resolver_factory *factory, grpc_resolver_args *args) {
return dns_create(args, "https", "pick_first");
}
static char *dns_factory_get_default_host_name(grpc_resolver_factory *factory,
grpc_uri *uri) {
const char *path = uri->path;
if (path[0] == '/') ++path;
return gpr_strdup(path);
}
static const grpc_resolver_factory_vtable dns_factory_vtable = {
dns_factory_ref, dns_factory_unref, dns_factory_create_resolver,
dns_factory_get_default_host_name, "dns"};
static grpc_resolver_factory dns_resolver_factory = {&dns_factory_vtable};
static grpc_resolver_factory *dns_resolver_factory_create() {
return &dns_resolver_factory;
}
void grpc_resolver_dns_ares_init(void) {
grpc_register_resolver_type(dns_resolver_factory_create());
}
void grpc_resolver_dns_ares_shutdown(void) {}
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