test/core/client_channel/resolvers/dns_resolver_cooldown_test.cc

   1 /*
   2  *
   3  * Copyright 2015 gRPC authors.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  *
  17  */
  18
  19 #include <cstring>
  20
  21 #include <grpc/grpc.h>
  22 #include <grpc/support/log.h>
  23
  24 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
  25 #include "src/core/ext/filters/client_channel/resolver_registry.h"
  26 #include "src/core/ext/filters/client_channel/server_address.h"
  27 #include "src/core/lib/channel/channel_args.h"
  28 #include "src/core/lib/gprpp/memory.h"
  29 #include "src/core/lib/iomgr/combiner.h"
  30 #include "src/core/lib/iomgr/sockaddr_utils.h"
  31 #include "test/core/util/test_config.h"
  32
  33 constexpr int kMinResolutionPeriodMs = 1000;
  34 // Provide some slack when checking intervals, to allow for test timing issues.
  35 constexpr int kMinResolutionPeriodForCheckMs = 900;
  36
  37 extern grpc_address_resolver_vtable* grpc_resolve_address_impl;
  38 static grpc_address_resolver_vtable* default_resolve_address;
  39
  40 static grpc_core::Combiner* g_combiner;
  41
  42 static grpc_ares_request* (*g_default_dns_lookup_ares_locked)(
  43     const char* dns_server, const char* name, const char* default_port,
  44     grpc_pollset_set* interested_parties, grpc_closure* on_done,
  45     std::unique_ptr<grpc_core::ServerAddressList>* addresses, bool check_grpclb,
  46     char** service_config_json, int query_timeout_ms,
  47     grpc_core::Combiner* combiner);
  48
  49 // Counter incremented by test_resolve_address_impl indicating the number of
  50 // times a system-level resolution has happened.
  51 static int g_resolution_count;
  52
  53 static struct iomgr_args {
  54   gpr_event ev;
  55   gpr_atm done_atm;
  56   gpr_mu* mu;
  57   grpc_pollset* pollset;
  58   grpc_pollset_set* pollset_set;
  59 } g_iomgr_args;
  60
  61 // Wrapper around default resolve_address in order to count the number of
  62 // times we incur in a system-level name resolution.
  63 static void test_resolve_address_impl(const char* name,
  64                                       const char* default_port,
  65                                       grpc_pollset_set* /*interested_parties*/,
  66                                       grpc_closure* on_done,
  67                                       grpc_resolved_addresses** addrs) {
  68   default_resolve_address->resolve_address(
  69       name, default_port, g_iomgr_args.pollset_set, on_done, addrs);
  70   ++g_resolution_count;
  71   static grpc_millis last_resolution_time = 0;
  72   if (last_resolution_time == 0) {
  73     last_resolution_time =
  74         grpc_timespec_to_millis_round_up(gpr_now(GPR_CLOCK_MONOTONIC));
  75   } else {
  76     grpc_millis now =
  77         grpc_timespec_to_millis_round_up(gpr_now(GPR_CLOCK_MONOTONIC));
  78     GPR_ASSERT(now - last_resolution_time >= kMinResolutionPeriodForCheckMs);
  79     last_resolution_time = now;
  80   }
  81 }
  82
  83 static grpc_error* test_blocking_resolve_address_impl(
  84     const char* name, const char* default_port,
  85     grpc_resolved_addresses** addresses) {
  86   return default_resolve_address->blocking_resolve_address(name, default_port,
  87                                                            addresses);
  88 }
  89
  90 static grpc_address_resolver_vtable test_resolver = {
  91     test_resolve_address_impl, test_blocking_resolve_address_impl};
  92
  93 static grpc_ares_request* test_dns_lookup_ares_locked(
  94     const char* dns_server, const char* name, const char* default_port,
  95     grpc_pollset_set* /*interested_parties*/, grpc_closure* on_done,
  96     std::unique_ptr<grpc_core::ServerAddressList>* addresses, bool check_grpclb,
  97     char** service_config_json, int query_timeout_ms,
  98     grpc_core::Combiner* combiner) {
  99   grpc_ares_request* result = g_default_dns_lookup_ares_locked(
 100       dns_server, name, default_port, g_iomgr_args.pollset_set, on_done,
 101       addresses, check_grpclb, service_config_json, query_timeout_ms, combiner);
 102   ++g_resolution_count;
 103   static grpc_millis last_resolution_time = 0;
 104   grpc_millis now =
 105       grpc_timespec_to_millis_round_up(gpr_now(GPR_CLOCK_MONOTONIC));
 106   gpr_log(GPR_DEBUG,
 107           "last_resolution_time:%" PRId64 " now:%" PRId64
 108           " min_time_between:%d",
 109           last_resolution_time, now, kMinResolutionPeriodForCheckMs);
 110   if (last_resolution_time == 0) {
 111     last_resolution_time =
 112         grpc_timespec_to_millis_round_up(gpr_now(GPR_CLOCK_MONOTONIC));
 113   } else {
 114     GPR_ASSERT(now - last_resolution_time >= kMinResolutionPeriodForCheckMs);
 115     last_resolution_time = now;
 116   }
 117   return result;
 118 }
 119
 120 static gpr_timespec test_deadline(void) {
 121   return grpc_timeout_seconds_to_deadline(100);
 122 }
 123
 124 static void do_nothing(void* /*arg*/, grpc_error* /*error*/) {}
 125
 126 static void iomgr_args_init(iomgr_args* args) {
 127   gpr_event_init(&args->ev);
 128   args->pollset = static_cast<grpc_pollset*>(gpr_zalloc(grpc_pollset_size()));
 129   grpc_pollset_init(args->pollset, &args->mu);
 130   args->pollset_set = grpc_pollset_set_create();
 131   grpc_pollset_set_add_pollset(args->pollset_set, args->pollset);
 132   gpr_atm_rel_store(&args->done_atm, 0);
 133 }
 134
 135 static void iomgr_args_finish(iomgr_args* args) {
 136   GPR_ASSERT(gpr_event_wait(&args->ev, test_deadline()));
 137   grpc_pollset_set_del_pollset(args->pollset_set, args->pollset);
 138   grpc_pollset_set_destroy(args->pollset_set);
 139   grpc_closure do_nothing_cb;
 140   GRPC_CLOSURE_INIT(&do_nothing_cb, do_nothing, nullptr,
 141                     grpc_schedule_on_exec_ctx);
 142   gpr_mu_lock(args->mu);
 143   grpc_pollset_shutdown(args->pollset, &do_nothing_cb);
 144   gpr_mu_unlock(args->mu);
 145   // exec_ctx needs to be flushed before calling grpc_pollset_destroy()
 146   grpc_core::ExecCtx::Get()->Flush();
 147   grpc_pollset_destroy(args->pollset);
 148   gpr_free(args->pollset);
 149 }
 150
 151 static grpc_millis n_sec_deadline(int seconds) {
 152   return grpc_timespec_to_millis_round_up(
 153       grpc_timeout_seconds_to_deadline(seconds));
 154 }
 155
 156 static void poll_pollset_until_request_done(iomgr_args* args) {
 157   grpc_core::ExecCtx exec_ctx;
 158   grpc_millis deadline = n_sec_deadline(10);
 159   while (true) {
 160     bool done = gpr_atm_acq_load(&args->done_atm) != 0;
 161     if (done) {
 162       break;
 163     }
 164     grpc_millis time_left = deadline - grpc_core::ExecCtx::Get()->Now();
 165     gpr_log(GPR_DEBUG, "done=%d, time_left=%" PRId64, done, time_left);
 166     GPR_ASSERT(time_left >= 0);
 167     grpc_pollset_worker* worker = nullptr;
 168     gpr_mu_lock(args->mu);
 169     GRPC_LOG_IF_ERROR("pollset_work", grpc_pollset_work(args->pollset, &worker,
 170                                                         n_sec_deadline(1)));
 171     gpr_mu_unlock(args->mu);
 172     grpc_core::ExecCtx::Get()->Flush();
 173   }
 174   gpr_event_set(&args->ev, (void*)1);
 175 }
 176
 177 struct OnResolutionCallbackArg;
 178
 179 class ResultHandler : public grpc_core::Resolver::ResultHandler {
 180  public:
 181   using ResultCallback = void (*)(OnResolutionCallbackArg* state);
 182
 183   void SetCallback(ResultCallback result_cb, OnResolutionCallbackArg* state) {
 184     GPR_ASSERT(result_cb_ == nullptr);
 185     result_cb_ = result_cb;
 186     GPR_ASSERT(state_ == nullptr);
 187     state_ = state;
 188   }
 189
 190   void ReturnResult(grpc_core::Resolver::Result /*result*/) override {
 191     GPR_ASSERT(result_cb_ != nullptr);
 192     GPR_ASSERT(state_ != nullptr);
 193     ResultCallback cb = result_cb_;
 194     OnResolutionCallbackArg* state = state_;
 195     result_cb_ = nullptr;
 196     state_ = nullptr;
 197     cb(state);
 198   }
 199
 200   void ReturnError(grpc_error* error) override {
 201     gpr_log(GPR_ERROR, "resolver returned error: %s", grpc_error_string(error));
 202     GPR_ASSERT(false);
 203   }
 204
 205  private:
 206   ResultCallback result_cb_ = nullptr;
 207   OnResolutionCallbackArg* state_ = nullptr;
 208 };
 209
 210 struct OnResolutionCallbackArg {
 211   const char* uri_str = nullptr;
 212   grpc_core::OrphanablePtr<grpc_core::Resolver> resolver;
 213   ResultHandler* result_handler;
 214 };
 215
 216 // Set to true by the last callback in the resolution chain.
 217 static bool g_all_callbacks_invoked;
 218
 219 // It's interesting to run a few rounds of this test because as
 220 // we run more rounds, the base starting time
 221 // (i.e. ExecCtx g_start_time) gets further and further away
 222 // from "Now()". Thus the more rounds ran, the more highlighted the
 223 // difference is between absolute and relative times values.
 224 static void on_fourth_resolution(OnResolutionCallbackArg* cb_arg) {
 225   gpr_log(GPR_INFO, "4th: g_resolution_count: %d", g_resolution_count);
 226   GPR_ASSERT(g_resolution_count == 4);
 227   cb_arg->resolver.reset();
 228   gpr_atm_rel_store(&g_iomgr_args.done_atm, 1);
 229   gpr_mu_lock(g_iomgr_args.mu);
 230   GRPC_LOG_IF_ERROR("pollset_kick",
 231                     grpc_pollset_kick(g_iomgr_args.pollset, nullptr));
 232   gpr_mu_unlock(g_iomgr_args.mu);
 233   delete cb_arg;
 234   g_all_callbacks_invoked = true;
 235 }
 236
 237 static void on_third_resolution(OnResolutionCallbackArg* cb_arg) {
 238   gpr_log(GPR_INFO, "3rd: g_resolution_count: %d", g_resolution_count);
 239   GPR_ASSERT(g_resolution_count == 3);
 240   cb_arg->result_handler->SetCallback(on_fourth_resolution, cb_arg);
 241   cb_arg->resolver->RequestReresolutionLocked();
 242   gpr_mu_lock(g_iomgr_args.mu);
 243   GRPC_LOG_IF_ERROR("pollset_kick",
 244                     grpc_pollset_kick(g_iomgr_args.pollset, nullptr));
 245   gpr_mu_unlock(g_iomgr_args.mu);
 246 }
 247
 248 static void on_second_resolution(OnResolutionCallbackArg* cb_arg) {
 249   gpr_log(GPR_INFO, "2nd: g_resolution_count: %d", g_resolution_count);
 250   // The resolution callback was not invoked until new data was
 251   // available, which was delayed until after the cooldown period.
 252   GPR_ASSERT(g_resolution_count == 2);
 253   cb_arg->result_handler->SetCallback(on_third_resolution, cb_arg);
 254   cb_arg->resolver->RequestReresolutionLocked();
 255   gpr_mu_lock(g_iomgr_args.mu);
 256   GRPC_LOG_IF_ERROR("pollset_kick",
 257                     grpc_pollset_kick(g_iomgr_args.pollset, nullptr));
 258   gpr_mu_unlock(g_iomgr_args.mu);
 259 }
 260
 261 static void on_first_resolution(OnResolutionCallbackArg* cb_arg) {
 262   gpr_log(GPR_INFO, "1st: g_resolution_count: %d", g_resolution_count);
 263   // There's one initial system-level resolution and one invocation of a
 264   // notification callback (the current function).
 265   GPR_ASSERT(g_resolution_count == 1);
 266   cb_arg->result_handler->SetCallback(on_second_resolution, cb_arg);
 267   cb_arg->resolver->RequestReresolutionLocked();
 268   gpr_mu_lock(g_iomgr_args.mu);
 269   GRPC_LOG_IF_ERROR("pollset_kick",
 270                     grpc_pollset_kick(g_iomgr_args.pollset, nullptr));
 271   gpr_mu_unlock(g_iomgr_args.mu);
 272 }
 273
 274 static void start_test_under_combiner(void* arg, grpc_error* /*error*/) {
 275   OnResolutionCallbackArg* res_cb_arg =
 276       static_cast<OnResolutionCallbackArg*>(arg);
 277   res_cb_arg->result_handler = new ResultHandler();
 278   grpc_core::ResolverFactory* factory =
 279       grpc_core::ResolverRegistry::LookupResolverFactory("dns");
 280   grpc_uri* uri = grpc_uri_parse(res_cb_arg->uri_str, 0);
 281   gpr_log(GPR_DEBUG, "test: '%s' should be valid for '%s'", res_cb_arg->uri_str,
 282           factory->scheme());
 283   GPR_ASSERT(uri != nullptr);
 284   grpc_core::ResolverArgs args;
 285   args.uri = uri;
 286   args.combiner = g_combiner;
 287   args.result_handler = std::unique_ptr<grpc_core::Resolver::ResultHandler>(
 288       res_cb_arg->result_handler);
 289   g_resolution_count = 0;
 290
 291   grpc_arg cooldown_arg = grpc_channel_arg_integer_create(
 292       const_cast<char*>(GRPC_ARG_DNS_MIN_TIME_BETWEEN_RESOLUTIONS_MS),
 293       kMinResolutionPeriodMs);
 294   grpc_channel_args cooldown_args = {1, &cooldown_arg};
 295   args.args = &cooldown_args;
 296   res_cb_arg->resolver = factory->CreateResolver(std::move(args));
 297   GPR_ASSERT(res_cb_arg->resolver != nullptr);
 298   grpc_uri_destroy(uri);
 299   // First resolution, would incur in system-level resolution.
 300   res_cb_arg->result_handler->SetCallback(on_first_resolution, res_cb_arg);
 301   res_cb_arg->resolver->StartLocked();
 302 }
 303
 304 static void test_cooldown() {
 305   grpc_core::ExecCtx exec_ctx;
 306   iomgr_args_init(&g_iomgr_args);
 307   OnResolutionCallbackArg* res_cb_arg = new OnResolutionCallbackArg();
 308   res_cb_arg->uri_str = "dns:127.0.0.1";
 309
 310   g_combiner->Run(
 311       GRPC_CLOSURE_CREATE(start_test_under_combiner, res_cb_arg, nullptr),
 312       GRPC_ERROR_NONE);
 313   grpc_core::ExecCtx::Get()->Flush();
 314   poll_pollset_until_request_done(&g_iomgr_args);
 315   iomgr_args_finish(&g_iomgr_args);
 316 }
 317
 318 int main(int argc, char** argv) {
 319   grpc::testing::TestEnvironment env(argc, argv);
 320   grpc_init();
 321
 322   g_combiner = grpc_combiner_create();
 323
 324   g_default_dns_lookup_ares_locked = grpc_dns_lookup_ares_locked;
 325   grpc_dns_lookup_ares_locked = test_dns_lookup_ares_locked;
 326   default_resolve_address = grpc_resolve_address_impl;
 327   grpc_set_resolver_impl(&test_resolver);
 328
 329   test_cooldown();
 330   {
 331     grpc_core::ExecCtx exec_ctx;
 332     GRPC_COMBINER_UNREF(g_combiner, "test");
 333   }
 334   grpc_shutdown_blocking();
 335   GPR_ASSERT(g_all_callbacks_invoked);
 336   return 0;
 337 }