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_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     grpc_core::UniquePtr<grpc_core::ServerAddressList>* addresses,
  46     bool check_grpclb, char** service_config_json, int query_timeout_ms,
  47     grpc_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     grpc_core::UniquePtr<grpc_core::ServerAddressList>* addresses,
  97     bool check_grpclb, char** service_config_json, int query_timeout_ms,
  98     grpc_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   if (last_resolution_time == 0) {
 105     last_resolution_time =
 106         grpc_timespec_to_millis_round_up(gpr_now(GPR_CLOCK_MONOTONIC));
 107   } else {
 108     grpc_millis now =
 109         grpc_timespec_to_millis_round_up(gpr_now(GPR_CLOCK_MONOTONIC));
 110     GPR_ASSERT(now - last_resolution_time >= kMinResolutionPeriodForCheckMs);
 111     last_resolution_time = now;
 112   }
 113   return result;
 114 }
 115
 116 static gpr_timespec test_deadline(void) {
 117   return grpc_timeout_seconds_to_deadline(100);
 118 }
 119
 120 static void do_nothing(void* arg, grpc_error* error) {}
 121
 122 static void iomgr_args_init(iomgr_args* args) {
 123   gpr_event_init(&args->ev);
 124   args->pollset = static_cast<grpc_pollset*>(gpr_zalloc(grpc_pollset_size()));
 125   grpc_pollset_init(args->pollset, &args->mu);
 126   args->pollset_set = grpc_pollset_set_create();
 127   grpc_pollset_set_add_pollset(args->pollset_set, args->pollset);
 128   gpr_atm_rel_store(&args->done_atm, 0);
 129 }
 130
 131 static void iomgr_args_finish(iomgr_args* args) {
 132   GPR_ASSERT(gpr_event_wait(&args->ev, test_deadline()));
 133   grpc_pollset_set_del_pollset(args->pollset_set, args->pollset);
 134   grpc_pollset_set_destroy(args->pollset_set);
 135   grpc_closure do_nothing_cb;
 136   GRPC_CLOSURE_INIT(&do_nothing_cb, do_nothing, nullptr,
 137                     grpc_schedule_on_exec_ctx);
 138   gpr_mu_lock(args->mu);
 139   grpc_pollset_shutdown(args->pollset, &do_nothing_cb);
 140   gpr_mu_unlock(args->mu);
 141   // exec_ctx needs to be flushed before calling grpc_pollset_destroy()
 142   grpc_core::ExecCtx::Get()->Flush();
 143   grpc_pollset_destroy(args->pollset);
 144   gpr_free(args->pollset);
 145 }
 146
 147 static grpc_millis n_sec_deadline(int seconds) {
 148   return grpc_timespec_to_millis_round_up(
 149       grpc_timeout_seconds_to_deadline(seconds));
 150 }
 151
 152 static void poll_pollset_until_request_done(iomgr_args* args) {
 153   grpc_core::ExecCtx exec_ctx;
 154   grpc_millis deadline = n_sec_deadline(10);
 155   while (true) {
 156     bool done = gpr_atm_acq_load(&args->done_atm) != 0;
 157     if (done) {
 158       break;
 159     }
 160     grpc_millis time_left = deadline - grpc_core::ExecCtx::Get()->Now();
 161     gpr_log(GPR_DEBUG, "done=%d, time_left=%" PRId64, done, time_left);
 162     GPR_ASSERT(time_left >= 0);
 163     grpc_pollset_worker* worker = nullptr;
 164     gpr_mu_lock(args->mu);
 165     GRPC_LOG_IF_ERROR("pollset_work", grpc_pollset_work(args->pollset, &worker,
 166                                                         n_sec_deadline(1)));
 167     gpr_mu_unlock(args->mu);
 168     grpc_core::ExecCtx::Get()->Flush();
 169   }
 170   gpr_event_set(&args->ev, (void*)1);
 171 }
 172
 173 struct OnResolutionCallbackArg;
 174
 175 class ResultHandler : public grpc_core::Resolver::ResultHandler {
 176  public:
 177   using ResultCallback = void (*)(OnResolutionCallbackArg* state);
 178
 179   void SetCallback(ResultCallback result_cb, OnResolutionCallbackArg* state) {
 180     GPR_ASSERT(result_cb_ == nullptr);
 181     result_cb_ = result_cb;
 182     GPR_ASSERT(state_ == nullptr);
 183     state_ = state;
 184   }
 185
 186   void ReturnResult(grpc_core::Resolver::Result result) override {
 187     GPR_ASSERT(result_cb_ != nullptr);
 188     GPR_ASSERT(state_ != nullptr);
 189     ResultCallback cb = result_cb_;
 190     OnResolutionCallbackArg* state = state_;
 191     result_cb_ = nullptr;
 192     state_ = nullptr;
 193     cb(state);
 194   }
 195
 196   void ReturnError(grpc_error* error) override {
 197     gpr_log(GPR_ERROR, "resolver returned error: %s", grpc_error_string(error));
 198     GPR_ASSERT(false);
 199   }
 200
 201  private:
 202   ResultCallback result_cb_ = nullptr;
 203   OnResolutionCallbackArg* state_ = nullptr;
 204 };
 205
 206 struct OnResolutionCallbackArg {
 207   const char* uri_str = nullptr;
 208   grpc_core::OrphanablePtr<grpc_core::Resolver> resolver;
 209   ResultHandler* result_handler;
 210 };
 211
 212 // Set to true by the last callback in the resolution chain.
 213 static bool g_all_callbacks_invoked;
 214
 215 static void on_second_resolution(OnResolutionCallbackArg* cb_arg) {
 216   gpr_log(GPR_INFO, "2nd: g_resolution_count: %d", g_resolution_count);
 217   // The resolution callback was not invoked until new data was
 218   // available, which was delayed until after the cooldown period.
 219   GPR_ASSERT(g_resolution_count == 2);
 220   cb_arg->resolver.reset();
 221   gpr_atm_rel_store(&g_iomgr_args.done_atm, 1);
 222   gpr_mu_lock(g_iomgr_args.mu);
 223   GRPC_LOG_IF_ERROR("pollset_kick",
 224                     grpc_pollset_kick(g_iomgr_args.pollset, nullptr));
 225   gpr_mu_unlock(g_iomgr_args.mu);
 226   grpc_core::Delete(cb_arg);
 227   g_all_callbacks_invoked = true;
 228 }
 229
 230 static void on_first_resolution(OnResolutionCallbackArg* cb_arg) {
 231   gpr_log(GPR_INFO, "1st: g_resolution_count: %d", g_resolution_count);
 232   // There's one initial system-level resolution and one invocation of a
 233   // notification callback (the current function).
 234   GPR_ASSERT(g_resolution_count == 1);
 235   cb_arg->result_handler->SetCallback(on_second_resolution, cb_arg);
 236   cb_arg->resolver->RequestReresolutionLocked();
 237   gpr_mu_lock(g_iomgr_args.mu);
 238   GRPC_LOG_IF_ERROR("pollset_kick",
 239                     grpc_pollset_kick(g_iomgr_args.pollset, nullptr));
 240   gpr_mu_unlock(g_iomgr_args.mu);
 241 }
 242
 243 static void start_test_under_combiner(void* arg, grpc_error* error) {
 244   OnResolutionCallbackArg* res_cb_arg =
 245       static_cast<OnResolutionCallbackArg*>(arg);
 246
 247   res_cb_arg->result_handler = grpc_core::New<ResultHandler>();
 248
 249   grpc_core::ResolverFactory* factory =
 250       grpc_core::ResolverRegistry::LookupResolverFactory("dns");
 251   grpc_uri* uri = grpc_uri_parse(res_cb_arg->uri_str, 0);
 252   gpr_log(GPR_DEBUG, "test: '%s' should be valid for '%s'", res_cb_arg->uri_str,
 253           factory->scheme());
 254   GPR_ASSERT(uri != nullptr);
 255   grpc_core::ResolverArgs args;
 256   args.uri = uri;
 257   args.combiner = g_combiner;
 258   args.result_handler =
 259       grpc_core::UniquePtr<grpc_core::Resolver::ResultHandler>(
 260           res_cb_arg->result_handler);
 261   g_resolution_count = 0;
 262
 263   grpc_arg cooldown_arg = grpc_channel_arg_integer_create(
 264       const_cast<char*>(GRPC_ARG_DNS_MIN_TIME_BETWEEN_RESOLUTIONS_MS),
 265       kMinResolutionPeriodMs);
 266   grpc_channel_args cooldown_args = {1, &cooldown_arg};
 267   args.args = &cooldown_args;
 268   res_cb_arg->resolver = factory->CreateResolver(std::move(args));
 269   GPR_ASSERT(res_cb_arg->resolver != nullptr);
 270   grpc_uri_destroy(uri);
 271   // First resolution, would incur in system-level resolution.
 272   res_cb_arg->result_handler->SetCallback(on_first_resolution, res_cb_arg);
 273   res_cb_arg->resolver->StartLocked();
 274 }
 275
 276 static void test_cooldown() {
 277   grpc_core::ExecCtx exec_ctx;
 278   iomgr_args_init(&g_iomgr_args);
 279   OnResolutionCallbackArg* res_cb_arg =
 280       grpc_core::New<OnResolutionCallbackArg>();
 281   res_cb_arg->uri_str = "dns:127.0.0.1";
 282
 283   GRPC_CLOSURE_SCHED(GRPC_CLOSURE_CREATE(start_test_under_combiner, res_cb_arg,
 284                                          grpc_combiner_scheduler(g_combiner)),
 285                      GRPC_ERROR_NONE);
 286   grpc_core::ExecCtx::Get()->Flush();
 287   poll_pollset_until_request_done(&g_iomgr_args);
 288   iomgr_args_finish(&g_iomgr_args);
 289 }
 290
 291 int main(int argc, char** argv) {
 292   grpc::testing::TestEnvironment env(argc, argv);
 293   grpc_init();
 294
 295   g_combiner = grpc_combiner_create();
 296
 297   g_default_dns_lookup_ares_locked = grpc_dns_lookup_ares_locked;
 298   grpc_dns_lookup_ares_locked = test_dns_lookup_ares_locked;
 299   default_resolve_address = grpc_resolve_address_impl;
 300   grpc_set_resolver_impl(&test_resolver);
 301
 302   test_cooldown();
 303
 304   {
 305     grpc_core::ExecCtx exec_ctx;
 306     GRPC_COMBINER_UNREF(g_combiner, "test");
 307   }
 308   grpc_shutdown_blocking();
 309   GPR_ASSERT(g_all_callbacks_invoked);
 310   return 0;
 311 }