test/core/end2end/goaway_server_test.cc - third_party/grpc - Git at Google

 /*
  *
  * Copyright 2016 gRPC authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  */

 /* With the addition of a libuv endpoint, sockaddr.h now includes uv.h when
    using that endpoint. Because of various transitive includes in uv.h,
    including windows.h on Windows, uv.h must be included before other system
    headers. Therefore, sockaddr.h must always be included first */
 #include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/iomgr/socket_utils.h"

 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 #include <string.h>
 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
 #include "src/core/ext/filters/client_channel/server_address.h"
 #include "src/core/lib/iomgr/resolve_address.h"
 #include "src/core/lib/iomgr/sockaddr.h"
 #include "test/core/end2end/cq_verifier.h"
 #include "test/core/util/port.h"
 #include "test/core/util/test_config.h"

 extern grpc_address_resolver_vtable* grpc_resolve_address_impl;
 static grpc_address_resolver_vtable* default_resolver;

 static void* tag(intptr_t i) { return (void*)i; }

 static gpr_mu g_mu;
 static int g_resolve_port = -1;

 static grpc_ares_request* (*iomgr_dns_lookup_ares_locked)(
     const char* dns_server, const char* addr, const char* default_port,
     grpc_pollset_set* interested_parties, grpc_closure* on_done,
     std::unique_ptr<grpc_core::ServerAddressList>* addresses,
     std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses,
     char** service_config_json, int query_timeout_ms,
     grpc_core::Combiner* combiner);

 static void (*iomgr_cancel_ares_request_locked)(grpc_ares_request* request);

 static void set_resolve_port(int port) {
   gpr_mu_lock(&g_mu);
   g_resolve_port = port;
   gpr_mu_unlock(&g_mu);
 }

 static void my_resolve_address(const char* addr, const char* default_port,
                                grpc_pollset_set* interested_parties,
                                grpc_closure* on_done,
                                grpc_resolved_addresses** addrs) {
   if (0 != strcmp(addr, "test")) {
     default_resolver->resolve_address(addr, default_port, interested_parties,
                                       on_done, addrs);
     return;
   }

   grpc_error* error = GRPC_ERROR_NONE;
   gpr_mu_lock(&g_mu);
   if (g_resolve_port < 0) {
     gpr_mu_unlock(&g_mu);
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Forced Failure");
   } else {
     *addrs = static_cast<grpc_resolved_addresses*>(gpr_malloc(sizeof(**addrs)));
     (*addrs)->naddrs = 1;
     (*addrs)->addrs = static_cast<grpc_resolved_address*>(
         gpr_malloc(sizeof(*(*addrs)->addrs)));
     memset((*addrs)->addrs, 0, sizeof(*(*addrs)->addrs));
     grpc_sockaddr_in* sa =
         reinterpret_cast<grpc_sockaddr_in*>((*addrs)->addrs[0].addr);
     sa->sin_family = GRPC_AF_INET;
     sa->sin_addr.s_addr = 0x100007f;
     sa->sin_port = grpc_htons(static_cast<uint16_t>(g_resolve_port));
     (*addrs)->addrs[0].len = static_cast<socklen_t>(sizeof(*sa));
     gpr_mu_unlock(&g_mu);
   }
   grpc_core::ExecCtx::Run(DEBUG_LOCATION, on_done, error);
 }

 static grpc_error* my_blocking_resolve_address(
     const char* name, const char* default_port,
     grpc_resolved_addresses** addresses) {
   return default_resolver->blocking_resolve_address(name, default_port,
                                                     addresses);
 }

 static grpc_address_resolver_vtable test_resolver = {
     my_resolve_address, my_blocking_resolve_address};

 static grpc_ares_request* my_dns_lookup_ares_locked(
     const char* dns_server, const char* addr, const char* default_port,
     grpc_pollset_set* interested_parties, grpc_closure* on_done,
     std::unique_ptr<grpc_core::ServerAddressList>* addresses,
     std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses,
     char** service_config_json, int query_timeout_ms,
     grpc_core::Combiner* combiner) {
   if (0 != strcmp(addr, "test")) {
     return iomgr_dns_lookup_ares_locked(
         dns_server, addr, default_port, interested_parties, on_done, addresses,
         balancer_addresses, service_config_json, query_timeout_ms, combiner);
   }

   grpc_error* error = GRPC_ERROR_NONE;
   gpr_mu_lock(&g_mu);
   if (g_resolve_port < 0) {
     gpr_mu_unlock(&g_mu);
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Forced Failure");
   } else {
     *addresses = grpc_core::MakeUnique<grpc_core::ServerAddressList>();
     grpc_sockaddr_in sa;
     sa.sin_family = GRPC_AF_INET;
     sa.sin_addr.s_addr = 0x100007f;
     sa.sin_port = grpc_htons(static_cast<uint16_t>(g_resolve_port));
     (*addresses)->emplace_back(&sa, sizeof(sa), nullptr);
     gpr_mu_unlock(&g_mu);
   }
   grpc_core::ExecCtx::Run(DEBUG_LOCATION, on_done, error);
   return nullptr;
 }

 static void my_cancel_ares_request_locked(grpc_ares_request* request) {
   if (request != nullptr) {
     iomgr_cancel_ares_request_locked(request);
   }
 }

 int main(int argc, char** argv) {
   grpc_completion_queue* cq;
   cq_verifier* cqv;
   grpc_op ops[6];
   grpc_op* op;

   grpc::testing::TestEnvironment env(argc, argv);

   gpr_mu_init(&g_mu);
   grpc_init();
   default_resolver = grpc_resolve_address_impl;
   grpc_set_resolver_impl(&test_resolver);
   iomgr_dns_lookup_ares_locked = grpc_dns_lookup_ares_locked;
   iomgr_cancel_ares_request_locked = grpc_cancel_ares_request_locked;
   grpc_dns_lookup_ares_locked = my_dns_lookup_ares_locked;
   grpc_cancel_ares_request_locked = my_cancel_ares_request_locked;

   int was_cancelled1;
   int was_cancelled2;

   grpc_metadata_array trailing_metadata_recv1;
   grpc_metadata_array request_metadata1;
   grpc_call_details request_details1;
   grpc_status_code status1;
   grpc_slice details1;
   grpc_metadata_array_init(&trailing_metadata_recv1);
   grpc_metadata_array_init(&request_metadata1);
   grpc_call_details_init(&request_details1);

   grpc_metadata_array trailing_metadata_recv2;
   grpc_metadata_array request_metadata2;
   grpc_call_details request_details2;
   grpc_status_code status2;
   grpc_slice details2;
   grpc_metadata_array_init(&trailing_metadata_recv2);
   grpc_metadata_array_init(&request_metadata2);
   grpc_call_details_init(&request_details2);

   cq = grpc_completion_queue_create_for_next(nullptr);
   cqv = cq_verifier_create(cq);

   /* reserve two ports */
   int port1 = grpc_pick_unused_port_or_die();
   int port2 = grpc_pick_unused_port_or_die();

   char* addr;

   grpc_channel_args client_args;
   grpc_arg arg_array[2];
   arg_array[0].type = GRPC_ARG_INTEGER;
   arg_array[0].key =
       const_cast<char*>("grpc.testing.fixed_reconnect_backoff_ms");
   arg_array[0].value.integer = 1000;
   /* When this test brings down server1 and then brings up server2,
    * the targetted server port number changes, and the client channel
    * needs to re-resolve to pick this up. This test requires that
    * happen within 10 seconds, but gRPC's DNS resolvers rate limit
    * resolution attempts to at most once every 30 seconds by default.
    * So we tweak it for this test. */
   arg_array[1].type = GRPC_ARG_INTEGER;
   arg_array[1].key =
       const_cast<char*>(GRPC_ARG_DNS_MIN_TIME_BETWEEN_RESOLUTIONS_MS);
   arg_array[1].value.integer = 1000;
   client_args.args = arg_array;
   client_args.num_args = 2;

   /* create a channel that picks first amongst the servers */
   grpc_channel* chan =
       grpc_insecure_channel_create("test", &client_args, nullptr);
   /* and an initial call to them */
   grpc_slice host = grpc_slice_from_static_string("127.0.0.1");
   grpc_call* call1 =
       grpc_channel_create_call(chan, nullptr, GRPC_PROPAGATE_DEFAULTS, cq,
                                grpc_slice_from_static_string("/foo"), &host,
                                grpc_timeout_seconds_to_deadline(20), nullptr);
   /* send initial metadata to probe connectivity */
   memset(ops, 0, sizeof(ops));
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = GRPC_INITIAL_METADATA_WAIT_FOR_READY;
   op->reserved = nullptr;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call1, ops,
                                                    (size_t)(op - ops),
                                                    tag(0x101), nullptr));
   /* and receive status to probe termination */
   memset(ops, 0, sizeof(ops));
   op = ops;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv1;
   op->data.recv_status_on_client.status = &status1;
   op->data.recv_status_on_client.status_details = &details1;
   op->flags = 0;
   op->reserved = nullptr;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call1, ops,
                                                    (size_t)(op - ops),
                                                    tag(0x102), nullptr));

   /* bring a server up on the first port */
   grpc_server* server1 = grpc_server_create(nullptr, nullptr);
   gpr_asprintf(&addr, "127.0.0.1:%d", port1);
   grpc_server_add_insecure_http2_port(server1, addr);
   grpc_server_register_completion_queue(server1, cq, nullptr);
   gpr_free(addr);
   grpc_server_start(server1);

   /* request a call to the server */
   grpc_call* server_call1;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_server_request_call(server1, &server_call1, &request_details1,
                                       &request_metadata1, cq, cq, tag(0x301)));

   set_resolve_port(port1);

   /* first call should now start */
   CQ_EXPECT_COMPLETION(cqv, tag(0x101), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0x301), 1);
   cq_verify(cqv);

   GPR_ASSERT(GRPC_CHANNEL_READY ==
              grpc_channel_check_connectivity_state(chan, 0));
   grpc_channel_watch_connectivity_state(chan, GRPC_CHANNEL_READY,
                                         gpr_inf_future(GPR_CLOCK_REALTIME), cq,
                                         tag(0x9999));

   /* listen for close on the server call to probe for finishing */
   memset(ops, 0, sizeof(ops));
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled1;
   op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(server_call1, ops,
                                                    (size_t)(op - ops),
                                                    tag(0x302), nullptr));

   /* shutdown first server:
    * we should see a connectivity change and then nothing */
   set_resolve_port(-1);
   grpc_server_shutdown_and_notify(server1, cq, tag(0xdead1));
   CQ_EXPECT_COMPLETION(cqv, tag(0x9999), 1);
   cq_verify(cqv);
   cq_verify_empty(cqv);

   /* and a new call: should go through to server2 when we start it */
   grpc_call* call2 =
       grpc_channel_create_call(chan, nullptr, GRPC_PROPAGATE_DEFAULTS, cq,
                                grpc_slice_from_static_string("/foo"), &host,
                                grpc_timeout_seconds_to_deadline(20), nullptr);
   /* send initial metadata to probe connectivity */
   memset(ops, 0, sizeof(ops));
   op = ops;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = GRPC_INITIAL_METADATA_WAIT_FOR_READY;
   op->reserved = nullptr;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call2, ops,
                                                    (size_t)(op - ops),
                                                    tag(0x201), nullptr));
   /* and receive status to probe termination */
   memset(ops, 0, sizeof(ops));
   op = ops;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv2;
   op->data.recv_status_on_client.status = &status2;
   op->data.recv_status_on_client.status_details = &details2;
   op->flags = 0;
   op->reserved = nullptr;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call2, ops,
                                                    (size_t)(op - ops),
                                                    tag(0x202), nullptr));

   /* and bring up second server */
   set_resolve_port(port2);
   grpc_server* server2 = grpc_server_create(nullptr, nullptr);
   gpr_asprintf(&addr, "127.0.0.1:%d", port2);
   grpc_server_add_insecure_http2_port(server2, addr);
   grpc_server_register_completion_queue(server2, cq, nullptr);
   gpr_free(addr);
   grpc_server_start(server2);

   /* request a call to the server */
   grpc_call* server_call2;
   GPR_ASSERT(GRPC_CALL_OK ==
              grpc_server_request_call(server2, &server_call2, &request_details2,
                                       &request_metadata2, cq, cq, tag(0x401)));

   /* second call should now start */
   CQ_EXPECT_COMPLETION(cqv, tag(0x201), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0x401), 1);
   cq_verify(cqv);

   /* listen for close on the server call to probe for finishing */
   memset(ops, 0, sizeof(ops));
   op = ops;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled2;
   op->flags = 0;
   op++;
   GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(server_call2, ops,
                                                    (size_t)(op - ops),
                                                    tag(0x402), nullptr));

   /* shutdown second server: we should see nothing */
   grpc_server_shutdown_and_notify(server2, cq, tag(0xdead2));
   cq_verify_empty(cqv);

   grpc_call_cancel(call1, nullptr);
   grpc_call_cancel(call2, nullptr);

   /* now everything else should finish */
   CQ_EXPECT_COMPLETION(cqv, tag(0x102), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0x202), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0x302), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0x402), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0xdead1), 1);
   CQ_EXPECT_COMPLETION(cqv, tag(0xdead2), 1);
   cq_verify(cqv);

   grpc_call_unref(call1);
   grpc_call_unref(call2);
   grpc_call_unref(server_call1);
   grpc_call_unref(server_call2);
   grpc_server_destroy(server1);
   grpc_server_destroy(server2);
   grpc_channel_destroy(chan);

   grpc_metadata_array_destroy(&trailing_metadata_recv1);
   grpc_metadata_array_destroy(&request_metadata1);
   grpc_call_details_destroy(&request_details1);
   grpc_slice_unref(details1);
   grpc_metadata_array_destroy(&trailing_metadata_recv2);
   grpc_metadata_array_destroy(&request_metadata2);
   grpc_call_details_destroy(&request_details2);
   grpc_slice_unref(details2);

   cq_verifier_destroy(cqv);
   grpc_completion_queue_destroy(cq);

   grpc_shutdown();
   gpr_mu_destroy(&g_mu);

   return 0;
 }
	/*
	*
	* Copyright 2016 gRPC authors.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	*/

	/* With the addition of a libuv endpoint, sockaddr.h now includes uv.h when
	using that endpoint. Because of various transitive includes in uv.h,
	including windows.h on Windows, uv.h must be included before other system
	headers. Therefore, sockaddr.h must always be included first */
	#include "src/core/lib/iomgr/sockaddr.h"
	#include "src/core/lib/iomgr/socket_utils.h"

	#include <grpc/grpc.h>
	#include <grpc/support/alloc.h>
	#include <grpc/support/log.h>
	#include <grpc/support/string_util.h>
	#include <string.h>
	#include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
	#include "src/core/ext/filters/client_channel/server_address.h"
	#include "src/core/lib/iomgr/resolve_address.h"
	#include "src/core/lib/iomgr/sockaddr.h"
	#include "test/core/end2end/cq_verifier.h"
	#include "test/core/util/port.h"
	#include "test/core/util/test_config.h"

	extern grpc_address_resolver_vtable* grpc_resolve_address_impl;
	static grpc_address_resolver_vtable* default_resolver;

	static void* tag(intptr_t i) { return (void*)i; }

	static gpr_mu g_mu;
	static int g_resolve_port = -1;

	static grpc_ares_request* (*iomgr_dns_lookup_ares_locked)(
	const char* dns_server, const char* addr, const char* default_port,
	grpc_pollset_set* interested_parties, grpc_closure* on_done,
	std::unique_ptr<grpc_core::ServerAddressList>* addresses,
	std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses,
	char** service_config_json, int query_timeout_ms,
	grpc_core::Combiner* combiner);

	static void (iomgr_cancel_ares_request_locked)(grpc_ares_request request);

	static void set_resolve_port(int port) {
	gpr_mu_lock(&g_mu);
	g_resolve_port = port;
	gpr_mu_unlock(&g_mu);
	}

	static void my_resolve_address(const char* addr, const char* default_port,
	grpc_pollset_set* interested_parties,
	grpc_closure* on_done,
	grpc_resolved_addresses** addrs) {
	if (0 != strcmp(addr, "test")) {
	default_resolver->resolve_address(addr, default_port, interested_parties,
	on_done, addrs);
	return;
	}

	grpc_error* error = GRPC_ERROR_NONE;
	gpr_mu_lock(&g_mu);
	if (g_resolve_port < 0) {
	gpr_mu_unlock(&g_mu);
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Forced Failure");
	} else {
	addrs = static_cast<grpc_resolved_addresses>(gpr_malloc(sizeof(**addrs)));
	(*addrs)->naddrs = 1;
	(addrs)->addrs = static_cast<grpc_resolved_address>(
	gpr_malloc(sizeof((addrs)->addrs)));
	memset((addrs)->addrs, 0, sizeof((*addrs)->addrs));
	grpc_sockaddr_in* sa =
	reinterpret_cast<grpc_sockaddr_in>((addrs)->addrs[0].addr);
	sa->sin_family = GRPC_AF_INET;
	sa->sin_addr.s_addr = 0x100007f;
	sa->sin_port = grpc_htons(static_cast<uint16_t>(g_resolve_port));
	(addrs)->addrs[0].len = static_cast<socklen_t>(sizeof(sa));
	gpr_mu_unlock(&g_mu);
	}
	grpc_core::ExecCtx::Run(DEBUG_LOCATION, on_done, error);
	}

	static grpc_error* my_blocking_resolve_address(
	const char* name, const char* default_port,
	grpc_resolved_addresses** addresses) {
	return default_resolver->blocking_resolve_address(name, default_port,
	addresses);
	}

	static grpc_address_resolver_vtable test_resolver = {
	my_resolve_address, my_blocking_resolve_address};

	static grpc_ares_request* my_dns_lookup_ares_locked(
	const char* dns_server, const char* addr, const char* default_port,
	grpc_pollset_set* interested_parties, grpc_closure* on_done,
	std::unique_ptr<grpc_core::ServerAddressList>* addresses,
	std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses,
	char** service_config_json, int query_timeout_ms,
	grpc_core::Combiner* combiner) {
	if (0 != strcmp(addr, "test")) {
	return iomgr_dns_lookup_ares_locked(
	dns_server, addr, default_port, interested_parties, on_done, addresses,
	balancer_addresses, service_config_json, query_timeout_ms, combiner);
	}

	grpc_error* error = GRPC_ERROR_NONE;
	gpr_mu_lock(&g_mu);
	if (g_resolve_port < 0) {
	gpr_mu_unlock(&g_mu);
	error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("Forced Failure");
	} else {
	*addresses = grpc_core::MakeUnique<grpc_core::ServerAddressList>();
	grpc_sockaddr_in sa;
	sa.sin_family = GRPC_AF_INET;
	sa.sin_addr.s_addr = 0x100007f;
	sa.sin_port = grpc_htons(static_cast<uint16_t>(g_resolve_port));
	(*addresses)->emplace_back(&sa, sizeof(sa), nullptr);
	gpr_mu_unlock(&g_mu);
	}
	grpc_core::ExecCtx::Run(DEBUG_LOCATION, on_done, error);
	return nullptr;
	}

	static void my_cancel_ares_request_locked(grpc_ares_request* request) {
	if (request != nullptr) {
	iomgr_cancel_ares_request_locked(request);
	}
	}

	int main(int argc, char** argv) {
	grpc_completion_queue* cq;
	cq_verifier* cqv;
	grpc_op ops[6];
	grpc_op* op;

	grpc::testing::TestEnvironment env(argc, argv);

	gpr_mu_init(&g_mu);
	grpc_init();
	default_resolver = grpc_resolve_address_impl;
	grpc_set_resolver_impl(&test_resolver);
	iomgr_dns_lookup_ares_locked = grpc_dns_lookup_ares_locked;
	iomgr_cancel_ares_request_locked = grpc_cancel_ares_request_locked;
	grpc_dns_lookup_ares_locked = my_dns_lookup_ares_locked;
	grpc_cancel_ares_request_locked = my_cancel_ares_request_locked;

	int was_cancelled1;
	int was_cancelled2;

	grpc_metadata_array trailing_metadata_recv1;
	grpc_metadata_array request_metadata1;
	grpc_call_details request_details1;
	grpc_status_code status1;
	grpc_slice details1;
	grpc_metadata_array_init(&trailing_metadata_recv1);
	grpc_metadata_array_init(&request_metadata1);
	grpc_call_details_init(&request_details1);

	grpc_metadata_array trailing_metadata_recv2;
	grpc_metadata_array request_metadata2;
	grpc_call_details request_details2;
	grpc_status_code status2;
	grpc_slice details2;
	grpc_metadata_array_init(&trailing_metadata_recv2);
	grpc_metadata_array_init(&request_metadata2);
	grpc_call_details_init(&request_details2);

	cq = grpc_completion_queue_create_for_next(nullptr);
	cqv = cq_verifier_create(cq);

	/* reserve two ports */
	int port1 = grpc_pick_unused_port_or_die();
	int port2 = grpc_pick_unused_port_or_die();

	char* addr;

	grpc_channel_args client_args;
	grpc_arg arg_array[2];
	arg_array[0].type = GRPC_ARG_INTEGER;
	arg_array[0].key =
	const_cast<char*>("grpc.testing.fixed_reconnect_backoff_ms");
	arg_array[0].value.integer = 1000;
	/* When this test brings down server1 and then brings up server2,
	* the targetted server port number changes, and the client channel
	* needs to re-resolve to pick this up. This test requires that
	* happen within 10 seconds, but gRPC's DNS resolvers rate limit
	* resolution attempts to at most once every 30 seconds by default.
	* So we tweak it for this test. */
	arg_array[1].type = GRPC_ARG_INTEGER;
	arg_array[1].key =
	const_cast<char*>(GRPC_ARG_DNS_MIN_TIME_BETWEEN_RESOLUTIONS_MS);
	arg_array[1].value.integer = 1000;
	client_args.args = arg_array;
	client_args.num_args = 2;

	/* create a channel that picks first amongst the servers */
	grpc_channel* chan =
	grpc_insecure_channel_create("test", &client_args, nullptr);
	/* and an initial call to them */
	grpc_slice host = grpc_slice_from_static_string("127.0.0.1");
	grpc_call* call1 =
	grpc_channel_create_call(chan, nullptr, GRPC_PROPAGATE_DEFAULTS, cq,
	grpc_slice_from_static_string("/foo"), &host,
	grpc_timeout_seconds_to_deadline(20), nullptr);
	/* send initial metadata to probe connectivity */
	memset(ops, 0, sizeof(ops));
	op = ops;
	op->op = GRPC_OP_SEND_INITIAL_METADATA;
	op->data.send_initial_metadata.count = 0;
	op->flags = GRPC_INITIAL_METADATA_WAIT_FOR_READY;
	op->reserved = nullptr;
	op++;
	GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call1, ops,
	(size_t)(op - ops),
	tag(0x101), nullptr));
	/* and receive status to probe termination */
	memset(ops, 0, sizeof(ops));
	op = ops;
	op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
	op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv1;
	op->data.recv_status_on_client.status = &status1;
	op->data.recv_status_on_client.status_details = &details1;
	op->flags = 0;
	op->reserved = nullptr;
	op++;
	GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call1, ops,
	(size_t)(op - ops),
	tag(0x102), nullptr));

	/* bring a server up on the first port */
	grpc_server* server1 = grpc_server_create(nullptr, nullptr);
	gpr_asprintf(&addr, "127.0.0.1:%d", port1);
	grpc_server_add_insecure_http2_port(server1, addr);
	grpc_server_register_completion_queue(server1, cq, nullptr);
	gpr_free(addr);
	grpc_server_start(server1);

	/* request a call to the server */
	grpc_call* server_call1;
	GPR_ASSERT(GRPC_CALL_OK ==
	grpc_server_request_call(server1, &server_call1, &request_details1,
	&request_metadata1, cq, cq, tag(0x301)));

	set_resolve_port(port1);

	/* first call should now start */
	CQ_EXPECT_COMPLETION(cqv, tag(0x101), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0x301), 1);
	cq_verify(cqv);

	GPR_ASSERT(GRPC_CHANNEL_READY ==
	grpc_channel_check_connectivity_state(chan, 0));
	grpc_channel_watch_connectivity_state(chan, GRPC_CHANNEL_READY,
	gpr_inf_future(GPR_CLOCK_REALTIME), cq,
	tag(0x9999));

	/* listen for close on the server call to probe for finishing */
	memset(ops, 0, sizeof(ops));
	op = ops;
	op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
	op->data.recv_close_on_server.cancelled = &was_cancelled1;
	op->flags = 0;
	op++;
	GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(server_call1, ops,
	(size_t)(op - ops),
	tag(0x302), nullptr));

	/* shutdown first server:
	* we should see a connectivity change and then nothing */
	set_resolve_port(-1);
	grpc_server_shutdown_and_notify(server1, cq, tag(0xdead1));
	CQ_EXPECT_COMPLETION(cqv, tag(0x9999), 1);
	cq_verify(cqv);
	cq_verify_empty(cqv);

	/* and a new call: should go through to server2 when we start it */
	grpc_call* call2 =
	grpc_channel_create_call(chan, nullptr, GRPC_PROPAGATE_DEFAULTS, cq,
	grpc_slice_from_static_string("/foo"), &host,
	grpc_timeout_seconds_to_deadline(20), nullptr);
	/* send initial metadata to probe connectivity */
	memset(ops, 0, sizeof(ops));
	op = ops;
	op->op = GRPC_OP_SEND_INITIAL_METADATA;
	op->data.send_initial_metadata.count = 0;
	op->flags = GRPC_INITIAL_METADATA_WAIT_FOR_READY;
	op->reserved = nullptr;
	op++;
	GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call2, ops,
	(size_t)(op - ops),
	tag(0x201), nullptr));
	/* and receive status to probe termination */
	memset(ops, 0, sizeof(ops));
	op = ops;
	op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
	op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv2;
	op->data.recv_status_on_client.status = &status2;
	op->data.recv_status_on_client.status_details = &details2;
	op->flags = 0;
	op->reserved = nullptr;
	op++;
	GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(call2, ops,
	(size_t)(op - ops),
	tag(0x202), nullptr));

	/* and bring up second server */
	set_resolve_port(port2);
	grpc_server* server2 = grpc_server_create(nullptr, nullptr);
	gpr_asprintf(&addr, "127.0.0.1:%d", port2);
	grpc_server_add_insecure_http2_port(server2, addr);
	grpc_server_register_completion_queue(server2, cq, nullptr);
	gpr_free(addr);
	grpc_server_start(server2);

	/* request a call to the server */
	grpc_call* server_call2;
	GPR_ASSERT(GRPC_CALL_OK ==
	grpc_server_request_call(server2, &server_call2, &request_details2,
	&request_metadata2, cq, cq, tag(0x401)));

	/* second call should now start */
	CQ_EXPECT_COMPLETION(cqv, tag(0x201), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0x401), 1);
	cq_verify(cqv);

	/* listen for close on the server call to probe for finishing */
	memset(ops, 0, sizeof(ops));
	op = ops;
	op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
	op->data.recv_close_on_server.cancelled = &was_cancelled2;
	op->flags = 0;
	op++;
	GPR_ASSERT(GRPC_CALL_OK == grpc_call_start_batch(server_call2, ops,
	(size_t)(op - ops),
	tag(0x402), nullptr));

	/* shutdown second server: we should see nothing */
	grpc_server_shutdown_and_notify(server2, cq, tag(0xdead2));
	cq_verify_empty(cqv);

	grpc_call_cancel(call1, nullptr);
	grpc_call_cancel(call2, nullptr);

	/* now everything else should finish */
	CQ_EXPECT_COMPLETION(cqv, tag(0x102), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0x202), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0x302), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0x402), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0xdead1), 1);
	CQ_EXPECT_COMPLETION(cqv, tag(0xdead2), 1);
	cq_verify(cqv);

	grpc_call_unref(call1);
	grpc_call_unref(call2);
	grpc_call_unref(server_call1);
	grpc_call_unref(server_call2);
	grpc_server_destroy(server1);
	grpc_server_destroy(server2);
	grpc_channel_destroy(chan);

	grpc_metadata_array_destroy(&trailing_metadata_recv1);
	grpc_metadata_array_destroy(&request_metadata1);
	grpc_call_details_destroy(&request_details1);
	grpc_slice_unref(details1);
	grpc_metadata_array_destroy(&trailing_metadata_recv2);
	grpc_metadata_array_destroy(&request_metadata2);
	grpc_call_details_destroy(&request_details2);
	grpc_slice_unref(details2);

	cq_verifier_destroy(cqv);
	grpc_completion_queue_destroy(cq);

	grpc_shutdown();
	gpr_mu_destroy(&g_mu);

	return 0;
	}