src/core/lib/surface/server.cc

   1 //
   2 // Copyright 2015-2016 gRPC authors.
   3 //
   4 // Licensed under the Apache License, Version 2.0 (the "License");
   5 // you may not use this file except in compliance with the License.
   6 // You may obtain a copy of the License at
   7 //
   8 //     http://www.apache.org/licenses/LICENSE-2.0
   9 //
  10 // Unless required by applicable law or agreed to in writing, software
  11 // distributed under the License is distributed on an "AS IS" BASIS,
  12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 // See the License for the specific language governing permissions and
  14 // limitations under the License.
  15 //
  16
  17 #include <grpc/support/port_platform.h>
  18
  19 #include "src/core/lib/surface/server.h"
  20
  21 #include <limits.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24
  25 #include <algorithm>
  26 #include <atomic>
  27 #include <iterator>
  28 #include <list>
  29 #include <queue>
  30 #include <utility>
  31 #include <vector>
  32
  33 #include "absl/memory/memory.h"
  34 #include "absl/types/optional.h"
  35
  36 #include <grpc/support/alloc.h>
  37 #include <grpc/support/log.h>
  38 #include <grpc/support/string_util.h>
  39
  40 #include "src/core/lib/channel/channel_args.h"
  41 #include "src/core/lib/channel/channelz.h"
  42 #include "src/core/lib/channel/connected_channel.h"
  43 #include "src/core/lib/debug/stats.h"
  44 #include "src/core/lib/gpr/spinlock.h"
  45 #include "src/core/lib/gpr/string.h"
  46 #include "src/core/lib/gprpp/mpscq.h"
  47 #include "src/core/lib/iomgr/executor.h"
  48 #include "src/core/lib/iomgr/iomgr.h"
  49 #include "src/core/lib/slice/slice_internal.h"
  50 #include "src/core/lib/surface/api_trace.h"
  51 #include "src/core/lib/surface/call.h"
  52 #include "src/core/lib/surface/channel.h"
  53 #include "src/core/lib/surface/completion_queue.h"
  54 #include "src/core/lib/surface/init.h"
  55 #include "src/core/lib/transport/metadata.h"
  56 #include "src/core/lib/transport/static_metadata.h"
  57
  58 namespace grpc_core {
  59
  60 TraceFlag grpc_server_channel_trace(false, "server_channel");
  61
  62 //
  63 // Server::RequestedCall
  64 //
  65
  66 struct Server::RequestedCall {
  67   enum class Type { BATCH_CALL, REGISTERED_CALL };
  68
  69   RequestedCall(void* tag_arg, grpc_completion_queue* call_cq,
  70                 grpc_call** call_arg, grpc_metadata_array* initial_md,
  71                 grpc_call_details* details)
  72       : type(Type::BATCH_CALL),
  73         tag(tag_arg),
  74         cq_bound_to_call(call_cq),
  75         call(call_arg),
  76         initial_metadata(initial_md) {
  77     details->reserved = nullptr;
  78     data.batch.details = details;
  79   }
  80
  81   RequestedCall(void* tag_arg, grpc_completion_queue* call_cq,
  82                 grpc_call** call_arg, grpc_metadata_array* initial_md,
  83                 RegisteredMethod* rm, gpr_timespec* deadline,
  84                 grpc_byte_buffer** optional_payload)
  85       : type(Type::REGISTERED_CALL),
  86         tag(tag_arg),
  87         cq_bound_to_call(call_cq),
  88         call(call_arg),
  89         initial_metadata(initial_md) {
  90     data.registered.method = rm;
  91     data.registered.deadline = deadline;
  92     data.registered.optional_payload = optional_payload;
  93   }
  94
  95   MultiProducerSingleConsumerQueue::Node mpscq_node;
  96   const Type type;
  97   void* const tag;
  98   grpc_completion_queue* const cq_bound_to_call;
  99   grpc_call** const call;
 100   grpc_cq_completion completion;
 101   grpc_metadata_array* const initial_metadata;
 102   union {
 103     struct {
 104       grpc_call_details* details;
 105     } batch;
 106     struct {
 107       RegisteredMethod* method;
 108       gpr_timespec* deadline;
 109       grpc_byte_buffer** optional_payload;
 110     } registered;
 111   } data;
 112 };
 113
 114 //
 115 // Server::RegisteredMethod
 116 //
 117
 118 struct Server::RegisteredMethod {
 119   RegisteredMethod(
 120       const char* method_arg, const char* host_arg,
 121       grpc_server_register_method_payload_handling payload_handling_arg,
 122       uint32_t flags_arg)
 123       : method(method_arg == nullptr ? "" : method_arg),
 124         host(host_arg == nullptr ? "" : host_arg),
 125         payload_handling(payload_handling_arg),
 126         flags(flags_arg) {}
 127
 128   ~RegisteredMethod() = default;
 129
 130   const std::string method;
 131   const std::string host;
 132   const grpc_server_register_method_payload_handling payload_handling;
 133   const uint32_t flags;
 134   // One request matcher per method.
 135   std::unique_ptr<RequestMatcherInterface> matcher;
 136 };
 137
 138 //
 139 // Server::RequestMatcherInterface
 140 //
 141
 142 // RPCs that come in from the transport must be matched against RPC requests
 143 // from the application. An incoming request from the application can be matched
 144 // to an RPC that has already arrived or can be queued up for later use.
 145 // Likewise, an RPC coming in from the transport can either be matched to a
 146 // request that already arrived from the application or can be queued up for
 147 // later use (marked pending). If there is a match, the request's tag is posted
 148 // on the request's notification CQ.
 149 //
 150 // RequestMatcherInterface is the base class to provide this functionality.
 151 class Server::RequestMatcherInterface {
 152  public:
 153   virtual ~RequestMatcherInterface() {}
 154
 155   // Unref the calls associated with any incoming RPCs in the pending queue (not
 156   // yet matched to an application-requested RPC).
 157   virtual void ZombifyPending() = 0;
 158
 159   // Mark all application-requested RPCs failed if they have not been matched to
 160   // an incoming RPC. The error parameter indicates why the RPCs are being
 161   // failed (always server shutdown in all current implementations).
 162   virtual void KillRequests(grpc_error* error) = 0;
 163
 164   // How many request queues are supported by this matcher. This is an abstract
 165   // concept that essentially maps to gRPC completion queues.
 166   virtual size_t request_queue_count() const = 0;
 167
 168   // This function is invoked when the application requests a new RPC whose
 169   // information is in the call parameter. The request_queue_index marks the
 170   // queue onto which to place this RPC, and is typically associated with a gRPC
 171   // CQ. If there are pending RPCs waiting to be matched, publish one (match it
 172   // and notify the CQ).
 173   virtual void RequestCallWithPossiblePublish(size_t request_queue_index,
 174                                               RequestedCall* call) = 0;
 175
 176   // This function is invoked on an incoming RPC, represented by the calld
 177   // object. The RequestMatcher will try to match it against an
 178   // application-requested RPC if possible or will place it in the pending queue
 179   // otherwise. To enable some measure of fairness between server CQs, the match
 180   // is done starting at the start_request_queue_index parameter in a cyclic
 181   // order rather than always starting at 0.
 182   virtual void MatchOrQueue(size_t start_request_queue_index,
 183                             CallData* calld) = 0;
 184
 185   // Returns the server associated with this request matcher
 186   virtual Server* server() const = 0;
 187 };
 188
 189 // The RealRequestMatcher is an implementation of RequestMatcherInterface that
 190 // actually uses all the features of RequestMatcherInterface: expecting the
 191 // application to explicitly request RPCs and then matching those to incoming
 192 // RPCs, along with a slow path by which incoming RPCs are put on a locked
 193 // pending list if they aren't able to be matched to an application request.
 194 class Server::RealRequestMatcher : public RequestMatcherInterface {
 195  public:
 196   explicit RealRequestMatcher(Server* server)
 197       : server_(server), requests_per_cq_(server->cqs_.size()) {}
 198
 199   ~RealRequestMatcher() override {
 200     for (LockedMultiProducerSingleConsumerQueue& queue : requests_per_cq_) {
 201       GPR_ASSERT(queue.Pop() == nullptr);
 202     }
 203   }
 204
 205   void ZombifyPending() override {
 206     while (!pending_.empty()) {
 207       CallData* calld = pending_.front();
 208       calld->SetState(CallData::CallState::ZOMBIED);
 209       calld->KillZombie();
 210       pending_.pop();
 211     }
 212   }
 213
 214   void KillRequests(grpc_error* error) override {
 215     for (size_t i = 0; i < requests_per_cq_.size(); i++) {
 216       RequestedCall* rc;
 217       while ((rc = reinterpret_cast<RequestedCall*>(
 218                   requests_per_cq_[i].Pop())) != nullptr) {
 219         server_->FailCall(i, rc, GRPC_ERROR_REF(error));
 220       }
 221     }
 222     GRPC_ERROR_UNREF(error);
 223   }
 224
 225   size_t request_queue_count() const override {
 226     return requests_per_cq_.size();
 227   }
 228
 229   void RequestCallWithPossiblePublish(size_t request_queue_index,
 230                                       RequestedCall* call) override {
 231     if (requests_per_cq_[request_queue_index].Push(&call->mpscq_node)) {
 232       /* this was the first queued request: we need to lock and start
 233          matching calls */
 234       struct PendingCall {
 235         RequestedCall* rc = nullptr;
 236         CallData* calld;
 237       };
 238       auto pop_next_pending = [this, request_queue_index] {
 239         PendingCall pending_call;
 240         {
 241           MutexLock lock(&server_->mu_call_);
 242           if (!pending_.empty()) {
 243             pending_call.rc = reinterpret_cast<RequestedCall*>(
 244                 requests_per_cq_[request_queue_index].Pop());
 245             if (pending_call.rc != nullptr) {
 246               pending_call.calld = pending_.front();
 247               pending_.pop();
 248             }
 249           }
 250         }
 251         return pending_call;
 252       };
 253       while (true) {
 254         PendingCall next_pending = pop_next_pending();
 255         if (next_pending.rc == nullptr) break;
 256         if (!next_pending.calld->MaybeActivate()) {
 257           // Zombied Call
 258           next_pending.calld->KillZombie();
 259         } else {
 260           next_pending.calld->Publish(request_queue_index, next_pending.rc);
 261         }
 262       }
 263     }
 264   }
 265
 266   void MatchOrQueue(size_t start_request_queue_index,
 267                     CallData* calld) override {
 268     for (size_t i = 0; i < requests_per_cq_.size(); i++) {
 269       size_t cq_idx = (start_request_queue_index + i) % requests_per_cq_.size();
 270       RequestedCall* rc =
 271           reinterpret_cast<RequestedCall*>(requests_per_cq_[cq_idx].TryPop());
 272       if (rc != nullptr) {
 273         GRPC_STATS_INC_SERVER_CQS_CHECKED(i);
 274         calld->SetState(CallData::CallState::ACTIVATED);
 275         calld->Publish(cq_idx, rc);
 276         return;
 277       }
 278     }
 279     // No cq to take the request found; queue it on the slow list.
 280     GRPC_STATS_INC_SERVER_SLOWPATH_REQUESTS_QUEUED();
 281     // We need to ensure that all the queues are empty.  We do this under
 282     // the server mu_call_ lock to ensure that if something is added to
 283     // an empty request queue, it will block until the call is actually
 284     // added to the pending list.
 285     RequestedCall* rc = nullptr;
 286     size_t cq_idx = 0;
 287     size_t loop_count;
 288     {
 289       MutexLock lock(&server_->mu_call_);
 290       for (loop_count = 0; loop_count < requests_per_cq_.size(); loop_count++) {
 291         cq_idx =
 292             (start_request_queue_index + loop_count) % requests_per_cq_.size();
 293         rc = reinterpret_cast<RequestedCall*>(requests_per_cq_[cq_idx].Pop());
 294         if (rc != nullptr) {
 295           break;
 296         }
 297       }
 298       if (rc == nullptr) {
 299         calld->SetState(CallData::CallState::PENDING);
 300         pending_.push(calld);
 301         return;
 302       }
 303     }
 304     GRPC_STATS_INC_SERVER_CQS_CHECKED(loop_count + requests_per_cq_.size());
 305     calld->SetState(CallData::CallState::ACTIVATED);
 306     calld->Publish(cq_idx, rc);
 307   }
 308
 309   Server* server() const override { return server_; }
 310
 311  private:
 312   Server* const server_;
 313   std::queue<CallData*> pending_;
 314   std::vector<LockedMultiProducerSingleConsumerQueue> requests_per_cq_;
 315 };
 316
 317 // AllocatingRequestMatchers don't allow the application to request an RPC in
 318 // advance or queue up any incoming RPC for later match. Instead, MatchOrQueue
 319 // will call out to an allocation function passed in at the construction of the
 320 // object. These request matchers are designed for the C++ callback API, so they
 321 // only support 1 completion queue (passed in at the constructor).
 322 class Server::AllocatingRequestMatcherBase : public RequestMatcherInterface {
 323  public:
 324   AllocatingRequestMatcherBase(Server* server, grpc_completion_queue* cq)
 325       : server_(server), cq_(cq) {
 326     size_t idx;
 327     for (idx = 0; idx < server->cqs_.size(); idx++) {
 328       if (server->cqs_[idx] == cq) {
 329         break;
 330       }
 331     }
 332     GPR_ASSERT(idx < server->cqs_.size());
 333     cq_idx_ = idx;
 334   }
 335
 336   void ZombifyPending() override {}
 337
 338   void KillRequests(grpc_error* error) override { GRPC_ERROR_UNREF(error); }
 339
 340   size_t request_queue_count() const override { return 0; }
 341
 342   void RequestCallWithPossiblePublish(size_t /*request_queue_index*/,
 343                                       RequestedCall* /*call*/) final {
 344     GPR_ASSERT(false);
 345   }
 346
 347   Server* server() const override { return server_; }
 348
 349   // Supply the completion queue related to this request matcher
 350   grpc_completion_queue* cq() const { return cq_; }
 351
 352   // Supply the completion queue's index relative to the server.
 353   size_t cq_idx() const { return cq_idx_; }
 354
 355  private:
 356   Server* const server_;
 357   grpc_completion_queue* const cq_;
 358   size_t cq_idx_;
 359 };
 360
 361 // An allocating request matcher for non-registered methods (used for generic
 362 // API and unimplemented RPCs).
 363 class Server::AllocatingRequestMatcherBatch
 364     : public AllocatingRequestMatcherBase {
 365  public:
 366   AllocatingRequestMatcherBatch(Server* server, grpc_completion_queue* cq,
 367                                 std::function<BatchCallAllocation()> allocator)
 368       : AllocatingRequestMatcherBase(server, cq),
 369         allocator_(std::move(allocator)) {}
 370
 371   void MatchOrQueue(size_t /*start_request_queue_index*/,
 372                     CallData* calld) override {
 373     BatchCallAllocation call_info = allocator_();
 374     GPR_ASSERT(server()->ValidateServerRequest(
 375                    cq(), static_cast<void*>(call_info.tag), nullptr, nullptr) ==
 376                GRPC_CALL_OK);
 377     RequestedCall* rc = new RequestedCall(
 378         static_cast<void*>(call_info.tag), cq(), call_info.call,
 379         call_info.initial_metadata, call_info.details);
 380     calld->SetState(CallData::CallState::ACTIVATED);
 381     calld->Publish(cq_idx(), rc);
 382   }
 383
 384  private:
 385   std::function<BatchCallAllocation()> allocator_;
 386 };
 387
 388 // An allocating request matcher for registered methods.
 389 class Server::AllocatingRequestMatcherRegistered
 390     : public AllocatingRequestMatcherBase {
 391  public:
 392   AllocatingRequestMatcherRegistered(
 393       Server* server, grpc_completion_queue* cq, RegisteredMethod* rm,
 394       std::function<RegisteredCallAllocation()> allocator)
 395       : AllocatingRequestMatcherBase(server, cq),
 396         registered_method_(rm),
 397         allocator_(std::move(allocator)) {}
 398
 399   void MatchOrQueue(size_t /*start_request_queue_index*/,
 400                     CallData* calld) override {
 401     RegisteredCallAllocation call_info = allocator_();
 402     GPR_ASSERT(
 403         server()->ValidateServerRequest(cq(), static_cast<void*>(call_info.tag),
 404                                         call_info.optional_payload,
 405                                         registered_method_) == GRPC_CALL_OK);
 406     RequestedCall* rc = new RequestedCall(
 407         static_cast<void*>(call_info.tag), cq(), call_info.call,
 408         call_info.initial_metadata, registered_method_, call_info.deadline,
 409         call_info.optional_payload);
 410     calld->SetState(CallData::CallState::ACTIVATED);
 411     calld->Publish(cq_idx(), rc);
 412   }
 413
 414  private:
 415   RegisteredMethod* const registered_method_;
 416   std::function<RegisteredCallAllocation()> allocator_;
 417 };
 418
 419 //
 420 // ChannelBroadcaster
 421 //
 422
 423 namespace {
 424
 425 class ChannelBroadcaster {
 426  public:
 427   // This can have an empty constructor and destructor since we want to control
 428   // when the actual setup and shutdown broadcast take place.
 429
 430   // Copies over the channels from the locked server.
 431   void FillChannelsLocked(std::vector<grpc_channel*> channels) {
 432     GPR_DEBUG_ASSERT(channels_.empty());
 433     channels_ = std::move(channels);
 434   }
 435
 436   // Broadcasts a shutdown on each channel.
 437   void BroadcastShutdown(bool send_goaway, grpc_error* force_disconnect) {
 438     for (grpc_channel* channel : channels_) {
 439       SendShutdown(channel, send_goaway, GRPC_ERROR_REF(force_disconnect));
 440       GRPC_CHANNEL_INTERNAL_UNREF(channel, "broadcast");
 441     }
 442     channels_.clear();  // just for safety against double broadcast
 443     GRPC_ERROR_UNREF(force_disconnect);
 444   }
 445
 446  private:
 447   struct ShutdownCleanupArgs {
 448     grpc_closure closure;
 449     grpc_slice slice;
 450   };
 451
 452   static void ShutdownCleanup(void* arg, grpc_error* /*error*/) {
 453     ShutdownCleanupArgs* a = static_cast<ShutdownCleanupArgs*>(arg);
 454     grpc_slice_unref_internal(a->slice);
 455     delete a;
 456   }
 457
 458   static void SendShutdown(grpc_channel* channel, bool send_goaway,
 459                            grpc_error* send_disconnect) {
 460     ShutdownCleanupArgs* sc = new ShutdownCleanupArgs;
 461     GRPC_CLOSURE_INIT(&sc->closure, ShutdownCleanup, sc,
 462                       grpc_schedule_on_exec_ctx);
 463     grpc_transport_op* op = grpc_make_transport_op(&sc->closure);
 464     grpc_channel_element* elem;
 465     op->goaway_error =
 466         send_goaway
 467             ? grpc_error_set_int(
 468                   GRPC_ERROR_CREATE_FROM_STATIC_STRING("Server shutdown"),
 469                   GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_OK)
 470             : GRPC_ERROR_NONE;
 471     op->set_accept_stream = true;
 472     sc->slice = grpc_slice_from_copied_string("Server shutdown");
 473     op->disconnect_with_error = send_disconnect;
 474     elem =
 475         grpc_channel_stack_element(grpc_channel_get_channel_stack(channel), 0);
 476     elem->filter->start_transport_op(elem, op);
 477   }
 478
 479   std::vector<grpc_channel*> channels_;
 480 };
 481
 482 }  // namespace
 483
 484 //
 485 // Server
 486 //
 487
 488 const grpc_channel_filter Server::kServerTopFilter = {
 489     Server::CallData::StartTransportStreamOpBatch,
 490     grpc_channel_next_op,
 491     sizeof(Server::CallData),
 492     Server::CallData::InitCallElement,
 493     grpc_call_stack_ignore_set_pollset_or_pollset_set,
 494     Server::CallData::DestroyCallElement,
 495     sizeof(Server::ChannelData),
 496     Server::ChannelData::InitChannelElement,
 497     Server::ChannelData::DestroyChannelElement,
 498     grpc_channel_next_get_info,
 499     "server",
 500 };
 501
 502 namespace {
 503
 504 grpc_resource_user* CreateDefaultResourceUser(const grpc_channel_args* args) {
 505   if (args != nullptr) {
 506     grpc_resource_quota* resource_quota =
 507         grpc_resource_quota_from_channel_args(args, false /* create */);
 508     if (resource_quota != nullptr) {
 509       return grpc_resource_user_create(resource_quota, "default");
 510     }
 511   }
 512   return nullptr;
 513 }
 514
 515 RefCountedPtr<channelz::ServerNode> CreateChannelzNode(
 516     const grpc_channel_args* args) {
 517   RefCountedPtr<channelz::ServerNode> channelz_node;
 518   if (grpc_channel_args_find_bool(args, GRPC_ARG_ENABLE_CHANNELZ,
 519                                   GRPC_ENABLE_CHANNELZ_DEFAULT)) {
 520     size_t channel_tracer_max_memory = grpc_channel_args_find_integer(
 521         args, GRPC_ARG_MAX_CHANNEL_TRACE_EVENT_MEMORY_PER_NODE,
 522         {GRPC_MAX_CHANNEL_TRACE_EVENT_MEMORY_PER_NODE_DEFAULT, 0, INT_MAX});
 523     channelz_node =
 524         MakeRefCounted<channelz::ServerNode>(channel_tracer_max_memory);
 525     channelz_node->AddTraceEvent(
 526         channelz::ChannelTrace::Severity::Info,
 527         grpc_slice_from_static_string("Server created"));
 528   }
 529   return channelz_node;
 530 }
 531
 532 }  // namespace
 533
 534 Server::Server(const grpc_channel_args* args)
 535     : channel_args_(grpc_channel_args_copy(args)),
 536       default_resource_user_(CreateDefaultResourceUser(args)),
 537       channelz_node_(CreateChannelzNode(args)) {}
 538
 539 Server::~Server() {
 540   grpc_channel_args_destroy(channel_args_);
 541   // Remove the cq pollsets from the config_fetcher.
 542   if (started_ && config_fetcher_ != nullptr &&
 543       config_fetcher_->interested_parties() != nullptr) {
 544     for (grpc_pollset* pollset : pollsets_) {
 545       grpc_pollset_set_del_pollset(config_fetcher_->interested_parties(),
 546                                    pollset);
 547     }
 548   }
 549   for (size_t i = 0; i < cqs_.size(); i++) {
 550     GRPC_CQ_INTERNAL_UNREF(cqs_[i], "server");
 551   }
 552 }
 553
 554 void Server::AddListener(OrphanablePtr<ListenerInterface> listener) {
 555   channelz::ListenSocketNode* listen_socket_node =
 556       listener->channelz_listen_socket_node();
 557   if (listen_socket_node != nullptr && channelz_node_ != nullptr) {
 558     channelz_node_->AddChildListenSocket(listen_socket_node->Ref());
 559   }
 560   listeners_.emplace_back(std::move(listener));
 561 }
 562
 563 void Server::Start() {
 564   started_ = true;
 565   for (grpc_completion_queue* cq : cqs_) {
 566     if (grpc_cq_can_listen(cq)) {
 567       pollsets_.push_back(grpc_cq_pollset(cq));
 568     }
 569   }
 570   if (unregistered_request_matcher_ == nullptr) {
 571     unregistered_request_matcher_ = absl::make_unique<RealRequestMatcher>(this);
 572   }
 573   for (std::unique_ptr<RegisteredMethod>& rm : registered_methods_) {
 574     if (rm->matcher == nullptr) {
 575       rm->matcher = absl::make_unique<RealRequestMatcher>(this);
 576     }
 577   }
 578   {
 579     MutexLock lock(&mu_global_);
 580     starting_ = true;
 581   }
 582   // Register the interested parties from the config fetcher to the cq pollsets
 583   // before starting listeners so that config fetcher is being polled when the
 584   // listeners start watch the fetcher.
 585   if (config_fetcher_ != nullptr &&
 586       config_fetcher_->interested_parties() != nullptr) {
 587     for (grpc_pollset* pollset : pollsets_) {
 588       grpc_pollset_set_add_pollset(config_fetcher_->interested_parties(),
 589                                    pollset);
 590     }
 591   }
 592   for (auto& listener : listeners_) {
 593     listener.listener->Start(this, &pollsets_);
 594   }
 595   MutexLock lock(&mu_global_);
 596   starting_ = false;
 597   starting_cv_.Signal();
 598 }
 599
 600 grpc_error* Server::SetupTransport(
 601     grpc_transport* transport, grpc_pollset* accepting_pollset,
 602     const grpc_channel_args* args,
 603     const RefCountedPtr<grpc_core::channelz::SocketNode>& socket_node,
 604     grpc_resource_user* resource_user) {
 605   // Create channel.
 606   grpc_error* error = GRPC_ERROR_NONE;
 607   grpc_channel* channel = grpc_channel_create(
 608       nullptr, args, GRPC_SERVER_CHANNEL, transport, resource_user, &error);
 609   if (channel == nullptr) {
 610     return error;
 611   }
 612   ChannelData* chand = static_cast<ChannelData*>(
 613       grpc_channel_stack_element(grpc_channel_get_channel_stack(channel), 0)
 614           ->channel_data);
 615   // Set up CQs.
 616   size_t cq_idx;
 617   for (cq_idx = 0; cq_idx < cqs_.size(); cq_idx++) {
 618     if (grpc_cq_pollset(cqs_[cq_idx]) == accepting_pollset) break;
 619   }
 620   if (cq_idx == cqs_.size()) {
 621     // Completion queue not found.  Pick a random one to publish new calls to.
 622     cq_idx = static_cast<size_t>(rand()) % cqs_.size();
 623   }
 624   // Set up channelz node.
 625   intptr_t channelz_socket_uuid = 0;
 626   if (socket_node != nullptr) {
 627     channelz_socket_uuid = socket_node->uuid();
 628     channelz_node_->AddChildSocket(socket_node);
 629   }
 630   // Initialize chand.
 631   chand->InitTransport(Ref(), channel, cq_idx, transport, channelz_socket_uuid);
 632   return GRPC_ERROR_NONE;
 633 }
 634
 635 bool Server::HasOpenConnections() {
 636   MutexLock lock(&mu_global_);
 637   return !channels_.empty();
 638 }
 639
 640 void Server::SetRegisteredMethodAllocator(
 641     grpc_completion_queue* cq, void* method_tag,
 642     std::function<RegisteredCallAllocation()> allocator) {
 643   RegisteredMethod* rm = static_cast<RegisteredMethod*>(method_tag);
 644   rm->matcher = absl::make_unique<AllocatingRequestMatcherRegistered>(
 645       this, cq, rm, std::move(allocator));
 646 }
 647
 648 void Server::SetBatchMethodAllocator(
 649     grpc_completion_queue* cq, std::function<BatchCallAllocation()> allocator) {
 650   GPR_DEBUG_ASSERT(unregistered_request_matcher_ == nullptr);
 651   unregistered_request_matcher_ =
 652       absl::make_unique<AllocatingRequestMatcherBatch>(this, cq,
 653                                                        std::move(allocator));
 654 }
 655
 656 void Server::RegisterCompletionQueue(grpc_completion_queue* cq) {
 657   for (grpc_completion_queue* queue : cqs_) {
 658     if (queue == cq) return;
 659   }
 660   GRPC_CQ_INTERNAL_REF(cq, "server");
 661   cqs_.push_back(cq);
 662 }
 663
 664 namespace {
 665
 666 bool streq(const std::string& a, const char* b) {
 667   return (a.empty() && b == nullptr) ||
 668          ((b != nullptr) && !strcmp(a.c_str(), b));
 669 }
 670
 671 }  // namespace
 672
 673 Server::RegisteredMethod* Server::RegisterMethod(
 674     const char* method, const char* host,
 675     grpc_server_register_method_payload_handling payload_handling,
 676     uint32_t flags) {
 677   if (!method) {
 678     gpr_log(GPR_ERROR,
 679             "grpc_server_register_method method string cannot be NULL");
 680     return nullptr;
 681   }
 682   for (std::unique_ptr<RegisteredMethod>& m : registered_methods_) {
 683     if (streq(m->method, method) && streq(m->host, host)) {
 684       gpr_log(GPR_ERROR, "duplicate registration for %s@%s", method,
 685               host ? host : "*");
 686       return nullptr;
 687     }
 688   }
 689   if ((flags & ~GRPC_INITIAL_METADATA_USED_MASK) != 0) {
 690     gpr_log(GPR_ERROR, "grpc_server_register_method invalid flags 0x%08x",
 691             flags);
 692     return nullptr;
 693   }
 694   registered_methods_.emplace_back(absl::make_unique<RegisteredMethod>(
 695       method, host, payload_handling, flags));
 696   return registered_methods_.back().get();
 697 }
 698
 699 void Server::DoneRequestEvent(void* req, grpc_cq_completion* /*c*/) {
 700   delete static_cast<RequestedCall*>(req);
 701 }
 702
 703 void Server::FailCall(size_t cq_idx, RequestedCall* rc, grpc_error* error) {
 704   *rc->call = nullptr;
 705   rc->initial_metadata->count = 0;
 706   GPR_ASSERT(error != GRPC_ERROR_NONE);
 707   grpc_cq_end_op(cqs_[cq_idx], rc->tag, error, DoneRequestEvent, rc,
 708                  &rc->completion);
 709 }
 710
 711 // Before calling MaybeFinishShutdown(), we must hold mu_global_ and not
 712 // hold mu_call_.
 713 void Server::MaybeFinishShutdown() {
 714   if (!shutdown_flag_.load(std::memory_order_acquire) || shutdown_published_) {
 715     return;
 716   }
 717   {
 718     MutexLock lock(&mu_call_);
 719     KillPendingWorkLocked(
 720         GRPC_ERROR_CREATE_FROM_STATIC_STRING("Server Shutdown"));
 721   }
 722   if (!channels_.empty() || listeners_destroyed_ < listeners_.size()) {
 723     if (gpr_time_cmp(gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME),
 724                                   last_shutdown_message_time_),
 725                      gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
 726       last_shutdown_message_time_ = gpr_now(GPR_CLOCK_REALTIME);
 727       gpr_log(GPR_DEBUG,
 728               "Waiting for %" PRIuPTR " channels and %" PRIuPTR "/%" PRIuPTR
 729               " listeners to be destroyed before shutting down server",
 730               channels_.size(), listeners_.size() - listeners_destroyed_,
 731               listeners_.size());
 732     }
 733     return;
 734   }
 735   shutdown_published_ = true;
 736   for (auto& shutdown_tag : shutdown_tags_) {
 737     Ref().release();
 738     grpc_cq_end_op(shutdown_tag.cq, shutdown_tag.tag, GRPC_ERROR_NONE,
 739                    DoneShutdownEvent, this, &shutdown_tag.completion);
 740   }
 741 }
 742
 743 void Server::KillPendingWorkLocked(grpc_error* error) {
 744   if (started_) {
 745     unregistered_request_matcher_->KillRequests(GRPC_ERROR_REF(error));
 746     unregistered_request_matcher_->ZombifyPending();
 747     for (std::unique_ptr<RegisteredMethod>& rm : registered_methods_) {
 748       rm->matcher->KillRequests(GRPC_ERROR_REF(error));
 749       rm->matcher->ZombifyPending();
 750     }
 751   }
 752   GRPC_ERROR_UNREF(error);
 753 }
 754
 755 std::vector<grpc_channel*> Server::GetChannelsLocked() const {
 756   std::vector<grpc_channel*> channels;
 757   channels.reserve(channels_.size());
 758   for (const ChannelData* chand : channels_) {
 759     channels.push_back(chand->channel());
 760     GRPC_CHANNEL_INTERNAL_REF(chand->channel(), "broadcast");
 761   }
 762   return channels;
 763 }
 764
 765 void Server::ListenerDestroyDone(void* arg, grpc_error* /*error*/) {
 766   Server* server = static_cast<Server*>(arg);
 767   MutexLock lock(&server->mu_global_);
 768   server->listeners_destroyed_++;
 769   server->MaybeFinishShutdown();
 770 }
 771
 772 namespace {
 773
 774 void DonePublishedShutdown(void* /*done_arg*/, grpc_cq_completion* storage) {
 775   delete storage;
 776 }
 777
 778 }  // namespace
 779
 780 // - Kills all pending requests-for-incoming-RPC-calls (i.e., the requests made
 781 //   via grpc_server_request_call() and grpc_server_request_registered_call()
 782 //   will now be cancelled). See KillPendingWorkLocked().
 783 //
 784 // - Shuts down the listeners (i.e., the server will no longer listen on the
 785 //   port for new incoming channels).
 786 //
 787 // - Iterates through all channels on the server and sends shutdown msg (see
 788 //   ChannelBroadcaster::BroadcastShutdown() for details) to the clients via
 789 //   the transport layer. The transport layer then guarantees the following:
 790 //    -- Sends shutdown to the client (e.g., HTTP2 transport sends GOAWAY).
 791 //    -- If the server has outstanding calls that are in the process, the
 792 //       connection is NOT closed until the server is done with all those calls.
 793 //    -- Once there are no more calls in progress, the channel is closed.
 794 void Server::ShutdownAndNotify(grpc_completion_queue* cq, void* tag) {
 795   ChannelBroadcaster broadcaster;
 796   {
 797     // Wait for startup to be finished.  Locks mu_global.
 798     MutexLock lock(&mu_global_);
 799     WaitUntil(&starting_cv_, &mu_global_, [this] { return !starting_; });
 800     // Stay locked, and gather up some stuff to do.
 801     GPR_ASSERT(grpc_cq_begin_op(cq, tag));
 802     if (shutdown_published_) {
 803       grpc_cq_end_op(cq, tag, GRPC_ERROR_NONE, DonePublishedShutdown, nullptr,
 804                      new grpc_cq_completion);
 805       return;
 806     }
 807     shutdown_tags_.emplace_back(tag, cq);
 808     if (shutdown_flag_.load(std::memory_order_acquire)) {
 809       return;
 810     }
 811     last_shutdown_message_time_ = gpr_now(GPR_CLOCK_REALTIME);
 812     broadcaster.FillChannelsLocked(GetChannelsLocked());
 813     shutdown_flag_.store(true, std::memory_order_release);
 814     // Collect all unregistered then registered calls.
 815     {
 816       MutexLock lock(&mu_call_);
 817       KillPendingWorkLocked(
 818           GRPC_ERROR_CREATE_FROM_STATIC_STRING("Server Shutdown"));
 819     }
 820     MaybeFinishShutdown();
 821   }
 822   // Shutdown listeners.
 823   for (auto& listener : listeners_) {
 824     channelz::ListenSocketNode* channelz_listen_socket_node =
 825         listener.listener->channelz_listen_socket_node();
 826     if (channelz_node_ != nullptr && channelz_listen_socket_node != nullptr) {
 827       channelz_node_->RemoveChildListenSocket(
 828           channelz_listen_socket_node->uuid());
 829     }
 830     GRPC_CLOSURE_INIT(&listener.destroy_done, ListenerDestroyDone, this,
 831                       grpc_schedule_on_exec_ctx);
 832     listener.listener->SetOnDestroyDone(&listener.destroy_done);
 833     listener.listener.reset();
 834   }
 835   broadcaster.BroadcastShutdown(/*send_goaway=*/true, GRPC_ERROR_NONE);
 836 }
 837
 838 void Server::CancelAllCalls() {
 839   ChannelBroadcaster broadcaster;
 840   {
 841     MutexLock lock(&mu_global_);
 842     broadcaster.FillChannelsLocked(GetChannelsLocked());
 843   }
 844   broadcaster.BroadcastShutdown(
 845       /*send_goaway=*/false,
 846       GRPC_ERROR_CREATE_FROM_STATIC_STRING("Cancelling all calls"));
 847 }
 848
 849 void Server::Orphan() {
 850   {
 851     MutexLock lock(&mu_global_);
 852     GPR_ASSERT(shutdown_flag_.load(std::memory_order_acquire) ||
 853                listeners_.empty());
 854     GPR_ASSERT(listeners_destroyed_ == listeners_.size());
 855   }
 856   if (default_resource_user_ != nullptr) {
 857     grpc_resource_quota_unref(grpc_resource_user_quota(default_resource_user_));
 858     grpc_resource_user_shutdown(default_resource_user_);
 859     grpc_resource_user_unref(default_resource_user_);
 860   }
 861   Unref();
 862 }
 863
 864 grpc_call_error Server::ValidateServerRequest(
 865     grpc_completion_queue* cq_for_notification, void* tag,
 866     grpc_byte_buffer** optional_payload, RegisteredMethod* rm) {
 867   if ((rm == nullptr && optional_payload != nullptr) ||
 868       ((rm != nullptr) && ((optional_payload == nullptr) !=
 869                            (rm->payload_handling == GRPC_SRM_PAYLOAD_NONE)))) {
 870     return GRPC_CALL_ERROR_PAYLOAD_TYPE_MISMATCH;
 871   }
 872   if (grpc_cq_begin_op(cq_for_notification, tag) == false) {
 873     return GRPC_CALL_ERROR_COMPLETION_QUEUE_SHUTDOWN;
 874   }
 875   return GRPC_CALL_OK;
 876 }
 877
 878 grpc_call_error Server::ValidateServerRequestAndCq(
 879     size_t* cq_idx, grpc_completion_queue* cq_for_notification, void* tag,
 880     grpc_byte_buffer** optional_payload, RegisteredMethod* rm) {
 881   size_t idx;
 882   for (idx = 0; idx < cqs_.size(); idx++) {
 883     if (cqs_[idx] == cq_for_notification) {
 884       break;
 885     }
 886   }
 887   if (idx == cqs_.size()) {
 888     return GRPC_CALL_ERROR_NOT_SERVER_COMPLETION_QUEUE;
 889   }
 890   grpc_call_error error =
 891       ValidateServerRequest(cq_for_notification, tag, optional_payload, rm);
 892   if (error != GRPC_CALL_OK) {
 893     return error;
 894   }
 895   *cq_idx = idx;
 896   return GRPC_CALL_OK;
 897 }
 898
 899 grpc_call_error Server::QueueRequestedCall(size_t cq_idx, RequestedCall* rc) {
 900   if (shutdown_flag_.load(std::memory_order_acquire)) {
 901     FailCall(cq_idx, rc,
 902              GRPC_ERROR_CREATE_FROM_STATIC_STRING("Server Shutdown"));
 903     return GRPC_CALL_OK;
 904   }
 905   RequestMatcherInterface* rm;
 906   switch (rc->type) {
 907     case RequestedCall::Type::BATCH_CALL:
 908       rm = unregistered_request_matcher_.get();
 909       break;
 910     case RequestedCall::Type::REGISTERED_CALL:
 911       rm = rc->data.registered.method->matcher.get();
 912       break;
 913   }
 914   rm->RequestCallWithPossiblePublish(cq_idx, rc);
 915   return GRPC_CALL_OK;
 916 }
 917
 918 grpc_call_error Server::RequestCall(grpc_call** call,
 919                                     grpc_call_details* details,
 920                                     grpc_metadata_array* request_metadata,
 921                                     grpc_completion_queue* cq_bound_to_call,
 922                                     grpc_completion_queue* cq_for_notification,
 923                                     void* tag) {
 924   size_t cq_idx;
 925   grpc_call_error error = ValidateServerRequestAndCq(
 926       &cq_idx, cq_for_notification, tag, nullptr, nullptr);
 927   if (error != GRPC_CALL_OK) {
 928     return error;
 929   }
 930   RequestedCall* rc =
 931       new RequestedCall(tag, cq_bound_to_call, call, request_metadata, details);
 932   return QueueRequestedCall(cq_idx, rc);
 933 }
 934
 935 grpc_call_error Server::RequestRegisteredCall(
 936     RegisteredMethod* rm, grpc_call** call, gpr_timespec* deadline,
 937     grpc_metadata_array* request_metadata, grpc_byte_buffer** optional_payload,
 938     grpc_completion_queue* cq_bound_to_call,
 939     grpc_completion_queue* cq_for_notification, void* tag_new) {
 940   size_t cq_idx;
 941   grpc_call_error error = ValidateServerRequestAndCq(
 942       &cq_idx, cq_for_notification, tag_new, optional_payload, rm);
 943   if (error != GRPC_CALL_OK) {
 944     return error;
 945   }
 946   RequestedCall* rc =
 947       new RequestedCall(tag_new, cq_bound_to_call, call, request_metadata, rm,
 948                         deadline, optional_payload);
 949   return QueueRequestedCall(cq_idx, rc);
 950 }
 951
 952 //
 953 // Server::ChannelData::ConnectivityWatcher
 954 //
 955
 956 class Server::ChannelData::ConnectivityWatcher
 957     : public AsyncConnectivityStateWatcherInterface {
 958  public:
 959   explicit ConnectivityWatcher(ChannelData* chand) : chand_(chand) {
 960     GRPC_CHANNEL_INTERNAL_REF(chand_->channel_, "connectivity");
 961   }
 962
 963   ~ConnectivityWatcher() override {
 964     GRPC_CHANNEL_INTERNAL_UNREF(chand_->channel_, "connectivity");
 965   }
 966
 967  private:
 968   void OnConnectivityStateChange(grpc_connectivity_state new_state,
 969                                  const absl::Status& /*status*/) override {
 970     // Don't do anything until we are being shut down.
 971     if (new_state != GRPC_CHANNEL_SHUTDOWN) return;
 972     // Shut down channel.
 973     MutexLock lock(&chand_->server_->mu_global_);
 974     chand_->Destroy();
 975   }
 976
 977   ChannelData* chand_;
 978 };
 979
 980 //
 981 // Server::ChannelData
 982 //
 983
 984 Server::ChannelData::~ChannelData() {
 985   if (registered_methods_ != nullptr) {
 986     for (const ChannelRegisteredMethod& crm : *registered_methods_) {
 987       grpc_slice_unref_internal(crm.method);
 988       GPR_DEBUG_ASSERT(crm.method.refcount == &kNoopRefcount ||
 989                        crm.method.refcount == nullptr);
 990       if (crm.has_host) {
 991         grpc_slice_unref_internal(crm.host);
 992         GPR_DEBUG_ASSERT(crm.host.refcount == &kNoopRefcount ||
 993                          crm.host.refcount == nullptr);
 994       }
 995     }
 996     registered_methods_.reset();
 997   }
 998   if (server_ != nullptr) {
 999     if (server_->channelz_node_ != nullptr && channelz_socket_uuid_ != 0) {
1000       server_->channelz_node_->RemoveChildSocket(channelz_socket_uuid_);
1001     }
1002     {
1003       MutexLock lock(&server_->mu_global_);
1004       if (list_position_.has_value()) {
1005         server_->channels_.erase(*list_position_);
1006         list_position_.reset();
1007       }
1008       server_->MaybeFinishShutdown();
1009     }
1010   }
1011 }
1012
1013 void Server::ChannelData::InitTransport(RefCountedPtr<Server> server,
1014                                         grpc_channel* channel, size_t cq_idx,
1015                                         grpc_transport* transport,
1016                                         intptr_t channelz_socket_uuid) {
1017   server_ = std::move(server);
1018   channel_ = channel;
1019   cq_idx_ = cq_idx;
1020   channelz_socket_uuid_ = channelz_socket_uuid;
1021   // Build a lookup table phrased in terms of mdstr's in this channels context
1022   // to quickly find registered methods.
1023   size_t num_registered_methods = server_->registered_methods_.size();
1024   if (num_registered_methods > 0) {
1025     uint32_t max_probes = 0;
1026     size_t slots = 2 * num_registered_methods;
1027     registered_methods_ =
1028         absl::make_unique<std::vector<ChannelRegisteredMethod>>(slots);
1029     for (std::unique_ptr<RegisteredMethod>& rm : server_->registered_methods_) {
1030       ExternallyManagedSlice host;
1031       ExternallyManagedSlice method(rm->method.c_str());
1032       const bool has_host = !rm->host.empty();
1033       if (has_host) {
1034         host = ExternallyManagedSlice(rm->host.c_str());
1035       }
1036       uint32_t hash =
1037           GRPC_MDSTR_KV_HASH(has_host ? host.Hash() : 0, method.Hash());
1038       uint32_t probes = 0;
1039       for (probes = 0; (*registered_methods_)[(hash + probes) % slots]
1040                            .server_registered_method != nullptr;
1041            probes++) {
1042       }
1043       if (probes > max_probes) max_probes = probes;
1044       ChannelRegisteredMethod* crm =
1045           &(*registered_methods_)[(hash + probes) % slots];
1046       crm->server_registered_method = rm.get();
1047       crm->flags = rm->flags;
1048       crm->has_host = has_host;
1049       if (has_host) {
1050         crm->host = host;
1051       }
1052       crm->method = method;
1053     }
1054     GPR_ASSERT(slots <= UINT32_MAX);
1055     registered_method_max_probes_ = max_probes;
1056   }
1057   // Publish channel.
1058   {
1059     MutexLock lock(&server_->mu_global_);
1060     server_->channels_.push_front(this);
1061     list_position_ = server_->channels_.begin();
1062   }
1063   // Start accept_stream transport op.
1064   grpc_transport_op* op = grpc_make_transport_op(nullptr);
1065   op->set_accept_stream = true;
1066   op->set_accept_stream_fn = AcceptStream;
1067   op->set_accept_stream_user_data = this;
1068   op->start_connectivity_watch = MakeOrphanable<ConnectivityWatcher>(this);
1069   if (server_->shutdown_flag_.load(std::memory_order_acquire)) {
1070     op->disconnect_with_error =
1071         GRPC_ERROR_CREATE_FROM_STATIC_STRING("Server shutdown");
1072   }
1073   grpc_transport_perform_op(transport, op);
1074 }
1075
1076 Server::ChannelRegisteredMethod* Server::ChannelData::GetRegisteredMethod(
1077     const grpc_slice& host, const grpc_slice& path, bool is_idempotent) {
1078   if (registered_methods_ == nullptr) return nullptr;
1079   /* TODO(ctiller): unify these two searches */
1080   /* check for an exact match with host */
1081   uint32_t hash = GRPC_MDSTR_KV_HASH(grpc_slice_hash_internal(host),
1082                                      grpc_slice_hash_internal(path));
1083   for (size_t i = 0; i <= registered_method_max_probes_; i++) {
1084     ChannelRegisteredMethod* rm =
1085         &(*registered_methods_)[(hash + i) % registered_methods_->size()];
1086     if (rm->server_registered_method == nullptr) break;
1087     if (!rm->has_host) continue;
1088     if (rm->host != host) continue;
1089     if (rm->method != path) continue;
1090     if ((rm->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) &&
1091         !is_idempotent) {
1092       continue;
1093     }
1094     return rm;
1095   }
1096   /* check for a wildcard method definition (no host set) */
1097   hash = GRPC_MDSTR_KV_HASH(0, grpc_slice_hash_internal(path));
1098   for (size_t i = 0; i <= registered_method_max_probes_; i++) {
1099     ChannelRegisteredMethod* rm =
1100         &(*registered_methods_)[(hash + i) % registered_methods_->size()];
1101     if (rm->server_registered_method == nullptr) break;
1102     if (rm->has_host) continue;
1103     if (rm->method != path) continue;
1104     if ((rm->flags & GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST) &&
1105         !is_idempotent) {
1106       continue;
1107     }
1108     return rm;
1109   }
1110   return nullptr;
1111 }
1112
1113 void Server::ChannelData::AcceptStream(void* arg, grpc_transport* /*transport*/,
1114                                        const void* transport_server_data) {
1115   auto* chand = static_cast<Server::ChannelData*>(arg);
1116   /* create a call */
1117   grpc_call_create_args args;
1118   args.channel = chand->channel_;
1119   args.server = chand->server_.get();
1120   args.parent = nullptr;
1121   args.propagation_mask = 0;
1122   args.cq = nullptr;
1123   args.pollset_set_alternative = nullptr;
1124   args.server_transport_data = transport_server_data;
1125   args.add_initial_metadata = nullptr;
1126   args.add_initial_metadata_count = 0;
1127   args.send_deadline = GRPC_MILLIS_INF_FUTURE;
1128   grpc_call* call;
1129   grpc_error* error = grpc_call_create(&args, &call);
1130   grpc_call_element* elem =
1131       grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
1132   auto* calld = static_cast<Server::CallData*>(elem->call_data);
1133   if (error != GRPC_ERROR_NONE) {
1134     GRPC_ERROR_UNREF(error);
1135     calld->FailCallCreation();
1136     return;
1137   }
1138   calld->Start(elem);
1139 }
1140
1141 void Server::ChannelData::FinishDestroy(void* arg, grpc_error* /*error*/) {
1142   auto* chand = static_cast<Server::ChannelData*>(arg);
1143   Server* server = chand->server_.get();
1144   GRPC_CHANNEL_INTERNAL_UNREF(chand->channel_, "server");
1145   server->Unref();
1146 }
1147
1148 void Server::ChannelData::Destroy() {
1149   if (!list_position_.has_value()) return;
1150   GPR_ASSERT(server_ != nullptr);
1151   server_->channels_.erase(*list_position_);
1152   list_position_.reset();
1153   server_->Ref().release();
1154   server_->MaybeFinishShutdown();
1155   GRPC_CLOSURE_INIT(&finish_destroy_channel_closure_, FinishDestroy, this,
1156                     grpc_schedule_on_exec_ctx);
1157   if (GRPC_TRACE_FLAG_ENABLED(grpc_server_channel_trace)) {
1158     gpr_log(GPR_INFO, "Disconnected client");
1159   }
1160   grpc_transport_op* op =
1161       grpc_make_transport_op(&finish_destroy_channel_closure_);
1162   op->set_accept_stream = true;
1163   grpc_channel_next_op(
1164       grpc_channel_stack_element(grpc_channel_get_channel_stack(channel_), 0),
1165       op);
1166 }
1167
1168 grpc_error* Server::ChannelData::InitChannelElement(
1169     grpc_channel_element* elem, grpc_channel_element_args* args) {
1170   GPR_ASSERT(args->is_first);
1171   GPR_ASSERT(!args->is_last);
1172   new (elem->channel_data) ChannelData();
1173   return GRPC_ERROR_NONE;
1174 }
1175
1176 void Server::ChannelData::DestroyChannelElement(grpc_channel_element* elem) {
1177   auto* chand = static_cast<ChannelData*>(elem->channel_data);
1178   chand->~ChannelData();
1179 }
1180
1181 //
1182 // Server::CallData
1183 //
1184
1185 Server::CallData::CallData(grpc_call_element* elem,
1186                            const grpc_call_element_args& args,
1187                            RefCountedPtr<Server> server)
1188     : server_(std::move(server)),
1189       call_(grpc_call_from_top_element(elem)),
1190       call_combiner_(args.call_combiner) {
1191   GRPC_CLOSURE_INIT(&recv_initial_metadata_ready_, RecvInitialMetadataReady,
1192                     elem, grpc_schedule_on_exec_ctx);
1193   GRPC_CLOSURE_INIT(&recv_trailing_metadata_ready_, RecvTrailingMetadataReady,
1194                     elem, grpc_schedule_on_exec_ctx);
1195 }
1196
1197 Server::CallData::~CallData() {
1198   GPR_ASSERT(state_.Load(MemoryOrder::RELAXED) != CallState::PENDING);
1199   GRPC_ERROR_UNREF(recv_initial_metadata_error_);
1200   if (host_.has_value()) {
1201     grpc_slice_unref_internal(*host_);
1202   }
1203   if (path_.has_value()) {
1204     grpc_slice_unref_internal(*path_);
1205   }
1206   grpc_metadata_array_destroy(&initial_metadata_);
1207   grpc_byte_buffer_destroy(payload_);
1208 }
1209
1210 void Server::CallData::SetState(CallState state) {
1211   state_.Store(state, MemoryOrder::RELAXED);
1212 }
1213
1214 bool Server::CallData::MaybeActivate() {
1215   CallState expected = CallState::PENDING;
1216   return state_.CompareExchangeStrong(&expected, CallState::ACTIVATED,
1217                                       MemoryOrder::ACQ_REL,
1218                                       MemoryOrder::RELAXED);
1219 }
1220
1221 void Server::CallData::FailCallCreation() {
1222   CallState expected_not_started = CallState::NOT_STARTED;
1223   CallState expected_pending = CallState::PENDING;
1224   if (state_.CompareExchangeStrong(&expected_not_started, CallState::ZOMBIED,
1225                                    MemoryOrder::ACQ_REL,
1226                                    MemoryOrder::ACQUIRE)) {
1227     KillZombie();
1228   } else if (state_.CompareExchangeStrong(&expected_pending, CallState::ZOMBIED,
1229                                           MemoryOrder::ACQ_REL,
1230                                           MemoryOrder::RELAXED)) {
1231     // Zombied call will be destroyed when it's removed from the pending
1232     // queue... later.
1233   }
1234 }
1235
1236 void Server::CallData::Start(grpc_call_element* elem) {
1237   grpc_op op;
1238   op.op = GRPC_OP_RECV_INITIAL_METADATA;
1239   op.flags = 0;
1240   op.reserved = nullptr;
1241   op.data.recv_initial_metadata.recv_initial_metadata = &initial_metadata_;
1242   GRPC_CLOSURE_INIT(&recv_initial_metadata_batch_complete_,
1243                     RecvInitialMetadataBatchComplete, elem,
1244                     grpc_schedule_on_exec_ctx);
1245   grpc_call_start_batch_and_execute(call_, &op, 1,
1246                                     &recv_initial_metadata_batch_complete_);
1247 }
1248
1249 void Server::CallData::Publish(size_t cq_idx, RequestedCall* rc) {
1250   grpc_call_set_completion_queue(call_, rc->cq_bound_to_call);
1251   *rc->call = call_;
1252   cq_new_ = server_->cqs_[cq_idx];
1253   GPR_SWAP(grpc_metadata_array, *rc->initial_metadata, initial_metadata_);
1254   switch (rc->type) {
1255     case RequestedCall::Type::BATCH_CALL:
1256       GPR_ASSERT(host_.has_value());
1257       GPR_ASSERT(path_.has_value());
1258       rc->data.batch.details->host = grpc_slice_ref_internal(*host_);
1259       rc->data.batch.details->method = grpc_slice_ref_internal(*path_);
1260       rc->data.batch.details->deadline =
1261           grpc_millis_to_timespec(deadline_, GPR_CLOCK_MONOTONIC);
1262       rc->data.batch.details->flags = recv_initial_metadata_flags_;
1263       break;
1264     case RequestedCall::Type::REGISTERED_CALL:
1265       *rc->data.registered.deadline =
1266           grpc_millis_to_timespec(deadline_, GPR_CLOCK_MONOTONIC);
1267       if (rc->data.registered.optional_payload != nullptr) {
1268         *rc->data.registered.optional_payload = payload_;
1269         payload_ = nullptr;
1270       }
1271       break;
1272     default:
1273       GPR_UNREACHABLE_CODE(return );
1274   }
1275   grpc_cq_end_op(cq_new_, rc->tag, GRPC_ERROR_NONE, Server::DoneRequestEvent,
1276                  rc, &rc->completion, true);
1277 }
1278
1279 void Server::CallData::PublishNewRpc(void* arg, grpc_error* error) {
1280   grpc_call_element* call_elem = static_cast<grpc_call_element*>(arg);
1281   auto* calld = static_cast<Server::CallData*>(call_elem->call_data);
1282   auto* chand = static_cast<Server::ChannelData*>(call_elem->channel_data);
1283   RequestMatcherInterface* rm = calld->matcher_;
1284   Server* server = rm->server();
1285   if (error != GRPC_ERROR_NONE ||
1286       server->shutdown_flag_.load(std::memory_order_acquire)) {
1287     calld->state_.Store(CallState::ZOMBIED, MemoryOrder::RELAXED);
1288     calld->KillZombie();
1289     return;
1290   }
1291   rm->MatchOrQueue(chand->cq_idx(), calld);
1292 }
1293
1294 namespace {
1295
1296 void KillZombieClosure(void* call, grpc_error* /*error*/) {
1297   grpc_call_unref(static_cast<grpc_call*>(call));
1298 }
1299
1300 }  // namespace
1301
1302 void Server::CallData::KillZombie() {
1303   GRPC_CLOSURE_INIT(&kill_zombie_closure_, KillZombieClosure, call_,
1304                     grpc_schedule_on_exec_ctx);
1305   ExecCtx::Run(DEBUG_LOCATION, &kill_zombie_closure_, GRPC_ERROR_NONE);
1306 }
1307
1308 void Server::CallData::StartNewRpc(grpc_call_element* elem) {
1309   auto* chand = static_cast<ChannelData*>(elem->channel_data);
1310   if (server_->shutdown_flag_.load(std::memory_order_acquire)) {
1311     state_.Store(CallState::ZOMBIED, MemoryOrder::RELAXED);
1312     KillZombie();
1313     return;
1314   }
1315   // Find request matcher.
1316   matcher_ = server_->unregistered_request_matcher_.get();
1317   grpc_server_register_method_payload_handling payload_handling =
1318       GRPC_SRM_PAYLOAD_NONE;
1319   if (path_.has_value() && host_.has_value()) {
1320     ChannelRegisteredMethod* rm =
1321         chand->GetRegisteredMethod(*host_, *path_,
1322                                    (recv_initial_metadata_flags_ &
1323                                     GRPC_INITIAL_METADATA_IDEMPOTENT_REQUEST));
1324     if (rm != nullptr) {
1325       matcher_ = rm->server_registered_method->matcher.get();
1326       payload_handling = rm->server_registered_method->payload_handling;
1327     }
1328   }
1329   // Start recv_message op if needed.
1330   switch (payload_handling) {
1331     case GRPC_SRM_PAYLOAD_NONE:
1332       PublishNewRpc(elem, GRPC_ERROR_NONE);
1333       break;
1334     case GRPC_SRM_PAYLOAD_READ_INITIAL_BYTE_BUFFER: {
1335       grpc_op op;
1336       op.op = GRPC_OP_RECV_MESSAGE;
1337       op.flags = 0;
1338       op.reserved = nullptr;
1339       op.data.recv_message.recv_message = &payload_;
1340       GRPC_CLOSURE_INIT(&publish_, PublishNewRpc, elem,
1341                         grpc_schedule_on_exec_ctx);
1342       grpc_call_start_batch_and_execute(call_, &op, 1, &publish_);
1343       break;
1344     }
1345   }
1346 }
1347
1348 void Server::CallData::RecvInitialMetadataBatchComplete(void* arg,
1349                                                         grpc_error* error) {
1350   grpc_call_element* elem = static_cast<grpc_call_element*>(arg);
1351   auto* calld = static_cast<Server::CallData*>(elem->call_data);
1352   if (error != GRPC_ERROR_NONE) {
1353     calld->FailCallCreation();
1354     return;
1355   }
1356   calld->StartNewRpc(elem);
1357 }
1358
1359 void Server::CallData::StartTransportStreamOpBatchImpl(
1360     grpc_call_element* elem, grpc_transport_stream_op_batch* batch) {
1361   if (batch->recv_initial_metadata) {
1362     GPR_ASSERT(batch->payload->recv_initial_metadata.recv_flags == nullptr);
1363     recv_initial_metadata_ =
1364         batch->payload->recv_initial_metadata.recv_initial_metadata;
1365     original_recv_initial_metadata_ready_ =
1366         batch->payload->recv_initial_metadata.recv_initial_metadata_ready;
1367     batch->payload->recv_initial_metadata.recv_initial_metadata_ready =
1368         &recv_initial_metadata_ready_;
1369     batch->payload->recv_initial_metadata.recv_flags =
1370         &recv_initial_metadata_flags_;
1371   }
1372   if (batch->recv_trailing_metadata) {
1373     original_recv_trailing_metadata_ready_ =
1374         batch->payload->recv_trailing_metadata.recv_trailing_metadata_ready;
1375     batch->payload->recv_trailing_metadata.recv_trailing_metadata_ready =
1376         &recv_trailing_metadata_ready_;
1377   }
1378   grpc_call_next_op(elem, batch);
1379 }
1380
1381 void Server::CallData::RecvInitialMetadataReady(void* arg, grpc_error* error) {
1382   grpc_call_element* elem = static_cast<grpc_call_element*>(arg);
1383   CallData* calld = static_cast<CallData*>(elem->call_data);
1384   grpc_millis op_deadline;
1385   if (error == GRPC_ERROR_NONE) {
1386     GPR_DEBUG_ASSERT(calld->recv_initial_metadata_->idx.named.path != nullptr);
1387     GPR_DEBUG_ASSERT(calld->recv_initial_metadata_->idx.named.authority !=
1388                      nullptr);
1389     calld->path_.emplace(grpc_slice_ref_internal(
1390         GRPC_MDVALUE(calld->recv_initial_metadata_->idx.named.path->md)));
1391     calld->host_.emplace(grpc_slice_ref_internal(
1392         GRPC_MDVALUE(calld->recv_initial_metadata_->idx.named.authority->md)));
1393     grpc_metadata_batch_remove(calld->recv_initial_metadata_, GRPC_BATCH_PATH);
1394     grpc_metadata_batch_remove(calld->recv_initial_metadata_,
1395                                GRPC_BATCH_AUTHORITY);
1396   } else {
1397     GRPC_ERROR_REF(error);
1398   }
1399   op_deadline = calld->recv_initial_metadata_->deadline;
1400   if (op_deadline != GRPC_MILLIS_INF_FUTURE) {
1401     calld->deadline_ = op_deadline;
1402   }
1403   if (calld->host_.has_value() && calld->path_.has_value()) {
1404     /* do nothing */
1405   } else {
1406     /* Pass the error reference to calld->recv_initial_metadata_error */
1407     grpc_error* src_error = error;
1408     error = GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
1409         "Missing :authority or :path", &src_error, 1);
1410     GRPC_ERROR_UNREF(src_error);
1411     calld->recv_initial_metadata_error_ = GRPC_ERROR_REF(error);
1412   }
1413   grpc_closure* closure = calld->original_recv_initial_metadata_ready_;
1414   calld->original_recv_initial_metadata_ready_ = nullptr;
1415   if (calld->seen_recv_trailing_metadata_ready_) {
1416     GRPC_CALL_COMBINER_START(calld->call_combiner_,
1417                              &calld->recv_trailing_metadata_ready_,
1418                              calld->recv_trailing_metadata_error_,
1419                              "continue server recv_trailing_metadata_ready");
1420   }
1421   Closure::Run(DEBUG_LOCATION, closure, error);
1422 }
1423
1424 void Server::CallData::RecvTrailingMetadataReady(void* arg, grpc_error* error) {
1425   grpc_call_element* elem = static_cast<grpc_call_element*>(arg);
1426   CallData* calld = static_cast<CallData*>(elem->call_data);
1427   if (calld->original_recv_initial_metadata_ready_ != nullptr) {
1428     calld->recv_trailing_metadata_error_ = GRPC_ERROR_REF(error);
1429     calld->seen_recv_trailing_metadata_ready_ = true;
1430     GRPC_CLOSURE_INIT(&calld->recv_trailing_metadata_ready_,
1431                       RecvTrailingMetadataReady, elem,
1432                       grpc_schedule_on_exec_ctx);
1433     GRPC_CALL_COMBINER_STOP(calld->call_combiner_,
1434                             "deferring server recv_trailing_metadata_ready "
1435                             "until after recv_initial_metadata_ready");
1436     return;
1437   }
1438   error =
1439       grpc_error_add_child(GRPC_ERROR_REF(error),
1440                            GRPC_ERROR_REF(calld->recv_initial_metadata_error_));
1441   Closure::Run(DEBUG_LOCATION, calld->original_recv_trailing_metadata_ready_,
1442                error);
1443 }
1444
1445 grpc_error* Server::CallData::InitCallElement(
1446     grpc_call_element* elem, const grpc_call_element_args* args) {
1447   auto* chand = static_cast<ChannelData*>(elem->channel_data);
1448   new (elem->call_data) Server::CallData(elem, *args, chand->server());
1449   return GRPC_ERROR_NONE;
1450 }
1451
1452 void Server::CallData::DestroyCallElement(
1453     grpc_call_element* elem, const grpc_call_final_info* /*final_info*/,
1454     grpc_closure* /*ignored*/) {
1455   auto* calld = static_cast<CallData*>(elem->call_data);
1456   calld->~CallData();
1457 }
1458
1459 void Server::CallData::StartTransportStreamOpBatch(
1460     grpc_call_element* elem, grpc_transport_stream_op_batch* batch) {
1461   auto* calld = static_cast<CallData*>(elem->call_data);
1462   calld->StartTransportStreamOpBatchImpl(elem, batch);
1463 }
1464
1465 }  // namespace grpc_core
1466
1467 //
1468 // C-core API
1469 //
1470
1471 grpc_server* grpc_server_create(const grpc_channel_args* args, void* reserved) {
1472   grpc_core::ExecCtx exec_ctx;
1473   GRPC_API_TRACE("grpc_server_create(%p, %p)", 2, (args, reserved));
1474   grpc_server* c_server = new grpc_server;
1475   c_server->core_server = grpc_core::MakeOrphanable<grpc_core::Server>(args);
1476   return c_server;
1477 }
1478
1479 void grpc_server_register_completion_queue(grpc_server* server,
1480                                            grpc_completion_queue* cq,
1481                                            void* reserved) {
1482   GRPC_API_TRACE(
1483       "grpc_server_register_completion_queue(server=%p, cq=%p, reserved=%p)", 3,
1484       (server, cq, reserved));
1485   GPR_ASSERT(!reserved);
1486   auto cq_type = grpc_get_cq_completion_type(cq);
1487   if (cq_type != GRPC_CQ_NEXT && cq_type != GRPC_CQ_CALLBACK) {
1488     gpr_log(GPR_INFO,
1489             "Completion queue of type %d is being registered as a "
1490             "server-completion-queue",
1491             static_cast<int>(cq_type));
1492     /* Ideally we should log an error and abort but ruby-wrapped-language API
1493        calls grpc_completion_queue_pluck() on server completion queues */
1494   }
1495   server->core_server->RegisterCompletionQueue(cq);
1496 }
1497
1498 void* grpc_server_register_method(
1499     grpc_server* server, const char* method, const char* host,
1500     grpc_server_register_method_payload_handling payload_handling,
1501     uint32_t flags) {
1502   GRPC_API_TRACE(
1503       "grpc_server_register_method(server=%p, method=%s, host=%s, "
1504       "flags=0x%08x)",
1505       4, (server, method, host, flags));
1506   return server->core_server->RegisterMethod(method, host, payload_handling,
1507                                              flags);
1508 }
1509
1510 void grpc_server_start(grpc_server* server) {
1511   grpc_core::ExecCtx exec_ctx;
1512   GRPC_API_TRACE("grpc_server_start(server=%p)", 1, (server));
1513   server->core_server->Start();
1514 }
1515
1516 void grpc_server_shutdown_and_notify(grpc_server* server,
1517                                      grpc_completion_queue* cq, void* tag) {
1518   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1519   grpc_core::ExecCtx exec_ctx;
1520   GRPC_API_TRACE("grpc_server_shutdown_and_notify(server=%p, cq=%p, tag=%p)", 3,
1521                  (server, cq, tag));
1522   server->core_server->ShutdownAndNotify(cq, tag);
1523 }
1524
1525 void grpc_server_cancel_all_calls(grpc_server* server) {
1526   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1527   grpc_core::ExecCtx exec_ctx;
1528   GRPC_API_TRACE("grpc_server_cancel_all_calls(server=%p)", 1, (server));
1529   server->core_server->CancelAllCalls();
1530 }
1531
1532 void grpc_server_destroy(grpc_server* server) {
1533   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1534   grpc_core::ExecCtx exec_ctx;
1535   GRPC_API_TRACE("grpc_server_destroy(server=%p)", 1, (server));
1536   delete server;
1537 }
1538
1539 grpc_call_error grpc_server_request_call(
1540     grpc_server* server, grpc_call** call, grpc_call_details* details,
1541     grpc_metadata_array* request_metadata,
1542     grpc_completion_queue* cq_bound_to_call,
1543     grpc_completion_queue* cq_for_notification, void* tag) {
1544   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1545   grpc_core::ExecCtx exec_ctx;
1546   GRPC_STATS_INC_SERVER_REQUESTED_CALLS();
1547   GRPC_API_TRACE(
1548       "grpc_server_request_call("
1549       "server=%p, call=%p, details=%p, initial_metadata=%p, "
1550       "cq_bound_to_call=%p, cq_for_notification=%p, tag=%p)",
1551       7,
1552       (server, call, details, request_metadata, cq_bound_to_call,
1553        cq_for_notification, tag));
1554   return server->core_server->RequestCall(call, details, request_metadata,
1555                                           cq_bound_to_call, cq_for_notification,
1556                                           tag);
1557 }
1558
1559 grpc_call_error grpc_server_request_registered_call(
1560     grpc_server* server, void* registered_method, grpc_call** call,
1561     gpr_timespec* deadline, grpc_metadata_array* request_metadata,
1562     grpc_byte_buffer** optional_payload,
1563     grpc_completion_queue* cq_bound_to_call,
1564     grpc_completion_queue* cq_for_notification, void* tag_new) {
1565   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1566   grpc_core::ExecCtx exec_ctx;
1567   GRPC_STATS_INC_SERVER_REQUESTED_CALLS();
1568   auto* rm =
1569       static_cast<grpc_core::Server::RegisteredMethod*>(registered_method);
1570   GRPC_API_TRACE(
1571       "grpc_server_request_registered_call("
1572       "server=%p, registered_method=%p, call=%p, deadline=%p, "
1573       "request_metadata=%p, "
1574       "optional_payload=%p, cq_bound_to_call=%p, cq_for_notification=%p, "
1575       "tag=%p)",
1576       9,
1577       (server, registered_method, call, deadline, request_metadata,
1578        optional_payload, cq_bound_to_call, cq_for_notification, tag_new));
1579   return server->core_server->RequestRegisteredCall(
1580       rm, call, deadline, request_metadata, optional_payload, cq_bound_to_call,
1581       cq_for_notification, tag_new);
1582 }
1583
1584 void grpc_server_set_config_fetcher(
1585     grpc_server* server, grpc_server_config_fetcher* server_config_fetcher) {
1586   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1587   grpc_core::ExecCtx exec_ctx;
1588   GRPC_API_TRACE("grpc_server_set_config_fetcher(server=%p, config_fetcher=%p)",
1589                  2, (server, server_config_fetcher));
1590   server->core_server->set_config_fetcher(
1591       std::unique_ptr<grpc_server_config_fetcher>(server_config_fetcher));
1592 }
1593
1594 void grpc_server_config_fetcher_destroy(
1595     grpc_server_config_fetcher* server_config_fetcher) {
1596   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
1597   grpc_core::ExecCtx exec_ctx;
1598   GRPC_API_TRACE("grpc_server_config_fetcher_destroy(config_fetcher=%p)", 1,
1599                  (server_config_fetcher));
1600   delete server_config_fetcher;
1601 }