Initial checkin of gRPC to third_party/

third_party/grpc/src/core/surface/server.c

+/*
+ *
+ * Copyright 2015-2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/surface/server.h"
+
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
+#include "src/core/census/grpc_filter.h"
+#include "src/core/channel/channel_args.h"
+#include "src/core/channel/connected_channel.h"
+#include "src/core/iomgr/iomgr.h"
+#include "src/core/support/stack_lockfree.h"
+#include "src/core/support/string.h"
+#include "src/core/surface/api_trace.h"
+#include "src/core/surface/call.h"
+#include "src/core/surface/channel.h"
+#include "src/core/surface/completion_queue.h"
+#include "src/core/surface/init.h"
+#include "src/core/transport/metadata.h"
+#include "src/core/transport/static_metadata.h"
+
+typedef struct listener {
+  void *arg;
+  void (*start)(grpc_exec_ctx *exec_ctx, grpc_server *server, void *arg,
+                grpc_pollset **pollsets, size_t pollset_count);
+  void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_server *server, void *arg,
+                  grpc_closure *closure);
+  struct listener *next;
+  grpc_closure destroy_done;
+} listener;
+
+typedef struct call_data call_data;
+typedef struct channel_data channel_data;
+typedef struct registered_method registered_method;
+
+typedef struct {
+  call_data *next;
+  call_data *prev;
+} call_link;
+
+typedef enum { BATCH_CALL, REGISTERED_CALL } requested_call_type;
+
+typedef struct requested_call {
+  requested_call_type type;
+  void *tag;
+  grpc_server *server;
+  grpc_completion_queue *cq_bound_to_call;
+  grpc_completion_queue *cq_for_notification;
+  grpc_call **call;
+  grpc_cq_completion completion;
+  grpc_metadata_array *initial_metadata;
+  union {
+    struct {
+      grpc_call_details *details;
+    } batch;
+    struct {
+      registered_method *registered_method;
+      gpr_timespec *deadline;
+      grpc_byte_buffer **optional_payload;
+    } registered;
+  } data;
+  grpc_closure publish;
+} requested_call;
+
+typedef struct channel_registered_method {
+  registered_method *server_registered_method;
+  grpc_mdstr *method;
+  grpc_mdstr *host;
+} channel_registered_method;
+
+struct channel_data {
+  grpc_server *server;
+  grpc_connectivity_state connectivity_state;
+  grpc_channel *channel;
+  /* linked list of all channels on a server */
+  channel_data *next;
+  channel_data *prev;
+  channel_registered_method *registered_methods;
+  uint32_t registered_method_slots;
+  uint32_t registered_method_max_probes;
+  grpc_closure finish_destroy_channel_closure;
+  grpc_closure channel_connectivity_changed;
+};
+
+typedef struct shutdown_tag {
+  void *tag;
+  grpc_completion_queue *cq;
+  grpc_cq_completion completion;
+} shutdown_tag;
+
+typedef enum {
+  /* waiting for metadata */
+  NOT_STARTED,
+  /* inital metadata read, not flow controlled in yet */
+  PENDING,
+  /* flow controlled in, on completion queue */
+  ACTIVATED,
+  /* cancelled before being queued */
+  ZOMBIED
+} call_state;
+
+typedef struct request_matcher request_matcher;
+
+struct call_data {
+  grpc_call *call;
+
+  /** protects state */
+  gpr_mu mu_state;
+  /** the current state of a call - see call_state */
+  call_state state;
+
+  grpc_mdstr *path;
+  grpc_mdstr *host;
+  gpr_timespec deadline;
+
+  grpc_completion_queue *cq_new;
+
+  grpc_metadata_batch *recv_initial_metadata;
+  grpc_metadata_array initial_metadata;
+
+  grpc_closure got_initial_metadata;
+  grpc_closure server_on_recv_initial_metadata;
+  grpc_closure kill_zombie_closure;
+  grpc_closure *on_done_recv_initial_metadata;
+
+  call_data *pending_next;
+};
+
+struct request_matcher {
+  call_data *pending_head;
+  call_data *pending_tail;
+  gpr_stack_lockfree *requests;
+};
+
+struct registered_method {
+  char *method;
+  char *host;
+  request_matcher request_matcher;
+  registered_method *next;
+};
+
+typedef struct {
+  grpc_channel **channels;
+  size_t num_channels;
+} channel_broadcaster;
+
+struct grpc_server {
+  size_t channel_filter_count;
+  grpc_channel_filter const **channel_filters;
+  grpc_channel_args *channel_args;
+
+  grpc_completion_queue **cqs;
+  grpc_pollset **pollsets;
+  size_t cq_count;
+
+  /* The two following mutexes control access to server-state
+     mu_global controls access to non-call-related state (e.g., channel state)
+     mu_call controls access to call-related state (e.g., the call lists)
+
+     If they are ever required to be nested, you must lock mu_global
+     before mu_call. This is currently used in shutdown processing
+     (grpc_server_shutdown_and_notify and maybe_finish_shutdown) */
+  gpr_mu mu_global; /* mutex for server and channel state */
+  gpr_mu mu_call;   /* mutex for call-specific state */
+
+  registered_method *registered_methods;
+  request_matcher unregistered_request_matcher;
+  /** free list of available requested_calls indices */
+  gpr_stack_lockfree *request_freelist;
+  /** requested call backing data */
+  requested_call *requested_calls;
+  size_t max_requested_calls;
+
+  gpr_atm shutdown_flag;
+  uint8_t shutdown_published;
+  size_t num_shutdown_tags;
+  shutdown_tag *shutdown_tags;
+
+  channel_data root_channel_data;
+
+  listener *listeners;
+  int listeners_destroyed;
+  gpr_refcount internal_refcount;
+
+  /** when did we print the last shutdown progress message */
+  gpr_timespec last_shutdown_message_time;
+};
+
+#define SERVER_FROM_CALL_ELEM(elem) \
+  (((channel_data *)(elem)->channel_data)->server)
+
+static void begin_call(grpc_exec_ctx *exec_ctx, grpc_server *server,
+                       call_data *calld, requested_call *rc);
+static void fail_call(grpc_exec_ctx *exec_ctx, grpc_server *server,
+                      requested_call *rc);
+/* Before calling maybe_finish_shutdown, we must hold mu_global and not
+   hold mu_call */
+static void maybe_finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_server *server);
+
+/*
+ * channel broadcaster
+ */
+
+/* assumes server locked */
+static void channel_broadcaster_init(grpc_server *s, channel_broadcaster *cb) {
+  channel_data *c;
+  size_t count = 0;
+  for (c = s->root_channel_data.next; c != &s->root_channel_data; c = c->next) {
+    count++;
+  }
+  cb->num_channels = count;
+  cb->channels = gpr_malloc(sizeof(*cb->channels) * cb->num_channels);
+  count = 0;
+  for (c = s->root_channel_data.next; c != &s->root_channel_data; c = c->next) {
+    cb->channels[count++] = c->channel;
+    GRPC_CHANNEL_INTERNAL_REF(c->channel, "broadcast");
+  }
+}
+
+struct shutdown_cleanup_args {
+  grpc_closure closure;
+  gpr_slice slice;
+};
+
+static void shutdown_cleanup(grpc_exec_ctx *exec_ctx, void *arg,
+                             bool iomgr_status_ignored) {
+  struct shutdown_cleanup_args *a = arg;
+  gpr_slice_unref(a->slice);
+  gpr_free(a);
+}
+
+static void send_shutdown(grpc_exec_ctx *exec_ctx, grpc_channel *channel,
+                          int send_goaway, int send_disconnect) {
+  grpc_transport_op op;
+  struct shutdown_cleanup_args *sc;
+  grpc_channel_element *elem;
+
+  memset(&op, 0, sizeof(op));
+  op.send_goaway = send_goaway;
+  sc = gpr_malloc(sizeof(*sc));
+  sc->slice = gpr_slice_from_copied_string("Server shutdown");
+  op.goaway_message = &sc->slice;
+  op.goaway_status = GRPC_STATUS_OK;
+  op.disconnect = send_disconnect;
+  grpc_closure_init(&sc->closure, shutdown_cleanup, sc);
+  op.on_consumed = &sc->closure;
+
+  elem = grpc_channel_stack_element(grpc_channel_get_channel_stack(channel), 0);
+  elem->filter->start_transport_op(exec_ctx, elem, &op);
+}
+
+static void channel_broadcaster_shutdown(grpc_exec_ctx *exec_ctx,
+                                         channel_broadcaster *cb,
+                                         int send_goaway,
+                                         int force_disconnect) {
+  size_t i;
+
+  for (i = 0; i < cb->num_channels; i++) {
+    send_shutdown(exec_ctx, cb->channels[i], send_goaway, force_disconnect);
+    GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, cb->channels[i], "broadcast");
+  }
+  gpr_free(cb->channels);
+}
+
+/*
+ * request_matcher
+ */
+
+static void request_matcher_init(request_matcher *rm, size_t entries) {
+  memset(rm, 0, sizeof(*rm));
+  rm->requests = gpr_stack_lockfree_create(entries);
+}
+
+static void request_matcher_destroy(request_matcher *rm) {
+  GPR_ASSERT(gpr_stack_lockfree_pop(rm->requests) == -1);
+  gpr_stack_lockfree_destroy(rm->requests);
+}
+
+static void kill_zombie(grpc_exec_ctx *exec_ctx, void *elem, bool success) {
+  grpc_call_destroy(grpc_call_from_top_element(elem));
+}
+
+static void request_matcher_zombify_all_pending_calls(grpc_exec_ctx *exec_ctx,
+                                                      request_matcher *rm) {
+  while (rm->pending_head) {
+    call_data *calld = rm->pending_head;
+    rm->pending_head = calld->pending_next;
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ZOMBIED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_closure_init(
+        &calld->kill_zombie_closure, kill_zombie,
+        grpc_call_stack_element(grpc_call_get_call_stack(calld->call), 0));
+    grpc_exec_ctx_enqueue(exec_ctx, &calld->kill_zombie_closure, true, NULL);
+  }
+}
+
+static void request_matcher_kill_requests(grpc_exec_ctx *exec_ctx,
+                                          grpc_server *server,
+                                          request_matcher *rm) {
+  int request_id;
+  while ((request_id = gpr_stack_lockfree_pop(rm->requests)) != -1) {
+    fail_call(exec_ctx, server, &server->requested_calls[request_id]);
+  }
+}
+
+/*
+ * server proper
+ */
+
+static void server_ref(grpc_server *server) {
+  gpr_ref(&server->internal_refcount);
+}
+
+static void server_delete(grpc_exec_ctx *exec_ctx, grpc_server *server) {
+  registered_method *rm;
+  size_t i;
+  grpc_channel_args_destroy(server->channel_args);
+  gpr_mu_destroy(&server->mu_global);
+  gpr_mu_destroy(&server->mu_call);
+  gpr_free((void *)server->channel_filters);
+  while ((rm = server->registered_methods) != NULL) {
+    server->registered_methods = rm->next;
+    request_matcher_destroy(&rm->request_matcher);
+    gpr_free(rm->method);
+    gpr_free(rm->host);
+    gpr_free(rm);
+  }
+  for (i = 0; i < server->cq_count; i++) {
+    GRPC_CQ_INTERNAL_UNREF(server->cqs[i], "server");
+  }
+  request_matcher_destroy(&server->unregistered_request_matcher);
+  gpr_stack_lockfree_destroy(server->request_freelist);
+  gpr_free(server->cqs);
+  gpr_free(server->pollsets);
+  gpr_free(server->shutdown_tags);
+  gpr_free(server->requested_calls);
+  gpr_free(server);
+}
+
+static void server_unref(grpc_exec_ctx *exec_ctx, grpc_server *server) {
+  if (gpr_unref(&server->internal_refcount)) {
+    server_delete(exec_ctx, server);
+  }
+}
+
+static int is_channel_orphaned(channel_data *chand) {
+  return chand->next == chand;
+}
+
+static void orphan_channel(channel_data *chand) {
+  chand->next->prev = chand->prev;
+  chand->prev->next = chand->next;
+  chand->next = chand->prev = chand;
+}
+
+static void finish_destroy_channel(grpc_exec_ctx *exec_ctx, void *cd,
+                                   bool success) {
+  channel_data *chand = cd;
+  grpc_server *server = chand->server;
+  GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, chand->channel, "server");
+  server_unref(exec_ctx, server);
+}
+
+static void destroy_channel(grpc_exec_ctx *exec_ctx, channel_data *chand) {
+  if (is_channel_orphaned(chand)) return;
+  GPR_ASSERT(chand->server != NULL);
+  orphan_channel(chand);
+  server_ref(chand->server);
+  maybe_finish_shutdown(exec_ctx, chand->server);
+  chand->finish_destroy_channel_closure.cb = finish_destroy_channel;
+  chand->finish_destroy_channel_closure.cb_arg = chand;
+
+  grpc_transport_op op;
+  memset(&op, 0, sizeof(op));
+  op.set_accept_stream = true;
+  op.on_consumed = &chand->finish_destroy_channel_closure;
+  grpc_channel_next_op(exec_ctx,
+                       grpc_channel_stack_element(
+                           grpc_channel_get_channel_stack(chand->channel), 0),
+                       &op);
+}
+
+static void finish_start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_server *server,
+                                 grpc_call_element *elem, request_matcher *rm) {
+  call_data *calld = elem->call_data;
+  int request_id;
+
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ZOMBIED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_closure_init(&calld->kill_zombie_closure, kill_zombie, elem);
+    grpc_exec_ctx_enqueue(exec_ctx, &calld->kill_zombie_closure, true, NULL);
+    return;
+  }
+
+  request_id = gpr_stack_lockfree_pop(rm->requests);
+  if (request_id == -1) {
+    gpr_mu_lock(&server->mu_call);
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = PENDING;
+    gpr_mu_unlock(&calld->mu_state);
+    if (rm->pending_head == NULL) {
+      rm->pending_tail = rm->pending_head = calld;
+    } else {
+      rm->pending_tail->pending_next = calld;
+      rm->pending_tail = calld;
+    }
+    calld->pending_next = NULL;
+    gpr_mu_unlock(&server->mu_call);
+  } else {
+    gpr_mu_lock(&calld->mu_state);
+    calld->state = ACTIVATED;
+    gpr_mu_unlock(&calld->mu_state);
+    begin_call(exec_ctx, server, calld, &server->requested_calls[request_id]);
+  }
+}
+
+static void start_new_rpc(grpc_exec_ctx *exec_ctx, grpc_call_element *elem) {
+  channel_data *chand = elem->channel_data;
+  call_data *calld = elem->call_data;
+  grpc_server *server = chand->server;
+  uint32_t i;
+  uint32_t hash;
+  channel_registered_method *rm;
+
+  if (chand->registered_methods && calld->path && calld->host) {
+    /* TODO(ctiller): unify these two searches */
+    /* check for an exact match with host */
+    hash = GRPC_MDSTR_KV_HASH(calld->host->hash, calld->path->hash);
+    for (i = 0; i <= chand->registered_method_max_probes; i++) {
+      rm = &chand->registered_methods[(hash + i) %
+                                      chand->registered_method_slots];
+      if (!rm) break;
+      if (rm->host != calld->host) continue;
+      if (rm->method != calld->path) continue;
+      finish_start_new_rpc(exec_ctx, server, elem,
+                           &rm->server_registered_method->request_matcher);
+      return;
+    }
+    /* check for a wildcard method definition (no host set) */
+    hash = GRPC_MDSTR_KV_HASH(0, calld->path->hash);
+    for (i = 0; i <= chand->registered_method_max_probes; i++) {
+      rm = &chand->registered_methods[(hash + i) %
+                                      chand->registered_method_slots];
+      if (!rm) break;
+      if (rm->host != NULL) continue;
+      if (rm->method != calld->path) continue;
+      finish_start_new_rpc(exec_ctx, server, elem,
+                           &rm->server_registered_method->request_matcher);
+      return;
+    }
+  }
+  finish_start_new_rpc(exec_ctx, server, elem,
+                       &server->unregistered_request_matcher);
+}
+
+static int num_listeners(grpc_server *server) {
+  listener *l;
+  int n = 0;
+  for (l = server->listeners; l; l = l->next) {
+    n++;
+  }
+  return n;
+}
+
+static void done_shutdown_event(grpc_exec_ctx *exec_ctx, void *server,
+                                grpc_cq_completion *completion) {
+  server_unref(exec_ctx, server);
+}
+
+static int num_channels(grpc_server *server) {
+  channel_data *chand;
+  int n = 0;
+  for (chand = server->root_channel_data.next;
+       chand != &server->root_channel_data; chand = chand->next) {
+    n++;
+  }
+  return n;
+}
+
+static void kill_pending_work_locked(grpc_exec_ctx *exec_ctx,
+                                     grpc_server *server) {
+  registered_method *rm;
+  request_matcher_kill_requests(exec_ctx, server,
+                                &server->unregistered_request_matcher);
+  request_matcher_zombify_all_pending_calls(
+      exec_ctx, &server->unregistered_request_matcher);
+  for (rm = server->registered_methods; rm; rm = rm->next) {
+    request_matcher_kill_requests(exec_ctx, server, &rm->request_matcher);
+    request_matcher_zombify_all_pending_calls(exec_ctx, &rm->request_matcher);
+  }
+}
+
+static void maybe_finish_shutdown(grpc_exec_ctx *exec_ctx,
+                                  grpc_server *server) {
+  size_t i;
+  if (!gpr_atm_acq_load(&server->shutdown_flag) || server->shutdown_published) {
+    return;
+  }
+
+  kill_pending_work_locked(exec_ctx, server);
+
+  if (server->root_channel_data.next != &server->root_channel_data ||
+      server->listeners_destroyed < num_listeners(server)) {
+    if (gpr_time_cmp(gpr_time_sub(gpr_now(GPR_CLOCK_REALTIME),
+                                  server->last_shutdown_message_time),
+                     gpr_time_from_seconds(1, GPR_TIMESPAN)) >= 0) {
+      server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
+      gpr_log(GPR_DEBUG,
+              "Waiting for %d channels and %d/%d listeners to be destroyed"
+              " before shutting down server",
+              num_channels(server),
+              num_listeners(server) - server->listeners_destroyed,
+              num_listeners(server));
+    }
+    return;
+  }
+  server->shutdown_published = 1;
+  for (i = 0; i < server->num_shutdown_tags; i++) {
+    server_ref(server);
+    grpc_cq_end_op(exec_ctx, server->shutdown_tags[i].cq,
+                   server->shutdown_tags[i].tag, 1, done_shutdown_event, server,
+                   &server->shutdown_tags[i].completion);
+  }
+}
+
+static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
+  grpc_call_element *elem = user_data;
+  call_data *calld = elem->call_data;
+  if (md->key == GRPC_MDSTR_PATH) {
+    calld->path = GRPC_MDSTR_REF(md->value);
+    return NULL;
+  } else if (md->key == GRPC_MDSTR_AUTHORITY) {
+    calld->host = GRPC_MDSTR_REF(md->value);
+    return NULL;
+  }
+  return md;
+}
+
+static void server_on_recv_initial_metadata(grpc_exec_ctx *exec_ctx, void *ptr,
+                                            bool success) {
+  grpc_call_element *elem = ptr;
+  call_data *calld = elem->call_data;
+  gpr_timespec op_deadline;
+
+  grpc_metadata_batch_filter(calld->recv_initial_metadata, server_filter, elem);
+  op_deadline = calld->recv_initial_metadata->deadline;
+  if (0 != gpr_time_cmp(op_deadline, gpr_inf_future(op_deadline.clock_type))) {
+    calld->deadline = op_deadline;
+  }
+  if (calld->host && calld->path) {
+    /* do nothing */
+  } else {
+    success = 0;
+  }
+
+  calld->on_done_recv_initial_metadata->cb(
+      exec_ctx, calld->on_done_recv_initial_metadata->cb_arg, success);
+}
+
+static void server_mutate_op(grpc_call_element *elem,
+                             grpc_transport_stream_op *op) {
+  call_data *calld = elem->call_data;
+
+  if (op->recv_initial_metadata != NULL) {
+    calld->recv_initial_metadata = op->recv_initial_metadata;
+    calld->on_done_recv_initial_metadata = op->recv_initial_metadata_ready;
+    op->recv_initial_metadata_ready = &calld->server_on_recv_initial_metadata;
+  }
+}
+
+static void server_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
+                                             grpc_call_element *elem,
+                                             grpc_transport_stream_op *op) {
+  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
+  server_mutate_op(elem, op);
+  grpc_call_next_op(exec_ctx, elem, op);
+}
+
+static void got_initial_metadata(grpc_exec_ctx *exec_ctx, void *ptr,
+                                 bool success) {
+  grpc_call_element *elem = ptr;
+  call_data *calld = elem->call_data;
+  if (success) {
+    start_new_rpc(exec_ctx, elem);
+  } else {
+    gpr_mu_lock(&calld->mu_state);
+    if (calld->state == NOT_STARTED) {
+      calld->state = ZOMBIED;
+      gpr_mu_unlock(&calld->mu_state);
+      grpc_closure_init(&calld->kill_zombie_closure, kill_zombie, elem);
+      grpc_exec_ctx_enqueue(exec_ctx, &calld->kill_zombie_closure, true, NULL);
+    } else if (calld->state == PENDING) {
+      calld->state = ZOMBIED;
+      gpr_mu_unlock(&calld->mu_state);
+      /* zombied call will be destroyed when it's removed from the pending
+         queue... later */
+    } else {
+      gpr_mu_unlock(&calld->mu_state);
+    }
+  }
+}
+
+static void accept_stream(grpc_exec_ctx *exec_ctx, void *cd,
+                          grpc_transport *transport,
+                          const void *transport_server_data) {
+  channel_data *chand = cd;
+  /* create a call */
+  grpc_call *call =
+      grpc_call_create(chand->channel, NULL, 0, NULL, transport_server_data,
+                       NULL, 0, gpr_inf_future(GPR_CLOCK_MONOTONIC));
+  grpc_call_element *elem =
+      grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
+  call_data *calld = elem->call_data;
+  grpc_op op;
+  memset(&op, 0, sizeof(op));
+  op.op = GRPC_OP_RECV_INITIAL_METADATA;
+  op.data.recv_initial_metadata = &calld->initial_metadata;
+  grpc_closure_init(&calld->got_initial_metadata, got_initial_metadata, elem);
+  grpc_call_start_batch_and_execute(exec_ctx, call, &op, 1,
+                                    &calld->got_initial_metadata);
+}
+
+static void channel_connectivity_changed(grpc_exec_ctx *exec_ctx, void *cd,
+                                         bool iomgr_status_ignored) {
+  channel_data *chand = cd;
+  grpc_server *server = chand->server;
+  if (chand->connectivity_state != GRPC_CHANNEL_FATAL_FAILURE) {
+    grpc_transport_op op;
+    memset(&op, 0, sizeof(op));
+    op.on_connectivity_state_change = &chand->channel_connectivity_changed,
+    op.connectivity_state = &chand->connectivity_state;
+    grpc_channel_next_op(exec_ctx,
+                         grpc_channel_stack_element(
+                             grpc_channel_get_channel_stack(chand->channel), 0),
+                         &op);
+  } else {
+    gpr_mu_lock(&server->mu_global);
+    destroy_channel(exec_ctx, chand);
+    gpr_mu_unlock(&server->mu_global);
+    GRPC_CHANNEL_INTERNAL_UNREF(exec_ctx, chand->channel, "connectivity");
+  }
+}
+
+static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+                           grpc_call_element_args *args) {
+  call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
+  memset(calld, 0, sizeof(call_data));
+  calld->deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
+  calld->call = grpc_call_from_top_element(elem);
+  gpr_mu_init(&calld->mu_state);
+
+  grpc_closure_init(&calld->server_on_recv_initial_metadata,
+                    server_on_recv_initial_metadata, elem);
+
+  server_ref(chand->server);
+}
+
+static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
+                              grpc_call_element *elem) {
+  channel_data *chand = elem->channel_data;
+  call_data *calld = elem->call_data;
+
+  GPR_ASSERT(calld->state != PENDING);
+
+  if (calld->host) {
+    GRPC_MDSTR_UNREF(calld->host);
+  }
+  if (calld->path) {
+    GRPC_MDSTR_UNREF(calld->path);
+  }
+  grpc_metadata_array_destroy(&calld->initial_metadata);
+
+  gpr_mu_destroy(&calld->mu_state);
+
+  server_unref(exec_ctx, chand->server);
+}
+
+static void init_channel_elem(grpc_exec_ctx *exec_ctx,
+                              grpc_channel_element *elem,
+                              grpc_channel_element_args *args) {
+  channel_data *chand = elem->channel_data;
+  GPR_ASSERT(args->is_first);
+  GPR_ASSERT(!args->is_last);
+  chand->server = NULL;
+  chand->channel = NULL;
+  chand->next = chand->prev = chand;
+  chand->registered_methods = NULL;
+  chand->connectivity_state = GRPC_CHANNEL_IDLE;
+  grpc_closure_init(&chand->channel_connectivity_changed,
+                    channel_connectivity_changed, chand);
+}
+
+static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
+                                 grpc_channel_element *elem) {
+  size_t i;
+  channel_data *chand = elem->channel_data;
+  if (chand->registered_methods) {
+    for (i = 0; i < chand->registered_method_slots; i++) {
+      if (chand->registered_methods[i].method) {
+        GRPC_MDSTR_UNREF(chand->registered_methods[i].method);
+      }
+      if (chand->registered_methods[i].host) {
+        GRPC_MDSTR_UNREF(chand->registered_methods[i].host);
+      }
+    }
+    gpr_free(chand->registered_methods);
+  }
+  if (chand->server) {
+    gpr_mu_lock(&chand->server->mu_global);
+    chand->next->prev = chand->prev;
+    chand->prev->next = chand->next;
+    chand->next = chand->prev = chand;
+    maybe_finish_shutdown(exec_ctx, chand->server);
+    gpr_mu_unlock(&chand->server->mu_global);
+    server_unref(exec_ctx, chand->server);
+  }
+}
+
+static const grpc_channel_filter server_surface_filter = {
+    server_start_transport_stream_op, grpc_channel_next_op, sizeof(call_data),
+    init_call_elem, grpc_call_stack_ignore_set_pollset, destroy_call_elem,
+    sizeof(channel_data), init_channel_elem, destroy_channel_elem,
+    grpc_call_next_get_peer, "server",
+};
+
+void grpc_server_register_completion_queue(grpc_server *server,
+                                           grpc_completion_queue *cq,
+                                           void *reserved) {
+  size_t i, n;
+  GRPC_API_TRACE(
+      "grpc_server_register_completion_queue(server=%p, cq=%p, reserved=%p)", 3,
+      (server, cq, reserved));
+  GPR_ASSERT(!reserved);
+  for (i = 0; i < server->cq_count; i++) {
+    if (server->cqs[i] == cq) return;
+  }
+  GRPC_CQ_INTERNAL_REF(cq, "server");
+  grpc_cq_mark_server_cq(cq);
+  n = server->cq_count++;
+  server->cqs = gpr_realloc(server->cqs,
+                            server->cq_count * sizeof(grpc_completion_queue *));
+  server->cqs[n] = cq;
+}
+
+grpc_server *grpc_server_create_from_filters(
+    const grpc_channel_filter **filters, size_t filter_count,
+    const grpc_channel_args *args) {
+  size_t i;
+  int census_enabled = grpc_channel_args_is_census_enabled(args);
+
+  grpc_server *server = gpr_malloc(sizeof(grpc_server));
+
+  GPR_ASSERT(grpc_is_initialized() && "call grpc_init()");
+
+  memset(server, 0, sizeof(grpc_server));
+
+  gpr_mu_init(&server->mu_global);
+  gpr_mu_init(&server->mu_call);
+
+  /* decremented by grpc_server_destroy */
+  gpr_ref_init(&server->internal_refcount, 1);
+  server->root_channel_data.next = server->root_channel_data.prev =
+      &server->root_channel_data;
+
+  /* TODO(ctiller): expose a channel_arg for this */
+  server->max_requested_calls = 32768;
+  server->request_freelist =
+      gpr_stack_lockfree_create(server->max_requested_calls);
+  for (i = 0; i < (size_t)server->max_requested_calls; i++) {
+    gpr_stack_lockfree_push(server->request_freelist, (int)i);
+  }
+  request_matcher_init(&server->unregistered_request_matcher,
+                       server->max_requested_calls);
+  server->requested_calls = gpr_malloc(server->max_requested_calls *
+                                       sizeof(*server->requested_calls));
+
+  /* Server filter stack is:
+
+     server_surface_filter - for making surface API calls
+     grpc_server_census_filter (optional) - for stats collection and tracing
+     {passed in filter stack}
+     grpc_connected_channel_filter - for interfacing with transports */
+  server->channel_filter_count = filter_count + 1u + (census_enabled ? 1u : 0u);
+  server->channel_filters =
+      gpr_malloc(server->channel_filter_count * sizeof(grpc_channel_filter *));
+  server->channel_filters[0] = &server_surface_filter;
+  if (census_enabled) {
+    server->channel_filters[1] = &grpc_server_census_filter;
+  }
+  for (i = 0; i < filter_count; i++) {
+    server->channel_filters[i + 1u + (census_enabled ? 1u : 0u)] = filters[i];
+  }
+
+  server->channel_args = grpc_channel_args_copy(args);
+
+  return server;
+}
+
+static int streq(const char *a, const char *b) {
+  if (a == NULL && b == NULL) return 1;
+  if (a == NULL) return 0;
+  if (b == NULL) return 0;
+  return 0 == strcmp(a, b);
+}
+
+void *grpc_server_register_method(grpc_server *server, const char *method,
+                                  const char *host) {
+  registered_method *m;
+  GRPC_API_TRACE("grpc_server_register_method(server=%p, method=%s, host=%s)",
+                 3, (server, method, host));
+  if (!method) {
+    gpr_log(GPR_ERROR,
+            "grpc_server_register_method method string cannot be NULL");
+    return NULL;
+  }
+  for (m = server->registered_methods; m; m = m->next) {
+    if (streq(m->method, method) && streq(m->host, host)) {
+      gpr_log(GPR_ERROR, "duplicate registration for %s@%s", method,
+              host ? host : "*");
+      return NULL;
+    }
+  }
+  m = gpr_malloc(sizeof(registered_method));
+  memset(m, 0, sizeof(*m));
+  request_matcher_init(&m->request_matcher, server->max_requested_calls);
+  m->method = gpr_strdup(method);
+  m->host = gpr_strdup(host);
+  m->next = server->registered_methods;
+  server->registered_methods = m;
+  return m;
+}
+
+void grpc_server_start(grpc_server *server) {
+  listener *l;
+  size_t i;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+
+  GRPC_API_TRACE("grpc_server_start(server=%p)", 1, (server));
+
+  server->pollsets = gpr_malloc(sizeof(grpc_pollset *) * server->cq_count);
+  for (i = 0; i < server->cq_count; i++) {
+    server->pollsets[i] = grpc_cq_pollset(server->cqs[i]);
+  }
+
+  for (l = server->listeners; l; l = l->next) {
+    l->start(&exec_ctx, server, l->arg, server->pollsets, server->cq_count);
+  }
+
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+void grpc_server_setup_transport(grpc_exec_ctx *exec_ctx, grpc_server *s,
+                                 grpc_transport *transport,
+                                 grpc_channel_filter const **extra_filters,
+                                 size_t num_extra_filters,
+                                 const grpc_channel_args *args) {
+  size_t num_filters = s->channel_filter_count + num_extra_filters + 1;
+  grpc_channel_filter const **filters =
+      gpr_malloc(sizeof(grpc_channel_filter *) * num_filters);
+  size_t i;
+  size_t num_registered_methods;
+  size_t alloc;
+  registered_method *rm;
+  channel_registered_method *crm;
+  grpc_channel *channel;
+  channel_data *chand;
+  grpc_mdstr *host;
+  grpc_mdstr *method;
+  uint32_t hash;
+  size_t slots;
+  uint32_t probes;
+  uint32_t max_probes = 0;
+  grpc_transport_op op;
+
+  for (i = 0; i < s->channel_filter_count; i++) {
+    filters[i] = s->channel_filters[i];
+  }
+  for (; i < s->channel_filter_count + num_extra_filters; i++) {
+    filters[i] = extra_filters[i - s->channel_filter_count];
+  }
+  filters[i] = &grpc_connected_channel_filter;
+
+  for (i = 0; i < s->cq_count; i++) {
+    memset(&op, 0, sizeof(op));
+    op.bind_pollset = grpc_cq_pollset(s->cqs[i]);
+    grpc_transport_perform_op(exec_ctx, transport, &op);
+  }
+
+  channel = grpc_channel_create_from_filters(exec_ctx, NULL, filters,
+                                             num_filters, args, 0);
+  chand = (channel_data *)grpc_channel_stack_element(
+              grpc_channel_get_channel_stack(channel), 0)->channel_data;
+  chand->server = s;
+  server_ref(s);
+  chand->channel = channel;
+
+  num_registered_methods = 0;
+  for (rm = s->registered_methods; rm; rm = rm->next) {
+    num_registered_methods++;
+  }
+  /* build a lookup table phrased in terms of mdstr's in this channels context
+     to quickly find registered methods */
+  if (num_registered_methods > 0) {
+    slots = 2 * num_registered_methods;
+    alloc = sizeof(channel_registered_method) * slots;
+    chand->registered_methods = gpr_malloc(alloc);
+    memset(chand->registered_methods, 0, alloc);
+    for (rm = s->registered_methods; rm; rm = rm->next) {
+      host = rm->host ? grpc_mdstr_from_string(rm->host) : NULL;
+      method = grpc_mdstr_from_string(rm->method);
+      hash = GRPC_MDSTR_KV_HASH(host ? host->hash : 0, method->hash);
+      for (probes = 0; chand->registered_methods[(hash + probes) % slots]
+                               .server_registered_method != NULL;
+           probes++)
+        ;
+      if (probes > max_probes) max_probes = probes;
+      crm = &chand->registered_methods[(hash + probes) % slots];
+      crm->server_registered_method = rm;
+      crm->host = host;
+      crm->method = method;
+    }
+    GPR_ASSERT(slots <= UINT32_MAX);
+    chand->registered_method_slots = (uint32_t)slots;
+    chand->registered_method_max_probes = max_probes;
+  }
+
+  grpc_connected_channel_bind_transport(grpc_channel_get_channel_stack(channel),
+                                        transport);
+
+  gpr_mu_lock(&s->mu_global);
+  chand->next = &s->root_channel_data;
+  chand->prev = chand->next->prev;
+  chand->next->prev = chand->prev->next = chand;
+  gpr_mu_unlock(&s->mu_global);
+
+  gpr_free((void *)filters);
+
+  GRPC_CHANNEL_INTERNAL_REF(channel, "connectivity");
+  memset(&op, 0, sizeof(op));
+  op.set_accept_stream = true;
+  op.set_accept_stream_fn = accept_stream;
+  op.set_accept_stream_user_data = chand;
+  op.on_connectivity_state_change = &chand->channel_connectivity_changed;
+  op.connectivity_state = &chand->connectivity_state;
+  op.disconnect = gpr_atm_acq_load(&s->shutdown_flag) != 0;
+  grpc_transport_perform_op(exec_ctx, transport, &op);
+}
+
+void done_published_shutdown(grpc_exec_ctx *exec_ctx, void *done_arg,
+                             grpc_cq_completion *storage) {
+  (void)done_arg;
+  gpr_free(storage);
+}
+
+static void listener_destroy_done(grpc_exec_ctx *exec_ctx, void *s,
+                                  bool success) {
+  grpc_server *server = s;
+  gpr_mu_lock(&server->mu_global);
+  server->listeners_destroyed++;
+  maybe_finish_shutdown(exec_ctx, server);
+  gpr_mu_unlock(&server->mu_global);
+}
+
+void grpc_server_shutdown_and_notify(grpc_server *server,
+                                     grpc_completion_queue *cq, void *tag) {
+  listener *l;
+  shutdown_tag *sdt;
+  channel_broadcaster broadcaster;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+
+  GRPC_API_TRACE("grpc_server_shutdown_and_notify(server=%p, cq=%p, tag=%p)", 3,
+                 (server, cq, tag));
+
+  /* lock, and gather up some stuff to do */
+  gpr_mu_lock(&server->mu_global);
+  grpc_cq_begin_op(cq, tag);
+  if (server->shutdown_published) {
+    grpc_cq_end_op(&exec_ctx, cq, tag, 1, done_published_shutdown, NULL,
+                   gpr_malloc(sizeof(grpc_cq_completion)));
+    gpr_mu_unlock(&server->mu_global);
+    goto done;
+  }
+  server->shutdown_tags =
+      gpr_realloc(server->shutdown_tags,
+                  sizeof(shutdown_tag) * (server->num_shutdown_tags + 1));
+  sdt = &server->shutdown_tags[server->num_shutdown_tags++];
+  sdt->tag = tag;
+  sdt->cq = cq;
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    gpr_mu_unlock(&server->mu_global);
+    goto done;
+  }
+
+  server->last_shutdown_message_time = gpr_now(GPR_CLOCK_REALTIME);
+
+  channel_broadcaster_init(server, &broadcaster);
+
+  gpr_atm_rel_store(&server->shutdown_flag, 1);
+
+  /* collect all unregistered then registered calls */
+  gpr_mu_lock(&server->mu_call);
+  kill_pending_work_locked(&exec_ctx, server);
+  gpr_mu_unlock(&server->mu_call);
+
+  maybe_finish_shutdown(&exec_ctx, server);
+  gpr_mu_unlock(&server->mu_global);
+
+  /* Shutdown listeners */
+  for (l = server->listeners; l; l = l->next) {
+    grpc_closure_init(&l->destroy_done, listener_destroy_done, server);
+    l->destroy(&exec_ctx, server, l->arg, &l->destroy_done);
+  }
+
+  channel_broadcaster_shutdown(&exec_ctx, &broadcaster, 1, 0);
+
+done:
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+void grpc_server_cancel_all_calls(grpc_server *server) {
+  channel_broadcaster broadcaster;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+
+  GRPC_API_TRACE("grpc_server_cancel_all_calls(server=%p)", 1, (server));
+
+  gpr_mu_lock(&server->mu_global);
+  channel_broadcaster_init(server, &broadcaster);
+  gpr_mu_unlock(&server->mu_global);
+
+  channel_broadcaster_shutdown(&exec_ctx, &broadcaster, 0, 1);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+void grpc_server_destroy(grpc_server *server) {
+  listener *l;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+
+  GRPC_API_TRACE("grpc_server_destroy(server=%p)", 1, (server));
+
+  gpr_mu_lock(&server->mu_global);
+  GPR_ASSERT(gpr_atm_acq_load(&server->shutdown_flag) || !server->listeners);
+  GPR_ASSERT(server->listeners_destroyed == num_listeners(server));
+
+  while (server->listeners) {
+    l = server->listeners;
+    server->listeners = l->next;
+    gpr_free(l);
+  }
+
+  gpr_mu_unlock(&server->mu_global);
+
+  server_unref(&exec_ctx, server);
+  grpc_exec_ctx_finish(&exec_ctx);
+}
+
+void grpc_server_add_listener(
+    grpc_exec_ctx *exec_ctx, grpc_server *server, void *arg,
+    void (*start)(grpc_exec_ctx *exec_ctx, grpc_server *server, void *arg,
+                  grpc_pollset **pollsets, size_t pollset_count),
+    void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_server *server, void *arg,
+                    grpc_closure *on_done)) {
+  listener *l = gpr_malloc(sizeof(listener));
+  l->arg = arg;
+  l->start = start;
+  l->destroy = destroy;
+  l->next = server->listeners;
+  server->listeners = l;
+}
+
+static grpc_call_error queue_call_request(grpc_exec_ctx *exec_ctx,
+                                          grpc_server *server,
+                                          requested_call *rc) {
+  call_data *calld = NULL;
+  request_matcher *rm = NULL;
+  int request_id;
+  if (gpr_atm_acq_load(&server->shutdown_flag)) {
+    fail_call(exec_ctx, server, rc);
+    return GRPC_CALL_OK;
+  }
+  request_id = gpr_stack_lockfree_pop(server->request_freelist);
+  if (request_id == -1) {
+    /* out of request ids: just fail this one */
+    fail_call(exec_ctx, server, rc);
+    return GRPC_CALL_OK;
+  }
+  switch (rc->type) {
+    case BATCH_CALL:
+      rm = &server->unregistered_request_matcher;
+      break;
+    case REGISTERED_CALL:
+      rm = &rc->data.registered.registered_method->request_matcher;
+      break;
+  }
+  server->requested_calls[request_id] = *rc;
+  gpr_free(rc);
+  if (gpr_stack_lockfree_push(rm->requests, request_id)) {
+    /* this was the first queued request: we need to lock and start
+       matching calls */
+    gpr_mu_lock(&server->mu_call);
+    while ((calld = rm->pending_head) != NULL) {
+      request_id = gpr_stack_lockfree_pop(rm->requests);
+      if (request_id == -1) break;
+      rm->pending_head = calld->pending_next;
+      gpr_mu_unlock(&server->mu_call);
+      gpr_mu_lock(&calld->mu_state);
+      if (calld->state == ZOMBIED) {
+        gpr_mu_unlock(&calld->mu_state);
+        grpc_closure_init(
+            &calld->kill_zombie_closure, kill_zombie,
+            grpc_call_stack_element(grpc_call_get_call_stack(calld->call), 0));
+        grpc_exec_ctx_enqueue(exec_ctx, &calld->kill_zombie_closure, true,
+                              NULL);
+      } else {
+        GPR_ASSERT(calld->state == PENDING);
+        calld->state = ACTIVATED;
+        gpr_mu_unlock(&calld->mu_state);
+        begin_call(exec_ctx, server, calld,
+                   &server->requested_calls[request_id]);
+      }
+      gpr_mu_lock(&server->mu_call);
+    }
+    gpr_mu_unlock(&server->mu_call);
+  }
+  return GRPC_CALL_OK;
+}
+
+grpc_call_error grpc_server_request_call(
+    grpc_server *server, grpc_call **call, grpc_call_details *details,
+    grpc_metadata_array *initial_metadata,
+    grpc_completion_queue *cq_bound_to_call,
+    grpc_completion_queue *cq_for_notification, void *tag) {
+  grpc_call_error error;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  requested_call *rc = gpr_malloc(sizeof(*rc));
+  GRPC_API_TRACE(
+      "grpc_server_request_call("
+      "server=%p, call=%p, details=%p, initial_metadata=%p, "
+      "cq_bound_to_call=%p, cq_for_notification=%p, tag=%p)",
+      7, (server, call, details, initial_metadata, cq_bound_to_call,
+          cq_for_notification, tag));
+  if (!grpc_cq_is_server_cq(cq_for_notification)) {
+    gpr_free(rc);
+    error = GRPC_CALL_ERROR_NOT_SERVER_COMPLETION_QUEUE;
+    goto done;
+  }
+  grpc_cq_begin_op(cq_for_notification, tag);
+  details->reserved = NULL;
+  rc->type = BATCH_CALL;
+  rc->server = server;
+  rc->tag = tag;
+  rc->cq_bound_to_call = cq_bound_to_call;
+  rc->cq_for_notification = cq_for_notification;
+  rc->call = call;
+  rc->data.batch.details = details;
+  rc->initial_metadata = initial_metadata;
+  error = queue_call_request(&exec_ctx, server, rc);
+done:
+  grpc_exec_ctx_finish(&exec_ctx);
+  return error;
+}
+
+grpc_call_error grpc_server_request_registered_call(
+    grpc_server *server, void *rmp, grpc_call **call, gpr_timespec *deadline,
+    grpc_metadata_array *initial_metadata, grpc_byte_buffer **optional_payload,
+    grpc_completion_queue *cq_bound_to_call,
+    grpc_completion_queue *cq_for_notification, void *tag) {
+  grpc_call_error error;
+  grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
+  requested_call *rc = gpr_malloc(sizeof(*rc));
+  registered_method *rm = rmp;
+  GRPC_API_TRACE(
+      "grpc_server_request_registered_call("
+      "server=%p, rmp=%p, call=%p, deadline=%p, initial_metadata=%p, "
+      "optional_payload=%p, cq_bound_to_call=%p, cq_for_notification=%p, "
+      "tag=%p)",
+      9, (server, rmp, call, deadline, initial_metadata, optional_payload,
+          cq_bound_to_call, cq_for_notification, tag));
+  if (!grpc_cq_is_server_cq(cq_for_notification)) {
+    gpr_free(rc);
+    error = GRPC_CALL_ERROR_NOT_SERVER_COMPLETION_QUEUE;
+    goto done;
+  }
+  grpc_cq_begin_op(cq_for_notification, tag);
+  rc->type = REGISTERED_CALL;
+  rc->server = server;
+  rc->tag = tag;
+  rc->cq_bound_to_call = cq_bound_to_call;
+  rc->cq_for_notification = cq_for_notification;
+  rc->call = call;
+  rc->data.registered.registered_method = rm;
+  rc->data.registered.deadline = deadline;
+  rc->initial_metadata = initial_metadata;
+  rc->data.registered.optional_payload = optional_payload;
+  error = queue_call_request(&exec_ctx, server, rc);
+done:
+  grpc_exec_ctx_finish(&exec_ctx);
+  return error;
+}
+
+static void publish_registered_or_batch(grpc_exec_ctx *exec_ctx,
+                                        void *user_data, bool success);
+
+static void cpstr(char **dest, size_t *capacity, grpc_mdstr *value) {
+  gpr_slice slice = value->slice;
+  size_t len = GPR_SLICE_LENGTH(slice);
+
+  if (len + 1 > *capacity) {
+    *capacity = GPR_MAX(len + 1, *capacity * 2);
+    *dest = gpr_realloc(*dest, *capacity);
+  }
+  memcpy(*dest, grpc_mdstr_as_c_string(value), len + 1);
+}
+
+static void begin_call(grpc_exec_ctx *exec_ctx, grpc_server *server,
+                       call_data *calld, requested_call *rc) {
+  grpc_op ops[1];
+  grpc_op *op = ops;
+
+  memset(ops, 0, sizeof(ops));
+
+  /* called once initial metadata has been read by the call, but BEFORE
+     the ioreq to fetch it out of the call has been executed.
+     This means metadata related fields can be relied on in calld, but to
+     fill in the metadata array passed by the client, we need to perform
+     an ioreq op, that should complete immediately. */
+
+  grpc_call_set_completion_queue(exec_ctx, calld->call, rc->cq_bound_to_call);
+  grpc_closure_init(&rc->publish, publish_registered_or_batch, rc);
+  *rc->call = calld->call;
+  calld->cq_new = rc->cq_for_notification;
+  GPR_SWAP(grpc_metadata_array, *rc->initial_metadata, calld->initial_metadata);
+  switch (rc->type) {
+    case BATCH_CALL:
+      GPR_ASSERT(calld->host != NULL);
+      GPR_ASSERT(calld->path != NULL);
+      cpstr(&rc->data.batch.details->host,
+            &rc->data.batch.details->host_capacity, calld->host);
+      cpstr(&rc->data.batch.details->method,
+            &rc->data.batch.details->method_capacity, calld->path);
+      rc->data.batch.details->deadline = calld->deadline;
+      break;
+    case REGISTERED_CALL:
+      *rc->data.registered.deadline = calld->deadline;
+      if (rc->data.registered.optional_payload) {
+        op->op = GRPC_OP_RECV_MESSAGE;
+        op->data.recv_message = rc->data.registered.optional_payload;
+        op++;
+      }
+      break;
+    default:
+      GPR_UNREACHABLE_CODE(return );
+  }
+
+  GRPC_CALL_INTERNAL_REF(calld->call, "server");
+  grpc_call_start_batch_and_execute(exec_ctx, calld->call, ops,
+                                    (size_t)(op - ops), &rc->publish);
+}
+
+static void done_request_event(grpc_exec_ctx *exec_ctx, void *req,
+                               grpc_cq_completion *c) {
+  requested_call *rc = req;
+  grpc_server *server = rc->server;
+
+  if (rc >= server->requested_calls &&
+      rc < server->requested_calls + server->max_requested_calls) {
+    GPR_ASSERT(rc - server->requested_calls <= INT_MAX);
+    gpr_stack_lockfree_push(server->request_freelist,
+                            (int)(rc - server->requested_calls));
+  } else {
+    gpr_free(req);
+  }
+
+  server_unref(exec_ctx, server);
+}
+
+static void fail_call(grpc_exec_ctx *exec_ctx, grpc_server *server,
+                      requested_call *rc) {
+  *rc->call = NULL;
+  rc->initial_metadata->count = 0;
+
+  server_ref(server);
+  grpc_cq_end_op(exec_ctx, rc->cq_for_notification, rc->tag, 0,
+                 done_request_event, rc, &rc->completion);
+}
+
+static void publish_registered_or_batch(grpc_exec_ctx *exec_ctx, void *prc,
+                                        bool success) {
+  requested_call *rc = prc;
+  grpc_call *call = *rc->call;
+  grpc_call_element *elem =
+      grpc_call_stack_element(grpc_call_get_call_stack(call), 0);
+  call_data *calld = elem->call_data;
+  channel_data *chand = elem->channel_data;
+  server_ref(chand->server);
+  grpc_cq_end_op(exec_ctx, calld->cq_new, rc->tag, success, done_request_event,
+                 rc, &rc->completion);
+  GRPC_CALL_INTERNAL_UNREF(exec_ctx, call, "server");
+}
+
+const grpc_channel_args *grpc_server_get_channel_args(grpc_server *server) {
+  return server->channel_args;
+}
+
+int grpc_server_has_open_connections(grpc_server *server) {
+  int r;
+  gpr_mu_lock(&server->mu_global);
+  r = server->root_channel_data.next != &server->root_channel_data;
+  gpr_mu_unlock(&server->mu_global);
+  return r;
+}