text: /*
   *
   * Copyright 2015 gRPC authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   */
  
  #include "test/core/util/reconnect_server.h"
  
  #include <grpc/grpc.h>
  #include <grpc/support/alloc.h>
  #include <grpc/support/log.h>
  #include <grpc/support/string_util.h>
  #include <grpc/support/sync.h>
  #include <grpc/support/time.h>
  #include <string.h>
  
  #include "absl/strings/string_view.h"
  #include "src/core/lib/iomgr/endpoint.h"
  #include "src/core/lib/iomgr/sockaddr.h"
  #include "src/core/lib/iomgr/tcp_server.h"
  #include "test/core/util/port.h"
  #include "test/core/util/test_tcp_server.h"
  
  static void pretty_print_backoffs(reconnect_server* server) {
    gpr_timespec diff;
    int i = 1;
    double expected_backoff = 1000.0, backoff;
    timestamp_list* head = server->head;
    gpr_log(GPR_INFO, "reconnect server: new connection");
    for (head = server->head; head && head->next; head = head->next, i++) {
      diff = gpr_time_sub(head->next->timestamp, head->timestamp);
      backoff = gpr_time_to_millis(diff);
      gpr_log(GPR_INFO,
              "retry %2d:backoff %6.2fs,expected backoff %6.2fs, jitter %4.2f%%",
              i, backoff / 1000.0, expected_backoff / 1000.0,
              (backoff - expected_backoff) * 100.0 / expected_backoff);
      expected_backoff *= 1.6;
      int max_reconnect_backoff_ms = 120 * 1000;
      if (server->max_reconnect_backoff_ms > 0) {
        max_reconnect_backoff_ms = server->max_reconnect_backoff_ms;
      }
      if (expected_backoff > max_reconnect_backoff_ms) {
        expected_backoff = max_reconnect_backoff_ms;
      }
    }
  }
  
  static void on_connect(void* arg, grpc_endpoint* tcp,
                         grpc_pollset* /*accepting_pollset*/,
                         grpc_tcp_server_acceptor* acceptor) {
    gpr_free(acceptor);
    absl::string_view peer;
    absl::string_view::size_type last_colon;
    reconnect_server* server = static_cast<reconnect_server*>(arg);
    gpr_timespec now = gpr_now(GPR_CLOCK_REALTIME);
    timestamp_list* new_tail;
    peer = grpc_endpoint_get_peer(tcp);
    grpc_endpoint_shutdown(tcp,
                           GRPC_ERROR_CREATE_FROM_STATIC_STRING("Connected"));
    grpc_endpoint_destroy(tcp);
    last_colon = peer.rfind(':');
    if (server->peer == nullptr) {
      server->peer = new std::string(peer);
    } else {
      if (last_colon == std::string::npos) {
        gpr_log(GPR_ERROR, "peer does not contain a ':'");
      } else if (peer.compare(0, static_cast<size_t>(last_colon),
                              *server->peer) != 0) {
        gpr_log(GPR_ERROR, "mismatched peer! %s vs %s", server->peer->c_str(),
                std::string(peer).c_str());
      }
    }
    new_tail = static_cast<timestamp_list*>(gpr_malloc(sizeof(timestamp_list)));
    new_tail->timestamp = now;
    new_tail->next = nullptr;
    if (server->tail == nullptr) {
      server->head = new_tail;
      server->tail = new_tail;
    } else {
      server->tail->next = new_tail;
      server->tail = new_tail;
    }
    pretty_print_backoffs(server);
  }
  
  void reconnect_server_init(reconnect_server* server) {
    test_tcp_server_init(&server->tcp_server, on_connect, server);
    server->head = nullptr;
    server->tail = nullptr;
    server->peer = nullptr;
    server->max_reconnect_backoff_ms = 0;
  }
  
  void reconnect_server_start(reconnect_server* server, int port) {
    test_tcp_server_start(&server->tcp_server, port);
  }
  
  void reconnect_server_poll(reconnect_server* server, int seconds) {
    test_tcp_server_poll(&server->tcp_server, 1000 * seconds);
  }
  
  void reconnect_server_clear_timestamps(reconnect_server* server) {
    timestamp_list* new_head = server->head;
    while (server->head) {
      new_head = server->head->next;
      gpr_free(server->head);
      server->head = new_head;
    }
    server->tail = nullptr;
    delete server->peer;
    server->peer = nullptr;
  }
  
  void reconnect_server_destroy(reconnect_server* server) {
    reconnect_server_clear_timestamps(server);
    test_tcp_server_destroy(&server->tcp_server);
  }
  