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 <grpc/support/port_platform.h>
  
  #include "src/core/lib/surface/channel.h"
  
  #include <string.h>
  
  #include <grpc/support/alloc.h>
  #include <grpc/support/log.h>
  
  #include "src/core/lib/surface/api_trace.h"
  #include "src/core/lib/surface/completion_queue.h"
  
  typedef struct {
    grpc_closure closure;
    void* tag;
    grpc_completion_queue* cq;
    grpc_cq_completion completion_storage;
  } ping_result;
  
  static void ping_destroy(void* arg, grpc_cq_completion* /*storage*/) {
    gpr_free(arg);
  }
  
  static void ping_done(void* arg, grpc_error* error) {
    ping_result* pr = static_cast<ping_result*>(arg);
    grpc_cq_end_op(pr->cq, pr->tag, GRPC_ERROR_REF(error), ping_destroy, pr,
                   &pr->completion_storage);
  }
  
  void grpc_channel_ping(grpc_channel* channel, grpc_completion_queue* cq,
                         void* tag, void* reserved) {
    GRPC_API_TRACE("grpc_channel_ping(channel=%p, cq=%p, tag=%p, reserved=%p)", 4,
                   (channel, cq, tag, reserved));
    grpc_transport_op* op = grpc_make_transport_op(nullptr);
    ping_result* pr = static_cast<ping_result*>(gpr_malloc(sizeof(*pr)));
    grpc_channel_element* top_elem =
        grpc_channel_stack_element(grpc_channel_get_channel_stack(channel), 0);
    grpc_core::ExecCtx exec_ctx;
    GPR_ASSERT(reserved == nullptr);
    pr->tag = tag;
    pr->cq = cq;
    GRPC_CLOSURE_INIT(&pr->closure, ping_done, pr, grpc_schedule_on_exec_ctx);
    op->send_ping.on_ack = &pr->closure;
    op->bind_pollset = grpc_cq_pollset(cq);
    GPR_ASSERT(grpc_cq_begin_op(cq, tag));
    top_elem->filter->start_transport_op(top_elem, op);
  }
  