/*
 *
 * Copyright 2017, Google Inc.
 * All rights reserved.
 *
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 * 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,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */

#include <benchmark/benchmark.h>
#include <string.h>
#include <atomic>

#include <grpc/grpc.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include "test/cpp/microbenchmarks/helpers.h"

extern "C" {
#include "src/core/lib/iomgr/ev_posix.h"
#include "src/core/lib/iomgr/port.h"
#include "src/core/lib/surface/completion_queue.h"
}

struct grpc_pollset {
  gpr_mu mu;
};

namespace grpc {
namespace testing {

static void* g_tag = (void*)(intptr_t)10;  // Some random number
static grpc_completion_queue* g_cq;
static grpc_event_engine_vtable g_vtable;

static void pollset_shutdown(grpc_exec_ctx* exec_ctx, grpc_pollset* ps,
                             grpc_closure* closure) {
  grpc_closure_sched(exec_ctx, closure, GRPC_ERROR_NONE);
}

static void pollset_init(grpc_pollset* ps, gpr_mu** mu) {
  gpr_mu_init(&ps->mu);
  *mu = &ps->mu;
}

static void pollset_destroy(grpc_pollset* ps) { gpr_mu_destroy(&ps->mu); }

static grpc_error* pollset_kick(grpc_pollset* p, grpc_pollset_worker* worker) {
  return GRPC_ERROR_NONE;
}

/* Callback when the tag is dequeued from the completion queue. Does nothing */
static void cq_done_cb(grpc_exec_ctx* exec_ctx, void* done_arg,
                       grpc_cq_completion* cq_completion) {
  gpr_free(cq_completion);
}

/* Queues a completion tag. ZERO polling overhead */
static grpc_error* pollset_work(grpc_exec_ctx* exec_ctx, grpc_pollset* ps,
                                grpc_pollset_worker** worker, gpr_timespec now,
                                gpr_timespec deadline) {
  gpr_mu_unlock(&ps->mu);
  grpc_cq_begin_op(g_cq, g_tag);
  grpc_cq_end_op(exec_ctx, g_cq, g_tag, GRPC_ERROR_NONE, cq_done_cb, NULL,
                 (grpc_cq_completion*)gpr_malloc(sizeof(grpc_cq_completion)));
  grpc_exec_ctx_flush(exec_ctx);
  gpr_mu_lock(&ps->mu);
  return GRPC_ERROR_NONE;
}

static void init_engine_vtable() {
  memset(&g_vtable, 0, sizeof(g_vtable));

  g_vtable.pollset_size = sizeof(grpc_pollset);
  g_vtable.pollset_init = pollset_init;
  g_vtable.pollset_shutdown = pollset_shutdown;
  g_vtable.pollset_destroy = pollset_destroy;
  g_vtable.pollset_work = pollset_work;
  g_vtable.pollset_kick = pollset_kick;
}

static void setup() {
  grpc_init();
  init_engine_vtable();
  grpc_set_event_engine_test_only(&g_vtable);

  g_cq = grpc_completion_queue_create_for_next(NULL);
}

static void teardown() {
  grpc_completion_queue_shutdown(g_cq);
  grpc_completion_queue_destroy(g_cq);
}

/* A few notes about Multi-threaded benchmarks:

 Setup:
  The benchmark framework ensures that none of the threads proceed beyond the
  state.KeepRunning() call unless all the threads have called state.keepRunning
  atleast once.  So it is safe to do the initialization in one of the threads
  before state.KeepRunning() is called.

 Teardown:
  The benchmark framework also ensures that no thread is running the benchmark
  code (i.e the code between two successive calls of state.KeepRunning()) if
  state.KeepRunning() returns false. So it is safe to do the teardown in one
  of the threads after state.keepRunning() returns false.
*/
static void BM_Cq_Throughput(benchmark::State& state) {
  TrackCounters track_counters;
  gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_MONOTONIC);

  if (state.thread_index == 0) {
    setup();
  }

  while (state.KeepRunning()) {
    GPR_ASSERT(grpc_completion_queue_next(g_cq, deadline, NULL).type ==
               GRPC_OP_COMPLETE);
  }

  state.SetItemsProcessed(state.iterations());

  if (state.thread_index == 0) {
    teardown();
  }

  track_counters.Finish(state);
}

BENCHMARK(BM_Cq_Throughput)->ThreadRange(1, 16)->UseRealTime();

}  // namespace testing
}  // namespace grpc

BENCHMARK_MAIN();