urbit/outside/libuv_0.11/test/benchmark-async-pummel.c

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 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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#include "task.h"
#include "uv.h"

#include <stdio.h>
#include <stdlib.h>

#define NUM_PINGS               (1000 * 1000)
#define ACCESS_ONCE(type, var)  (*(volatile type*) &(var))

static unsigned int callbacks;
static volatile int done;

static const char running[] = "running";
static const char stop[]    = "stop";
static const char stopped[] = "stopped";


static void async_cb(uv_async_t* handle) {
  if (++callbacks == NUM_PINGS) {
    /* Tell the pummel thread to stop. */
    ACCESS_ONCE(const char*, handle->data) = stop;

    /* Wait for for the pummel thread to acknowledge that it has stoppped. */
    while (ACCESS_ONCE(const char*, handle->data) != stopped)
      uv_sleep(0);

    uv_close((uv_handle_t*) handle, NULL);
  }
}


static void pummel(void* arg) {
  uv_async_t* handle = (uv_async_t*) arg;

  while (ACCESS_ONCE(const char*, handle->data) == running)
    uv_async_send(handle);

  /* Acknowledge that we've seen handle->data change. */
  ACCESS_ONCE(const char*, handle->data) = stopped;
}


static int test_async_pummel(int nthreads) {
  uv_thread_t* tids;
  uv_async_t handle;
  uint64_t time;
  int i;

  tids = calloc(nthreads, sizeof(tids[0]));
  ASSERT(tids != NULL);

  ASSERT(0 == uv_async_init(uv_default_loop(), &handle, async_cb));
  ACCESS_ONCE(const char*, handle.data) = running;

  for (i = 0; i < nthreads; i++)
    ASSERT(0 == uv_thread_create(tids + i, pummel, &handle));

  time = uv_hrtime();

  ASSERT(0 == uv_run(uv_default_loop(), UV_RUN_DEFAULT));

  time = uv_hrtime() - time;
  done = 1;

  for (i = 0; i < nthreads; i++)
    ASSERT(0 == uv_thread_join(tids + i));

  printf("async_pummel_%d: %s callbacks in %.2f seconds (%s/sec)\n",
         nthreads,
         fmt(callbacks),
         time / 1e9,
         fmt(callbacks / (time / 1e9)));

  free(tids);

  MAKE_VALGRIND_HAPPY();
  return 0;
}


BENCHMARK_IMPL(async_pummel_1) {
  return test_async_pummel(1);
}


BENCHMARK_IMPL(async_pummel_2) {
  return test_async_pummel(2);
}


BENCHMARK_IMPL(async_pummel_4) {
  return test_async_pummel(4);
}


BENCHMARK_IMPL(async_pummel_8) {
  return test_async_pummel(8);
}