curl/docs/examples/multi-uv.c

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/* <DESC>
 * multi_socket API using libuv
 * </DESC>
 */
/* Example application code using the multi socket interface to download
   multiple files at once, but instead of using curl_multi_perform and
   curl_multi_wait, which uses select(), we use libuv.
   It supports epoll, kqueue, etc. on unixes and fast IO completion ports on
   Windows, which means, it should be very fast on all platforms..

   Written by Clemens Gruber, based on an outdated example from uvbook and
   some tests from libuv.

   Requires libuv and (of course) libcurl.

   See http://nikhilm.github.com/uvbook/ for more information on libuv.
*/

#include <stdio.h>
#include <stdlib.h>
#include <uv.h>
#include <curl/curl.h>

uv_loop_t *loop;
CURLM *curl_handle;
uv_timer_t timeout;

typedef struct curl_context_s {
  uv_poll_t poll_handle;
  curl_socket_t sockfd;
} curl_context_t;

curl_context_t* create_curl_context(curl_socket_t sockfd)
{
  curl_context_t *context;

  context = (curl_context_t *) malloc(sizeof *context);

  context->sockfd = sockfd;

  uv_poll_init_socket(loop, &context->poll_handle, sockfd);
  context->poll_handle.data = context;

  return context;
}

void curl_close_cb(uv_handle_t *handle)
{
  curl_context_t *context = (curl_context_t *) handle->data;
  free(context);
}

void destroy_curl_context(curl_context_t *context)
{
  uv_close((uv_handle_t *) &context->poll_handle, curl_close_cb);
}

void add_download(const char *url, int num)
{
  char filename[50];
  FILE *file;
  CURL *handle;

  snprintf(filename, 50, "%d.download", num);

  file = fopen(filename, "wb");
  if(!file) {
    fprintf(stderr, "Error opening %s\n", filename);
    return;
  }

  handle = curl_easy_init();
  curl_easy_setopt(handle, CURLOPT_WRITEDATA, file);
  curl_easy_setopt(handle, CURLOPT_PRIVATE, file);
  curl_easy_setopt(handle, CURLOPT_URL, url);
  curl_multi_add_handle(curl_handle, handle);
  fprintf(stderr, "Added download %s -> %s\n", url, filename);
}

static void check_multi_info(void)
{
  char *done_url;
  CURLMsg *message;
  int pending;
  CURL *easy_handle;
  FILE *file;

  while((message = curl_multi_info_read(curl_handle, &pending))) {
    switch(message->msg) {
    case CURLMSG_DONE:
      /* Do not use message data after calling curl_multi_remove_handle() and
         curl_easy_cleanup(). As per curl_multi_info_read() docs:
         "WARNING: The data the returned pointer points to will not survive
         calling curl_multi_cleanup, curl_multi_remove_handle or
         curl_easy_cleanup." */
      easy_handle = message->easy_handle;

      curl_easy_getinfo(easy_handle, CURLINFO_EFFECTIVE_URL, &done_url);
      curl_easy_getinfo(easy_handle, CURLINFO_PRIVATE, &file);
      printf("%s DONE\n", done_url);

      curl_multi_remove_handle(curl_handle, easy_handle);
      curl_easy_cleanup(easy_handle);
      if(file) {
        fclose(file);
      }
      break;

    default:
      fprintf(stderr, "CURLMSG default\n");
      break;
    }
  }
}

void curl_perform(uv_poll_t *req, int status, int events)
{
  int running_handles;
  int flags = 0;
  curl_context_t *context;

  uv_timer_stop(&timeout);

  if(events & UV_READABLE)
    flags |= CURL_CSELECT_IN;
  if(events & UV_WRITABLE)
    flags |= CURL_CSELECT_OUT;

  context = (curl_context_t *) req->data;

  curl_multi_socket_action(curl_handle, context->sockfd, flags,
                           &running_handles);

  check_multi_info();
}

void on_timeout(uv_timer_t *req, int status)
{
  int running_handles;
  curl_multi_socket_action(curl_handle, CURL_SOCKET_TIMEOUT, 0,
                           &running_handles);
  check_multi_info();
}

void start_timeout(CURLM *multi, long timeout_ms, void *userp)
{
  if(timeout_ms <= 0)
    timeout_ms = 1; /* 0 means directly call socket_action, but we'll do it in
                       a bit */
  uv_timer_start(&timeout, on_timeout, timeout_ms, 0);
}

int handle_socket(CURL *easy, curl_socket_t s, int action, void *userp,
                  void *socketp)
{
  curl_context_t *curl_context;
  if(action == CURL_POLL_IN || action == CURL_POLL_OUT) {
    if(socketp) {
      curl_context = (curl_context_t *) socketp;
    }
    else {
      curl_context = create_curl_context(s);
    }
    curl_multi_assign(curl_handle, s, (void *) curl_context);
  }

  switch(action) {
  case CURL_POLL_IN:
    uv_poll_start(&curl_context->poll_handle, UV_READABLE, curl_perform);
    break;
  case CURL_POLL_OUT:
    uv_poll_start(&curl_context->poll_handle, UV_WRITABLE, curl_perform);
    break;
  case CURL_POLL_REMOVE:
    if(socketp) {
      uv_poll_stop(&((curl_context_t*)socketp)->poll_handle);
      destroy_curl_context((curl_context_t*) socketp);
      curl_multi_assign(curl_handle, s, NULL);
    }
    break;
  default:
    abort();
  }

  return 0;
}

int main(int argc, char **argv)
{
  loop = uv_default_loop();

  if(argc <= 1)
    return 0;

  if(curl_global_init(CURL_GLOBAL_ALL)) {
    fprintf(stderr, "Could not init cURL\n");
    return 1;
  }

  uv_timer_init(loop, &timeout);

  curl_handle = curl_multi_init();
  curl_multi_setopt(curl_handle, CURLMOPT_SOCKETFUNCTION, handle_socket);
  curl_multi_setopt(curl_handle, CURLMOPT_TIMERFUNCTION, start_timeout);

  while(argc-- > 1) {
    add_download(argv[argc], argc);
  }

  uv_run(loop, UV_RUN_DEFAULT);
  curl_multi_cleanup(curl_handle);

  return 0;
}