threaded-shared-conn.c

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 * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
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 * furnished to do so, under the terms of the COPYING file.
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/* <DESC>
 * Multi-threaded transfers sharing a single connection pool
 * </DESC>
 *
 * This example fires up NUM_THREADS threads and in each single thread, it
 * downloads the same fixed URL a URL_ITERATIONS number of times. The received
 * data is just thrown away. It sets up a single shared object that holds the
 * connection cache and all easy handles in all threads share that same cache.
 *
 * This example uses pthreads for threads and mutexes, but should be easy to
 * modify to use different thread/mutex system should you want to.
 *
 */ 
 
#include <stdio.h>
#include <pthread.h>
#include <curl/curl.h>
 
/*
  URL to fetch. If you select HTTPS, you need to use a TLS backend with mutex
  locks taken care of (OpenSSL 1.1.x, NSS, etc) or add SSL mutex callbacks!
*/ 
#define URL "http://localhost/4KB"
 
/* number of threads to fire up in parallel */ 
#define NUM_THREADS 67
 
/* how many times each URL is transferred per thread */ 
#define URL_ITERATIONS 11235
 
static pthread_mutex_t connlock;
 
static size_t write_db(void *ptr, size_t size, size_t nmemb, void *data)
{
  /* not interested in the downloaded bytes, return the size */ 
  (void)ptr;  /* unused */ 
  (void)data; /* unused */ 
  return (size_t)(size * nmemb);
}
 
static void lock_cb(CURL *handle, curl_lock_data data,
                    curl_lock_access access, void *userptr)
{
  (void)access; /* unused */ 
  (void)userptr; /* unused */ 
  (void)handle; /* unused */ 
  (void)data; /* unused */ 
  pthread_mutex_lock(&connlock);
}
 
static void unlock_cb(CURL *handle, curl_lock_data data,
                      void *userptr)
{
  (void)userptr; /* unused */ 
  (void)handle;  /* unused */ 
  (void)data;    /* unused */ 
  pthread_mutex_unlock(&connlock);
}
 
static void init_locks(void)
{
  pthread_mutex_init(&connlock, NULL);
}
 
static void kill_locks(void)
{
  pthread_mutex_destroy(&connlock);
}
 
struct initurl {
  const char *url;
  CURLSH *share;
  int threadno;
};
 
static void *run_thread(void *ptr)
{
  struct initurl *u = (struct initurl *)ptr;
  int i;
 
  for(i = 0; i < URL_ITERATIONS; i++) {
    CURL *curl = curl_easy_init();
    curl_easy_setopt(curl, CURLOPT_URL, u->url);
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 0L);
    curl_easy_setopt(curl, CURLOPT_SHARE, u->share);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_db);
    curl_easy_perform(curl); /* ignores error */ 
    curl_easy_cleanup(curl);
    fprintf(stderr, "Thread %d transfer %d\n", u->threadno, i);
  }
 
  return NULL;
}
 
int main(void)
{
  pthread_t tid[NUM_THREADS];
  int i;
  CURLSH *share;
  struct initurl url[NUM_THREADS];
 
  /* Must initialize libcurl before any threads are started */ 
  curl_global_init(CURL_GLOBAL_ALL);
 
  share = curl_share_init();
  curl_share_setopt(share, CURLSHOPT_LOCKFUNC, lock_cb);
  curl_share_setopt(share, CURLSHOPT_UNLOCKFUNC, unlock_cb);
  curl_share_setopt(share, CURLSHOPT_SHARE, CURL_LOCK_DATA_CONNECT);
 
  init_locks();
 
  for(i = 0; i< NUM_THREADS; i++) {
    int error;
    url[i].url = URL;
    url[i].share = share;
    url[i].threadno = i;
    error = pthread_create(&tid[i], NULL, run_thread, &url[i]);
    if(0 != error)
      fprintf(stderr, "Couldn't run thread number %d, errno %d\n", i, error);
    else
      fprintf(stderr, "Thread %d, gets %s\n", i, URL);
  }
 
  /* now wait for all threads to terminate */ 
  for(i = 0; i< NUM_THREADS; i++) {
    pthread_join(tid[i], NULL);
    fprintf(stderr, "Thread %d terminated\n", i);
  }
 
  kill_locks();
 
  curl_share_cleanup(share);
  curl_global_cleanup();
  return 0;
}