Annotation of embedaddon/curl/docs/examples/multi-event.c, revision 1.1.1.1

1.1       misho       1: /***************************************************************************
                      2:  *                                  _   _ ____  _
                      3:  *  Project                     ___| | | |  _ \| |
                      4:  *                             / __| | | | |_) | |
                      5:  *                            | (__| |_| |  _ <| |___
                      6:  *                             \___|\___/|_| \_\_____|
                      7:  *
                      8:  * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
                      9:  *
                     10:  * This software is licensed as described in the file COPYING, which
                     11:  * you should have received as part of this distribution. The terms
                     12:  * are also available at https://curl.haxx.se/docs/copyright.html.
                     13:  *
                     14:  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
                     15:  * copies of the Software, and permit persons to whom the Software is
                     16:  * furnished to do so, under the terms of the COPYING file.
                     17:  *
                     18:  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
                     19:  * KIND, either express or implied.
                     20:  *
                     21:  ***************************************************************************/
                     22: 
                     23: /* <DESC>
                     24:  * multi_socket API using libevent
                     25:  * </DESC>
                     26:  */
                     27: 
                     28: #include <stdio.h>
                     29: #include <stdlib.h>
                     30: #include <event2/event.h>
                     31: #include <curl/curl.h>
                     32: 
                     33: struct event_base *base;
                     34: CURLM *curl_handle;
                     35: struct event *timeout;
                     36: 
                     37: typedef struct curl_context_s {
                     38:   struct event *event;
                     39:   curl_socket_t sockfd;
                     40: } curl_context_t;
                     41: 
                     42: static void curl_perform(int fd, short event, void *arg);
                     43: 
                     44: static curl_context_t* create_curl_context(curl_socket_t sockfd)
                     45: {
                     46:   curl_context_t *context;
                     47: 
                     48:   context = (curl_context_t *) malloc(sizeof(*context));
                     49: 
                     50:   context->sockfd = sockfd;
                     51: 
                     52:   context->event = event_new(base, sockfd, 0, curl_perform, context);
                     53: 
                     54:   return context;
                     55: }
                     56: 
                     57: static void destroy_curl_context(curl_context_t *context)
                     58: {
                     59:   event_del(context->event);
                     60:   event_free(context->event);
                     61:   free(context);
                     62: }
                     63: 
                     64: static void add_download(const char *url, int num)
                     65: {
                     66:   char filename[50];
                     67:   FILE *file;
                     68:   CURL *handle;
                     69: 
                     70:   snprintf(filename, 50, "%d.download", num);
                     71: 
                     72:   file = fopen(filename, "wb");
                     73:   if(!file) {
                     74:     fprintf(stderr, "Error opening %s\n", filename);
                     75:     return;
                     76:   }
                     77: 
                     78:   handle = curl_easy_init();
                     79:   curl_easy_setopt(handle, CURLOPT_WRITEDATA, file);
                     80:   curl_easy_setopt(handle, CURLOPT_PRIVATE, file);
                     81:   curl_easy_setopt(handle, CURLOPT_URL, url);
                     82:   curl_multi_add_handle(curl_handle, handle);
                     83:   fprintf(stderr, "Added download %s -> %s\n", url, filename);
                     84: }
                     85: 
                     86: static void check_multi_info(void)
                     87: {
                     88:   char *done_url;
                     89:   CURLMsg *message;
                     90:   int pending;
                     91:   CURL *easy_handle;
                     92:   FILE *file;
                     93: 
                     94:   while((message = curl_multi_info_read(curl_handle, &pending))) {
                     95:     switch(message->msg) {
                     96:     case CURLMSG_DONE:
                     97:       /* Do not use message data after calling curl_multi_remove_handle() and
                     98:          curl_easy_cleanup(). As per curl_multi_info_read() docs:
                     99:          "WARNING: The data the returned pointer points to will not survive
                    100:          calling curl_multi_cleanup, curl_multi_remove_handle or
                    101:          curl_easy_cleanup." */
                    102:       easy_handle = message->easy_handle;
                    103: 
                    104:       curl_easy_getinfo(easy_handle, CURLINFO_EFFECTIVE_URL, &done_url);
                    105:       curl_easy_getinfo(easy_handle, CURLINFO_PRIVATE, &file);
                    106:       printf("%s DONE\n", done_url);
                    107: 
                    108:       curl_multi_remove_handle(curl_handle, easy_handle);
                    109:       curl_easy_cleanup(easy_handle);
                    110:       if(file) {
                    111:         fclose(file);
                    112:       }
                    113:       break;
                    114: 
                    115:     default:
                    116:       fprintf(stderr, "CURLMSG default\n");
                    117:       break;
                    118:     }
                    119:   }
                    120: }
                    121: 
                    122: static void curl_perform(int fd, short event, void *arg)
                    123: {
                    124:   int running_handles;
                    125:   int flags = 0;
                    126:   curl_context_t *context;
                    127: 
                    128:   if(event & EV_READ)
                    129:     flags |= CURL_CSELECT_IN;
                    130:   if(event & EV_WRITE)
                    131:     flags |= CURL_CSELECT_OUT;
                    132: 
                    133:   context = (curl_context_t *) arg;
                    134: 
                    135:   curl_multi_socket_action(curl_handle, context->sockfd, flags,
                    136:                            &running_handles);
                    137: 
                    138:   check_multi_info();
                    139: }
                    140: 
                    141: static void on_timeout(evutil_socket_t fd, short events, void *arg)
                    142: {
                    143:   int running_handles;
                    144:   curl_multi_socket_action(curl_handle, CURL_SOCKET_TIMEOUT, 0,
                    145:                            &running_handles);
                    146:   check_multi_info();
                    147: }
                    148: 
                    149: static int start_timeout(CURLM *multi, long timeout_ms, void *userp)
                    150: {
                    151:   if(timeout_ms < 0) {
                    152:     evtimer_del(timeout);
                    153:   }
                    154:   else {
                    155:     if(timeout_ms == 0)
                    156:       timeout_ms = 1; /* 0 means directly call socket_action, but we'll do it
                    157:                          in a bit */
                    158:     struct timeval tv;
                    159:     tv.tv_sec = timeout_ms / 1000;
                    160:     tv.tv_usec = (timeout_ms % 1000) * 1000;
                    161:     evtimer_del(timeout);
                    162:     evtimer_add(timeout, &tv);
                    163:   }
                    164:   return 0;
                    165: }
                    166: 
                    167: static int handle_socket(CURL *easy, curl_socket_t s, int action, void *userp,
                    168:                   void *socketp)
                    169: {
                    170:   curl_context_t *curl_context;
                    171:   int events = 0;
                    172: 
                    173:   switch(action) {
                    174:   case CURL_POLL_IN:
                    175:   case CURL_POLL_OUT:
                    176:   case CURL_POLL_INOUT:
                    177:     curl_context = socketp ?
                    178:       (curl_context_t *) socketp : create_curl_context(s);
                    179: 
                    180:     curl_multi_assign(curl_handle, s, (void *) curl_context);
                    181: 
                    182:     if(action != CURL_POLL_IN)
                    183:       events |= EV_WRITE;
                    184:     if(action != CURL_POLL_OUT)
                    185:       events |= EV_READ;
                    186: 
                    187:     events |= EV_PERSIST;
                    188: 
                    189:     event_del(curl_context->event);
                    190:     event_assign(curl_context->event, base, curl_context->sockfd, events,
                    191:       curl_perform, curl_context);
                    192:     event_add(curl_context->event, NULL);
                    193: 
                    194:     break;
                    195:   case CURL_POLL_REMOVE:
                    196:     if(socketp) {
                    197:       event_del(((curl_context_t*) socketp)->event);
                    198:       destroy_curl_context((curl_context_t*) socketp);
                    199:       curl_multi_assign(curl_handle, s, NULL);
                    200:     }
                    201:     break;
                    202:   default:
                    203:     abort();
                    204:   }
                    205: 
                    206:   return 0;
                    207: }
                    208: 
                    209: int main(int argc, char **argv)
                    210: {
                    211:   if(argc <= 1)
                    212:     return 0;
                    213: 
                    214:   if(curl_global_init(CURL_GLOBAL_ALL)) {
                    215:     fprintf(stderr, "Could not init curl\n");
                    216:     return 1;
                    217:   }
                    218: 
                    219:   base = event_base_new();
                    220:   timeout = evtimer_new(base, on_timeout, NULL);
                    221: 
                    222:   curl_handle = curl_multi_init();
                    223:   curl_multi_setopt(curl_handle, CURLMOPT_SOCKETFUNCTION, handle_socket);
                    224:   curl_multi_setopt(curl_handle, CURLMOPT_TIMERFUNCTION, start_timeout);
                    225: 
                    226:   while(argc-- > 1) {
                    227:     add_download(argv[argc], argc);
                    228:   }
                    229: 
                    230:   event_base_dispatch(base);
                    231: 
                    232:   curl_multi_cleanup(curl_handle);
                    233:   event_free(timeout);
                    234:   event_base_free(base);
                    235: 
                    236:   libevent_global_shutdown();
                    237:   curl_global_cleanup();
                    238: 
                    239:   return 0;
                    240: }

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