quickjs-tart

quickjs-based runtime for wallet-core logic
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curl_multi_info_read.md (2971B)

      1 ---
      2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
      3 SPDX-License-Identifier: curl
      4 Title: curl_multi_info_read
      5 Section: 3
      6 Source: libcurl
      7 See-also:
      8   - curl_multi_cleanup (3)
      9   - curl_multi_init (3)
     10   - curl_multi_perform (3)
     11 Protocol:
     12   - All
     13 Added-in: 7.9.6
     14 ---
     15 
     16 # NAME
     17 
     18 curl_multi_info_read - read multi stack information
     19 
     20 # SYNOPSIS
     21 
     22 ~~~c
     23 #include <curl/curl.h>
     24 
     25 CURLMsg *curl_multi_info_read(CURLM *multi_handle, int *msgs_in_queue);
     26 ~~~
     27 
     28 # DESCRIPTION
     29 
     30 Ask the multi handle if there are any messages from the individual
     31 transfers. Messages may include information such as an error code from the
     32 transfer or just the fact that a transfer is completed. More details on these
     33 should be written down as well.
     34 
     35 Repeated calls to this function returns a new struct each time, until a NULL
     36 is returned as a signal that there is no more to get at this point. The
     37 integer pointed to with *msgs_in_queue* contains the number of remaining
     38 messages after this function was called.
     39 
     40 When you fetch a message using this function, it is removed from the internal
     41 queue so calling this function again does not return the same message
     42 again. It instead returns new messages at each new invoke until the queue is
     43 emptied.
     44 
     45 **WARNING:** The data the returned pointer points to does not survive
     46 calling curl_multi_cleanup(3), curl_multi_remove_handle(3) or
     47 curl_easy_cleanup(3).
     48 
     49 The *CURLMsg* struct is simple and only contains basic information. If
     50 more involved information is wanted, the particular "easy handle" is present
     51 in that struct and can be used in subsequent regular
     52 curl_easy_getinfo(3) calls (or similar):
     53 
     54 ~~~c
     55  struct CURLMsg {
     56    CURLMSG msg;       /* what this message means */
     57    CURL *easy_handle; /* the handle it concerns */
     58    union {
     59      void *whatever;    /* message-specific data */
     60      CURLcode result;   /* return code for transfer */
     61    } data;
     62  };
     63 ~~~
     64 When **msg** is *CURLMSG_DONE*, the message identifies a transfer that
     65 is done, and then **result** contains the return code for the easy handle
     66 that just completed.
     67 
     68 At this point, there are no other **msg** types defined.
     69 
     70 # %PROTOCOLS%
     71 
     72 # EXAMPLE
     73 
     74 ~~~c
     75 int main(void)
     76 {
     77   CURLM *multi = curl_multi_init();
     78   CURL *curl = curl_easy_init();
     79   if(curl) {
     80     struct CURLMsg *m;
     81 
     82     /* call curl_multi_perform or curl_multi_socket_action first, then loop
     83        through and check if there are any transfers that have completed */
     84 
     85     do {
     86       int msgq = 0;
     87       m = curl_multi_info_read(multi, &msgq);
     88       if(m && (m->msg == CURLMSG_DONE)) {
     89         CURL *e = m->easy_handle;
     90         /* m->data.result holds the error code for the transfer */
     91         curl_multi_remove_handle(multi, e);
     92         curl_easy_cleanup(e);
     93       }
     94     } while(m);
     95   }
     96 }
     97 ~~~
     98 
     99 # %AVAILABILITY%
    100 
    101 # RETURN VALUE
    102 
    103 A pointer to a filled-in struct, or NULL if it failed or ran out of structs.
    104 It also writes the number of messages left in the queue (after this read) in
    105 the integer the second argument points to.