quickjs-tart

quickjs-based runtime for wallet-core logic
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curl_multi_wait.md (3223B)

      1 ---
      2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
      3 SPDX-License-Identifier: curl
      4 Title: curl_multi_wait
      5 Section: 3
      6 Source: libcurl
      7 See-also:
      8   - curl_multi_fdset (3)
      9   - curl_multi_perform (3)
     10   - curl_multi_poll (3)
     11 Protocol:
     12   - All
     13 Added-in: 7.28.0
     14 ---
     15 
     16 # NAME
     17 
     18 curl_multi_wait - poll on all easy handles in a multi handle
     19 
     20 # SYNOPSIS
     21 
     22 ~~~c
     23 #include <curl/curl.h>
     24 
     25 CURLMcode curl_multi_wait(CURLM *multi_handle,
     26                           struct curl_waitfd extra_fds[],
     27                           unsigned int extra_nfds,
     28                           int timeout_ms,
     29                           int *numfds);
     30 ~~~
     31 
     32 # DESCRIPTION
     33 
     34 curl_multi_wait(3) polls all file descriptors used by the curl easy
     35 handles contained in the given multi handle set. It blocks until activity is
     36 detected on at least one of the handles or *timeout_ms* has passed.
     37 Alternatively, if the multi handle has a pending internal timeout that has a
     38 shorter expiry time than *timeout_ms*, that shorter time is being used
     39 instead to make sure timeout accuracy is reasonably kept.
     40 
     41 The calling application may pass additional *curl_waitfd* structures which
     42 are similar to *poll(2)*'s *pollfd* structure to be waited on in the
     43 same call.
     44 
     45 On completion, if *numfds* is non-NULL, it gets populated with the total
     46 number of file descriptors on which interesting events occurred. This number
     47 can include both libcurl internal descriptors as well as descriptors provided
     48 in *extra_fds*.
     49 
     50 If no extra file descriptors are provided and libcurl has no file descriptor
     51 to offer to wait for, this function returns immediately. (Consider using
     52 curl_multi_poll(3) to avoid this behavior.)
     53 
     54 This function is encouraged to be used instead of select(3) when using the
     55 multi interface to allow applications to easier circumvent the common problem
     56 with 1024 maximum file descriptors.
     57 
     58 # curl_waitfd
     59 
     60 ~~~c
     61 struct curl_waitfd {
     62   curl_socket_t fd;
     63   short events;
     64   short revents;
     65 };
     66 ~~~
     67 
     68 ## CURL_WAIT_POLLIN
     69 
     70 Bit flag to *curl_waitfd.events* indicating the socket should poll on read
     71 events such as new data received.
     72 
     73 ## CURL_WAIT_POLLPRI
     74 
     75 Bit flag to *curl_waitfd.events* indicating the socket should poll on high
     76 priority read events such as out of band data.
     77 
     78 ## CURL_WAIT_POLLOUT
     79 
     80 Bit flag to *curl_waitfd.events* indicating the socket should poll on
     81 write events such as the socket being clear to write without blocking.
     82 
     83 # %PROTOCOLS%
     84 
     85 # EXAMPLE
     86 
     87 ~~~c
     88 int main(void)
     89 {
     90   CURL *easy;
     91   CURLM *multi = curl_multi_init();
     92   int still_running;
     93 
     94   easy = curl_easy_init();
     95 
     96   /* add the individual easy handle */
     97   curl_multi_add_handle(multi, easy);
     98 
     99   do {
    100     CURLMcode mc;
    101     int numfds;
    102 
    103     mc = curl_multi_perform(multi, &still_running);
    104 
    105     if(mc == CURLM_OK) {
    106       /* wait for activity, timeout or "nothing" */
    107       mc = curl_multi_wait(multi, NULL, 0, 1000, &numfds);
    108     }
    109 
    110     if(mc != CURLM_OK) {
    111       fprintf(stderr, "curl_multi failed, code %d.\n", mc);
    112       break;
    113     }
    114 
    115   } while(still_running);
    116 
    117   curl_multi_remove_handle(multi, easy);
    118 }
    119 ~~~
    120 
    121 # %AVAILABILITY%
    122 
    123 # RETURN VALUE
    124 
    125 This function returns a CURLMcode indicating success or error.
    126 
    127 CURLM_OK (0) means everything was OK, non-zero means an error occurred, see
    128 libcurl-errors(3).