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        !            22: .TH curl_multi_poll 3 "November 17, 2019" "libcurl 7.70.0" "libcurl Manual"
        !            23: 
        !            24: .SH NAME
        !            25: curl_multi_poll - polls on all easy handles in a multi handle
        !            26: .SH SYNOPSIS
        !            27: .nf
        !            28: #include <curl/curl.h>
        !            29: 
        !            30: CURLMcode curl_multi_poll(CURLM *multi_handle,
        !            31:                           struct curl_waitfd extra_fds[],
        !            32:                           unsigned int extra_nfds,
        !            33:                           int timeout_ms,
        !            34:                           int *numfds);
        !            35: .ad
        !            36: .SH DESCRIPTION
        !            37: \fIcurl_multi_poll(3)\fP polls all file descriptors used by the curl easy
        !            38: handles contained in the given multi handle set.  It will block until activity
        !            39: is detected on at least one of the handles or \fItimeout_ms\fP has passed.
        !            40: Alternatively, if the multi handle has a pending internal timeout that has a
        !            41: shorter expiry time than \fItimeout_ms\fP, that shorter time will be used
        !            42: instead to make sure timeout accuracy is reasonably kept.
        !            43: 
        !            44: The calling application may pass additional curl_waitfd structures which are
        !            45: similar to \fIpoll(2)\fP's pollfd structure to be waited on in the same call.
        !            46: 
        !            47: On completion, if \fInumfds\fP is non-NULL, it will be populated with the
        !            48: total number of file descriptors on which interesting events occurred. This
        !            49: number can include both libcurl internal descriptors as well as descriptors
        !            50: provided in \fIextra_fds\fP.
        !            51: 
        !            52: The \fIcurl_multi_wakeup(3)\fP function can be used from another thread to
        !            53: wake up this function and return faster. This is one of the details
        !            54: that makes this function different than \fIcurl_multi_wait(3)\fP which cannot
        !            55: be woken up this way.
        !            56: 
        !            57: If no extra file descriptors are provided and libcurl has no file descriptor
        !            58: to offer to wait for, this function will instead wait during \fItimeout_ms\fP
        !            59: milliseconds (or shorter if an internal timer indicates so). This is the
        !            60: other detail that makes this function different than
        !            61: \fIcurl_multi_wait(3)\fP.
        !            62: 
        !            63: This function is encouraged to be used instead of select(3) when using the
        !            64: multi interface to allow applications to easier circumvent the common problem
        !            65: with 1024 maximum file descriptors.
        !            66: .SH curl_waitfd
        !            67: .nf
        !            68: struct curl_waitfd {
        !            69:   curl_socket_t fd;
        !            70:   short events;
        !            71:   short revents;
        !            72: };
        !            73: .fi
        !            74: .IP CURL_WAIT_POLLIN
        !            75: Bit flag to curl_waitfd.events indicating the socket should poll on read
        !            76: events such as new data received.
        !            77: .IP CURL_WAIT_POLLPRI
        !            78: Bit flag to curl_waitfd.events indicating the socket should poll on high
        !            79: priority read events such as out of band data.
        !            80: .IP CURL_WAIT_POLLOUT
        !            81: Bit flag to curl_waitfd.events indicating the socket should poll on write
        !            82: events such as the socket being clear to write without blocking.
        !            83: .SH EXAMPLE
        !            84: .nf
        !            85: CURL *easy_handle;
        !            86: CURLM *multi_handle;
        !            87: 
        !            88: /* add the individual easy handle */
        !            89: curl_multi_add_handle(multi_handle, easy_handle);
        !            90: 
        !            91: do {
        !            92:   CURLMcode mc;
        !            93:   int numfds;
        !            94: 
        !            95:   mc = curl_multi_perform(multi_handle, &still_running);
        !            96: 
        !            97:   if(mc == CURLM_OK) {
        !            98:     /* wait for activity or timeout */
        !            99:     mc = curl_multi_poll(multi_handle, NULL, 0, 1000, &numfds);
        !           100:   }
        !           101: 
        !           102:   if(mc != CURLM_OK) {
        !           103:     fprintf(stderr, "curl_multi failed, code %d.\\n", mc);
        !           104:     break;
        !           105:   }
        !           106: 
        !           107: } while(still_running);
        !           108: 
        !           109: curl_multi_remove_handle(multi_handle, easy_handle);
        !           110: .fi
        !           111: .SH RETURN VALUE
        !           112: CURLMcode type, general libcurl multi interface error code. See
        !           113: \fIlibcurl-errors(3)\fP
        !           114: .SH AVAILABILITY
        !           115: This function was added in libcurl 7.66.0.
        !           116: .SH "SEE ALSO"
        !           117: .BR curl_multi_fdset "(3), " curl_multi_perform "(3), "
        !           118: .BR curl_multi_wait "(3), " curl_multi_wakeup "(3)"