curl_multi_wait.3: add example

docs/libcurl/curl_multi_wait.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2016, 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
@@ -71,6 +71,48 @@ priority read events such as out of band data.
 .IP CURL_WAIT_POLLOUT
 Bit flag to curl_waitfd.events indicating the socket should poll on write
 events such as the socket being clear to write without blocking.
+.SH EXAMPLE
+.nf
+CURL *easy_handle;
+CURLM *multi_handle;
+
+/* add the individual easy handle */
+curl_multi_add_handle(multi_handle, easy_handle);
+
+do {
+  CURLMcode mc;
+  int numfds;
+
+  mc = curl_multi_perform(multi_handle, &still_running);
+
+  if(mc == CURLM_OK ) {
+    /* wait for activity, timeout or "nothing" */
+    mc = curl_multi_wait(multi_handle, NULL, 0, 1000, &numfds);
+  }
+
+  if(mc != CURLM_OK) {
+    fprintf(stderr, "curl_multi failed, code %d.\n", mc);
+    break;
+  }
+
+  /* 'numfds' being zero means either a timeout or no file descriptors to
+     wait for. Try timeout on first occurrence, then assume no file
+     descriptors and no file descriptors to wait for means wait for 100
+     milliseconds. */
+
+  if(!numfds) {
+    repeats++; /* count number of repeated zero numfds */
+    if(repeats > 1) {
+      WAITMS(100); /* sleep 100 milliseconds */
+    }
+  }
+  else
+    repeats = 0;
+
+} while(still_running);
+
+curl_multi_remove_handle(multi_handle, easy_handle);
+.fi
 .SH RETURN VALUE
 CURLMcode type, general libcurl multi interface error code. See
 \fIlibcurl-errors(3)\fP