curl_multi_wait implementation

(based on andelf#69 in @andelf repo)

Signed-off-by: Vadim A. Misbakh-Soloviov <[email protected]>

Author: msva

examples/multi_and_wait.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+	"github.com/msva/go-curl"
+	"time"
+)
+
+func main() {
+	ch1 := curl.EasyInit()
+	ch2 := curl.EasyInit()
+
+	ch1.Setopt(curl.OPT_URL, "http://www.google.com")
+	ch1.Setopt(curl.OPT_HEADER, 1)
+	ch1.Setopt(curl.OPT_VERBOSE, true)
+	ch2.Setopt(curl.OPT_URL, "http://www.microsoft.com")
+	ch2.Setopt(curl.OPT_HEADER, 1)
+	ch2.Setopt(curl.OPT_VERBOSE, true)
+
+	mh := curl.MultiInit()
+
+	mh.AddHandle(ch1)
+	mh.AddHandle(ch2)
+
+	var repeats int
+
+	for {
+		stillRunning, err := mh.Perform()
+		if err != nil {
+			fmt.Printf("Error perform: %s\n", err)
+			break
+		} else if stillRunning > 0 {
+			fmt.Printf("Still running: %d\n", stillRunning)
+		} else {
+			break
+		}
+
+		timeoutMs := 1000
+		curlTimeout, err := mh.Timeout()
+		if err != nil {
+			fmt.Printf("Error multi_timeout: %s\n", err)
+		}
+		if curlTimeout >= 0 {
+			timeoutMs = curlTimeout
+		}
+
+		numFds, err := mh.Wait(timeoutMs)
+		if err != nil {
+			fmt.Printf("Error wait: %s\n", err)
+			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, which means wait for 100 milliseconds to prevent spinning
+		// in Perform + Wait.
+		if numFds == 0 {
+			repeats++ // count number of repeated zero numFds
+			if repeats > 1 {
+				time.Sleep(100 * time.Millisecond)
+			}
+		} else {
+			repeats = 0
+		}
+	}
+}

multi.go

@@ -96,6 +96,14 @@ func (mcurl *CURLM) Perform() (int, error) {
 	return int(running_handles), err
 }
 
+// curl_multi_wait - polls on all easy handles in a multi handle
+func (mcurl *CURLM) Wait(timeoutMs int) (int, error) {
+	p := mcurl.handle
+	handles_with_events := C.int(0)
+	err := newCurlMultiError(C.curl_multi_wait(p, nil, 0, C.int(timeoutMs), &handles_with_events))
+	return int(handles_with_events), err
+}
+
 // curl_multi_add_handle - add an easy handle to a multi session
 func (mcurl *CURLM) AddHandle(easy *CURL) error {
 	mp := mcurl.handle