[PATCH] http.c: Use curl_multi_fdset to select on curl fds instead of just sleeping

[Mika Fischer <mika.fischer@zoopnet.de>]

Previously, when nothing could be read from the connections curl had
open, git would just sleep unconditionally for 50ms. This patch changes
this behavior and instead obtains the recommended timeout and the actual
file descriptors from curl. This should eliminate time spent sleeping when
data could actually be read/written on the socket.

Signed-off-by: Mika Fischer <mika.fischer@zoopnet.de>
---
 http.c |   21 ++++++++++++++++-----
 1 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/http.c b/http.c
index a4bc770..12180f3 100644
--- a/http.c
+++ b/http.c
@@ -649,6 +649,7 @@ void run_active_slot(struct active_request_slot *slot)
 	fd_set excfds;
 	int max_fd;
 	struct timeval select_timeout;
+	long int curl_timeout;
 	int finished = 0;
 
 	slot->finished = &finished;
@@ -664,14 +665,24 @@ void run_active_slot(struct active_request_slot *slot)
 		}
 
 		if (slot->in_use && !data_received) {
-			max_fd = 0;
+			curl_multi_timeout(curlm, &curl_timeout);
+			if (curl_timeout == 0) {
+				continue;
+			} else if (curl_timeout == -1) {
+				select_timeout.tv_sec  = 0;
+				select_timeout.tv_usec = 50000;
+			} else {
+				select_timeout.tv_sec  =  curl_timeout / 1000;
+				select_timeout.tv_usec = (curl_timeout % 1000) * 1000;
+			}
+
+			max_fd = -1;
 			FD_ZERO(&readfds);
 			FD_ZERO(&writefds);
 			FD_ZERO(&excfds);
-			select_timeout.tv_sec = 0;
-			select_timeout.tv_usec = 50000;
-			select(max_fd, &readfds, &writefds,
-			       &excfds, &select_timeout);
+			curl_multi_fdset(curlm, &readfds, &writefds, &excfds, &max_fd);
+
+			select(max_fd+1, &readfds, &writefds, &excfds, &select_timeout);
 		}
 	}
 #else
-- 
1.7.7.1.489.g1fee