Smart push over HTTP: client side

The git-remote-curl backend detects if the remote server supports
the git-receive-pack service, and if so, runs git-send-pack in a
pipe to dump the command and pack data as a single POST request.

The advertisements from the server that were obtained during the
discovery are passed into git-send-pack before the POST request
starts.  This permits git-send-pack to operate largely unmodified.

For smaller packs (those under 1 MiB) a HTTP/1.0 POST with a
Content-Length is used, permitting interaction with any server.
The 1 MiB limit is arbitrary, but is sufficent to fit most deltas
created by human authors against text sources with the occasional
small binary file (e.g. few KiB icon image).  The configuration
option http.postBuffer can be used to increase (or shink) this
buffer if the default is not sufficient.

For larger packs which cannot be spooled entirely into the helper's
memory space (due to http.postBuffer being too small), the POST
request requires HTTP/1.1 and sets "Transfer-Encoding: chunked".
This permits the client to upload an unknown amount of data in one
HTTP transaction without needing to pregenerate the entire pack
file locally.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/http.c b/http.c
index 23b2a1932..ed6414a2a 100644
--- a/http.c
+++ b/http.c
@@ -1,9 +1,11 @@
 #include "http.h"
 #include "pack.h"
+#include "sideband.h"
 
 int data_received;
 int active_requests;
 int http_is_verbose;
+size_t http_post_buffer = 16 * LARGE_PACKET_MAX;
 
 #ifdef USE_CURL_MULTI
 static int max_requests = -1;
@@ -97,8 +99,6 @@ size_t fwrite_null(const void *ptr, size_t eltsize, size_t nmemb, void *strbuf)
 	return eltsize * nmemb;
 }
 
-static void finish_active_slot(struct active_request_slot *slot);
-
 #ifdef USE_CURL_MULTI
 static void process_curl_messages(void)
 {
@@ -174,6 +174,13 @@ static int http_options(const char *var, const char *value, void *cb)
 	if (!strcmp("http.proxy", var))
 		return git_config_string(&curl_http_proxy, var, value);
 
+	if (!strcmp("http.postbuffer", var)) {
+		http_post_buffer = git_config_int(var, value);
+		if (http_post_buffer < LARGE_PACKET_MAX)
+			http_post_buffer = LARGE_PACKET_MAX;
+		return 0;
+	}
+
 	/* Fall back on the default ones */
 	return git_default_config(var, value, cb);
 }
@@ -638,7 +645,7 @@ void release_active_slot(struct active_request_slot *slot)
 #endif
 }
 
-static void finish_active_slot(struct active_request_slot *slot)
+void finish_active_slot(struct active_request_slot *slot)
 {
 	closedown_active_slot(slot);
 	curl_easy_getinfo(slot->curl, CURLINFO_HTTP_CODE, &slot->http_code);