Move negotiation to the transport

There are many ways how a transport might negotiate with the server,
so instead of making it fit into the smart protocol model, let the
transport do its thing. For now, the git protocol limits itself to
send only 160 "have" lines so we don't flood the server.

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

src/fetch.c

@@ -98,14 +98,8 @@ cleanup:
  */
 int git_fetch_negotiate(git_remote *remote)
 {
-	git_revwalk *walk;
 	int error;
-	unsigned int i;
-	git_reference *ref;
-	git_strarray refs;
 	git_headarray *list = &remote->refs;
-	git_repository *repo = remote->repo;
-	git_oid oid;
 
 	error = filter_wants(remote);
 	if (error < GIT_SUCCESS)
@@ -119,47 +113,11 @@ int git_fetch_negotiate(git_remote *remote)
 	 * what we want and what we have.
 	 */
 	remote->need_pack = 1;
-	git_transport_send_wants(remote->transport, list);
-
-	error = git_reference_listall(&refs, repo, GIT_REF_LISTALL);
-	if (error < GIT_ERROR)
-		return git__rethrow(error, "Failed to list all references");
-
-	error = git_revwalk_new(&walk, repo);
-	if (error < GIT_ERROR) {
-		error = git__rethrow(error, "Failed to list all references");
-		goto cleanup;
-	}
-	git_revwalk_sorting(walk, GIT_SORT_TIME);
-
-	for (i = 0; i < refs.count; ++i) {
-		error = git_reference_lookup(&ref, repo, refs.strings[i]);
-		if (error < GIT_ERROR) {
-			error = git__rethrow(error, "Failed to lookup %s", refs.strings[i]);
-			goto cleanup;
-		}
-
-		error = git_revwalk_push(walk, git_reference_oid(ref));
-		if (error < GIT_ERROR) {
-			error = git__rethrow(error, "Failed to push %s", refs.strings[i]);
-			goto cleanup;
-		}
-	}
-	git_strarray_free(&refs);
-
-	while ((error = git_revwalk_next(&oid, walk)) == GIT_SUCCESS) {
-		git_transport_send_have(remote->transport, &oid);
-	}
-	if (error == GIT_EREVWALKOVER)
-		error = GIT_SUCCESS;
-
-	/* TODO: git_pkt_send_flush(fd), or git_transport_flush() */
-	git_transport_send_flush(remote->transport);
-	git_transport_send_done(remote->transport);
+	error = git_transport_send_wants(remote->transport, list);
+	if (error < GIT_SUCCESS)
+		return git__rethrow(error, "Failed to send want list");
 
-cleanup:
-	git_revwalk_free(walk);
-	return error;
+	return git_transport_negotiate_fetch(remote->transport, remote->repo, &remote->refs);
 }
 
 int git_fetch_download_pack(char **out, git_remote *remote)

src/fetch.h

@@ -2,5 +2,6 @@
 #define INCLUDE_fetch_h__
 
 int git_fetch_negotiate(git_remote *remote);
+int git_fetch_download_pack(char **out, git_remote *remote);
 
 #endif

src/transport.c

@@ -90,6 +90,11 @@ int git_transport_send_have(struct git_transport *transport, git_oid *oid)
 	return transport->send_have(transport, oid);
 }
 
+int git_transport_negotiate_fetch(struct git_transport *transport, git_repository *repo, git_headarray *list)
+{
+	return transport->negotiate_fetch(transport, repo, list);
+}
+
 int git_transport_send_flush(struct git_transport *transport)
 {
 	return transport->send_flush(transport);

src/transport.h

@@ -73,6 +73,11 @@ struct git_transport {
 	 */
 	int (*send_done)(struct git_transport *transport);
 	/**
+	 * Negotiate the minimal amount of objects that need to be
+	 * retrieved
+	 */
+	int (*negotiate_fetch)(struct git_transport *transport, git_repository *repo, git_headarray *list);
+	/**
 	 * Send a flush
 	 */
 	int (*send_flush)(struct git_transport *transport);
@@ -99,6 +104,7 @@ int git_transport_git(struct git_transport **transport);
 int git_transport_dummy(struct git_transport **transport);
 
 int git_transport_send_wants(struct git_transport *transport, git_headarray *array);
+int git_transport_negotiate_fetch(struct git_transport *transport, git_repository *repo, git_headarray *array);
 int git_transport_send_have(struct git_transport *transport, git_oid *oid);
 int git_transport_send_done(struct git_transport *transport);
 int git_transport_send_flush(struct git_transport *transport);

src/transport_git.c

@@ -27,6 +27,8 @@
 #include "git2/common.h"
 #include "git2/types.h"
 #include "git2/errors.h"
+#include "git2/net.h"
+#include "git2/revwalk.h"
 
 #include "vector.h"
 #include "transport.h"
@@ -325,6 +327,70 @@ static int git_send_have(git_transport *transport, git_oid *oid)
 	return git_pkt_send_have(oid, t->socket);
 }
 
+static int git_negotiate_fetch(git_transport *transport, git_repository *repo, git_headarray *list)
+{
+	transport_git *t = (transport_git *) transport;
+	git_revwalk *walk;
+	git_reference *ref;
+	git_strarray refs;
+	git_oid oid;
+	int error;
+	unsigned int i;
+
+	error = git_reference_listall(&refs, repo, GIT_REF_LISTALL);
+	if (error < GIT_ERROR)
+		return git__rethrow(error, "Failed to list all references");
+
+	error = git_revwalk_new(&walk, repo);
+	if (error < GIT_ERROR) {
+		error = git__rethrow(error, "Failed to list all references");
+		goto cleanup;
+	}
+	git_revwalk_sorting(walk, GIT_SORT_TIME);
+
+	for (i = 0; i < refs.count; ++i) {
+		error = git_reference_lookup(&ref, repo, refs.strings[i]);
+		if (error < GIT_ERROR) {
+			error = git__rethrow(error, "Failed to lookup %s", refs.strings[i]);
+			goto cleanup;
+		}
+
+		error = git_revwalk_push(walk, git_reference_oid(ref));
+		if (error < GIT_ERROR) {
+			error = git__rethrow(error, "Failed to push %s", refs.strings[i]);
+			goto cleanup;
+		}
+	}
+	git_strarray_free(&refs);
+
+	/*
+	 * We don't support any kind of ACK extensions, so the negotiation
+	 * boils down to sending what we have and listening for an ACK
+	 * every once in a while.
+	 */
+	i = 0;
+	while ((error = git_revwalk_next(&oid, walk)) == GIT_SUCCESS) {
+		error = git_pkt_send_have(&oid, t->socket);
+		i++;
+		/*
+		 * This is a magic number so we don't flood the server. We
+		 * should check every once in a while to see if the server has
+		 * sent an ACK.
+		 */
+		if (i % 160 == 0)
+			break;
+	}
+	if (error == GIT_EREVWALKOVER)
+		error = GIT_SUCCESS;
+
+	git_pkt_send_flush(t->socket);
+	git_pkt_send_done(t->socket);
+
+cleanup:
+	git_revwalk_free(walk);
+	return error;
+}
+
 static int git_send_flush(git_transport *transport)
 {
 	transport_git *t = (transport_git *) transport;
@@ -476,6 +542,7 @@ int git_transport_git(git_transport **out)
 	t->parent.ls = git_ls;
 	t->parent.send_wants = git_send_wants;
 	t->parent.send_have = git_send_have;
+	t->parent.negotiate_fetch = git_negotiate_fetch;
 	t->parent.send_flush = git_send_flush;
 	t->parent.send_done = git_send_done;
 	t->parent.download_pack = git_download_pack;