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Smart fetch over HTTP: client side
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The git-remote-curl backend detects if the remote server supports
the git-upload-pack service, and if so, runs git-fetch-pack locally
in a pipe to generate the want/have commands.

The advertisements from the server that were obtained during the
discovery are passed into git-fetch-pack before the POST request
starts, permitting server capability discovery and enablement.

Common objects that are discovered are appended onto the request as
have lines and are sent again on the next request.  This allows the
remote side to reinitialize its in-memory list of common objects
during the next request.

Because all requests are relatively short, below git-remote-curl's
1 MiB buffer limit, requests will use the standard Content-Length
header and be valid HTTP/1.0 POST requests.  This makes the fetch
client more tolerant of proxy servers which don't support HTTP/1.1
or the chunked transfer encoding.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Shawn O. Pearce authored and Junio C Hamano committed Nov 5, 2009
1 parent de1a2fd commit 249b200
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Showing 3 changed files with 160 additions and 22 deletions.
110 changes: 93 additions & 17 deletions builtin-fetch-pack.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,24 @@ enum ack_type {
ACK_ready
};

static void consume_shallow_list(int fd)
{
if (args.stateless_rpc && args.depth > 0) {
/* If we sent a depth we will get back "duplicate"
* shallow and unshallow commands every time there
* is a block of have lines exchanged.
*/
char line[1000];
while (packet_read_line(fd, line, sizeof(line))) {
if (!prefixcmp(line, "shallow "))
continue;
if (!prefixcmp(line, "unshallow "))
continue;
die("git fetch-pack: expected shallow list");
}
}
}

static enum ack_type get_ack(int fd, unsigned char *result_sha1)
{
static char line[1000];
Expand All @@ -190,6 +208,15 @@ static enum ack_type get_ack(int fd, unsigned char *result_sha1)
die("git fetch_pack: expected ACK/NAK, got '%s'", line);
}

static void send_request(int fd, struct strbuf *buf)
{
if (args.stateless_rpc) {
send_sideband(fd, -1, buf->buf, buf->len, LARGE_PACKET_MAX);
packet_flush(fd);
} else
safe_write(fd, buf->buf, buf->len);
}

static int find_common(int fd[2], unsigned char *result_sha1,
struct ref *refs)
{
Expand All @@ -199,7 +226,10 @@ static int find_common(int fd[2], unsigned char *result_sha1,
unsigned in_vain = 0;
int got_continue = 0;
struct strbuf req_buf = STRBUF_INIT;
size_t state_len = 0;

if (args.stateless_rpc && multi_ack == 1)
die("--stateless-rpc requires multi_ack_detailed");
if (marked)
for_each_ref(clear_marks, NULL);
marked = 1;
Expand Down Expand Up @@ -256,13 +286,13 @@ static int find_common(int fd[2], unsigned char *result_sha1,
if (args.depth > 0)
packet_buf_write(&req_buf, "deepen %d", args.depth);
packet_buf_flush(&req_buf);

safe_write(fd[1], req_buf.buf, req_buf.len);
state_len = req_buf.len;

if (args.depth > 0) {
char line[1024];
unsigned char sha1[20];

send_request(fd[1], &req_buf);
while (packet_read_line(fd[0], line, sizeof(line))) {
if (!prefixcmp(line, "shallow ")) {
if (get_sha1_hex(line + 8, sha1))
Expand All @@ -284,28 +314,40 @@ static int find_common(int fd[2], unsigned char *result_sha1,
}
die("expected shallow/unshallow, got %s", line);
}
} else if (!args.stateless_rpc)
send_request(fd[1], &req_buf);

if (!args.stateless_rpc) {
/* If we aren't using the stateless-rpc interface
* we don't need to retain the headers.
*/
strbuf_setlen(&req_buf, 0);
state_len = 0;
}

flushes = 0;
retval = -1;
while ((sha1 = get_rev())) {
packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
packet_buf_write(&req_buf, "have %s\n", sha1_to_hex(sha1));
if (args.verbose)
fprintf(stderr, "have %s\n", sha1_to_hex(sha1));
in_vain++;
if (!(31 & ++count)) {
int ack;

packet_flush(fd[1]);
packet_buf_flush(&req_buf);
send_request(fd[1], &req_buf);
strbuf_setlen(&req_buf, state_len);
flushes++;

/*
* We keep one window "ahead" of the other side, and
* will wait for an ACK only on the next one
*/
if (count == 32)
if (!args.stateless_rpc && count == 32)
continue;

consume_shallow_list(fd[0]);
do {
ack = get_ack(fd[0], result_sha1);
if (args.verbose && ack)
Expand All @@ -322,6 +364,17 @@ static int find_common(int fd[2], unsigned char *result_sha1,
case ACK_continue: {
struct commit *commit =
lookup_commit(result_sha1);
if (args.stateless_rpc
&& ack == ACK_common
&& !(commit->object.flags & COMMON)) {
/* We need to replay the have for this object
* on the next RPC request so the peer knows
* it is in common with us.
*/
const char *hex = sha1_to_hex(result_sha1);
packet_buf_write(&req_buf, "have %s\n", hex);
state_len = req_buf.len;
}
mark_common(commit, 0, 1);
retval = 0;
in_vain = 0;
Expand All @@ -339,7 +392,8 @@ static int find_common(int fd[2], unsigned char *result_sha1,
}
}
done:
packet_write(fd[1], "done\n");
packet_buf_write(&req_buf, "done\n");
send_request(fd[1], &req_buf);
if (args.verbose)
fprintf(stderr, "done\n");
if (retval != 0) {
Expand All @@ -348,6 +402,7 @@ static int find_common(int fd[2], unsigned char *result_sha1,
}
strbuf_release(&req_buf);

consume_shallow_list(fd[0]);
while (flushes || multi_ack) {
int ack = get_ack(fd[0], result_sha1);
if (ack) {
Expand Down Expand Up @@ -672,6 +727,8 @@ static struct ref *do_fetch_pack(int fd[2],
*/
warning("no common commits");

if (args.stateless_rpc)
packet_flush(fd[1]);
if (get_pack(fd, pack_lockfile))
die("git fetch-pack: fetch failed.");

Expand Down Expand Up @@ -742,6 +799,8 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
struct ref *ref = NULL;
char *dest = NULL, **heads;
int fd[2];
char *pack_lockfile = NULL;
char **pack_lockfile_ptr = NULL;
struct child_process *conn;

nr_heads = 0;
Expand Down Expand Up @@ -791,6 +850,15 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
args.no_progress = 1;
continue;
}
if (!strcmp("--stateless-rpc", arg)) {
args.stateless_rpc = 1;
continue;
}
if (!strcmp("--lock-pack", arg)) {
args.lock_pack = 1;
pack_lockfile_ptr = &pack_lockfile;
continue;
}
usage(fetch_pack_usage);
}
dest = (char *)arg;
Expand All @@ -801,19 +869,27 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
if (!dest)
usage(fetch_pack_usage);

conn = git_connect(fd, (char *)dest, args.uploadpack,
args.verbose ? CONNECT_VERBOSE : 0);
if (conn) {
get_remote_heads(fd[0], &ref, 0, NULL, 0, NULL);

ref = fetch_pack(&args, fd, conn, ref, dest, nr_heads, heads, NULL);
close(fd[0]);
close(fd[1]);
if (finish_connect(conn))
ref = NULL;
if (args.stateless_rpc) {
conn = NULL;
fd[0] = 0;
fd[1] = 1;
} else {
ref = NULL;
conn = git_connect(fd, (char *)dest, args.uploadpack,
args.verbose ? CONNECT_VERBOSE : 0);
}

get_remote_heads(fd[0], &ref, 0, NULL, 0, NULL);

ref = fetch_pack(&args, fd, conn, ref, dest,
nr_heads, heads, pack_lockfile_ptr);
if (pack_lockfile) {
printf("lock %s\n", pack_lockfile);
fflush(stdout);
}
close(fd[0]);
close(fd[1]);
if (finish_connect(conn))
ref = NULL;
ret = !ref;

if (!ret && nr_heads) {
Expand Down
3 changes: 2 additions & 1 deletion fetch-pack.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,8 @@ struct fetch_pack_args
fetch_all:1,
verbose:1,
no_progress:1,
include_tag:1;
include_tag:1,
stateless_rpc:1;
};

struct ref *fetch_pack(struct fetch_pack_args *args,
Expand Down
69 changes: 65 additions & 4 deletions remote-curl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -45,15 +45,15 @@ static int set_option(const char *name, const char *value)
options.progress = 0;
else
return -1;
return 1 /* TODO implement later */;
return 0;
}
else if (!strcmp(name, "depth")) {
char *end;
unsigned long v = strtoul(value, &end, 10);
if (value == end || *end)
return -1;
options.depth = v;
return 1 /* TODO implement later */;
return 0;
}
else if (!strcmp(name, "followtags")) {
if (!strcmp(value, "true"))
Expand All @@ -62,7 +62,7 @@ static int set_option(const char *name, const char *value)
options.followtags = 0;
else
return -1;
return 1 /* TODO implement later */;
return 0;
}
else if (!strcmp(name, "dry-run")) {
if (!strcmp(value, "true"))
Expand Down Expand Up @@ -463,6 +463,8 @@ static int fetch_dumb(int nr_heads, struct ref **to_fetch)
char **targets = xmalloc(nr_heads * sizeof(char*));
int ret, i;

if (options.depth)
die("dumb http transport does not support --depth");
for (i = 0; i < nr_heads; i++)
targets[i] = xstrdup(sha1_to_hex(to_fetch[i]->old_sha1));

Expand All @@ -481,6 +483,65 @@ static int fetch_dumb(int nr_heads, struct ref **to_fetch)
return ret ? error("Fetch failed.") : 0;
}

static int fetch_git(struct discovery *heads,
int nr_heads, struct ref **to_fetch)
{
struct rpc_state rpc;
char *depth_arg = NULL;
const char **argv;
int argc = 0, i, err;

argv = xmalloc((15 + nr_heads) * sizeof(char*));
argv[argc++] = "fetch-pack";
argv[argc++] = "--stateless-rpc";
argv[argc++] = "--lock-pack";
if (options.followtags)
argv[argc++] = "--include-tag";
if (options.thin)
argv[argc++] = "--thin";
if (options.verbosity >= 3) {
argv[argc++] = "-v";
argv[argc++] = "-v";
}
if (!options.progress)
argv[argc++] = "--no-progress";
if (options.depth) {
struct strbuf buf = STRBUF_INIT;
strbuf_addf(&buf, "--depth=%lu", options.depth);
depth_arg = strbuf_detach(&buf, NULL);
argv[argc++] = depth_arg;
}
argv[argc++] = url;
for (i = 0; i < nr_heads; i++) {
struct ref *ref = to_fetch[i];
if (!ref->name || !*ref->name)
die("cannot fetch by sha1 over smart http");
argv[argc++] = ref->name;
}
argv[argc++] = NULL;

memset(&rpc, 0, sizeof(rpc));
rpc.service_name = "git-upload-pack",
rpc.argv = argv;

err = rpc_service(&rpc, heads);
if (rpc.result.len)
safe_write(1, rpc.result.buf, rpc.result.len);
strbuf_release(&rpc.result);
free(argv);
free(depth_arg);
return err;
}

static int fetch(int nr_heads, struct ref **to_fetch)
{
struct discovery *d = discover_refs("git-upload-pack");
if (d->proto_git)
return fetch_git(d, nr_heads, to_fetch);
else
return fetch_dumb(nr_heads, to_fetch);
}

static void parse_fetch(struct strbuf *buf)
{
struct ref **to_fetch = NULL;
Expand Down Expand Up @@ -523,7 +584,7 @@ static void parse_fetch(struct strbuf *buf)
break;
} while (1);

if (fetch_dumb(nr_heads, to_fetch))
if (fetch(nr_heads, to_fetch))
exit(128); /* error already reported */
free_refs(list_head);
free(to_fetch);
Expand Down

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