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List: git
Subject: [PATCH v4 20/35] upload-pack: introduce fetch server command
From: Brandon Williams <bmwill () google ! com>
Date: 2018-02-28 23:22:37
Message-ID: 20180228232252.102167-21-bmwill () google ! com
[Download RAW message or body]
Introduce the 'fetch' server command.
Signed-off-by: Brandon Williams <bmwill@google.com>
---
Documentation/technical/protocol-v2.txt | 128 ++++++++++++
serve.c | 2 +
t/t5701-git-serve.sh | 1 +
upload-pack.c | 267 ++++++++++++++++++++++++
upload-pack.h | 5 +
5 files changed, 403 insertions(+)
diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt
index 7f50e6462..99c70a1e4 100644
--- a/Documentation/technical/protocol-v2.txt
+++ b/Documentation/technical/protocol-v2.txt
@@ -205,3 +205,131 @@ The output of ls-refs is as follows:
ref-attribute = (symref | peeled)
symref = "symref-target:" symref-target
peeled = "peeled:" obj-id
+
+ fetch
+-------
+
+`fetch` is the command used to fetch a packfile in v2. It can be looked
+at as a modified version of the v1 fetch where the ref-advertisement is
+stripped out (since the `ls-refs` command fills that role) and the
+message format is tweaked to eliminate redundancies and permit easy
+addition of future extensions.
+
+Additional features not supported in the base command will be advertised
+as the value of the command in the capability advertisement in the form
+of a space separated list of features, e.g. "<command>=<feature 1>
+<feature 2>".
+
+A `fetch` request can take the following arguments:
+
+ want <oid>
+ Indicates to the server an object which the client wants to
+ retrieve. Wants can be anything and are not limited to
+ advertised objects.
+
+ have <oid>
+ Indicates to the server an object which the client has locally.
+ This allows the server to make a packfile which only contains
+ the objects that the client needs. Multiple 'have' lines can be
+ supplied.
+
+ done
+ Indicates to the server that negotiation should terminate (or
+ not even begin if performing a clone) and that the server should
+ use the information supplied in the request to construct the
+ packfile.
+
+ thin-pack
+ Request that a thin pack be sent, which is a pack with deltas
+ which reference base objects not contained within the pack (but
+ are known to exist at the receiving end). This can reduce the
+ network traffic significantly, but it requires the receiving end
+ to know how to "thicken" these packs by adding the missing bases
+ to the pack.
+
+ no-progress
+ Request that progress information that would normally be sent on
+ side-band channel 2, during the packfile transfer, should not be
+ sent. However, the side-band channel 3 is still used for error
+ responses.
+
+ include-tag
+ Request that annotated tags should be sent if the objects they
+ point to are being sent.
+
+ ofs-delta
+ Indicate that the client understands PACKv2 with delta referring
+ to its base by position in pack rather than by an oid. That is,
+ they can read OBJ_OFS_DELTA (ake type 6) in a packfile.
+
+The response of `fetch` is broken into a number of sections separated by
+delimiter packets (0001), with each section beginning with its section
+header.
+
+ output = *section
+ section = (acknowledgments | packfile)
+ (flush-pkt | delim-pkt)
+
+ acknowledgments = PKT-LINE("acknowledgments" LF)
+ (nak | *ack)
+ (ready)
+ ready = PKT-LINE("ready" LF)
+ nak = PKT-LINE("NAK" LF)
+ ack = PKT-LINE("ACK" SP obj-id LF)
+
+ packfile = PKT-LINE("packfile" LF)
+ [PACKFILE]
+
+----
+ acknowledgments section
+ * Always begins with the section header "acknowledgments"
+
+ * The server will respond with "NAK" if none of the object ids sent
+ as have lines were common.
+
+ * The server will respond with "ACK obj-id" for all of the
+ object ids sent as have lines which are common.
+
+ * A response cannot have both "ACK" lines as well as a "NAK"
+ line.
+
+ * The server will respond with a "ready" line indicating that
+ the server has found an acceptable common base and is ready to
+ make and send a packfile (which will be found in the packfile
+ section of the same response)
+
+ * If the client determines that it is finished with negotiations
+ by sending a "done" line, the acknowledgments sections MUST be
+ omitted from the server's response.
+
+ * If the server has found a suitable cut point and has decided
+ to send a "ready" line, then the server can decide to (as an
+ optimization) omit any "ACK" lines it would have sent during
+ its response. This is because the server will have already
+ determined the objects it plans to send to the client and no
+ further negotiation is needed.
+
+----
+ packfile section
+ * Always begins with the section header "packfile"
+
+ * The transmission of the packfile begins immediately after the
+ section header
+
+ * The data transfer of the packfile is always multiplexed, using
+ the same semantics of the 'side-band-64k' capability from
+ protocol version 1. This means that each packet, during the
+ packfile data stream, is made up of a leading 4-byte pkt-line
+ length (typical of the pkt-line format), followed by a 1-byte
+ stream code, followed by the actual data.
+
+ The stream code can be one of:
+ 1 - pack data
+ 2 - progress messages
+ 3 - fatal error message just before stream aborts
+
+ * This section is only included if the client has sent 'want'
+ lines in its request and either requested that no more
+ negotiation be done by sending 'done' or if the server has
+ decided it has found a sufficient cut point to produce a
+ packfile.
diff --git a/serve.c b/serve.c
index c7925c5c7..05cc434cf 100644
--- a/serve.c
+++ b/serve.c
@@ -6,6 +6,7 @@
#include "argv-array.h"
#include "ls-refs.h"
#include "serve.h"
+#include "upload-pack.h"
static int always_advertise(struct repository *r,
struct strbuf *value)
@@ -52,6 +53,7 @@ struct protocol_capability {
static struct protocol_capability capabilities[] = {
{ "agent", agent_advertise, NULL },
{ "ls-refs", always_advertise, ls_refs },
+ { "fetch", always_advertise, upload_pack_v2 },
};
static void advertise_capabilities(void)
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index 11aeb0541..cc5918a67 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -9,6 +9,7 @@ test_expect_success 'test capability advertisement' '
version 2
agent=git/$(git version | cut -d" " -f3)
ls-refs
+ fetch
0000
EOF
diff --git a/upload-pack.c b/upload-pack.c
index 1e8a9e1ca..2af6b1382 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -18,6 +18,7 @@
#include "prio-queue.h"
#include "protocol.h"
#include "upload-pack.h"
+#include "serve.h"
/* Remember to update object flag allocation in object.h */
#define THEY_HAVE (1u << 11)
@@ -1065,3 +1066,269 @@ void upload_pack(struct upload_pack_options *options)
create_pack_file();
}
}
+
+struct upload_pack_data {
+ struct object_array wants;
+ struct oid_array haves;
+
+ unsigned stateless_rpc : 1;
+
+ unsigned use_thin_pack : 1;
+ unsigned use_ofs_delta : 1;
+ unsigned no_progress : 1;
+ unsigned use_include_tag : 1;
+ unsigned done : 1;
+};
+
+static void upload_pack_data_init(struct upload_pack_data *data)
+{
+ struct object_array wants = OBJECT_ARRAY_INIT;
+ struct oid_array haves = OID_ARRAY_INIT;
+
+ memset(data, 0, sizeof(*data));
+ data->wants = wants;
+ data->haves = haves;
+}
+
+static void upload_pack_data_clear(struct upload_pack_data *data)
+{
+ object_array_clear(&data->wants);
+ oid_array_clear(&data->haves);
+}
+
+static int parse_want(const char *line)
+{
+ const char *arg;
+ if (skip_prefix(line, "want ", &arg)) {
+ struct object_id oid;
+ struct object *o;
+
+ if (get_oid_hex(arg, &oid))
+ die("git upload-pack: protocol error, "
+ "expected to get oid, not '%s'", line);
+
+ o = parse_object(&oid);
+ if (!o) {
+ packet_write_fmt(1,
+ "ERR upload-pack: not our ref %s",
+ oid_to_hex(&oid));
+ die("git upload-pack: not our ref %s",
+ oid_to_hex(&oid));
+ }
+
+ if (!(o->flags & WANTED)) {
+ o->flags |= WANTED;
+ add_object_array(o, NULL, &want_obj);
+ }
+
+ return 1;
+ }
+
+ return 0;
+}
+
+static int parse_have(const char *line, struct oid_array *haves)
+{
+ const char *arg;
+ if (skip_prefix(line, "have ", &arg)) {
+ struct object_id oid;
+
+ if (get_oid_hex(arg, &oid))
+ die("git upload-pack: expected SHA1 object, got '%s'", arg);
+ oid_array_append(haves, &oid);
+ return 1;
+ }
+
+ return 0;
+}
+
+static void process_args(struct argv_array *args, struct upload_pack_data *data)
+{
+ int i;
+
+ for (i = 0; i < args->argc; i++) {
+ const char *arg = args->argv[i];
+
+ /* process want */
+ if (parse_want(arg))
+ continue;
+ /* process have line */
+ if (parse_have(arg, &data->haves))
+ continue;
+
+ /* process args like thin-pack */
+ if (!strcmp(arg, "thin-pack")) {
+ use_thin_pack = 1;
+ continue;
+ }
+ if (!strcmp(arg, "ofs-delta")) {
+ use_ofs_delta = 1;
+ continue;
+ }
+ if (!strcmp(arg, "no-progress")) {
+ no_progress = 1;
+ continue;
+ }
+ if (!strcmp(arg, "include-tag")) {
+ use_include_tag = 1;
+ continue;
+ }
+ if (!strcmp(arg, "done")) {
+ data->done = 1;
+ continue;
+ }
+
+ /* ignore unknown lines maybe? */
+ die("unexpect line: '%s'", arg);
+ }
+}
+
+static int process_haves(struct oid_array *haves, struct oid_array *common)
+{
+ int i;
+
+ /* Process haves */
+ for (i = 0; i < haves->nr; i++) {
+ const struct object_id *oid = &haves->oid[i];
+ struct object *o;
+ int we_knew_they_have = 0;
+
+ if (!has_object_file(oid))
+ continue;
+
+ oid_array_append(common, oid);
+
+ o = parse_object(oid);
+ if (!o)
+ die("oops (%s)", oid_to_hex(oid));
+ if (o->type == OBJ_COMMIT) {
+ struct commit_list *parents;
+ struct commit *commit = (struct commit *)o;
+ if (o->flags & THEY_HAVE)
+ we_knew_they_have = 1;
+ else
+ o->flags |= THEY_HAVE;
+ if (!oldest_have || (commit->date < oldest_have))
+ oldest_have = commit->date;
+ for (parents = commit->parents;
+ parents;
+ parents = parents->next)
+ parents->item->object.flags |= THEY_HAVE;
+ }
+ if (!we_knew_they_have)
+ add_object_array(o, NULL, &have_obj);
+ }
+
+ return 0;
+}
+
+static int send_acks(struct oid_array *acks, struct strbuf *response)
+{
+ int i;
+
+ packet_buf_write(response, "acknowledgments\n");
+
+ /* Send Acks */
+ if (!acks->nr)
+ packet_buf_write(response, "NAK\n");
+
+ for (i = 0; i < acks->nr; i++) {
+ packet_buf_write(response, "ACK %s\n",
+ oid_to_hex(&acks->oid[i]));
+ }
+
+ if (ok_to_give_up()) {
+ /* Send Ready */
+ packet_buf_write(response, "ready\n");
+ return 1;
+ }
+
+ return 0;
+}
+
+static int process_haves_and_send_acks(struct upload_pack_data *data)
+{
+ struct oid_array common = OID_ARRAY_INIT;
+ struct strbuf response = STRBUF_INIT;
+ int ret = 0;
+
+ process_haves(&data->haves, &common);
+ if (data->done) {
+ ret = 1;
+ } else if (send_acks(&common, &response)) {
+ packet_buf_delim(&response);
+ ret = 1;
+ } else {
+ /* Add Flush */
+ packet_buf_flush(&response);
+ ret = 0;
+ }
+
+ /* Send response */
+ write_or_die(1, response.buf, response.len);
+ strbuf_release(&response);
+
+ oid_array_clear(&data->haves);
+ oid_array_clear(&common);
+ return ret;
+}
+
+enum fetch_state {
+ FETCH_PROCESS_ARGS = 0,
+ FETCH_SEND_ACKS,
+ FETCH_SEND_PACK,
+ FETCH_DONE,
+};
+
+int upload_pack_v2(struct repository *r, struct argv_array *keys,
+ struct argv_array *args)
+{
+ enum fetch_state state = FETCH_PROCESS_ARGS;
+ struct upload_pack_data data;
+
+ upload_pack_data_init(&data);
+ use_sideband = LARGE_PACKET_MAX;
+
+ while (state != FETCH_DONE) {
+ switch (state) {
+ case FETCH_PROCESS_ARGS:
+ process_args(args, &data);
+
+ if (!want_obj.nr) {
+ /*
+ * Request didn't contain any 'want' lines,
+ * guess they didn't want anything.
+ */
+ state = FETCH_DONE;
+ } else if (data.haves.nr) {
+ /*
+ * Request had 'have' lines, so lets ACK them.
+ */
+ state = FETCH_SEND_ACKS;
+ } else {
+ /*
+ * Request had 'want's but no 'have's so we can
+ * immedietly go to construct and send a pack.
+ */
+ state = FETCH_SEND_PACK;
+ }
+ break;
+ case FETCH_SEND_ACKS:
+ if (process_haves_and_send_acks(&data))
+ state = FETCH_SEND_PACK;
+ else
+ state = FETCH_DONE;
+ break;
+ case FETCH_SEND_PACK:
+ packet_write_fmt(1, "packfile\n");
+ create_pack_file();
+ state = FETCH_DONE;
+ break;
+ case FETCH_DONE:
+ continue;
+ }
+ }
+
+ upload_pack_data_clear(&data);
+ return 0;
+}
diff --git a/upload-pack.h b/upload-pack.h
index a71e4dc7e..6b7890238 100644
--- a/upload-pack.h
+++ b/upload-pack.h
@@ -10,4 +10,9 @@ struct upload_pack_options {
void upload_pack(struct upload_pack_options *options);
+struct repository;
+struct argv_array;
+extern int upload_pack_v2(struct repository *r, struct argv_array *keys,
+ struct argv_array *args);
+
#endif /* UPLOAD_PACK_H */
--
2.16.2.395.g2e18187dfd-goog
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