From 3145ea957d2ca6ba7afb087c9ed680e08d705690 Mon Sep 17 00:00:00 2001 From: Brandon Williams Date: Thu, 15 Mar 2018 10:31:27 -0700 Subject: [PATCH] upload-pack: introduce fetch server command Introduce the 'fetch' server command. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano --- Documentation/technical/protocol-v2.txt | 125 +++++++++++ serve.c | 2 + t/t5701-git-serve.sh | 1 + upload-pack.c | 266 ++++++++++++++++++++++++ upload-pack.h | 6 + 5 files changed, 400 insertions(+) diff --git a/Documentation/technical/protocol-v2.txt b/Documentation/technical/protocol-v2.txt index bbb8b14d27..307dc1489b 100644 --- a/Documentation/technical/protocol-v2.txt +++ b/Documentation/technical/protocol-v2.txt @@ -199,3 +199,128 @@ 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: "= " + +A `fetch` request can take the following arguments: + + want + Indicates to the server an object which the client wants to + retrieve. Wants can be anything and are not limited to + advertised objects. + + have + 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) + *PKT-LINE(%x01-03 *%x00-ff) + + acknowledgments section + * 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. + + * 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 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 + * 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. + + * 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 diff --git a/serve.c b/serve.c index 1cb5fb9b5b..3692dda801 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) @@ -54,6 +55,7 @@ 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 d03e08eebd..888a700443 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 1e8a9e1caf..198e9f046b 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 +1066,268 @@ 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 packet_reader *request, + struct upload_pack_data *data) +{ + while (packet_reader_read(request) != PACKET_READ_FLUSH) { + const char *arg = request->line; + + /* 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 packet_reader *request) +{ + 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(request, &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 a71e4dc7e2..5bbdb7e445 100644 --- a/upload-pack.h +++ b/upload-pack.h @@ -10,4 +10,10 @@ struct upload_pack_options { void upload_pack(struct upload_pack_options *options); +struct repository; +struct argv_array; +struct packet_reader; +extern int upload_pack_v2(struct repository *r, struct argv_array *keys, + struct packet_reader *request); + #endif /* UPLOAD_PACK_H */