Re: git version statistics
- From
Jeff King <peff@peff.net>
- Date
- May 31, 2012, 12:00 UTC
- Message-ID
- <20120531120018.GA24986@sigill.intra.peff.net>
- In-Reply-To
- <20120531114801.GA21367@sigill.intra.peff.net>
On Thu, May 31, 2012 at 07:48:01AM -0400, Jeff King wrote:
Show 5 quoted lines
> Just for fun, I've assembled a few statistics on git client versions > that hit github.com. These are collected from the http user-agent > strings provided by smart-http requests (we don't allow dumb http at all > these days, and the git protocol does not provide any version > information).
We have capabilities, and I looked into trying to fingerprint client versions based on the capabilities. Unfortunately, it's extremely coarse-grained, because we just don't add capabilities very often.
I came up with this list of fetch-pack capabilities, and when they were introduced:
- multi_ack v0.99.9 - thin-pack v1.3.0 - side-band v1.4.1 - side-band-64k v1.4.3 - ofs-delta v1.4.4 - shallow v1.5.0 - no-progress v1.5.1 - include-tag v1.5.5 - multi_ack_detailed v1.6.6 - no-done v1.7.5
But note that "shallow" is not requested explicitly by the client; you can detect it by the client sending "shallow" commands, but then only if it is a shallow repository. Similarly, "no-progress" is only requested if the client is run with "--no-progress" or without a tty.
The "no-done" capability is only requested in stateless-rpc mode (i.e., over smart-http). So we can use it only for smart-http, in which case we have more accurate numbers already (because git puts the version in the http user-agent string).
So realistically you are looking at identifying whether a client version is >= v1.6.6 (if it has multi_ack_detailed) or >= v1.5.5 (if it has include-tag). Beyond that it gets uselessly old, and that's really not very fine-grained at all.
I'm really tempted to do something like the patch below, which adds an agent field to the capability string. It wouldn't help with identifying older versions, but eventually all versions of git would send it (and those that didn't could be stuck in the "wow, that's old" bin).
-Peff
-- >8 -- Subject: include agent identifier in capability string
Instead of having the client advertise a particular version number in the git protocol, we have managed extensions and backwards compatibility by having clients and servers advertise capabilities that they support. This is far more robust than having each side consult a table of known versions, and provides sufficient information for the protocol interaction to complete.
However, it does not allow servers to keep statistics on which client versions are being used. This information is not necessary to complete the network request (the capabilities provide enough information for that), but it may be helpful to conduct a general survey of client versions in use.
We already send the client version in the user-agent header for http requests; adding it here would allow us to gather similar statistics for non-http requests.
Signed-off-by: Jeff King <peff@peff.net> --- builtin/fetch-pack.c | 1 + builtin/send-pack.c | 6 ++++-- 2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c index 149db88..f3b8422 100644 --- a/builtin/fetch-pack.c +++ b/builtin/fetch-pack.c @@ -327,6 +327,7 @@ static int find_common(int fd[2], unsigned char *result_sha1, if (args.no_progress) strbuf_addstr(&c, " no-progress"); if (args.include_tag) strbuf_addstr(&c, " include-tag"); if (prefer_ofs_delta) strbuf_addstr(&c, " ofs-delta"); + strbuf_addf(&c, " agent=git/%s", git_version_string); packet_buf_write(&req_buf, "want %s%s\n", remote_hex, c.buf); strbuf_release(&c); } else diff --git a/builtin/send-pack.c b/builtin/send-pack.c index d5d7105..3d87c71 100644 --- a/builtin/send-pack.c +++ b/builtin/send-pack.c @@ -306,11 +306,13 @@ int send_pack(struct send_pack_args *args, int quiet = quiet_supported && (args->quiet || !args->progress); if (!cmds_sent && (status_report || use_sideband || args->quiet)) { - packet_buf_write(&req_buf, "%s %s %s%c%s%s%s", + packet_buf_write(&req_buf, + "%s %s %s%c%s%s%s agent=git/%s", old_hex, new_hex, ref->name, 0, status_report ? " report-status" : "", use_sideband ? " side-band-64k" : "", - quiet ? " quiet" : ""); + quiet ? " quiet" : "", + git_version_string); } else packet_buf_write(&req_buf, "%s %s %s",
-- 1.7.11.rc0.35.ga99aee0