If the remote peer upload-pack process supports the include-tag
protocol extension then we can avoid running a second fetch cycle
on the client side by letting the server send us the annotated tags
along with the objects it is packing for us. In the following graph
we can now fetch both "tag1" and "tag2" on the same connection that
we fetched "master" from the remote when we only have L available
on the local side:
T - tag1 S - tag2
/ /
L - o ------ o ------ B
\ \
\ \
origin/master master
The objects for "tag1" are implicitly downloaded without our direct
knowledge. The existing "quickfetch" optimization within git-fetch
discovers that tag1 is complete after the first connection and does
not open a second connection.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If the situation is the following on the remote and L is the common
base between both sides:
T - tag1 S - tag2
/ /
L - A - O - O - B
\ \
origin/master master
and we have decided to fetch "master" to acquire the range L..B we
can also nab tag S at the same time during the first connection,
as we can clearly see from the refs advertised by upload-pack that
S^{} = B and master = B.
Unfortunately we still cannot nab T at the same time as we are not
able to see that T^{} will also be in the range implied by L..B.
Such computations must be performed on the remote side (not yet
supported) or on the client side as post-processing (the current
behavior).
This optimization is an extension of the previous one in that it
helps on projects which tend to publish both a new commit and a
new tag, then lay idle for a while before publishing anything else.
Most followers are able to download both the new commit and the new
tag in one connection, rather than two. git.git tends to follow
such patterns with its roughly once-daily updates from Junio.
A protocol extension and additional server side logic would be
necessary to also ensure T is grabbed on the first connection.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
