When fetching, connectivity is checked after the shallow file is
updated. There are 2 issues with this: (1) the connectivity check is
only performed up to ancestors of existing refs (which is not thorough
enough if we were deepening an existing ref in the first place), and (2)
there is no rollback of the shallow file if the connectivity check
fails.
To solve (1), update the connectivity check to check the ancestry chain
completely in the case of a deepening fetch by refraining from passing
"--not --all" when invoking rev-list in connected.c.
To solve (2), have fetch_pack() perform its own connectivity check
before updating the shallow file. To support existing use cases in which
"git fetch-pack" is used to download objects without much regard as to
the connectivity of the resulting objects with respect to the existing
repository, the connectivity check is only done if necessary (that is,
the fetch is not a clone, and the fetch involves shallow/deepen
functionality). "git fetch" still performs its own connectivity check,
preserving correctness but sometimes performing redundant work. This
redundancy is mitigated by the fact that fetch_pack() reports if it has
performed a connectivity check itself, and if the transport supports
connect or stateless-connect, it will bubble up that report so that "git
fetch" knows not to perform the connectivity check in such a case.
This was noticed when a user tried to deepen an existing repository by
fetching with --no-shallow from a server that did not send all necessary
objects - the connectivity check as run by "git fetch" succeeded, but a
subsequent "git fsck" failed.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert check_connected and the callbacks it takes to use struct
object_id.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This lets callers influence the environment seen by
rev-list, which will be useful when we start providing
quarantined objects.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Connectivity checks have to traverse the entire object graph
in the worst case (e.g., a full clone or a full push). For
large repositories like linux.git, this can take 30-60
seconds, during which time git may produce little or no
output.
Let's add the option of showing progress, which is taken
care of by rev-list.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Unless the "quiet" flag is given, check_connected sends any
errors to the stderr of the caller (because the child
rev-list inherits that descriptor). However, server-side
callers may want to send these over a sideband channel
instead. Let's make that possible.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The number of variants of check_everything_connected has
grown over the years, so that the "real" function takes
several possibly-zero, possibly-NULL arguments. We hid the
complexity behind some wrapper functions, but this doesn't
scale well when we want to add new options.
If we add more wrapper variants to handle the new options,
then we can get a combinatorial explosion when those options
might be used together (right now nobody wants to use both
"shallow" and "transport" together, so we get by with just a
few wrappers).
If instead we add new parameters to each function, each of
which can have a default value, then callers who want the
defaults end up with confusing invocations like:
check_everything_connected(fn, 0, data, -1, 0, NULL);
where it is unclear which parameter is which (and every
caller needs updated when we add new options).
Instead, let's add a struct to hold all of the optional
parameters. This is a little more verbose for the callers
(who have to declare the struct and fill it in), but it
makes their code much easier to follow, because every option
is named as it is set (and unused options do not have to be
mentioned at all).
Note that we could also stick the iteration function and its
callback data into the option struct, too. But since those
are required for each call, by avoiding doing so, we can let
very simple callers just pass "NULL" for the options and not
worry about the struct at all.
While we're touching each site, let's also rename the
function to check_connected(). The existing name was quite
long, and not all of the wrappers even used the full name.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In order to make sure the cloned repository is good, we run "rev-list
--objects --not --all $new_refs" on the repository. This is expensive
on large repositories. This patch attempts to mitigate the impact in
this special case.
In the "good" clone case, we only have one pack. If all of the
following are met, we can be sure that all objects reachable from the
new refs exist, which is the intention of running "rev-list ...":
- all refs point to an object in the pack
- there are no dangling pointers in any object in the pack
- no objects in the pack point to objects outside the pack
The second and third checks can be done with the help of index-pack as
a slight variation of --strict check (which introduces a new condition
for the shortcut: pack transfer must be used and the number of objects
large enough to call index-pack). The first is checked in
check_everything_connected after we get an "ok" from index-pack.
"index-pack + new checks" is still faster than the current "index-pack
+ rev-list", which is the whole point of this patch. If any of the
conditions fail, we fall back to the good old but expensive "rev-list
..". In that case it's even more expensive because we have to pay for
the new checks in index-pack. But that should only happen when the
other side is either buggy or malicious.
Cloning linux-2.6 over file://
before after
real 3m25.693s 2m53.050s
user 5m2.037s 4m42.396s
sys 0m13.750s 0m16.574s
A more realistic test with ssh:// over wireless
before after
real 11m26.629s 10m4.213s
user 5m43.196s 5m19.444s
sys 0m35.812s 0m37.630s
This shortcut is not applied to shallow clones, partly because shallow
clones should have no more objects than a usual fetch and the cost of
rev-list is acceptable, partly to avoid dealing with corner cases when
grafting is involved.
This shortcut does not apply to unpack-objects code path either
because the number of objects must be small in order to trigger that
code path.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extract the helper function and the type definition of the iterator
function it uses out of builtin/fetch.c into a separate source and a
header file.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
