Long ago in 628522ec14 (sha1-lookup: more memory efficient
search in sorted list of SHA-1, 2007-12-29) we added
sha1_entry_pos(), a binary search that uses the uniform
distribution of sha1s to scale the selection of mid-points.
As this was a performance experiment, we tied it to the
GIT_USE_LOOKUP environment variable and never enabled it by
default.
This code was successful in reducing the number of steps in
each search. But the overhead of the scaling ends up making
it slower when the cache is warm. Here are best-of-five
timings for running rev-list on linux.git, which will have
to look up every object:
$ time git rev-list --objects --all >/dev/null
real 0m35.357s
user 0m35.016s
sys 0m0.340s
$ time GIT_USE_LOOKUP=1 git rev-list --objects --all >/dev/null
real 0m37.364s
user 0m37.045s
sys 0m0.316s
The USE_LOOKUP version might have more benefit on a cold
cache, as the time to fault in each page would dominate. But
that would be for a single lookup. In practice, most
operations tend to look up many objects, and the whole pack
.idx will end up warm.
It's possible that the code could be better optimized to
compete with a naive binary search for the warm-cache case,
and we could have the best of both worlds. But over the
years nobody has done so, and this is largely dead code that
is rarely run outside of the test suite. Let's drop it in
the name of simplicity.
This lets us remove sha1_entry_pos() entirely, as the .idx
lookup code was the only caller. Note that sha1-lookup.c
still contains sha1_pos(), which differs from
sha1_entry_pos() in two ways:
- it has a different interface; it uses a function pointer
to access sha1 entries rather than a size/offset pair
describing the table's memory layout
- it only scales the initial selection of "mi", rather
than each iteration of the search
We can't get rid of this function, as it's called from
several places. It may be that we could replace it with a
simple binary search, but that's out of scope for this patch
(and would need benchmarking).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When a remote server uses git-shell, the client side will
connect to it like:
ssh server "git-upload-pack 'foo.git'"
and we literally exec ("git-upload-pack", "foo.git"). In
early versions of upload-pack and receive-pack, we took a
repository argument and nothing else. But over time they
learned to accept dashed options. If the user passes a
repository name that starts with a dash, the results are
confusing at best (we complain of a bogus option instead of
a non-existent repository) and malicious at worst (the user
can start an interactive pager via "--help").
We could pass "--" to the sub-process to make sure the
user's argument is interpreted as a branch name. I.e.:
git-upload-pack -- -foo.git
But adding "--" automatically would make us inconsistent
with a normal shell (i.e., when git-shell is not in use),
where "-foo.git" would still be an error. For that case, the
client would have to specify the "--", but they can't do so
reliably, as existing versions of git-shell do not allow
more than a single argument.
The simplest thing is to simply disallow "-" at the start of
the repo name argument. This hasn't worked either with or
without git-shell since version 1.0.0, and nobody has
complained.
Note that this patch just applies to do_generic_cmd(), which
runs upload-pack, receive-pack, and upload-archive. There
are two other types of commands that git-shell runs:
- do_cvs_cmd(), but this already restricts the argument to
be the literal string "server"
- admin-provided commands in the git-shell-commands
directory. We'll pass along arbitrary arguments there,
so these commands could have similar problems. But these
commands might actually understand dashed arguments, so
we cannot just block them here. It's up to the writer of
the commands to make sure they are safe. With great
power comes great responsibility.
Reported-by: Timo Schmid <tschmid@ernw.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Code clean-up.
* jk/pack-name-cleanups:
index-pack: make pointer-alias fallbacks safer
replace snprintf with odb_pack_name()
odb_pack_keep(): stop generating keepfile name
sha1_file.c: make pack-name helper globally accessible
move odb_* declarations out of git-compat-util.h
A few unterminated here documents in tests were fixed, which in
turn revealed incorrect expectations the tests make. These tests
have been updated.
* st/verify-tag:
t7004, t7030: fix here-doc syntax errors
Recent versions of Git treats http alternates (used in dumb http
transport) just like HTTP redirects and requires the client to
enable following it, due to security concerns. But we forgot to
give a warning when we decide not to honor the alternates.
* ew/http-alternates-as-redirects-warning:
http: release strbuf on disabled alternates
http: inform about alternates-as-redirects behavior
"git filter-branch --prune-empty" drops a single-parent commit that
becomes a no-op, but did not drop a root commit whose tree is empty.
* dp/filter-branch-prune-empty:
p7000: add test for filter-branch with --prune-empty
filter-branch: fix --prune-empty on parentless commits
t7003: ensure --prune-empty removes entire branch when applicable
t7003: ensure --prune-empty can prune root commit
"git fetch" that requests a commit by object name, when the other
side does not allow such an request, failed without much
explanation.
* mm/fetch-show-error-message-on-unadvertised-object:
fetch-pack: add specific error for fetching an unadvertised object
fetch_refs_via_pack: call report_unmatched_refs
fetch-pack: move code to report unmatched refs to a function
"git branch @" created refs/heads/@ as a branch, and in general the
code that handled @{-1} and @{upstream} was a bit too loose in
disambiguating.
* jk/interpret-branch-name:
checkout: restrict @-expansions when finding branch
strbuf_check_ref_format(): expand only local branches
branch: restrict @-expansions when deleting
t3204: test git-branch @-expansion corner cases
interpret_branch_name: allow callers to restrict expansions
strbuf_branchname: add docstring
strbuf_branchname: drop return value
interpret_branch_name: move docstring to header file
interpret_branch_name(): handle auto-namelen for @{-1}
A few tests were run conditionally under (rare) conditions where
they cannot be run (like running cvs tests under 'root' account).
* ab/cond-skip-tests:
gitweb tests: skip tests when we don't have Time::HiRes
gitweb tests: change confusing "skip_all" phrasing
cvs tests: skip tests that call "cvs commit" when running as root
user.email that consists of only cruft chars should consistently
error out, but didn't.
* jk/ident-empty:
ident: do not ignore empty config name/email
ident: reject all-crud ident name
ident: handle NULL email when complaining of empty name
ident: mark error messages for translation
"git repack --depth=<n>" for a long time busted the specified depth
when reusing delta from existing packs. This has been corrected.
* jk/delta-chain-limit:
pack-objects: convert recursion to iteration in break_delta_chain()
pack-objects: enforce --depth limit in reused deltas
Teach the "debug" helper used in the test framework that allows a
command to run under "gdb" to make the session interactive.
* sg/test-with-stdin:
tests: make the 'test_pause' helper work in non-verbose mode
tests: create an interactive gdb session with the 'debug' helper
Picking two versions of Git and running tests to make sure the
older one and the newer one interoperate happily has now become
possible.
* jk/interop-test:
t/interop: add test of old clients against modern git-daemon
t: add an interoperability test harness
The t/perf performance test suite was not prepared to test not so
old versions of Git, but now it covers versions of Git that are not
so ancient.
* jt/perf-updates:
t/perf: add fallback for pre-bin-wrappers versions of git
t/perf: use $MODERN_GIT for all repo-copying steps
t/perf: export variable used in other blocks
An helper function to make it easier to append the result from
real_path() to a strbuf has been added.
* rs/strbuf-add-real-path:
strbuf: add strbuf_add_real_path()
cocci: use ALLOC_ARRAY
The "parse_config_key()" API function has been cleaned up.
* jk/parse-config-key-cleanup:
parse_hide_refs_config: tell parse_config_key we don't want a subsection
parse_config_key: allow matching single-level config
parse_config_key: use skip_prefix instead of starts_with
refs: parse_hide_refs_config to use parse_config_key
