Use `git_config_get_*()` family instead of `git_config()` to take
advantage of the config-set API which provides a cleaner control flow.
Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we see a file change in a commit, we expect one of:
1. A mark.
2. An "inline" keyword.
3. An object sha1.
The handling of spaces is inconsistent between the three
options. Option 1 calls a sub-function which checks for the
space, but doesn't parse past it. Option 2 parses the space,
then deliberately avoids moving the pointer past it. Option
3 detects the space locally but doesn't move past it.
This is confusing, because it looks like option 1 forgets to
check for the space (it's just buried). And option 2 checks
for "inline ", but only moves strlen("inline") characters
forward, which looks like a bug but isn't.
We can make this more clear by just having each branch move
past the space as it is checked (and we can replace the
doubled use of "inline" with a call to skip_prefix).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fast-import does a lot of parsing of commands and
dispatching to sub-functions. For example, given "option
foo", we might recognize "option " using starts_with, and
then hand it off to parse_option() to do the rest.
However, we do not let parse_option know that we have parsed
the first part already. It gets the full buffer, and has to
skip past the uninteresting bits. Some functions simply add
a magic constant:
char *option = command_buf.buf + 7;
Others use strlen:
char *option = command_buf.buf + strlen("option ");
And others use strchr:
char *option = strchr(command_buf.buf, ' ') + 1;
All of these are brittle and easy to get wrong (especially
given that the starts_with call and the code that assumes
the presence of the prefix are far apart). Instead, we can
use skip_prefix, and just pass each handler a pointer to its
arguments.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It's a common idiom to match a prefix and then skip past it
with a magic number, like:
if (starts_with(foo, "bar"))
foo += 3;
This is easy to get wrong, since you have to count the
prefix string yourself, and there's no compiler check if the
string changes. We can use skip_prefix to avoid the magic
numbers here.
Note that some of these conversions could be much shorter.
For example:
if (starts_with(arg, "--foo=")) {
bar = arg + 6;
continue;
}
could become:
if (skip_prefix(arg, "--foo=", &bar))
continue;
However, I have left it as:
if (skip_prefix(arg, "--foo=", &v)) {
bar = v;
continue;
}
to visually match nearby cases which need to actually
process the string. Like:
if (skip_prefix(arg, "--foo=", &v)) {
bar = atoi(v);
continue;
}
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fast-import shares code between its command-line parser and
the "option" command. To do so, it strips the "--" from any
command-line options and passes them to the option parser.
However, it does not confirm that the option even begins
with "--" before blindly passing "arg + 2".
It does confirm that the option starts with "-", so the only
affected case was:
git fast-import -
which would read uninitialized memory after the argument. We
can fix it by using skip_prefix and checking the result. As
a bonus, this gets rid of some magic numbers.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Avoid scanning strings twice, once with strchr() and then with
strlen(), by using strchrnul().
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Rohit Mani <rohit.mani@outlook.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Leaving only the function definitions and declarations so that any
new topic in flight can still make use of the old functions, replace
existing uses of the prefixcmp() and suffixcmp() with new API
functions.
The change can be recreated by mechanically applying this:
$ git grep -l -e prefixcmp -e suffixcmp -- \*.c |
grep -v strbuf\\.c |
xargs perl -pi -e '
s|!prefixcmp\(|starts_with\(|g;
s|prefixcmp\(|!starts_with\(|g;
s|!suffixcmp\(|ends_with\(|g;
s|suffixcmp\(|!ends_with\(|g;
'
on the result of preparatory changes in this series.
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Give "update-refs" a "--stdin" option to read multiple update
requests and perform them in an all-or-none fashion.
* bk/refs-multi-update:
update-ref: add test cases covering --stdin signature
update-ref: support multiple simultaneous updates
refs: add update_refs for multiple simultaneous updates
refs: add function to repack without multiple refs
refs: factor delete_ref loose ref step into a helper
refs: factor update_ref steps into helpers
refs: report ref type from lock_any_ref_for_update
reset: rename update_refs to reset_refs
We liberally use "committish" and "commit-ish" (and "treeish" and
"tree-ish"); as these are non-words, let's unify these terms to
their dashed form. More importantly, clarify the documentation on
object peeling using these terms.
* rh/ishes-doc:
glossary: fix and clarify the definition of 'ref'
revisions.txt: fix and clarify <rev>^{<type>}
glossary: more precise definition of tree-ish (a.k.a. treeish)
use 'commit-ish' instead of 'committish'
use 'tree-ish' instead of 'treeish'
glossary: define commit-ish (a.k.a. committish)
glossary: mention 'treeish' as an alternative to 'tree-ish'
Replace 'committish' in documentation and comments with 'commit-ish'
to match gitglossary(7) and to be consistent with 'tree-ish'.
The only remaining instances of 'committish' are:
* variable, function, and macro names
* "(also committish)" in the definition of commit-ish in
gitglossary[7]
Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Replace 'treeish' in documentation and comments with 'tree-ish' to
match gitglossary(7).
The only remaining instances of 'treeish' are:
* variable, function, and macro names
* "(also treeish)" in the definition of tree-ish in gitglossary(7)
Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* jk/fast-import-empty-ls:
fast-import: allow moving the root tree
fast-import: allow ls or filecopy of the root tree
fast-import: set valid mode on root tree in "ls"
t9300: document fast-import empty path issues
Expose lock_ref_sha1_basic's type_p argument to callers of
lock_any_ref_for_update. Update all call sites to ignore it by passing
NULL for now.
Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Because fast-import.c::tree_content_remove does not check for the empty
path, it is not possible to move the root tree to a subdirectory.
Instead the error "Path not in branch" is produced (note the double
space where the empty path has been inserted).
Fix this by explicitly checking for the empty path and handling it.
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit 178e1de (fast-import: don't allow 'ls' of path with empty
components, 2012-03-09) restricted paths which:
. contain an empty directory component (e.g. foo//bar is invalid),
. end with a directory separator (e.g. foo/ is invalid),
. start with a directory separator (e.g. /foo is invalid).
However, the implementation also caught the empty path, which should
represent the root tree. Relax this restriction so that the empty path
is explicitly allowed and refers to the root tree.
Reported-by: Dave Abrahams <dave@boostpro.com>
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This prevents a failure later when we lift the restriction on ls with
the empty path.
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Optimization for fast-export by avoiding unnecessarily resolving
arbitrary object name and parsing object when only presence and
type information is necessary, etc.
* fc/fast-export-persistent-marks:
fast-{import,export}: use get_sha1_hex() to read from marks file
fast-export: don't parse commits while reading marks file
fast-export: do not parse non-commit objects while reading marks file
It's wrong to call get_sha1() if they should be SHA-1s, plus
inefficient.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Sparse issues 68 errors (two errors for each main() function) such
as the following:
SP git.c
git.c:510:5: error: too many arguments for function mingw_main
git.c:510:5: error: symbol 'mingw_main' redeclared with different type \
(originally declared at git.c:510) - different argument counts
The errors are caused by the 'main' macro used by the MinGW build
to provide a replacement main() function. The original main function
is effectively renamed to 'mingw_main' and is called from the new
main function. The replacement main is used to execute certain actions
common to all git programs on MinGW (e.g. ensure the standard I/O
streams are in binary mode).
In order to suppress the errors, we change the macro to include the
parameters in the declaration of the mingw_main function.
Unfortunately, this change provokes both sparse and gcc to complain
about 9 calls to mingw_main(), such as the following:
CC git.o
git.c: In function 'main':
git.c:510: warning: passing argument 2 of 'mingw_main' from \
incompatible pointer type
git.c:510: note: expected 'const char **' but argument is of \
type 'char **'
In order to suppress these warnings, since both of the main
functions need to be declared with the same prototype, we
change the declaration of the 9 main functions, thus:
int main(int argc, char **argv)
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit cbfd5e1c ("drop some obsolete "x = x" compiler warning hacks",
21-03-2013) removed a gcc hack that suppressed an "might be used
uninitialized" warning issued by older versions of gcc.
However, commit 3aa99df8 ('fast-import: clarify "inline" logic in
file_change_m', 21-03-2013) addresses an (almost) identical issue
(with very similar code), but includes additional code in it's
resolution. The solution used by this commit, unlike that used by
commit cbfd5e1c, also suppresses the -Wuninitialized warning on
older versions of gcc.
In order to suppress the warning (against the 'oe' symbol) in the
note_change_n() function, we adopt the same solution used by commit
3aa99df8.
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we read a fast-import line like:
M 100644 :1 foo.c
we point the local object_entry variable "oe" to the object
named by the mark ":1". When the input uses the "inline"
construct, however, we do not have such an object_entry.
The current code is careful not to access "oe" in the inline
case, but we can make the assumption even more obvious (and
catch violations of it) by setting oe to NULL and adding a
comment. As a bonus, this also squelches an over-zealous gcc
-Wuninitialized warning, which means we can drop the "oe =
oe" initialization hack.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In cases where the setting and access of a variable are
protected by the same conditional flag, older versions of
gcc would generate a "might be used unitialized" warning. We
silence the warning by initializing the variable to itself,
a hack that gcc recognizes.
Modern versions of gcc are smart enough to get this right,
going back to at least version 4.3.5. gcc 4.1 does get it
wrong in both cases, but is sufficiently old that we
probably don't need to care about it anymore.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is shorter, idiomatic, and it means the compiler does
not get confused about whether our "e" pointer is valid,
letting us drop the "e = e" hack.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Optimise the "merge-base" computation a bit, and also update its
users that do not need the full merge-base information to call a
cheaper subset.
* jc/merge-bases:
reduce_heads(): reimplement on top of remove_redundant()
merge-base: "--is-ancestor A B"
get_merge_bases_many(): walk from many tips in parallel
in_merge_bases(): use paint_down_to_common()
merge_bases_many(): split out the logic to paint history
in_merge_bases(): omit unnecessary redundant common ancestor reduction
http-push: use in_merge_bases() for fast-forward check
receive-pack: use in_merge_bases() for fast-forward check
in_merge_bases(): support only one "other" commit
In early days of its life, I planned to make it possible to compute
"is a commit contained in all of these other commits?" with this
function, but it turned out that no caller needed it.
Just make it take two commit objects and add a comment to say what
these two functions do.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The syntax for the use of mark references in fast-import
demands either a SP (space) or LF (end-of-line) after
a mark reference. Fast-import does not complain when garbage
appears after a mark reference in some cases.
Factor out parsing of mark references and complain if
errant characters are found. Also be a little more careful
when parsing "inline" and SHA1s, complaining if extra
characters appear or if the form of the dataref is unrecognized.
Buggy input can cause fast-import to produce the wrong output,
silently, without error. This makes it difficult to track
down buggy generators of fast-import streams. An example is
seen in the last line of this commit command:
commit refs/heads/S2
committer Name <name@example.com> 1112912893 -0400
data <<COMMIT
commit message
COMMIT
from :1M 100644 :103 hello.c
It is missing a newline and should be:
[...]
from :1
M 100644 :103 hello.c
What fast-import does is to produce a commit with the same
contents for hello.c as in refs/heads/S2^. What the buggy
program was expecting was the contents of blob :103. While
the resulting commit graph looked correct, the contents in
some commits were wrong.
Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As the fast-import manual explains:
The value of <path> must be in canonical form. That is it must
not:
. contain an empty directory component (e.g. foo//bar is invalid),
. end with a directory separator (e.g. foo/ is invalid),
. start with a directory separator (e.g. /foo is invalid),
Unfortunately the "ls" command accepts these invalid syntaxes and
responds by declaring that the indicated path is missing. This is too
subtle and causes importers to silently misbehave; better to error out
so the operator knows what's happening.
The C, R, and M commands already error out for such paths.
Reported-by: Andrew Sayers <andrew-git@pileofstuff.org>
Analysis-by: David Barr <davidbarr@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
When the chosen directory has changed since it was last written to
pack, "tree_content_get" makes a deep copy of its content to scribble
on while computing the tree name, which we forgot to free.
This leak has been present since the 'ls' command was introduced in
v1.7.5-rc0~3^2~33 (fast-import: add 'ls' command, 2010-12-02).
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
When running t9300, valgrind (correctly) complains about an
uninitialized value in write_crash_report:
==2971== Use of uninitialised value of size 8
==2971== at 0x4164F4: sha1_to_hex (hex.c:70)
==2971== by 0x4073E4: die_nicely (fast-import.c:468)
==2971== by 0x43284C: die (usage.c:86)
==2971== by 0x40420D: main (fast-import.c:2731)
==2971== Uninitialised value was created by a heap allocation
==2971== at 0x4C29B3D: malloc (vg_replace_malloc.c:263)
==2971== by 0x433645: xmalloc (wrapper.c:35)
==2971== by 0x405DF5: pool_alloc (fast-import.c:619)
==2971== by 0x407755: pool_calloc.constprop.14 (fast-import.c:634)
==2971== by 0x403F33: main (fast-import.c:3324)
Fix this by zeroing all of the 'struct tag'. We would only need to
zero out the 'sha1' field, but this way seems more future-proof.
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
On Solaris the system headers define the "tmpfile" name, which'll
cause Git compiled with Sun Studio 12 Update 1 to whine about us
redefining the name:
"pack-write.c", line 76: warning: name redefined by pragma redefine_extname declared static: tmpfile (E_PRAGMA_REDEFINE_STATIC)
"sha1_file.c", line 2455: warning: name redefined by pragma redefine_extname declared static: tmpfile (E_PRAGMA_REDEFINE_STATIC)
"fast-import.c", line 858: warning: name redefined by pragma redefine_extname declared static: tmpfile (E_PRAGMA_REDEFINE_STATIC)
"builtin/index-pack.c", line 175: warning: name redefined by pragma redefine_extname declared static: tmpfile (E_PRAGMA_REDEFINE_STATIC)
Just renaming the "tmpfile" variable to "tmp_file" in the relevant
places is the easiest way to fix this.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* jc/stream-to-pack:
bulk-checkin: replace fast-import based implementation
csum-file: introduce sha1file_checkpoint
finish_tmp_packfile(): a helper function
create_tmp_packfile(): a helper function
write_pack_header(): a helper function
Conflicts:
pack.h
Change the skeleton implementation of i18n in Git to one that can show
localized strings to users for our C, Shell and Perl programs using
either GNU libintl or the Solaris gettext implementation.
This new internationalization support is enabled by default. If
gettext isn't available, or if Git is compiled with
NO_GETTEXT=YesPlease, Git falls back on its current behavior of
showing interface messages in English. When using the autoconf script
we'll auto-detect if the gettext libraries are installed and act
appropriately.
This change is somewhat large because as well as adding a C, Shell and
Perl i18n interface we're adding a lot of tests for them, and for
those tests to work we need a skeleton PO file to actually test
translations. A minimal Icelandic translation is included for this
purpose. Icelandic includes multi-byte characters which makes it easy
to test various edge cases, and it's a language I happen to
understand.
The rest of the commit message goes into detail about various
sub-parts of this commit.
= Installation
Gettext .mo files will be installed and looked for in the standard
$(prefix)/share/locale path. GIT_TEXTDOMAINDIR can also be set to
override that, but that's only intended to be used to test Git itself.
= Perl
Perl code that's to be localized should use the new Git::I18n
module. It imports a __ function into the caller's package by default.
Instead of using the high level Locale::TextDomain interface I've
opted to use the low-level (equivalent to the C interface)
Locale::Messages module, which Locale::TextDomain itself uses.
Locale::TextDomain does a lot of redundant work we don't need, and
some of it would potentially introduce bugs. It tries to set the
$TEXTDOMAIN based on package of the caller, and has its own
hardcoded paths where it'll search for messages.
I found it easier just to completely avoid it rather than try to
circumvent its behavior. In any case, this is an issue wholly
internal Git::I18N. Its guts can be changed later if that's deemed
necessary.
See <AANLkTilYD_NyIZMyj9dHtVk-ylVBfvyxpCC7982LWnVd@mail.gmail.com> for
a further elaboration on this topic.
= Shell
Shell code that's to be localized should use the git-sh-i18n
library. It's basically just a wrapper for the system's gettext.sh.
If gettext.sh isn't available we'll fall back on gettext(1) if it's
available. The latter is available without the former on Solaris,
which has its own non-GNU gettext implementation. We also need to
emulate eval_gettext() there.
If neither are present we'll use a dumb printf(1) fall-through
wrapper.
= About libcharset.h and langinfo.h
We use libcharset to query the character set of the current locale if
it's available. I.e. we'll use it instead of nl_langinfo if
HAVE_LIBCHARSET_H is set.
The GNU gettext manual recommends using langinfo.h's
nl_langinfo(CODESET) to acquire the current character set, but on
systems that have libcharset.h's locale_charset() using the latter is
either saner, or the only option on those systems.
GNU and Solaris have a nl_langinfo(CODESET), FreeBSD can use either,
but MinGW and some others need to use libcharset.h's locale_charset()
instead.
=Credits
This patch is based on work by Jeff Epler <jepler@unpythonic.net> who
did the initial Makefile / C work, and a lot of comments from the Git
mailing list, including Jonathan Nieder, Jakub Narebski, Johannes
Sixt, Erik Faye-Lund, Peter Krefting, Junio C Hamano, Thomas Rast and
others.
[jc: squashed a small Makefile fix from Ramsay]
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It is useful to be able to rewind a check-summed file to a certain
previous state after writing data into it using sha1write() API. The
fast-import command does this after streaming a blob data to the packfile
being generated and then noticing that the same blob has already been
written, and it does this with a private code truncate_pack() that is
commented as "Yes, this is a layering violation".
Introduce two API functions, sha1file_checkpoint(), that allows the caller
to save a state of a sha1file, and then later revert it to the saved state.
Use it to reimplement truncate_pack().
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This fixes the bug uncovered by the tests added in the previous two patches.
When an existing notes ref was loaded into the fast-import machinery, the
num_notes counter associated with that ref remained == 0, even though the
true number of notes in the loaded ref was higher. This caused a fanout
level of 0 to be used, although the actual fanout of the tree could be > 0.
Manipulating the notes tree at an incorrect fanout level causes removals to
silently fail, and modifications of existing notes to instead produce an
additional note (leaving the old object in place at a different fanout level).
This patch fixes the bug by explicitly counting the number of notes in the
notes tree whenever it looks like the num_notes counter could be wrong (when
num_notes == 0). There may be false positives (i.e. triggering the counting
when the notes tree is truly empty), but in those cases, the counting should
not take long.
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Change check_ref_format() to take a flags argument that indicates what
is acceptable in the reference name (analogous to "git
check-ref-format"'s "--allow-onelevel" and "--refspec-pattern"). This
is more convenient for callers and also fixes a failure in the test
suite (and likely elsewhere in the code) by enabling "onelevel" and
"refspec-pattern" to be allowed independently of each other.
Also rename check_ref_format() to check_refname_format() to make it
obvious that it deals with refnames rather than references themselves.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
'reset' command makes fast-import start a branch from scratch. It's name
is kept in lookup table but it's sha1 is null_sha1 (special value).
'notemodify' command can be used to add a note on branch head given it's
name. lookup_branch() is used it that case and it doesn't check for
null_sha1. So fast-import writes a note for null_sha1 object instead of
giving a error.
Add a check to deny adding a note on empty branch and add a corresponding
test.
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
'reset' command makes fast-import start a branch from scratch. It's name
is kept in lookup table but it's sha1 is null_sha1 (special value).
'tag' command can be used to tag a branch by it's name. lookup_branch()
is used it that case and it doesn't check for null_sha1. So fast-import
writes a tag for null_sha1 object instead of giving a error.
Add a check to deny tagging an empty branch and add a corresponding test.
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* di/fast-import-blob-tweak:
fast-import: treat cat-blob as a delta base hint for next blob
fast-import: count and report # of calls to diff_delta in stats
* di/fast-import-ident:
fsck: improve committer/author check
fsck: add a few committer name tests
fast-import: check committer name more strictly
fast-import: don't fail on omitted committer name
fast-import: add input format tests
fast-import allows to tag objects by sha1 and to query sha1 of objects
being imported. So it should allow to tag these objects, make it do so.
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-import allows to create an annotated tag that annotates a blob,
via mark or direct sha1 specification.
For mark it works, for sha1 it tries to read the object. It tries to
do so via read_sha1_file, and then checks the size to be at least 46.
That's weird, let's just allow to (annotated) tag any object referenced
by sha1. If the object originates from our packfile, we still fail though.
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Delta base for blobs is chosen as a previously saved blob. If we
treat cat-blob's blob as a delta base for the next blob, nothing
is likely to become worse.
For fast-import stream producer like svn-fe cat-blob is used like
following:
- svn-fe reads file delta in svn format
- to apply it, svn-fe asks cat-blob 'svn delta base'
- applies 'svn delta' to the response
- produces a blob command to store the result
Currently there is no way for svn-fe to give fast-import a hint on
object delta base. While what's requested in cat-blob is most of
the time a best delta base possible. Of course, it could be not a
good delta base, but we don't know any better one anyway.
So do treat cat-blob's result as a delta base for next blob. The
profit is nice: 2x to 7x reduction in pack size AND 1.2x to 3x
time speedup due to diff_delta being faster on good deltas. git gc
--aggressive can compress it even more, by 10% to 70%, utilizing
more cpu time, real time and 3 cpu cores.
Tested on 213M and 2.7G fast-import streams, resulting packs are 22M
and 113M, import time is 7s and 60s, both streams are produced by
svn-fe, sniffed and then used as raw input for fast-import.
For git-fast-export produced streams there is no change as it doesn't
use cat-blob and doesn't try to reorder blobs in some smart way to
make successive deltas small.
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Acked-by: David Barr <davidbarr@google.com>
Acked-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It's an interesting number, how often do we try to deltify each type of
objects and how often do we succeed. So do add it to stats.
Success doesn't mean much gain in pack size though. As we allow delta to
be as big as (data.len - 20). And delta close to data.len gains nothing
compared to no delta at all even after zlib compression (delta is pretty
much the same as data, just with few modifications).
We should try to make less attempts that result in huge deltas as these
consume more cpu than trivial small deltas. Either by choosing a better
delta base or reducing delta size upper bound or doing less delta attempts
at all.
Currently, delta base for blobs is a waste literally. Each blob delta
base is chosen as a previously stored blob. Disabling deltas for blobs
doesn't increase pack size and reduce import time, or at least doesn't
increase time for all fast-import streams I've tried.
Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
Acked-by: David Barr <davidbarr@google.com>
Acked-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
