kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Junio C Hamano	4175e9e3a8	More static There still are quite a few symbols that ought to be static. Signed-off-by: Junio C Hamano <gitster@pobox.com>	18 years ago
Dana L. How	f02153696f	Alter sha1close() 3rd argument to request flush only update=0 suppressed writing the final SHA-1 but was not used. Now final=0 suppresses SHA-1 finalization, SHA-1 writing, and closing -- in other words, only flush the buffer. Signed-off-by: Dana L. How <danahow@gmail.com> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Dana How	960ccca680	Custom compression levels for objects and packs Add config variables pack.compression and core.loosecompression , and switch --compression=level to pack-objects. Loose objects will be compressed using core.loosecompression if set, else core.compression if set, else Z_BEST_SPEED. Packed objects will be compressed using --compression=level if seen, else pack.compression if set, else core.compression if set, else Z_DEFAULT_COMPRESSION. This is the "pack compression level". Loose objects added to a pack undeltified will be recompressed to the pack compression level if it is unequal to the current loose compression level by the preceding rules, or if the loose object was written while core.legacyheaders = true. Newly deltified loose objects are always compressed to the current pack compression level. Previously packed objects added to a pack are recompressed to the current pack compression level exactly when their deltification status changes, since the previous pack data cannot be reused. In either case, the --no-reuse-object switch from the first patch below will always force recompression to the current pack compression level, instead of assuming the pack compression level hasn't changed and pack data can be reused when possible. This applies on top of the following patches from Nicolas Pitre: [PATCH] allow for undeltified objects not to be reused [PATCH] make "repack -f" imply "pack-objects --no-reuse-object" Signed-off-by: Dana L. How <danahow@gmail.com> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Nicolas Pitre	78d1e84fe5	compute a CRC32 for each object as stored in a pack The most important optimization for performance when repacking is the ability to reuse data from a previous pack as is and bypass any delta or even SHA1 computation by simply copying the raw data from one pack to another directly. The problem with this is that any data corruption within a copied object would go unnoticed and the new (repacked) pack would be self-consistent with its own checksum despite containing a corrupted object. This is a real issue that already happened at least once in the past. In some attempt to prevent this, we validate the copied data by inflating it and making sure no error is signaled by zlib. But this is still not perfect as a significant portion of a pack content is made of object headers and references to delta base objects which are not deflated and therefore not validated when repacking actually making the pack data reuse still not as safe as it could be. Of course a full SHA1 validation could be performed, but that implies full data inflating and delta replaying which is extremely costly, which cost the data reuse optimization was designed to avoid in the first place. So the best solution to this is simply to store a CRC32 of the raw pack data for each object in the pack index. This way any object in a pack can be validated before being copied as is in another pack, including header and any other non deflated data. Why CRC32 instead of a faster checksum like Adler32? Quoting Wikipedia: Jonathan Stone discovered in 2001 that Adler-32 has a weakness for very short messages. He wrote "Briefly, the problem is that, for very short packets, Adler32 is guaranteed to give poor coverage of the available bits. Don't take my word for it, ask Mark Adler. :-)" The problem is that sum A does not wrap for short messages. The maximum value of A for a 128-byte message is 32640, which is below the value 65521 used by the modulo operation. An extended explanation can be found in RFC 3309, which mandates the use of CRC32 instead of Adler-32 for SCTP, the Stream Control Transmission Protocol. In the context of a GIT pack, we have lots of small objects, especially deltas, which are likely to be quite small and in a size range for which Adler32 is dimed not to be sufficient. Another advantage of CRC32 is the possibility for recovery from certain types of small corruptions like single bit errors which are the most probable type of corruptions. OK what this patch does is to compute the CRC32 of each object written to a pack within pack-objects. It is not written to the index yet and it is obviously not validated when reusing pack data yet either. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	18 years ago
Shawn Pearce	e702496e43	Convert memcpy(a,b,20) to hashcpy(a,b). This abstracts away the size of the hash values when copying them from memory location to memory location, much as the introduction of hashcmp abstracted away hash value comparsion. A few call sites were using char* rather than unsigned char* so I added the cast rather than open hashcpy to be void. This is a reasonable tradeoff as most call sites already use unsigned char and the existing hashcmp is also declared to be unsigned char*. [jc: Splitted the patch to "master" part, to be followed by a patch for merge-recursive.c which is not in "master" yet. Fixed the cast in the latter hunk to combine-diff.c which was wrong in the original. Also converted ones left-over in combine-diff.c, diff-lib.c and upload-pack.c ] Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
David Rientjes	78b713a1d0	Make sha1flush void and remove conditional return. Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Joachim B Haga	12f6c308d5	Make zlib compression level configurable, and change default. With the change in default, "git add ." on kernel dir is about twice as fast as before, with only minimal (0.5%) change in object size. The speed difference is even more noticeable when committing large files, which is now up to 8 times faster. The configurability is through setting core.compression = [-1..9] which maps to the zlib constants; -1 is the default, 0 is no compression, and 1..9 are various speed/size tradeoffs, 9 being slowest. Signed-off-by: Joachim B Haga (cjhaga@fys.uio.no) Acked-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Florian Forster	1d7f171c3a	Remove all void-pointer arithmetic. ANSI C99 doesn't allow void-pointer arithmetic. This patch fixes this in various ways. Usually the strategy that required the least changes was used. Signed-off-by: Florian Forster <octo@verplant.org> Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Junio C Hamano	1c15afb934	xread/xwrite: do not worry about EINTR at calling sites. We had errno==EINTR check after read(2)/write(2) sprinkled all over the places, always doing continue. Consolidate them into xread()/xwrite() wrapper routines. Credits for suggestion goes to HPA -- bugs are mine. Signed-off-by: Junio C Hamano <junkio@cox.net>	19 years ago
Sergey Vlasov	7bf058f008	[PATCH] Plug memory leak in sha1close() sha1create() and sha1fd() malloc the returned struct sha1file; sha1close() should free it. Signed-off-by: Sergey Vlasov <vsu@altlinux.ru> Signed-off-by: Junio C Hamano <junkio@cox.net>	20 years ago
Junio C Hamano	f312de018b	[PATCH] Let umask do its work upon filesystem object creation. IIRC our strategy was to let the users' umask take care of the final mode bits. This patch fixes places that deviate from it. Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>	20 years ago
Linus Torvalds	4397f0148a	csum-file: add "sha1fd()" to create a SHA1 csum file from an existing file descriptor We'll use this soon to write pack-files to stdout.	20 years ago
Linus Torvalds	2700628e64	csum-file: fix missing buf pointer update This would create broken pack archives for anything nontrivial.	20 years ago
Linus Torvalds	e18088451d	csum-file interface updates: return resulting SHA1 Also, make the writing of the SHA1 as a end-header be conditional: not every user will necessarily want to write the SHA1 to the file itself, even though current users do (but we migh end up using the same helper functions for the object files themselves, that don't do this). This also makes the packed index file contain the SHA1 of the packed data file at the end (just before its own SHA1). That way you can validate the pairing of the two if you want to.	20 years ago
Linus Torvalds	c38138cd78	git-pack-objects: write the pack files with a SHA1 csum We want to be able to check their integrity later, and putting the sha1-sum of the contents at the end is a good thing. The writing routines are generic, so we could try to re-use them for the index file, instead of having the same logic duplicated. Update unpack-objects to know about the extra 20 bytes at the end of the index.	20 years ago

15 Commits (3c740268c40f10010dd5dec7df85a1f0d2062c59)