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2017-03-15hash.h: move SHA-1 implementation selection into a header fileLibravatar brian m. carlson1-0/+14
Many developers use functionality in their editors that allows for quick syntax checks, including warning about questionable constructs. This functionality allows rapid development with fewer errors. However, such functionality generally does not allow the specification of project-specific defines or command-line options. Since the SHA1_HEADER include is not defined in such a case, developers see spurious errors when using these tools. Furthermore, there are known implementations of "cc" whose '#include' is unhappy with this construct. Instead of using SHA1_HEADER, create a hash.h header and use #if and #elif to select the desired header. Have the Makefile pass an appropriate option to help the header select the right implementation to use. [jc: make BLK_SHA1 the fallback default as discussed on list, e.g. <20170314201424.vccij5z2ortq4a4o@sigill.intra.peff.net>; also remove SHA1_HEADER and SHA1_HEADER_SQ that are no longer used]. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-11-18remove old hash.[ch] implementationLibravatar Karsten Blees1-50/+0
Signed-off-by: Karsten Blees <blees@dcon.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-16Preallocate hash tables when the number of inserts are known in advanceLibravatar Nguyễn Thái Ngọc Duy1-0/+7
This avoids unnecessary re-allocations and reinsertions. On webkit.git (i.e. about 182k inserts to the name hash table), this reduces about 100ms out of 3s user time. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-02-18for_each_hash: allow passing a 'void *data' pointer to callbackLibravatar Linus Torvalds1-1/+1
For the find_exact_renames() function, this allows us to pass the diff_options structure pointer to the low-level routines. We will use that to distinguish between the "rename" and "copy" cases. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-03-09Add 'const' where appropriate to index handling functionsLibravatar Linus Torvalds1-2/+2
This is in an effort to make the source index of 'unpack_trees()' as being const, and thus making the compiler help us verify that we only access it for reading. The constification also extended to some of the hashing helpers that get called indirectly. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-10-26Do linear-time/space rename logic for exact renamesLibravatar Linus Torvalds1-0/+43
This implements a smarter rename detector for exact renames, which rather than doing a pairwise comparison (time O(m*n)) will just hash the files into a hash-table (size O(n+m)), and only do pairwise comparisons to renames that have the same hash (time O(n+m) except for unrealistic hash collissions, which we just cull aggressively). Admittedly the exact rename case is not nearly as interesting as the generic case, but it's an important case none-the-less. A similar general approach should work for the generic case too, but even then you do need to handle the exact renames/copies separately (to avoid the inevitable added cost factor that comes from the _size_ of the file), so this is worth doing. In the expectation that we will indeed do the same hashing trick for the general rename case, this code uses a generic hash-table implementation that can be used for other things too. In fact, we might be able to consolidate some of our existing hash tables with the new generic code in hash.[ch]. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>