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Author	SHA1	Message	Date
Brandon Casey	040a655116	cleanup: use internal memory allocation wrapper functions everywhere The "x"-prefixed versions of strdup, malloc, etc. will check whether the allocation was successful and terminate the process otherwise. A few uses of malloc were left alone since they already implemented a graceful path of failure or were in a quasi external library like xdiff. Additionally, the call to malloc in compat/win32/syslog.c was not modified since the syslog() implemented there is a die handler and a call to the x-wrappers within a die handler could result in recursion should memory allocation fail. This will have to be addressed separately. Signed-off-by: Brandon Casey <drafnel@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	13 years ago
Brian Downing	43fe901b71	compat: Add simplified merge sort implementation from glibc qsort in Windows 2000 (and various other C libraries) is a Quicksort with the usual O(n^2) worst case. Unfortunately, sorting Git trees seems to get very close to that worst case quite often: $ /git/gitbad runstatus # On branch master qsort, nmemb = 30842 done, 237838087 comparisons. This patch adds a simplified version of the merge sort that is glibc's qsort(3). As a merge sort, this needs a temporary array equal in size to the array that is to be sorted, but has a worst-case performance of O(n log n). The complexity that was removed is: * Doing direct stores for word-size and -aligned data. * Falling back to quicksort if the allocation required to perform the merge sort would likely push the machine into swap. Even with these simplifications, this seems to outperform the Windows qsort(3) implementation, even in Windows XP (where it is "fixed" and doesn't trigger O(n^2) complexity on trees). [jes: moved into compat/qsort.c, as per Johannes Sixt's suggestion] [bcd: removed gcc-ism, thanks to Edgar Toernig. renamed make variable per Junio's comment.] Signed-off-by: Brian Downing <bdowning@lavos.net> Signed-off-by: Steffen Prohaska <prohaska@zib.de> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	17 years ago

Author

SHA1

Message

Date

Brandon Casey

040a655116

cleanup: use internal memory allocation wrapper functions everywhere

The "x"-prefixed versions of strdup, malloc, etc. will check whether the
allocation was successful and terminate the process otherwise.

A few uses of malloc were left alone since they already implemented a
graceful path of failure or were in a quasi external library like xdiff.

Additionally, the call to malloc in compat/win32/syslog.c was not modified
since the syslog() implemented there is a die handler and a call to the
x-wrappers within a die handler could result in recursion should memory
allocation fail.  This will have to be addressed separately.

Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

13 years ago

Brian Downing

43fe901b71

compat: Add simplified merge sort implementation from glibc

qsort in Windows 2000 (and various other C libraries) is a Quicksort
with the usual O(n^2) worst case.  Unfortunately, sorting Git trees
seems to get very close to that worst case quite often:

    $ /git/gitbad runstatus
    # On branch master
    qsort, nmemb = 30842
    done, 237838087 comparisons.

This patch adds a simplified version of the merge sort that is glibc's
qsort(3).  As a merge sort, this needs a temporary array equal in size
to the array that is to be sorted, but has a worst-case performance of
O(n log n).

The complexity that was removed is:

* Doing direct stores for word-size and -aligned data.
* Falling back to quicksort if the allocation required to perform the
  merge sort would likely push the machine into swap.

Even with these simplifications, this seems to outperform the Windows
qsort(3) implementation, even in Windows XP (where it is "fixed" and
doesn't trigger O(n^2) complexity on trees).

[jes: moved into compat/qsort.c, as per Johannes Sixt's suggestion]
[bcd: removed gcc-ism, thanks to Edgar Toernig.  renamed make variable
      per Junio's comment.]

Signed-off-by: Brian Downing <bdowning@lavos.net>
Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

17 years ago

2 Commits (c09cd77ea2fe3580b33918a99fe138d239ac2aaf)