[PATCH]: Optimize merge_file_trivial() (Was: Fix issue #4128)
From: Markus Schaber <m.schaber_at_3s-software.com>
Date: Wed, 13 Jun 2012 10:45:04 +0000
Von: Philip Martin [email@example.com]
>> [Context: merge_file_trivial() in merge.c]
> I wonder if we could reduce the file IO by comparing all three files in
> one operation instead of two operations on pairs of files?
In follow-up to my last patch fixing issue #4128, the following patch optimizes merge_file_trivial(). It avoids reading the files twice by using a new comparison function which compares 3 files at once.
Open issues (AFAICS):
- The naming of the functions. (I did use the word three instead of the cipher 3 to avoid confusion with revisioned APIs.)
- The order of parameters. I'm not sure whether 12,23,13 is more natural, or 12,13,23.
Summary of test results:
1618 tests PASSED
85 tests SKIPPED
39 tests XFAILED (1 WORK-IN-PROGRESS)
Optimize merge_file_trivial() by avoiding to read the files twice by using a
new comparison function which compares 3 files at once.
(svn_io_filesizes_three_different_p): Add new declaration
(svn_io_files_contents_three_same_p): Add new declaration
(svn_io_filesizes_three_different_p): Add new function in analogy to svn_io_filesizes_different_p().
(contents_three_identical_p): Add new function in analogy to contents_identical_p().
(svn_io_files_contents_three_same_p): Add new function in analogy to svn_io_files_contents_same_p.
(merge_file_trivial): Use the new three-file comparison functions to avoid reading files twice.
Patch by: Markus Schaber <firstname.lastname@example.org>
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