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Revision 24ff4d56cf400126aa93ac9a5b9d8a21afadf3f6 authored by Björn Gustavsson on 06 March 2010, 14:30:29 UTC, committed by Junio C Hamano on 07 March 2010, 07:53:00 UTC 
apply: Remove the quick rejection test
 
In the next commit, we will make it possible for blank context
lines to match beyond the end of the file. That means that a hunk
with a preimage that has more lines than present in the file may
be possible to successfully apply. Therefore, we must remove
the quick rejection test in find_pos().

find_pos() will already work correctly without the quick
rejection test, but that might not be obvious. Therefore,
comment the test for handling out-of-range line numbers in
find_pos() and cast the "line" variable to the same (unsigned)
type as img->nr.

What are performance implications of removing the quick
rejection test?

It can only help "git apply" to reject a patch faster. For example,
if I have a file with one million lines and a patch that removes
slightly more than 50 percent of the lines and try to apply that
patch twice, the second attempt will fail slightly faster
with the test than without (based on actual measurements).

However, there is the pathological case of a patch with many
more context lines than the default three, and applying that patch
using "git apply -C1". Without the rejection test, the running
time will be roughly proportional to the number of context lines
times the size of the file. That could be handled by writing
a more complicated rejection test (it would have to count the
number of blanks at the end of the preimage), but I don't find
that worth doing until there is a real-world use case that
would benfit from it.

It would be possible to keep the quick rejection test if
--whitespace=fix is not given, but I don't like that from
a testing point of view.

Signed-off-by: Björn Gustavsson <bgustavsson@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 9b25949
Raw File
attr.h 
#ifndef ATTR_H
#define ATTR_H

/* An attribute is a pointer to this opaque structure */
struct git_attr;

/*
 * Given a string, return the gitattribute object that
 * corresponds to it.
 */
struct git_attr *git_attr(const char *);

/* Internal use */
extern const char git_attr__true[];
extern const char git_attr__false[];

/* For public to check git_attr_check results */
#define ATTR_TRUE(v) ((v) == git_attr__true)
#define ATTR_FALSE(v) ((v) == git_attr__false)
#define ATTR_UNSET(v) ((v) == NULL)

/*
 * Send one or more git_attr_check to git_checkattr(), and
 * each 'value' member tells what its value is.
 * Unset one is returned as NULL.
 */
struct git_attr_check {
	struct git_attr *attr;
	const char *value;
};

int git_checkattr(const char *path, int, struct git_attr_check *);

enum git_attr_direction {
	GIT_ATTR_CHECKIN,
	GIT_ATTR_CHECKOUT,
	GIT_ATTR_INDEX,
};
void git_attr_set_direction(enum git_attr_direction, struct index_state *);

#endif /* ATTR_H */
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