This introduces make variable NO_PTHREADS for platforms that lack the
support for pthreads library or people who do not want to use it for
whatever reason. When defined, it makes the multi-threaded index
preloading into a no-op, and also disables threaded delta searching by
pack-objects.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Mike Ralphson <mike@abacus.co.uk>
Tested-by: Johannes Sixt <j6t@kdbg.org> (AIX 4.3.x)
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the threaded index preloading case, we must be sure to always use the
CE_MATCH_RACY_IS_DIRTY flag when calling ie_match_stat(), in order to make
sure that we only ever look at the stat() data, and don't try to do
anything fancy.
Because most of git internals are not thread-safe, and must not be called
in parallel.
Otherwise, what happens is that if the timestamps indicate that an entry
_might_ be dirty, we might start actually comparing filesystem data with
the object database. And we mustn't do that, because that would involve
looking up and creating the object structure, and that whole code sequence
with read_sha1_file() where we look up and add objects to the hashes is
definitely not thread-safe.
Nor do we want to add locking, because the whole point of the preload was
to be simple and not affect anything else. With CE_MATCH_RACY_IS_DIRTY, we
get what we wanted, and we'll just leave the hard cases well alone, to be
done later in the much simpler serial case.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This can do the lstat() storm in parallel, giving potentially much
improved performance for cold-cache cases or things like NFS that have
weak metadata caching.
Just use "read_cache_preload()" instead of "read_cache()" to force an
optimistic preload of the index stat data. The function takes a
pathspec as its argument, allowing us to preload only the relevant
portion of the index.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
