Rewrote the AVL tree implementation:
- It is now non-recursive with fixed stack usage (large enough for
worst case tree height). twalk and tdestroy are still recursive as
that's smaller/simpler.
- Moved unrelated interfaces into separate translation units.
- The node structure is changed to use indexed children instead of
left/right pointers, this simplifies the balancing logic.
- Using void * pointers instead of struct node * in various places,
because this better fits the api (node address is passed in a void**
argument, so it is tempting to incorrectly cast it to struct node **).
- As a further performance improvement the rebalancing now stops
when it is not needed (subtree height is unchanged). Otherwise
the behaviour should be the same as before (checked over generated
random inputs that the resulting tree shape is equivalent).
- Removed the old copyright notice (including prng related one: it
should be licensed under the same terms as the rest of the project).
.text size of pic tsearch + tfind + tdelete + twalk:
x86_64 i386 aarch64 arm mips powerpc ppc64le sh4 m68k s390x
old 941 899 1220 1068 1852 1400 1600 1008 1008 1488
new 857 881 1040 976 1564 1192 1360 736 820 1408
libc.h was intended to be a header for access to global libc state and
related interfaces, but ended up included all over the place because
it was the way to get the weak_alias macro. most of the inclusions
removed here are places where weak_alias was needed. a few were
recently introduced for hidden. some go all the way back to when
libc.h defined CANCELPT_BEGIN and _END, and all (wrongly implemented)
cancellation points had to include it.
remaining spurious users are mostly callers of the LOCK/UNLOCK macros
and files that use the LFS64 macro to define the awful *64 aliases.
in a few places, new inclusion of libc.h is added because several
internal headers no longer implicitly include libc.h.
declarations for __lockfile and __unlockfile are moved from libc.h to
stdio_impl.h so that the latter does not need libc.h. putting them in
libc.h made no sense at all, since the macros in stdio_impl.h are
needed to use them correctly anyway.
this is not a conformance issue as posix does not specify the
argument order, but the order is specified for bsearch and some
systems document the order for lsearch consistently (openbsd).
since there were two indpendent reports of this issue it's better
to use the more widely expected argument order.
the tsearch data structure is an avl tree, but it did not implement
the deletion operation correctly so the tree could become unbalanced.
reported by Ed Schouten.
There are two changes here, both of which make sense to be done in a
single patch:
- Remove hash from struct elem and compute it at runtime wherever
necessary.
- Eliminate struct elem and use ENTRY directly.
As a result we cut down on the memory usage as each element in the
hash table now contains only an ENTRY not an ENTRY + size_t for the
hash. The downside is that the hash needs to be computed at runtime.
the size and alignment of struct hsearch_data are matched to the glibc
definition for binary compatibility. the members of the structure do
not match, which should not be a problem as long as applications
correctly treat the structure as opaque.
unlike the glibc implementation, this version of hcreate_r does not
require the caller to zero-fill the structure before use.
patch by nsz. the actual object the caller has storing the tree root
has type void *, so accessing it as struct node * is not valid.
instead, simply access the value, move it to a temporary of the
appropriate type and work from there, then move the result back.
