[postgis-devel] memory management questions #1

[Nicklas Avén]

Hallo

I'm trying to learn some more and are studying the distance-functions
through cunit and valgrind.

My first question is:

I think lwgeom_free and lwgeom_release seems to do much the same thing. 
Why do we have both? When to use which one?

and another small question:

I found that the bbox was not released when calling lwgeom_free with
points. For other types there is a check for bbox and they are freed but
not for points in lwpoint_free.

Is that for some reason or is it a bug?



Then I have a third question that maybe wrong time to ask since Paul is
working on the parser. But I get memory leaks when using
lwgeom_from_ewkt looking like this:

==32144== 37 bytes in 1 blocks are definitely lost in loss record 2 of 3
==32144==    at 0x4C274A8: malloc (vg_replace_malloc.c:236)
==32144==    by 0x42BB7F: make_serialized_lwgeom (lwgparse.c:1387)
==32144==    by 0x42CA2A: parse_it (lwgparse.c:1730)
==32144==    by 0x417253: serialized_lwgeom_from_ewkt (lwgeom.c:758)
==32144==    by 0x417DB3: lwgeom_from_ewkt (lwgeom.c:736)
==32144==    by 0x40A02F: test_mindistance2d_tolerance
(cu_measures.c:35)
==32144==    by 0x50B32A9: ??? (in /usr/lib/libcunit.so.1.0.1)
==32144==    by 0x50B3ACE: CU_run_test (in /usr/lib/libcunit.so.1.0.1)
==32144==    by 0x411B6B: main (cu_tester.c:138)


and the test then looked like this:

static void test_mindistance2d_tolerance(void)
{		
	LWGEOM *lw1;
	lw1 = lwgeom_from_ewkt("LINESTRING(0 0, 1 1)", PARSER_CHECK_NONE);
	lwgeom_free(lw1);
}


As I understand it we never free *serialized_lwgeom in
LWGEOM_PARSER_RESULT

and I think it should be done in lwgeom_from_ewkt after the result are
deserialized

in the structure LWGEOM_PARSER_RESULT there is also room for a pointer
to the LWGEOM version of the geometry, do we use that?


I have only tested those things above on trunk r6120 so maybe the parser
rewriting is affecting.

I am glad for any hint to help me understand.


Thanks
Nicklas
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