Ion Gaztañaga wrote:
I just don't know why this function is called when
you call close(). I would need more information. Could you just check if
that destructor does anything apart from closing the segment (if any
base or member has object destruction logic), and print the parameter
"name" just before the assertion so that I can have more clues?
Hi Ion,
yes, the destructor performs two destroy calls in front of the close
call (see below). But it should not give a damn about, destroyed is
destroyed. The call of close should only delete objects that still
exists. I've printed out the name of the named shared object which
triggers the error (it's "shmDefinition"). If I comment out the two
lines which destroy my named shared objects in the destructor, it works.
Hmm, I don't know why it not work when I destroy the objects by hand.
But definitely it should not be done twice.
Platform/Compiler: Linux version 2.6.17.1 (root@karo) (gcc version 4.0.4
20060507 (prerelease) (Debian 4.0.3-3))
Here is a short version of the class with con-/destructor:
13 class Myclass {
14 public:
15 Myclass();
16 ~Myclass();
...
27 private:
...
31 boost::shmem::named_shared_object segment;
32 typedef std::pair shmDefinition;
33 typedef std::pair errDefinition;
34 shmDefinition* shmDef;
35 errDefinition* errDef;
...
37 const char* shmDefStr;
38 const char* errDefStr;
39 };
25 Myclass::Myclass() : shmDefStr("shmDefinition"),
errDefStr("errDefinition")
26 {
27 /* create or open the shared memory segment */
28 if (!segment.open_or_create(SHMNAME,SHMMAX,(void*)0x30000000))
29 {
30 std::cerr << "Can't create or open shm segment!" << std::endl;
31 exit(1);
32 }
33
34 /* try to find a shmDefinition */
35 std::pair shmRef;
36 shmRef = segment.find<shmDefinition>(shmDefStr);
37
38 /* there should be exactly one or nothing */
39 assert(shmRef.second == 0 || shmRef.second == 1);
40
41 /* if there is an old definition, clear it */
42 if (shmRef.second == 1 && shmRef.first)
43 {
44 shmDef = shmRef.first;
45 if (shmDef->first && shmDef->second)
46 {
47 void *shmData =
segment.get_address_from_offset(shmDef->first);
48 segment.deallocate(shmData);
49 }
50 shmDef->first = shmDef->second = 0;
51 }
52 /* build a new one */
53 else
54 {
55 shmDef = segment.construct<shmDefinition>(shmDefStr)(0,0);
56 }
57
58 if (!shmDef)
59 {
60 std::cerr << "Can't create or open shmDef!" << std::endl;
61 exit(1);
62 }
...
90 }
92 Myclass::~Myclass()
93 {
94 /* destroy named definitions */
95 segment.destroy<shmDefinition>(shmDefStr);
96 segment.destroy<errDefinition>(errDefStr);
97 /* close segment, it should be deleted */
98 segment.close();
99 }
Thanks a lot for your reply, Sascha
