Number of calls to uthash_strlen about uthash HOT 5 CLOSED

Hmm. That's true, but isn't there a slippery slope here, given that every macro in uthash.h evaluates its arguments multiple times? In the general case, we ought to pull out every macro argument into a local variable, e.g.

#define HASH_VALUE(keyptr,keylen,hashv)                                          \
do {                                                                             \
  HASH_FCN(keyptr, keylen, hashv);                                               \
} while (0)

arguably ought to be

#define HASH_VALUE(keyptr,keylen,hashv)                                          \
do {                                                                             \
  const void *_hv_keyptr = (const void *)(keyptr);                               \
  unsigned _hv_keylen = (keylen);                                                \
  unsigned *_hv_hashv = &(hashv);                                                \
  HASH_FCN(_hv_keyptr, _hv_keylen, *_hv_hashv);                                  \
} while (0)

in order to avoid pessimizing user code like HASH_VALUE(message(i), strlen(message(i)), hasharr[i % hasharr_size()]). At a certain point we have to say "okay, the user should just rewrite their code to use a local variable themselves; they know this stuff is all macros." The question is just where is that point?

Arguably the difference here is that it's possible for user code to use HASH_VALUE efficiently by judicious use of local variables in user code; but it is currently not possible to use HASH_ADD_STR efficiently at all. So HASH_ADD_STR merits fixing and HASH_VALUE doesn't. What's your take on the situation?

from uthash.

I definitely would not touch macros like HASH_VALUE as long as the user has the chance to use local variables in his/her own code when calling the macro. However, it is impossible to do so when calling convenience macros like HASH_FIND_STR, HASH_ADD_STR and HASH_REPLACE_STR. Thus, I'd update only the necessary ones.

from uthash.

PVS-Studio reports:

• V814 Decreased performance. The 'strlen' function was called multiple times inside the body of a loop.

from uthash.

Any chance? PR welcome?

from uthash.

PR welcome.

from uthash.