/* given a peer key/len/hashv, reverse engineer its hash function */
static int infer_hash_function(char *key, size_t keylen, uint32_t hashv)
{
uint32_t ohashv;
/* BER SAX FNV OAT JEN SFH */
HASH_JEN(key,keylen,ohashv);
if (ohashv == hashv) {
return JEN;
}
HASH_BER(key,keylen,ohashv);
if (ohashv == hashv) {
return BER;
}
HASH_SFH(key,keylen,ohashv);
if (ohashv == hashv) {
return SFH;
}
HASH_SAX(key,keylen,ohashv);
if (ohashv == hashv) {
return SAX;
}
HASH_FNV(key,keylen,ohashv);
if (ohashv == hashv) {
return FNV;
}
HASH_OAT(key,keylen,ohashv);
if (ohashv == hashv) {
return OAT;
}
HASH_MUR(key,keylen,ohashv);
if (ohashv == hashv) {
return MUR;
}
return 0;
}
static ERL_NIF_TERM
get(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
ERL_NIF_TERM atom;
ErlNifBinary kbin;
struct cache *c;
struct cache_node *n;
struct cache_incr_node *in;
struct timespec now;
int incrqs, hashv, bkt;
ERL_NIF_TERM ret;
ErlNifTid tid;
if (!enif_is_atom(env, argv[0]))
return enif_make_badarg(env);
atom = argv[0];
if (!enif_inspect_binary(env, argv[1], &kbin))
return enif_make_badarg(env);
if ((c = get_cache(atom))) {
enif_rwlock_rlock(c->lookup_lock);
HASH_FIND(hh, c->lookup, kbin.data, kbin.size, n);
if (!n) {
enif_rwlock_runlock(c->lookup_lock);
__sync_add_and_fetch(&c->miss, 1);
enif_consume_timeslice(env, 10);
return enif_make_atom(env, "notfound");
}
if (n->expiry.tv_sec != 0) {
clock_now(&now);
if (n->expiry.tv_sec < now.tv_sec) {
enif_rwlock_runlock(c->lookup_lock);
__sync_add_and_fetch(&c->miss, 1);
enif_consume_timeslice(env, 10);
return enif_make_atom(env, "notfound");
}
}
in = enif_alloc(sizeof(*in));
memset(in, 0, sizeof(*in));
in->node = n;
__sync_add_and_fetch(&c->hit, 1);
tid = enif_thread_self();
HASH_SFH(&tid, sizeof(ErlNifTid), N_INCR_BKT, hashv, bkt);
enif_mutex_lock(c->incr_lock[bkt]);
TAILQ_INSERT_TAIL(&(c->incr_head[bkt]), in, entry);
enif_mutex_unlock(c->incr_lock[bkt]);
incrqs = __sync_add_and_fetch(&(c->incr_count), 1);
ret = enif_make_resource_binary(env, n->val, n->val, n->vsize);
enif_rwlock_runlock(c->lookup_lock);
if (incrqs > 1024)
enif_cond_broadcast(c->check_cond);
enif_consume_timeslice(env, 20);
return ret;
}
return enif_make_atom(env, "notfound");
}
