/**
* Build the PATRICIA that maps a message name string into our internal
* message ID.
*/
static void
g2_msg_build_map(void)
{
uint i;
STATIC_ASSERT(G2_MSG_MAX == G_N_ELEMENTS(g2_msg_english_names));
STATIC_ASSERT(G2_MSG_MAX == G_N_ELEMENTS(g2_msg_symbolic_names));
g_assert(NULL == g2_msg_pt);
/*
* We must be prepared to handle all the possible packet names, not just
* the ones we know. Therefore, the PATRICIA key size is computed to be
* able to handle the maximum architected size.
*/
g2_msg_pt = patricia_create(G2_FRAME_NAME_LEN_MAX * 8); /* Size in bits */
for (i = 0; i < G_N_ELEMENTS(g2_msg_symbolic_names); i++) {
const char *key = g2_msg_symbolic_names[i];
size_t len = strlen(key);
patricia_insert_k(g2_msg_pt, key, len * 8, int_to_pointer(i));
}
}
/**
* Create a map implemented as a PATRICIA tree with constant-width keys.
*
* @param keybits the size of all the keys, in bits.
*/
map_t *
map_create_patricia(size_t keybits)
{
map_t *m;
WALLOC(m);
m->magic = MAP_MAGIC;
m->type = MAP_PATRICIA;
m->u.pt = patricia_create(keybits);
return m;
}
/*
* Offload keys to remote node, as appropriate.
*
* Firstly we only consider remote nodes whose KUID falls within our k-ball.
*
* Secondly, we are only considering remote nodes that end-up being in our
* routing table (i.e. ones which are close enough to us to get room in the
* table, which also means they're not firewalled nor going to shutdown soon).
* This is normally ensured by our caller.
*
* Thirdly, we are only going to consider keys closer to the node than we are
* and for which we are the closest among our k-closest nodes, to avoid too
* many redundant STORE operations.
*/
void
keys_offload(const knode_t *kn)
{
struct offload_context ctx;
unsigned n;
knode_t *kclosest[KDA_K]; /* Our known k-closest nodes */
bool debug;
knode_check(kn);
if (kn->flags & (KNODE_F_FIREWALLED | KNODE_F_SHUTDOWNING))
return;
if (
!dht_bootstrapped() || /* Not bootstrapped */
!keys_within_kball(kn->id) || /* Node KUID outside our k-ball */
0 == hikset_count(keys) /* No keys held */
)
return;
debug = GNET_PROPERTY(dht_storage_debug) > 1 ||
GNET_PROPERTY(dht_publish_debug) > 1;
if (debug)
g_debug("DHT preparing key offloading to %s", knode_to_string(kn));
gnet_stats_inc_general(GNR_DHT_KEY_OFFLOADING_CHECKS);
ctx.our_kuid = get_our_kuid();
ctx.remote_kuid = kn->id;
ctx.found = NULL;
ctx.count = 0;
/*
* We need to have KDA_K closest known alive neighbours in order to
* be able to select proper keys to offload.
*
* Note that we make sure to NOT include the new node in our k-closest set
* since it would always be closer than ourselves to keys we wish to
* offload to it...
*/
n = dht_fill_closest(ctx.our_kuid, kclosest,
G_N_ELEMENTS(kclosest), ctx.remote_kuid, TRUE);
if (n < G_N_ELEMENTS(kclosest)) {
if (debug)
g_warning("DHT got only %u closest alive nodes, cannot offload", n);
return;
}
/*
* Prepare a PATRICIA containing the ID of our k-closest alive nodes
* plus ourselves.
*/
ctx.kclosest = patricia_create(KUID_RAW_BITSIZE);
for (n = 0; n < G_N_ELEMENTS(kclosest); n++) {
patricia_insert(ctx.kclosest, kclosest[n]->id, kclosest[n]->id);
}
patricia_insert(ctx.kclosest, ctx.our_kuid, ctx.our_kuid);
/*
* Select offloading candidate keys.
*/
hikset_foreach(keys, keys_offload_prepare, &ctx);
patricia_destroy(ctx.kclosest);
if (debug) {
g_debug("DHT found %u/%zu offloading candidate%s",
ctx.count, hikset_count(keys), plural(ctx.count));
}
if (ctx.count)
publish_offload(kn, ctx.found);
pslist_free_null(&ctx.found);
}
/**
* Update k-ball information.
*/
void
keys_update_kball(void)
{
kuid_t *our_kuid = get_our_kuid();
knode_t **kvec;
int kcnt;
patricia_t *pt;
int i;
WALLOC_ARRAY(kvec, KDA_K);
kcnt = dht_fill_closest(our_kuid, kvec, KDA_K, NULL, TRUE);
kball.seeded = TRUE;
/*
* If we know of no alive nodes yet, request any node we have in the
* routing table, even "zombies". If we get less than KDA_K of these,
* we definitively know not enough about the DHT structure yet!
*/
if (0 == kcnt) {
kcnt = dht_fill_closest(our_kuid, kvec, KDA_K, NULL, FALSE);
if (kcnt < KDA_K)
kball.seeded = FALSE;
}
pt = patricia_create(KUID_RAW_BITSIZE);
for (i = 0; i < kcnt; i++) {
knode_t *kn = kvec[i];
patricia_insert(pt, kn->id, kn);
}
if (patricia_count(pt)) {
knode_t *furthest = patricia_furthest(pt, our_kuid);
knode_t *closest = patricia_closest(pt, our_kuid);
size_t fbits;
size_t cbits;
kuid_atom_change(&kball.furthest, furthest->id);
kuid_atom_change(&kball.closest, closest->id);
fbits = kuid_common_prefix(kball.furthest, our_kuid);
cbits = kuid_common_prefix(kball.closest, our_kuid);
g_assert(fbits <= cbits);
g_assert(cbits <= KUID_RAW_BITSIZE);
if (GNET_PROPERTY(dht_debug)) {
uint8 width = cbits - fbits;
g_debug("DHT %sk-ball %s %u bit%s (was %u-bit wide)",
kball.seeded ? "" : "(not seeded yet) ",
width == kball.width ? "remained at" :
width > kball.width ? "expanded to" : "shrunk to",
width, plural(width), kball.width);
g_debug("DHT k-ball closest (%zu common bit%s) is %s",
cbits, plural(cbits), knode_to_string(closest));
g_debug("DHT k-ball furthest (%zu common bit%s) is %s",
fbits, plural(fbits), knode_to_string(furthest));
}
STATIC_ASSERT(KUID_RAW_BITSIZE < 256);
kball.furthest_bits = fbits & 0xff;
kball.closest_bits = cbits & 0xff;
kball.width = (cbits - fbits) & 0xff;
kball.theoretical_bits = dht_get_kball_furthest() & 0xff;
gnet_stats_set_general(GNR_DHT_KBALL_FURTHEST, kball.furthest_bits);
gnet_stats_set_general(GNR_DHT_KBALL_CLOSEST, kball.closest_bits);
}
WFREE_ARRAY(kvec, KDA_K);
patricia_destroy(pt);
}
