/**
* Callback for adns_resolve(), invoked when the resolution is complete.
*/
static void
uhc_host_resolved(const host_addr_t *addrs, size_t n, void *uu_udata)
{
(void) uu_udata;
g_assert(addrs);
/*
* If resolution failed, try again if possible.
*/
if (0 == n) {
if (GNET_PROPERTY(bootstrap_debug))
g_warning("could not resolve UDP host cache \"%s\"",
uhc_ctx.host);
uhc_try_next();
return;
}
if (n > 1) {
size_t i;
host_addr_t *hav;
/* Current UHC was moved to tail by uhc_get_next() */
struct uhc *uhc = hash_list_tail(uhc_list);
/*
* UHC resolved to multiple endpoints. Could be roundrobbin or
* IPv4 and IPv6 addresss. Adding them as seperate entries: if the
* IPv6 is unreachable we have an opportunity to skip it.
* -- JA 24/7/2011
*
* Shuffle the address array before appending them to the UHC list.
* --RAM, 2015-10-01
*/
hav = HCOPY_ARRAY(addrs, n);
SHUFFLE_ARRAY_N(hav, n);
for (i = 0; i < n; i++) {
const char *host = host_addr_port_to_string(hav[i], uhc_ctx.port);
g_debug("BOOT UDP host cache \"%s\" resolved to %s (#%zu)",
uhc_ctx.host, host, i + 1);
uhc_list_append(host);
}
hash_list_remove(uhc_list, uhc); /* Replaced by IP address list */
uhc_free(&uhc);
/*
* We're going to continue and process the first address (in our
* shuffled array). Make sure it is put at the end of the list
* and marked as being used, mimicing what uhc_get_next() would do.
* --RAM, 2015-10-01
*/
{
struct uhc key;
key.host = host_addr_port_to_string(hav[0], uhc_ctx.port);
uhc = hash_list_lookup(uhc_list, &key);
g_assert(uhc != NULL); /* We added the entry above! */
uhc->stamp = tm_time();
uhc->used++;
hash_list_moveto_tail(uhc_list, uhc);
}
uhc_ctx.addr = hav[0]; /* Struct copy */
HFREE_NULL(hav);
} else {
uhc_ctx.addr = addrs[0];
}
if (GNET_PROPERTY(bootstrap_debug))
g_debug("BOOT UDP host cache \"%s\" resolved to %s",
uhc_ctx.host, host_addr_to_string(uhc_ctx.addr));
/*
* Now send the ping.
*/
uhc_send_ping();
}
/**
* Get a new index in the cache, and update LRU data structures.
*
* @param db the database
* @param num page number in the DB for which we want a cache index
*
*
* @return -1 on error, or the allocated cache index.
*/
static int
getidx(DBM *db, long num)
{
struct lru_cache *cache = db->cache;
long n; /* Cache index */
/*
* If we invalidated pages, reuse their indices.
* If we have not used all the pages yet, get the next one.
* Otherwise, use the least-recently requested page.
*/
if (slist_length(cache->available)) {
void *v = slist_shift(cache->available);
n = pointer_to_int(v);
g_assert(n >= 0 && n < cache->pages);
g_assert(!cache->dirty[n]);
g_assert(-1 == cache->numpag[n]);
hash_list_prepend(cache->used, int_to_pointer(n));
} else if (cache->next < cache->pages) {
n = cache->next++;
cache->dirty[n] = FALSE;
hash_list_prepend(cache->used, int_to_pointer(n));
} else {
void *last = hash_list_tail(cache->used);
long oldnum;
gboolean had_ioerr = booleanize(db->flags & DBM_IOERR_W);
hash_list_moveto_head(cache->used, last);
n = pointer_to_int(last);
/*
* This page is no longer cached as its cache index is being reused
* Flush it to disk if dirty before discarding it.
*/
g_assert(n >= 0 && n < cache->pages);
oldnum = cache->numpag[n];
if (cache->dirty[n] && !writebuf(db, oldnum, n)) {
hash_list_iter_t *iter;
void *item;
gboolean found = FALSE;
/*
* Cannot flush dirty page now, probably because we ran out of
* disk space. Look through the cache whether we can reuse a
* non-dirty page instead, which would let us keep the dirty
* page a little longer in the cache, in the hope it can then
* be properly flushed later.
*/
iter = hash_list_iterator_tail(cache->used);
while (NULL != (item = hash_list_iter_previous(iter))) {
long i = pointer_to_int(item);
g_assert(i >= 0 && i < cache->pages);
if (!cache->dirty[i]) {
found = TRUE; /* OK, reuse cache slot #i then */
n = i;
oldnum = cache->numpag[i];
break;
}
}
hash_list_iter_release(&iter);
if (found) {
g_assert(item != NULL);
hash_list_moveto_head(cache->used, item);
/*
* Clear error condition if we had none prior to the flush
* attempt, since we can do without it for now.
*/
if (!had_ioerr)
db->flags &= ~DBM_IOERR_W;
g_warning("sdbm: \"%s\": "
"reusing cache slot used by clean page #%ld instead",
sdbm_name(db), oldnum);
} else {
g_warning("sdbm: \"%s\": cannot discard dirty page #%ld",
sdbm_name(db), oldnum);
return -1;
}
}
g_hash_table_remove(cache->pagnum, ulong_to_pointer(oldnum));
cache->dirty[n] = FALSE;
}
/*
* Record the association between the cache index and the page number.
*/
g_assert(n >= 0 && n < cache->pages);
cache->numpag[n] = num;
g_hash_table_insert(cache->pagnum,
ulong_to_pointer(num), int_to_pointer(n));
return n;
}