void calculate_all(void)
{
uint_fast8_t i;
for(i = 0; i < num_vertices; i++)
{
slots[1ul << i] = cut_rank(1ul << i);
cslots[1ul << i] = 0x0;
}
for(subset_size = 2; subset_size <= num_vertices; subset_size++)
{
subset_t i;
const subset_t end = binomial_coefficient(num_vertices, subset_size);
for(i = 0; i < end; i++)
fill_slot(i);
}
}
void calculate_level(uint_fast8_t ss)
{
uint_fast8_t i;
subset_size = ss;
if(subset_size == 0)
slots[0] = 0;
else if(subset_size == 1)
for(i = 0; i < num_vertices; i++)
{
slots[1ul << i] = cut_rank(1ul << i);
cslots[1ul << i] = 0x0;
}
else
{
subset_t i;
const subset_t end = binomial_coefficient(num_vertices, subset_size);
for(i = 0; i < end; i++)
fill_slot(i);
}
}
static int process_slot(struct cache_slot *slot)
{
int err;
err = open_slot(slot);
if (!err && slot->match) {
if (is_expired(slot)) {
if (!lock_slot(slot)) {
/* If the cachefile has been replaced between
* `open_slot` and `lock_slot`, we'll just
* serve the stale content from the original
* cachefile. This way we avoid pruning the
* newly generated slot. The same code-path
* is chosen if fill_slot() fails for some
* reason.
*
* TODO? check if the new slot contains the
* same key as the old one, since we would
* prefer to serve the newest content.
* This will require us to open yet another
* file-descriptor and read and compare the
* key from the new file, so for now we're
* lazy and just ignore the new file.
*/
if (is_modified(slot) || fill_slot(slot)) {
unlock_slot(slot, 0);
close_lock(slot);
} else {
close_slot(slot);
unlock_slot(slot, 1);
slot->cache_fd = slot->lock_fd;
}
}
}
if ((err = print_slot(slot)) != 0) {
cache_log("[cgit] error printing cache %s: %s (%d)\n",
slot->cache_name,
strerror(err),
err);
}
close_slot(slot);
return err;
}
/* If the cache slot does not exist (or its key doesn't match the
* current key), lets try to create a new cache slot for this
* request. If this fails (for whatever reason), lets just generate
* the content without caching it and fool the caller to belive
* everything worked out (but print a warning on stdout).
*/
close_slot(slot);
if ((err = lock_slot(slot)) != 0) {
cache_log("[cgit] Unable to lock slot %s: %s (%d)\n",
slot->lock_name, strerror(err), err);
slot->fn();
return 0;
}
if ((err = fill_slot(slot)) != 0) {
cache_log("[cgit] Unable to fill slot %s: %s (%d)\n",
slot->lock_name, strerror(err), err);
unlock_slot(slot, 0);
close_lock(slot);
slot->fn();
return 0;
}
// We've got a valid cache slot in the lock file, which
// is about to replace the old cache slot. But if we
// release the lockfile and then try to open the new cache
// slot, we might get a race condition with a concurrent
// writer for the same cache slot (with a different key).
// Lets avoid such a race by just printing the content of
// the lock file.
slot->cache_fd = slot->lock_fd;
unlock_slot(slot, 1);
if ((err = print_slot(slot)) != 0) {
cache_log("[cgit] error printing cache %s: %s (%d)\n",
slot->cache_name,
strerror(err),
err);
}
close_slot(slot);
return err;
}
