int cache_ls(const char *path)
{
DIR *dir;
struct dirent *ent;
int err = 0;
struct cache_slot slot = { NULL };
struct strbuf fullname = STRBUF_INIT;
size_t prefixlen;
if (!path) {
cache_log("[cgit] cache path not specified\n");
return -1;
}
dir = opendir(path);
if (!dir) {
err = errno;
cache_log("[cgit] unable to open path %s: %s (%d)\n",
path, strerror(err), err);
return err;
}
strbuf_addstr(&fullname, path);
strbuf_ensure_end(&fullname, '/');
prefixlen = fullname.len;
while ((ent = readdir(dir)) != NULL) {
if (strlen(ent->d_name) != 8)
continue;
strbuf_setlen(&fullname, prefixlen);
strbuf_addstr(&fullname, ent->d_name);
slot.cache_name = fullname.buf;
if ((err = open_slot(&slot)) != 0) {
cache_log("[cgit] unable to open path %s: %s (%d)\n",
fullname.buf, strerror(err), err);
continue;
}
htmlf("%s %s %10"PRIuMAX" %s\n",
fullname.buf,
sprintftime("%Y-%m-%d %H:%M:%S",
slot.cache_st.st_mtime),
(uintmax_t)slot.cache_st.st_size,
slot.buf);
close_slot(&slot);
}
closedir(dir);
strbuf_release(&fullname);
return 0;
}
/* Print cached content to stdout, generate the content if necessary. */
int cache_process(int size, const char *path, const char *key, int ttl,
cache_fill_fn fn, void *cbdata)
{
unsigned long hash;
int i;
struct strbuf filename = STRBUF_INIT;
struct strbuf lockname = STRBUF_INIT;
struct cache_slot slot;
int result;
/* If the cache is disabled, just generate the content */
if (size <= 0) {
fn(cbdata);
return 0;
}
/* Verify input, calculate filenames */
if (!path) {
cache_log("[cgit] Cache path not specified, caching is disabled\n");
fn(cbdata);
return 0;
}
if (!key)
key = "";
hash = hash_str(key) % size;
strbuf_addstr(&filename, path);
strbuf_ensure_end(&filename, '/');
for (i = 0; i < 8; i++) {
strbuf_addf(&filename, "%x", (unsigned char)(hash & 0xf));
hash >>= 4;
}
strbuf_addbuf(&lockname, &filename);
strbuf_addstr(&lockname, ".lock");
slot.fn = fn;
slot.cbdata = cbdata;
slot.ttl = ttl;
slot.cache_name = filename.buf;
slot.lock_name = lockname.buf;
slot.key = key;
slot.keylen = strlen(key);
result = process_slot(&slot);
strbuf_release(&filename);
strbuf_release(&lockname);
return result;
}
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;
}
