/**
* Is key present in the database?
*/
gboolean
dbmw_exists(dbmw_t *dw, gconstpointer key)
{
struct cached *entry;
gboolean ret;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
dw->r_hits++;
return !entry->absent;
}
dw->ioerr = FALSE;
ret = dbmap_contains(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
g_warning("DBMW \"%s\" I/O error whilst checking key existence: %s",
dw->name, dbmap_strerror(dw->dm));
return FALSE;
}
/*
* If the maximum value length of the DB is 0, then it is used as a
* "search table" only, meaning there will be no read to get values,
* only existence checks.
*
* Therefore, it makes sense to cache existence checks. A data read
* will also correctly return a null item from the cache.
*/
if (0 == dw->value_size) {
WALLOC0(entry);
entry->absent = !ret;
(void) allocate_entry(dw, key, entry);
}
return ret;
}
/**
* Is key present in the database?
*/
bool
dbmw_exists(dbmw_t *dw, const void *key)
{
struct cached *entry;
bool ret;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
if (dbg_ds_debugging(dw->dbg, 5, DBG_DSF_CACHING | DBG_DSF_ACCESS)) {
dbg_ds_log(dw->dbg, dw, "%s: read cache hit on %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (absent)" : "");
}
dw->r_hits++;
return !entry->absent;
}
dw->ioerr = FALSE;
ret = dbmap_contains(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
s_warning("DBMW \"%s\" I/O error whilst checking key existence: %s",
dw->name, dbmap_strerror(dw->dm));
return FALSE;
}
/*
* If the maximum value length of the DB is 0, then it is used as a
* "search table" only, meaning there will be no read to get values,
* only existence checks.
*
* Therefore, it makes sense to cache existence checks. A data read
* will also correctly return a null item from the cache.
*
* If the value length is not 0, we only cache negative lookups (i.e.
* the value was not found) because we did not get any value so it is
* possible to record an absent cache entry.
*/
if (0 == dw->value_size || !ret) {
WALLOC0(entry);
entry->absent = !ret;
(void) allocate_entry(dw, key, entry);
if (dbg_ds_debugging(dw->dbg, 2, DBG_DSF_CACHING)) {
dbg_ds_log(dw->dbg, dw, "%s: cached %s key=%s",
G_STRFUNC, entry->absent ? "absent" : "present",
dbg_ds_keystr(dw->dbg, key, (size_t) -1));
}
}
return ret;
}
