/**
* Clear the cache, discard everything.
*/
static void
dbmw_clear_cache(dbmw_t *dw)
{
dbmw_check(dw);
/*
* In the cache, the hash list and the value cache share the same
* key pointers. Therefore, we need to iterate on the map only
* to free both at the same time.
*/
hash_list_clear(dw->keys);
map_foreach_remove(dw->values, free_cached, dw);
}
/**
* Iterate over the DB, invoking the callback on each item along with the
* supplied argument and removing the item when the callback returns TRUE.
*/
void dbmw_foreach_remove(dbmw_t *dw, dbmw_cbr_t cbr, gpointer arg)
{
struct foreach_ctx ctx;
struct cache_foreach_ctx fctx;
dbmw_check(dw);
/*
* Before iterating we flush the deleted keys we know about in the cache
* and whose deletion was deferred, so that the underlying map will
* not have to iterate on them.
*/
dbmw_sync(dw, DBMW_SYNC_CACHE | DBMW_DELETED_ONLY);
/*
* Some values may be present only in the cache. Hence we clear all
* marks in the cache and each traversed value that happens to be
* present in the cache will be marked as "traversed".
*
* We flushed deleted keys above, but that does not remove them from
* the cache structure. We don't need to traverse these after iterating
* on the map, so we make sure they are artifically set to "traversed".
*/
ctx.u.cbr = cbr;
ctx.arg = arg;
ctx.dw = dw;
map_foreach(dw->values, cache_reset_before_traversal, NULL);
dbmap_foreach_remove(dw->dm, dbmw_foreach_remove_trampoline, &ctx);
fctx.removing = TRUE;
fctx.foreach = &ctx;
fctx.u.cbr = dbmw_foreach_remove_trampoline;
/*
* Continue traversal with all the cached entries that were not traversed
* already because they do not exist in the underlying map.
*
* Any cached entry that needs to be removed will be marked as such
* and we'll complete processing by discarding from the cache all
* the entries that have been marked as "removable" during the traversal.
*/
map_foreach(dw->values, cache_finish_traversal, &fctx);
map_foreach_remove(dw->values, cache_free_removable, dw);
}
/**
* Iterate over the DB, invoking the callback on each item along with the
* supplied argument and removing the item when the callback returns TRUE.
*
* @return the amount of removed entries.
*/
size_t
dbmw_foreach_remove(dbmw_t *dw, dbmw_cbr_t cbr, void *arg)
{
struct foreach_ctx ctx;
struct cache_foreach_ctx fctx;
size_t pruned;
dbmw_check(dw);
if (dbg_ds_debugging(dw->dbg, 1, DBG_DSF_ITERATOR)) {
dbg_ds_log(dw->dbg, dw, "%s: starting with %s(%p)", G_STRFUNC,
stacktrace_function_name(cbr), arg);
}
/*
* Before iterating we flush the deleted keys we know about in the cache
* and whose deletion was deferred, so that the underlying map will
* not have to iterate on them.
*/
dbmw_sync(dw, DBMW_SYNC_CACHE | DBMW_DELETED_ONLY);
/*
* Some values may be present only in the cache. Hence we clear all
* marks in the cache and each traversed value that happens to be
* present in the cache will be marked as "traversed".
*
* We flushed deleted keys above, but that does not remove them from
* the cache structure. We don't need to traverse these after iterating
* on the map, so we make sure they are artifically set to "traversed".
*/
ctx.u.cbr = cbr;
ctx.arg = arg;
ctx.dw = dw;
map_foreach(dw->values, cache_reset_before_traversal, NULL);
pruned = dbmap_foreach_remove(dw->dm, dbmw_foreach_remove_trampoline, &ctx);
ZERO(&fctx);
fctx.removing = TRUE;
fctx.foreach = &ctx;
fctx.u.cbr = dbmw_foreach_remove_trampoline;
/*
* Continue traversal with all the cached entries that were not traversed
* already because they do not exist in the underlying map.
*
* We count these and remember how many there are so that we can determine
* the correct overall item count after an iteration without having to
* flush all the dirty values!
*
* Any cached entry that needs to be removed will be marked as such
* and we'll complete processing by discarding from the cache all
* the entries that have been marked as "removable" during the traversal.
*/
map_foreach(dw->values, cache_finish_traversal, &fctx);
map_foreach_remove(dw->values, cache_free_removable, dw);
dw->cached = fctx.cached;
dw->count_needs_sync = FALSE; /* We just counted items the slow way! */
if (dbg_ds_debugging(dw->dbg, 1, DBG_DSF_ITERATOR)) {
dbg_ds_log(dw->dbg, dw, "%s: done with %s(%p): "
"pruned %zu from dbmap, %zu from cache (%zu total), "
"has %zu unflushed entr%s in cache",
G_STRFUNC,
stacktrace_function_name(cbr), arg,
pruned, fctx.removed, pruned + fctx.removed,
dw->cached, plural_y(dw->cached));
}
return pruned + fctx.removed;
}