/**
* This method is used to force a vacuum up to the current
* version. It is generally unsafe to use in bloomd,
* but can be used in an embeded or test environment.
*/
void filtmgr_vacuum(bloom_filtmgr *mgr) {
unsigned long long vsn = mgr->vsn;
merge_old_versions(mgr, mgr->delta, vsn);
swap_filter_maps(mgr, vsn);
merge_old_versions(mgr, mgr->delta, vsn);
delete_old_versions(mgr, vsn);
}
/**
* This method is used to force a vacuum up to the current
* version. It is generally unsafe to use in hlld,
* but can be used in an embeded or test environment.
*/
void setmgr_vacuum(hlld_setmgr *mgr) {
unsigned long long vsn = mgr->vsn;
merge_old_versions(mgr, mgr->delta, vsn);
swap_set_maps(mgr, vsn);
merge_old_versions(mgr, mgr->delta, vsn);
delete_old_versions(mgr, vsn);
}
/**
* Merges changes into the alternate tree from the delta lists
* Safety: Safe ONLY if no other thread is using alt_filter_map
*/
static void merge_old_versions(bloom_filtmgr *mgr, filter_list *delta, unsigned long long min_vsn) {
// Handle older delta first (bottom up)
if (delta->next) merge_old_versions(mgr, delta->next, min_vsn);
// Check if we should skip this update
if (delta->vsn > min_vsn) return;
// Handle current update
bloom_filter_wrapper *s = delta->filter;
switch (delta->type) {
case CREATE:
art_insert(mgr->alt_filter_map, (unsigned char*)s->filter->filter_name, strlen(s->filter->filter_name)+1, s);
break;
case DELETE:
art_delete(mgr->alt_filter_map, (unsigned char*)s->filter->filter_name, strlen(s->filter->filter_name)+1);
break;
case BARRIER:
// Ignore the barrier...
break;
}
}
/**
* This thread is started after initialization to maintain
* the state of the filter manager. It's current use is to
* cleanup the garbage created by our MVCC model. We do this
* by making use of periodic 'checkpoints'. Our worker threads
* report the version they are currently using, and we are always
* able to delete versions that are strictly less than the minimum.
*/
static void* filtmgr_thread_main(void *in) {
// Extract our arguments
bloom_filtmgr *mgr = in;
unsigned long long min_vsn, mgr_vsn;
while (mgr->should_run) {
// Do nothing if there is no changes
if (mgr->vsn == mgr->primary_vsn) {
usleep(VACUUM_POLL_USEC);
continue;
}
/*
* Because we use a version barrier, we always
* end up creating a new version when we try to
* apply delta updates. We need to handle the special case
* where we are 1 version behind and the only delta is
* a barrier. Do this by just updating primary_vsn.
*/
mgr_vsn = mgr->vsn;
if ((mgr_vsn - mgr->primary_vsn) == 1) {
pthread_mutex_lock(&mgr->write_lock);
// Ensure no version created in the mean time
int should_continue = 0;
if (mgr_vsn == mgr->vsn && mgr->delta->type == BARRIER) {
mgr->primary_vsn = mgr_vsn;
should_continue = 1;
}
// Release the lock and see if we should loop back
pthread_mutex_unlock(&mgr->write_lock);
if (should_continue) {
syslog(LOG_INFO, "All updates applied. (vsn: %llu)", mgr_vsn);
continue;
}
}
// Determine the minimum version
min_vsn = client_min_vsn(mgr);
// Warn if there are a lot of outstanding deltas
if (mgr->vsn - min_vsn > WARN_THRESHOLD) {
syslog(LOG_WARNING, "Many delta versions detected! min: %llu (vsn: %llu)",
min_vsn, mgr->vsn);
} else {
syslog(LOG_DEBUG, "Applying delta update up to: %llu (vsn: %llu)",
min_vsn, mgr->vsn);
}
// Merge the old versions into the alternate three
merge_old_versions(mgr, mgr->delta, min_vsn);
/*
* Mark any pending deletes so that create does not allow
* a filter to be created before we manage to call delete_old_versions.
* There is an unforunate race that can happen if a client
* does a create/drop/create cycle, where the create/drop are
* reflected in the filter_map, and thus the second create is allowed
* BEFORE we have had a chance to actually handle the delete.
*/
mark_pending_deletes(mgr, min_vsn);
// Swap the maps
swap_filter_maps(mgr, min_vsn);
// Wait on a barrier until nobody is using the old tree
version_barrier(mgr);
// Merge the changes into the other tree now that its safe
merge_old_versions(mgr, mgr->delta, min_vsn);
// Both trees have the changes incorporated, safe to delete
delete_old_versions(mgr, min_vsn);
// Clear the pending delete list, since delete_old_versions() will
// block untill all deletes are completed.
clear_pending_deletes(mgr);
// Log that we finished
syslog(LOG_INFO, "Finished delta updates up to: %llu (vsn: %llu)",
min_vsn, mgr->vsn);
}
return NULL;
}
