first pass at LRU maintainer thread

The basics work, but tests still do not pass.

A background thread wakes up once per second, or when signaled. It is signaled
if a slab class gets an allocation request and has fewer than N chunks free.

The background thread shuffles LRU's: HOT, WARM, COLD. HOT is where new items
exist. HOT and WARM flow into COLD. Active items in COLD flow back to WARM.
Evictions are pulled from COLD.

item_update's no longer do anything (and need to be fixed to tick it->time).
Items are reshuffled within or around LRU's as they reach the bottom.

Ratios of HOT/WARM memory are hardcoded, as are the low/high watermarks.
Thread is not fast enough right now, sets cannot block on it.

1 files changed, 7 insertions, 0 deletions

diff --git a/items.h b/items.h
index 88d7c21..3eccfa3 100644
--- a/items.h
+++ b/items.h
@@ -33,6 +33,13 @@ enum crawler_result_type {
     CRAWLER_OK=0, CRAWLER_RUNNING, CRAWLER_BADCLASS
 };
 
+int start_lru_maintainer_thread(void);
+int stop_lru_maintainer_thread(void);
+int init_lru_maintainer(void);
+void lru_maintainer_pause(void);
+void lru_maintainer_resume(void);
+void lru_maintainer_wake(int slabs_clsid);
+
 int start_item_crawler_thread(void);
 int stop_item_crawler_thread(void);
 int init_lru_crawler(void);