LRU crawler scheduling improvements

when trying to manually run a crawl, the internal autocrawler is now blocked
from restarting for 60 seconds.

the internal autocrawl now independently schedules LRU's, and can re-schedule
sub-LRU's while others are still running. should allow much better memory
control when some sub-lru's (such as TEMP or WARM) are small, or slab classes
are differently sized.

this also makes the crawler drop its lock frequently.. this fixes an issue
where a long crawl happening at the same time as a hash table expansion could
hang the server until the crawl finished.

to improve still:
 - elapsed time can be wrong in the logger entry
 - need to cap number of entries scanned. enough set pressure and a crawl may
   never finish.

1 files changed, 1 insertions, 0 deletions

diff --git a/items.h b/items.h
index 6683bf7..fd573aa 100644
--- a/items.h
+++ b/items.h
@@ -4,6 +4,7 @@
 #define TEMP_LRU 192
 
 #define CLEAR_LRU(id) (id & ~(3<<6))
+#define GET_LRU(id) (id & (3<<6))
 
 /* See items.c */
 uint64_t get_cas_id(void);