Report HashTable item counts in vbucket-details stat

In addition to the overall vbucket-level item counts, also report how
many items, in-memory items and deleted items are in the vbucket's
HashTable.

These can be useful when debugging issues related to item counts.

Change-Id: I19150cfb1945d5abc9f8c176c464cb885ffce8cd
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/158100
Tested-by: Build Bot <[email protected]>
Reviewed-by: Ben Huddleston <[email protected]>

Author: daverigby

engines/ep/docs/stats.org

@@ -543,6 +543,11 @@ The stats below are listed for each vbucket.
 | vb_pending_eject              | Number of times item values got ejected    |
 | vb_pending_expired            | Number of times an item was expired        |
 | ht_memory                     | Memory overhead of the hashtable           |
+| ht_num_deleted_items          | Number of deleted items in the hashtable   |
+| ht_num_in_memory_items        | Number of in-memory items in the hashtable |
+| ht_num_in_memory_non_resident_items | Number of in-memory non-resident items (i.e. items which only have their metadata in memory) |
+| ht_num_items                  | Number of items in the hashtable           |
+| ht_num_temp_items             | Number of temporary items in the hashable  |
 | ht_item_memory                | Total item memory                          |
 | ht_cache_size                 | Total size of cache (Includes non resident |
 |                               | items)                                     |

engines/ep/src/vbucket.cc

@@ -3125,6 +3125,17 @@ void VBucket::_addStats(VBucketStatsDetailLevel detail,
                 add_stat,
                 c);
         addStat("ht_memory", ht.memorySize(), add_stat, c);
+        addStat("ht_num_items", ht.getNumItems(), add_stat, c);
+        addStat("ht_num_deleted_items", ht.getNumDeletedItems(), add_stat, c);
+        addStat("ht_num_in_memory_items",
+                ht.getNumInMemoryItems(),
+                add_stat,
+                c);
+        addStat("ht_num_in_memory_non_resident_items",
+                ht.getNumInMemoryNonResItems(),
+                add_stat,
+                c);
+        addStat("ht_num_temp_items", ht.getNumTempItems(), add_stat, c);
         addStat("ht_item_memory", ht.getItemMemory(), add_stat, c);
         addStat("ht_item_memory_uncompressed",
                 ht.getUncompressedItemMemory(),

engines/ep/tests/ep_testsuite.cc

@@ -6826,6 +6826,11 @@ static enum test_result test_mb19687_fixed(EngineIface* h) {
               "vb_0:ht_item_memory",
               "vb_0:ht_item_memory_uncompressed",
               "vb_0:ht_memory",
+              "vb_0:ht_num_deleted_items",
+              "vb_0:ht_num_in_memory_items",
+              "vb_0:ht_num_in_memory_non_resident_items",
+              "vb_0:ht_num_items",
+              "vb_0:ht_num_temp_items",
               "vb_0:ht_size",
               "vb_0:logical_clock_ticks",
               "vb_0:max_cas",