MB-27554: [BP] Move numTotalItems from HashTable -> VBucket

Originally 04d6809

In Full-Eviction, items may exist in a VBucket without being in the
HashTable, as they may have been fully evicted. As such, numTotalItems
is not a property of the HashTable, it is a property of the VBucket.

Therefore move numTotalItems from HashTable to VBucket, to better
encapsulate the VBucket's state.

Change-Id: Ic45de1ee49468753d7cc76804f8c5cc9eb64f881
Reviewed-on: http://review.couchbase.org/88381
Well-Formed: Build Bot <[email protected]>
Reviewed-by: Jim Walker <[email protected]>
Tested-by: Build Bot <[email protected]>
Reviewed-by: Dave Rigby <[email protected]>

Author: daverigby

engines/ep/src/ep_bucket.cc

@@ -605,7 +605,7 @@ void EPBucket::flushOneDeleteAll() {
             getRWUnderlying(vb->getId())->reset(i);
         }
         // Reset disk item count.
-        vb->ht.setNumTotalItems(0);
+        vb->setNumTotalItems(0);
     }
 
     --stats.diskQueueSize;
@@ -941,7 +941,7 @@ class EPDiskRollbackCB : public RollbackCB {
         }
         // Irrespective of if the in-memory delete succeeded; the document
         // doesn't exist on disk; so decrement the item count.
-        vb.ht.decrNumTotalItems();
+        vb.decrNumTotalItems();
     }
 
 private:

engines/ep/src/ep_vb.cc

@@ -257,15 +257,27 @@ size_t EPVBucket::getNumItems() const {
     if (eviction == VALUE_ONLY) {
         return ht.getNumInMemoryItems() - ht.getNumDeletedItems();
     } else {
-        return ht.getNumTotalItems() - ht.getNumDeletedItems();
+        return onDiskTotalItems;
     }
 }
 
+void EPVBucket::setNumTotalItems(size_t totalItems) {
+    onDiskTotalItems = totalItems;
+}
+
+void EPVBucket::incrNumTotalItems() {
+    ++onDiskTotalItems;
+}
+
+void EPVBucket::decrNumTotalItems() {
+    --onDiskTotalItems;
+}
+
 size_t EPVBucket::getNumNonResidentItems() const {
     if (eviction == VALUE_ONLY) {
         return ht.getNumInMemoryNonResItems();
     } else {
-        size_t num_items = ht.getNumTotalItems();
+        size_t num_items = onDiskTotalItems;
         size_t num_res_items =
                 ht.getNumInMemoryItems() - ht.getNumInMemoryNonResItems();
         return num_items > num_res_items ? (num_items - num_res_items) : 0;

engines/ep/src/ep_vb.h

@@ -71,6 +71,12 @@ class EPVBucket : public VBucket {
 
     size_t getNumItems() const override;
 
+    void setNumTotalItems(size_t items) override;
+
+    void incrNumTotalItems() override;
+
+    void decrNumTotalItems() override;
+
     size_t getNumNonResidentItems() const override;
 
     ENGINE_ERROR_CODE statsVKey(const DocKey& key,
@@ -222,6 +228,14 @@ class EPVBucket : public VBucket {
         return st.getTotalMemoryUsed() + StoredValue::getRequiredStorage(item);
     }
 
+    /**
+     * Total number of alive (non-deleted) items on-disk in this vBucket.
+     * Initially populated during warmup as the number of items on disk;
+     * then incremented / decremented by persistence callbacks as new
+     * items are created & old items deleted.
+     */
+    cb::NonNegativeCounter<size_t> onDiskTotalItems;
+
     /* Indicates if multiple bg fetches are handled in a single bg fetch task */
     const bool multiBGFetchEnabled;
 

engines/ep/src/ephemeral_vb.h

@@ -159,6 +159,21 @@ class EphemeralVBucket : public VBucket {
         return 0;
     }
 
+    void incrNumTotalItems() override {
+        throw std::logic_error(
+                "EphemeralVBucket::incrNumTotalItems not supported");
+    }
+
+    void decrNumTotalItems() override {
+        throw std::logic_error(
+                "EphemeralVBucket::decrNumTotalItems not supported");
+    }
+
+    void setNumTotalItems(size_t items) override {
+        throw std::logic_error(
+                "EphemeralVBucket::setNumTotalItems not supported");
+    }
+
     void queueBackfillItem(queued_item& qi,
                            const GenerateBySeqno generateBySeqno) override;
 

engines/ep/src/hash_table.cc

@@ -49,7 +49,6 @@ HashTable::HashTable(EPStats& st,
       stats(st),
       valFact(std::move(svFactory)),
       visitors(0),
-      numTotalItems(0),
       numItems(0),
       numNonResidentItems(0),
       numDeletedItems(0),
@@ -110,7 +109,6 @@ void HashTable::clear_UNLOCKED(bool deactivate) {
     stats.currentSize.fetch_sub(clearedMemSize - clearedValSize);
 
     datatypeCounts.fill(0);
-    numTotalItems.store(0);
     numItems.store(0);
     numTempItems.store(0);
     numNonResidentItems.store(0);

engines/ep/src/hash_table.h

@@ -227,26 +227,10 @@ class HashTable {
         return numItems;
     }
 
-    void setNumTotalItems(size_t totalItems) {
-        numTotalItems = totalItems;
-    }
-
-    size_t getNumTotalItems() const {
-        return numTotalItems;
-    }
-
     void decrNumItems() {
         --numItems;
     }
 
-    void incrNumTotalItems() {
-        ++numTotalItems;
-    }
-
-    void decrNumTotalItems() {
-        --numTotalItems;
-    }
-
     void decrNumNonResidentItems() {
         --numNonResidentItems;
     }
@@ -672,8 +656,6 @@ class HashTable {
     std::unique_ptr<AbstractStoredValueFactory> valFact;
     std::atomic<size_t>       visitors;
 
-    cb::NonNegativeCounter<size_t> numTotalItems;
-
     /// Count of alive & deleted, in-memory non-resident and resident items.
     /// Excludes temporary items.
     cb::NonNegativeCounter<size_t> numItems;

engines/ep/src/persistence_callback.cc

@@ -51,7 +51,7 @@ void PersistenceCallback::callback(mutation_result& value) {
                 if (value.second) {
                     // Insert in value-only or full eviction mode.
                     ++vbucket->opsCreate;
-                    vbucket->ht.incrNumTotalItems();
+                    vbucket->incrNumTotalItems();
                     vbucket->incrMetaDataDisk(*queuedItem);
                 } else { // Update in full eviction mode.
                     ++vbucket->opsUpdate;

engines/ep/src/vbucket.cc

@@ -1880,7 +1880,7 @@ void VBucket::deletedOnDiskCbk(const Item& queuedItem, bool deleted) {
         }
         if (deleted) {
             // Removed an item from disk - decrement the count of total items.
-            ht.decrNumTotalItems();
+            decrNumTotalItems();
         }
 
         /**

engines/ep/src/vbucket.h

@@ -370,6 +370,17 @@ class VBucket : public std::enable_shared_from_this<VBucket> {
     void incrMetaDataDisk(const Item& qi);
     void decrMetaDataDisk(const Item& qi);
 
+    /// Increase the total count of items in this VBucket by 1.
+    virtual void incrNumTotalItems() = 0;
+
+    /// Decrease the total count of items in this VBucket by 1.
+    virtual void decrNumTotalItems() = 0;
+
+    /**
+     * Set the total count of items in this VBucket to the specified value.
+     */
+    virtual void setNumTotalItems(size_t items) = 0;
+
     /// Reset all statistics assocated with this vBucket.
     virtual void resetStats();
 

engines/ep/src/warmup.cc

@@ -940,7 +940,7 @@ void Warmup::estimateDatabaseItemCount(uint16_t shardId)
                                                         getItemCount(vbid);
         VBucketPtr vb = store.getVBucket(vbid);
         if (vb) {
-            vb->ht.setNumTotalItems(vbItemCount);
+            vb->setNumTotalItems(vbItemCount);
         }
         item_count += vbItemCount;
     }