MB-44056: Mark VBucketCountVisitor getters as const

Lots of simple getters in VBucketCountVisitor are already const in
behaviour but not marked as such.

Mark them as const to allow more convenient use of `const
VBucketCountVisitor&` where appropriate.

Change-Id: I93cb9b5cea30087372c497ad122ee560a29563c2
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/145065
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>

engines/ep/src/ephemeral_bucket.cc

@@ -375,15 +375,15 @@ std::unique_ptr<VBucketCountVisitor> EphemeralBucket::makeVBCountVisitor(
 }
 
 void EphemeralBucket::appendAggregatedVBucketStats(
-        VBucketCountVisitor& active,
-        VBucketCountVisitor& replica,
-        VBucketCountVisitor& pending,
-        VBucketCountVisitor& dead,
+        const VBucketCountVisitor& active,
+        const VBucketCountVisitor& replica,
+        const VBucketCountVisitor& pending,
+        const VBucketCountVisitor& dead,
         const BucketStatCollector& collector) {
     // The CountVisitors passed in are expected to all be Ephemeral subclasses.
-    auto& ephActive = dynamic_cast<EphemeralVBucket::CountVisitor&>(active);
-    auto& ephReplica = dynamic_cast<EphemeralVBucket::CountVisitor&>(replica);
-    auto& ephPending = dynamic_cast<EphemeralVBucket::CountVisitor&>(pending);
+    auto& ephActive = dynamic_cast<const EphemeralVBucket::CountVisitor&>(active);
+    auto& ephReplica = dynamic_cast<const EphemeralVBucket::CountVisitor&>(replica);
+    auto& ephPending = dynamic_cast<const EphemeralVBucket::CountVisitor&>(pending);
 
     // Add stats for the base class:
     KVBucket::appendAggregatedVBucketStats(

engines/ep/src/ephemeral_bucket.h

@@ -164,10 +164,10 @@ class EphemeralBucket : public KVBucket {
             vbucket_state_t state) override;
 
     void appendAggregatedVBucketStats(
-            VBucketCountVisitor& active,
-            VBucketCountVisitor& replica,
-            VBucketCountVisitor& pending,
-            VBucketCountVisitor& dead,
+            const VBucketCountVisitor& active,
+            const VBucketCountVisitor& replica,
+            const VBucketCountVisitor& pending,
+            const VBucketCountVisitor& dead,
             const BucketStatCollector& collector) override;
 
     bool isValidBucketDurabilityLevel(

engines/ep/src/kv_bucket.cc

@@ -1205,10 +1205,10 @@ std::unique_ptr<VBucketCountVisitor> KVBucket::makeVBCountVisitor(
 }
 
 void KVBucket::appendAggregatedVBucketStats(
-        VBucketCountVisitor& active,
-        VBucketCountVisitor& replica,
-        VBucketCountVisitor& pending,
-        VBucketCountVisitor& dead,
+        const VBucketCountVisitor& active,
+        const VBucketCountVisitor& replica,
+        const VBucketCountVisitor& pending,
+        const VBucketCountVisitor& dead,
         const BucketStatCollector& collector) {
     using namespace cb::stats;
     // Top-level stats:

engines/ep/src/kv_bucket.h

@@ -788,10 +788,10 @@ class KVBucket : public KVBucketIface {
      * bucket stats.
      */
     virtual void appendAggregatedVBucketStats(
-            VBucketCountVisitor& active,
-            VBucketCountVisitor& replica,
-            VBucketCountVisitor& pending,
-            VBucketCountVisitor& dead,
+            const VBucketCountVisitor& active,
+            const VBucketCountVisitor& replica,
+            const VBucketCountVisitor& pending,
+            const VBucketCountVisitor& dead,
             const BucketStatCollector& collector);
 
     /**

engines/ep/src/vb_count_visitor.h

@@ -36,27 +36,27 @@ class VBucketCountVisitor : public VBucketVisitor {
 
     void visitBucket(const VBucketPtr& vb) override;
 
-    vbucket_state_t getVBucketState() {
+    vbucket_state_t getVBucketState() const {
         return desired_state;
     }
 
-    size_t getNumItems() {
+    size_t getNumItems() const {
         return numItems;
     }
 
-    size_t getNumTempItems() {
+    size_t getNumTempItems() const {
         return numTempItems;
     }
 
-    size_t getNonResident() {
+    size_t getNonResident() const {
         return nonResident;
     }
 
-    size_t getVBucketNumber() {
+    size_t getVBucketNumber() const {
         return numVbucket;
     }
 
-    size_t getMemResidentPer() {
+    size_t getMemResidentPer() const {
         if (numItems && numItems >= nonResident) {
             size_t numResident = numItems - nonResident;
             return size_t(numResident * 100.0) / (numItems);
@@ -65,83 +65,83 @@ class VBucketCountVisitor : public VBucketVisitor {
         return 100;
     }
 
-    size_t getEjects() {
+    size_t getEjects() const {
         return numEjects;
     }
 
-    size_t getExpired() {
+    size_t getExpired() const {
         return numExpiredItems;
     }
 
-    size_t getMetaDataMemory() {
+    size_t getMetaDataMemory() const {
         return metaDataMemory;
     }
 
-    size_t getMetaDataDisk() {
+    size_t getMetaDataDisk() const {
         return metaDataDisk;
     }
 
-    size_t getCheckpointMemory() {
+    size_t getCheckpointMemory() const {
         return checkpointMemory;
     }
 
-    size_t getCheckpointMemoryUnreferenced() {
+    size_t getCheckpointMemoryUnreferenced() const {
         return checkpointMemoryUnreferenced;
     }
 
     size_t getCheckpointMemoryOverhead() const {
         return checkpointMemoryOverhead;
     }
 
-    size_t getHashtableMemory() {
+    size_t getHashtableMemory() const {
         return htMemory;
     }
 
-    size_t getItemMemory() {
+    size_t getItemMemory() const {
         return htItemMemory;
     }
 
-    size_t getUncompressedItemMemory() {
+    size_t getUncompressedItemMemory() const {
         return htUncompressedItemMemory;
     }
-    size_t getCacheSize() {
+    size_t getCacheSize() const {
         return htCacheSize;
     }
 
-    size_t getOpsCreate() {
+    size_t getOpsCreate() const {
         return opsCreate;
     }
-    size_t getOpsDelete() {
+    size_t getOpsDelete() const {
         return opsDelete;
     }
-    size_t getOpsGet() {
+    size_t getOpsGet() const {
         return opsGet;
     }
-    size_t getOpsReject() {
+    size_t getOpsReject() const {
         return opsReject;
     }
-    size_t getOpsUpdate() {
+    size_t getOpsUpdate() const {
         return opsUpdate;
     }
-    size_t getQueueSize() {
+    size_t getQueueSize() const {
         return queueSize;
     }
-    size_t getQueueMemory() {
+    size_t getQueueMemory() const {
         return queueMemory;
     }
-    size_t getQueueFill() {
+    size_t getQueueFill() const {
         return queueFill;
     }
-    size_t getQueueDrain() {
+    size_t getQueueDrain() const {
         return queueDrain;
     }
-    uint64_t getAge() {
+    uint64_t getAge() const {
         return queueAge;
     }
-    size_t getPendingWrites() {
+    size_t getPendingWrites() const {
         return pendingWrites;
     }
-    size_t getChkPersistRemaining() {
+    size_t getChkPersistRemaining() const {
         return chkPersistRemaining;
     }
 
@@ -152,30 +152,30 @@ class VBucketCountVisitor : public VBucketVisitor {
         return datatypeCounts.size();
     }
 
-    uint64_t getRollbackItemCount() {
+    uint64_t getRollbackItemCount() const {
         return rollbackItemCount;
     }
 
-    size_t getNumHpVBReqs() {
+    size_t getNumHpVBReqs() const {
         return numHpVBReqs;
     }
 
-    HLC::DriftStats getTotalAbsHLCDrift() {
+    HLC::DriftStats getTotalAbsHLCDrift() const {
         return totalAbsHLCDrift;
     }
-    HLC::DriftExceptions getTotalHLCDriftExceptionCounters() {
+    HLC::DriftExceptions getTotalHLCDriftExceptionCounters() const {
         return totalHLCDriftExceptionCounters;
     }
 
-    size_t getSyncWriteAcceptedCount() {
+    size_t getSyncWriteAcceptedCount() const {
         return syncWriteAcceptedCount;
     }
 
-    size_t getSyncWriteCommittedCount() {
+    size_t getSyncWriteCommittedCount() const {
         return syncWriteCommittedCount;
     }
 
-    size_t getSyncWriteAbortedCount() {
+    size_t getSyncWriteAbortedCount() const {
         return syncWriteAbortedCount;
     }