MB-51719: Add missing formattors for enum classes

Upgrading to fmtlib 8.1.1 removed support for implicitly converting
strongly-typed enums (enum class) to int when printing via fmtlib -
see fmtlib/fmt#1841

This is considered a bug by fmtlib, as strongly-typed enums should be
treated as such - to print them either provide a formatter, or cast to
their underlying type.

This highlighted that we had missed a number of operator<< overloads
for custom enum classes - and one instance where our operator<< was
not used as we were missing an include of <fmt/ostream.h>

Change-Id: If0f4e19f3eff4ebf4b4e3ccec1f0815c794a709b
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/173823
Tested-by: Build Bot <[email protected]>
Reviewed-by: Trond Norbye <[email protected]>

engines/ep/src/dcp/backfill_disk.cc

@@ -16,6 +16,7 @@
 #include "kv_bucket.h"
 #include "kvstore/kvstore.h"
 #include "vbucket.h"
+#include <fmt/ostream.h>
 
 CacheCallback::CacheCallback(KVBucket& bucket, std::shared_ptr<ActiveStream> s)
     : bucket(bucket), streamPtr(s) {

engines/ep/src/kvstore/kvstore.cc

@@ -487,32 +487,32 @@ void KVStore::delSystemEvent(TransactionContext& txnCtx,
     del(txnCtx, item);
 }
 
-std::string to_string(FlushStateDeletion state) {
+std::ostream& operator<<(std::ostream& os, const FlushStateDeletion& state) {
     switch (state) {
     case FlushStateDeletion::Delete:
-        return "FlushStateDeletion::Delete";
+        return os << "FlushStateDeletion::Delete";
     case FlushStateDeletion::LogicallyDocNotFound:
-        return "FlushStateDeletion::LogicallyDocNotFound";
+        return os << "FlushStateDeletion::LogicallyDocNotFound";
     case FlushStateDeletion::DocNotFound:
-        return "FlushStateDeletion::DocNotFound";
+        return os << "FlushStateDeletion::DocNotFound";
     case FlushStateDeletion::Failed:
-        return "FlushStateDeletion::Failed";
+        return os << "FlushStateDeletion::Failed";
     }
-    folly::assume_unreachable();
+    return os << "INVALID FlushStateDeletion value:" << static_cast<int>(state);
 }
 
-std::string to_string(FlushStateMutation state) {
+std::ostream& operator<<(std::ostream& os, const FlushStateMutation& state) {
     switch (state) {
     case FlushStateMutation::Failed:
-        return "FlushStateMutation::Failed";
+        return os << "FlushStateMutation::Failed";
     case FlushStateMutation::Insert:
-        return "FlushStateMutation::Insert";
+        return os << "FlushStateMutation::Insert";
     case FlushStateMutation::LogicalInsert:
-        return "FlushStateMutation::LogicalInsert";
+        return os << "FlushStateMutation::LogicalInsert";
     case FlushStateMutation::Update:
-        return "FlushStateMutation::Update";
+        return os << "FlushStateMutation::Update";
     }
-    folly::assume_unreachable();
+    return os << "INVALID FlushStateMutation value:" << static_cast<int>(state);
 }
 
 IORequest::IORequest(queued_item itm)
@@ -724,4 +724,30 @@ std::string to_string(KVStoreIface::ReadVBStateStatus status) {
         return "Error";
     }
     folly::assume_unreachable();
-}
+}
+
+std::ostream& operator<<(std::ostream& os, const CompactDBStatus& status) {
+    switch (status) {
+    case CompactDBStatus::Success:
+        return os << "CompactDBStatus::Success";
+    case CompactDBStatus::Aborted:
+        return os << "CompactDBStatus::Aborted";
+    case CompactDBStatus::Failed:
+        return os << "CompactDBStatus::Failed";
+    }
+    return os << "INVALID CompactDBStatus value:" << static_cast<int>(status);
+}
+
+std::ostream& operator<<(std::ostream& os,
+                         const KVStoreIface::GetCollectionStatsStatus& status) {
+    switch (status) {
+    case KVStoreIface::GetCollectionStatsStatus::Success:
+        return os << "GetCollectionStatsStatus::Success";
+    case KVStoreIface::GetCollectionStatsStatus::NotFound:
+        return os << "GetCollectionStatsStatus::NotFound";
+    case KVStoreIface::GetCollectionStatsStatus::Failed:
+        return os << "GetCollectionStatsStatus::Failed";
+    }
+    return os << "INVALID GetCollectionStatsStatus value:"
+              << static_cast<int>(status);
+}

engines/ep/src/kvstore/kvstore.h

@@ -1025,9 +1025,6 @@ class KVStore : public KVStoreIface {
     TestingHook<> saveDocsPostWriteDocsHook;
 };
 
-std::string to_string(FlushStateDeletion status);
-std::string to_string(FlushStateMutation state);
-
 /**
  * The KVStoreFactory creates the correct KVStore instance(s) when
  * needed by EPStore.
@@ -1064,4 +1061,4 @@ class RollbackCB : public StatusCallback<GetValue> {
 };
 
 std::ostream& operator<<(std::ostream& os, const ValueFilter& vf);
-std::ostream& operator<<(std::ostream& os, const DocumentFilter& df);
+std::ostream& operator<<(std::ostream& os, const DocumentFilter& df);

engines/ep/src/kvstore/kvstore_fwd.h

@@ -39,6 +39,8 @@ enum class FlushStateDeletion {
     Failed
 };
 
+std::ostream& operator<<(std::ostream& os, const FlushStateDeletion&);
+
 /// Result of flushing a Mutation, passed to the PersistenceCallback.
 enum class FlushStateMutation {
     // An item was inserted (item did not exist before or was previously
@@ -56,3 +58,5 @@ enum class FlushStateMutation {
     // The persistence of the mutation failed
     Failed
 };
+
+std::ostream& operator<<(std::ostream& os, const FlushStateMutation&);

engines/ep/src/kvstore/kvstore_iface.h

@@ -113,6 +113,8 @@ class KVStoreRevision {
  */
 enum class CompactDBStatus { Success, Aborted, Failed };
 
+std::ostream& operator<<(std::ostream&, const CompactDBStatus&);
+
 /**
  * Functional interface of a KVStore. Each KVStore implementation must implement
  * each of these functions.
@@ -759,3 +761,6 @@ class KVStoreIface {
 };
 
 std::string to_string(KVStoreIface::ReadVBStateStatus status);
+
+std::ostream& operator<<(std::ostream&,
+                         const KVStoreIface::GetCollectionStatsStatus&);

engines/ep/src/kvstore/magma-kvstore/magma-kvstore.cc

@@ -814,7 +814,7 @@ void MagmaKVStore::commitCallback(MagmaKVStoreTransactionContext& txnCtx,
                         txnCtx.vbid,
                         cb::UserData(req.getKey().to_string()),
                         errCode,
-                        to_string(state));
+                        state);
             }
 
             txnCtx.deleteCallback(req.getItem(), state);
@@ -848,7 +848,7 @@ void MagmaKVStore::commitCallback(MagmaKVStoreTransactionContext& txnCtx,
                         txnCtx.vbid,
                         cb::UserData(req.getKey().to_string()),
                         errCode,
-                        to_string(state));
+                        state);
             }
 
             txnCtx.setCallback(req.getItem(), state);