diff --git a/src/kvstore/Listener.cpp b/src/kvstore/Listener.cpp
index 523e733c00b..b07499e0b58 100644
--- a/src/kvstore/Listener.cpp
+++ b/src/kvstore/Listener.cpp
@@ -99,7 +99,7 @@ void Listener::stop() {
 bool Listener::preProcessLog(LogID logId,
                              TermID termId,
                              ClusterID clusterId,
-                             const std::string& log) {
+                             folly::StringPiece log) {
   UNUSED(logId);
   UNUSED(termId);
   UNUSED(clusterId);
@@ -147,6 +147,7 @@ void Listener::doApply() {
   if (isStopped()) {
     return;
   }
+
   if (needToCleanupSnapshot()) {
     cleanupSnapshot();
   }
@@ -156,87 +157,89 @@ void Listener::doApply() {
       bgWorkers_->addDelayTask(
           FLAGS_listener_commit_interval_secs * 1000, &Listener::doApply, this);
     };
+    processLogs();
+  });
+}
 
-    std::unique_ptr<LogIterator> iter;
-    {
-      std::lock_guard<std::mutex> guard(raftLock_);
-      if (lastApplyLogId_ >= committedLogId_) {
-        return;
-      }
-      iter = wal_->iterator(lastApplyLogId_ + 1, committedLogId_);
+void Listener::processLogs() {
+  std::unique_ptr<LogIterator> iter;
+  {
+    std::lock_guard<std::mutex> guard(raftLock_);
+    if (lastApplyLogId_ >= committedLogId_) {
+      return;
     }
+    iter = wal_->iterator(lastApplyLogId_ + 1, committedLogId_);
+  }
 
-    LogID lastApplyId = -1;
-    // the kv pair which can sync to remote safely
-    std::vector<KV> data;
-    while (iter->valid()) {
-      lastApplyId = iter->logId();
-
-      auto log = iter->logMsg();
-      if (log.empty()) {
-        // skip the heartbeat
-        ++(*iter);
-        continue;
-      }
+  LogID lastApplyId = -1;
+  // the kv pair which can sync to remote safely
+  std::vector<KV> data;
+  while (iter->valid()) {
+    lastApplyId = iter->logId();
 
-      DCHECK_GE(log.size(), sizeof(int64_t) + 1 + sizeof(uint32_t));
-      switch (log[sizeof(int64_t)]) {
-        case OP_PUT: {
-          auto pieces = decodeMultiValues(log);
-          DCHECK_EQ(2, pieces.size());
-          data.emplace_back(pieces[0], pieces[1]);
-          break;
-        }
-        case OP_MULTI_PUT: {
-          auto kvs = decodeMultiValues(log);
-          DCHECK_EQ((kvs.size() + 1) / 2, kvs.size() / 2);
-          for (size_t i = 0; i < kvs.size(); i += 2) {
-            data.emplace_back(kvs[i], kvs[i + 1]);
-          }
-          break;
-        }
-        case OP_REMOVE:
-        case OP_REMOVE_RANGE:
-        case OP_MULTI_REMOVE: {
-          break;
+    auto log = iter->logMsg();
+    if (log.empty()) {
+      // skip the heartbeat
+      ++(*iter);
+      continue;
+    }
+
+    DCHECK_GE(log.size(), sizeof(int64_t) + 1 + sizeof(uint32_t));
+    switch (log[sizeof(int64_t)]) {
+      case OP_PUT: {
+        auto pieces = decodeMultiValues(log);
+        DCHECK_EQ(2, pieces.size());
+        data.emplace_back(pieces[0], pieces[1]);
+        break;
+      }
+      case OP_MULTI_PUT: {
+        auto kvs = decodeMultiValues(log);
+        DCHECK_EQ(0, kvs.size() % 2);
+        for (size_t i = 0; i < kvs.size(); i += 2) {
+          data.emplace_back(kvs[i], kvs[i + 1]);
         }
-        case OP_BATCH_WRITE: {
-          auto batch = decodeBatchValue(log);
-          for (auto& op : batch) {
-            // OP_BATCH_PUT and OP_BATCH_REMOVE_RANGE is ignored
-            if (op.first == BatchLogType::OP_BATCH_PUT) {
-              data.emplace_back(op.second.first, op.second.second);
-            }
+        break;
+      }
+      case OP_REMOVE:
+      case OP_REMOVE_RANGE:
+      case OP_MULTI_REMOVE: {
+        break;
+      }
+      case OP_BATCH_WRITE: {
+        auto batch = decodeBatchValue(log);
+        for (auto& op : batch) {
+          // OP_BATCH_REMOVE and OP_BATCH_REMOVE_RANGE is igored
+          if (op.first == BatchLogType::OP_BATCH_PUT) {
+            data.emplace_back(op.second.first, op.second.second);
           }
-          break;
-        }
-        case OP_TRANS_LEADER:
-        case OP_ADD_LEARNER:
-        case OP_ADD_PEER:
-        case OP_REMOVE_PEER: {
-          break;
-        }
-        default: {
-          VLOG(2) << idStr_
-                  << "Should not reach here. Unknown operation: " << static_cast<int32_t>(log[0]);
         }
+        break;
       }
-
-      if (static_cast<int32_t>(data.size()) > FLAGS_listener_commit_batch_size) {
+      case OP_TRANS_LEADER:
+      case OP_ADD_LEARNER:
+      case OP_ADD_PEER:
+      case OP_REMOVE_PEER: {
         break;
       }
-      ++(*iter);
+      default: {
+        VLOG(2) << idStr_ << "Unknown operation: " << static_cast<int32_t>(log[0]);
+      }
     }
 
-    // apply to state machine
-    if (lastApplyId != -1 && apply(data)) {
-      std::lock_guard<std::mutex> guard(raftLock_);
-      lastApplyLogId_ = lastApplyId;
-      persist(committedLogId_, term_, lastApplyLogId_);
-      VLOG(2) << idStr_ << "Listener succeeded apply log to " << lastApplyLogId_;
-      lastApplyTime_ = time::WallClock::fastNowInMilliSec();
+    if (static_cast<int32_t>(data.size()) > FLAGS_listener_commit_batch_size) {
+      break;
     }
-  });
+    ++(*iter);
+  }
+
+  // apply to state machine
+  if (lastApplyId != -1 && apply(data)) {
+    std::lock_guard<std::mutex> guard(raftLock_);
+    lastApplyLogId_ = lastApplyId;
+    persist(committedLogId_, term_, lastApplyLogId_);
+    VLOG(2) << idStr_ << "Listener succeeded apply log to " << lastApplyLogId_;
+    lastApplyTime_ = time::WallClock::fastNowInMilliSec();
+  }
 }
 
 std::tuple<nebula::cpp2::ErrorCode, int64_t, int64_t> Listener::commitSnapshot(
@@ -303,5 +306,6 @@ bool Listener::pursueLeaderDone() {
       "pursue leader : leaderCommitId={}, lastApplyLogId_={}", leaderCommitId_, lastApplyLogId_);
   return (leaderCommitId_ - lastApplyLogId_) <= FLAGS_listener_pursue_leader_threshold;
 }
+
 }  // namespace kvstore
 }  // namespace nebula
diff --git a/src/kvstore/Listener.h b/src/kvstore/Listener.h
index 05523c2b248..6f3f994543c 100644
--- a/src/kvstore/Listener.h
+++ b/src/kvstore/Listener.h
@@ -68,6 +68,10 @@ using RaftClient = thrift::ThriftClientManager<raftex::cpp2::RaftexServiceAsyncC
  *        TermID committedLogTerm,
  *        bool finished) override;
  *
+ *   // extra cleanup work, will be invoked when listener is about to be removed,
+ *   // or raft is reset
+ *   void cleanup()；
+ *
  * * Must implement in derived class
  *   // extra initialize work could do here
  *   void init()
@@ -83,10 +87,6 @@ using RaftClient = thrift::ThriftClientManager<raftex::cpp2::RaftexServiceAsyncC
  *
  *   // persist last commit log id/term and lastApplyId
  *   bool persist(LogID, TermID, LogID)
- *
- *   // extra cleanup work, will be invoked when listener is about to be removed,
- *   // or raft is reset
- *   nebula::cpp2::ErrorCode cleanup() = 0
  */
 class Listener : public raftex::RaftPart {
  public:
@@ -270,7 +270,7 @@ class Listener : public raftex::RaftPart {
   bool preProcessLog(LogID logId,
                      TermID termId,
                      ClusterID clusterId,
-                     const std::string& log) override;
+                     folly::StringPiece log) override;
 
   /**
    * @brief If the listener falls behind way to much than leader, the leader will send all its data
@@ -295,6 +295,9 @@ class Listener : public raftex::RaftPart {
    */
   void doApply();
 
+  // Process logs and then call apply to execute
+  virtual void processLogs();
+
  protected:
   LogID leaderCommitId_ = 0;
   LogID lastApplyLogId_ = 0;
diff --git a/src/kvstore/Part.cpp b/src/kvstore/Part.cpp
index 5556b6ae6c9..20a4649fa41 100644
--- a/src/kvstore/Part.cpp
+++ b/src/kvstore/Part.cpp
@@ -409,7 +409,7 @@ nebula::cpp2::ErrorCode Part::putCommitMsg(WriteBatch* batch,
   return batch->put(NebulaKeyUtils::systemCommitKey(partId_), commitMsg);
 }
 
-bool Part::preProcessLog(LogID logId, TermID termId, ClusterID clusterId, const std::string& log) {
+bool Part::preProcessLog(LogID logId, TermID termId, ClusterID clusterId, folly::StringPiece log) {
   // We should apply any membership change which happens before start time. Because when we start
   // up, the peers comes from meta, has already contains all previous changes.
   VLOG(4) << idStr_ << "logId " << logId << ", termId " << termId << ", clusterId " << clusterId;
diff --git a/src/kvstore/Part.h b/src/kvstore/Part.h
index 7db8586dfea..72dc9433af8 100644
--- a/src/kvstore/Part.h
+++ b/src/kvstore/Part.h
@@ -274,7 +274,7 @@ class Part : public raftex::RaftPart {
   bool preProcessLog(LogID logId,
                      TermID termId,
                      ClusterID clusterId,
-                     const std::string& log) override;
+                     folly::StringPiece log) override;
 
   /**
    * @brief If a raft peer falls behind way to much than leader, the leader will send all its data
diff --git a/src/kvstore/raftex/RaftPart.cpp b/src/kvstore/raftex/RaftPart.cpp
index a328bcd967e..781db5f24fd 100644
--- a/src/kvstore/raftex/RaftPart.cpp
+++ b/src/kvstore/raftex/RaftPart.cpp
@@ -368,7 +368,7 @@ RaftPart::RaftPart(
       walRoot,
       std::move(info),
       std::move(policy),
-      [this](LogID logId, TermID logTermId, ClusterID logClusterId, const std::string& log) {
+      [this](LogID logId, TermID logTermId, ClusterID logClusterId, folly::StringPiece log) {
         return this->preProcessLog(logId, logTermId, logClusterId, log);
       },
       diskMan);
diff --git a/src/kvstore/raftex/RaftPart.h b/src/kvstore/raftex/RaftPart.h
index d5a91591c40..f2a33b2206d 100644
--- a/src/kvstore/raftex/RaftPart.h
+++ b/src/kvstore/raftex/RaftPart.h
@@ -516,7 +516,7 @@ class RaftPart : public std::enable_shared_from_this<RaftPart> {
   virtual bool preProcessLog(LogID logId,
                              TermID termId,
                              ClusterID clusterId,
-                             const std::string& log) = 0;
+                             folly::StringPiece log) = 0;
 
   /**
    * @brief If raft node falls behind way to much than leader, the leader will send all its data in
diff --git a/src/kvstore/raftex/test/TestShard.h b/src/kvstore/raftex/test/TestShard.h
index ddb5bc6f5b8..7eaa57a0df1 100644
--- a/src/kvstore/raftex/test/TestShard.h
+++ b/src/kvstore/raftex/test/TestShard.h
@@ -82,7 +82,7 @@ class TestShard : public RaftPart {
                                                                 bool wait,
                                                                 bool needLock) override;
 
-  bool preProcessLog(LogID, TermID, ClusterID, const std::string& log) override {
+  bool preProcessLog(LogID, TermID, ClusterID, folly::StringPiece log) override {
     if (!log.empty()) {
       switch (static_cast<CommandType>(log[0])) {
         case CommandType::ADD_LEARNER: {
diff --git a/src/kvstore/test/DiskManagerTest.cpp b/src/kvstore/test/DiskManagerTest.cpp
index 93435537b20..47e16eb559b 100644
--- a/src/kvstore/test/DiskManagerTest.cpp
+++ b/src/kvstore/test/DiskManagerTest.cpp
@@ -126,7 +126,7 @@ TEST(DiskManagerTest, WalNoSpaceTest) {
       walPath,
       info,
       policy,
-      [](LogID, TermID, ClusterID, const std::string&) { return true; },
+      [](LogID, TermID, ClusterID, folly::StringPiece) { return true; },
       diskMan);
 
   diskMan->freeBytes_[0] = FLAGS_minimum_reserved_bytes + 10000;
diff --git a/src/kvstore/wal/AtomicLogBuffer.h b/src/kvstore/wal/AtomicLogBuffer.h
index 9f150018a0e..1e23e14c875 100644
--- a/src/kvstore/wal/AtomicLogBuffer.h
+++ b/src/kvstore/wal/AtomicLogBuffer.h
@@ -26,8 +26,8 @@ struct Record {
   Record(Record&& record) noexcept = default;
   Record& operator=(Record&& record) noexcept = default;
 
-  Record(ClusterID clusterId, TermID termId, std::string msg)
-      : clusterId_(clusterId), termId_(termId), msg_(std::move(msg)) {}
+  Record(ClusterID clusterId, TermID termId, folly::StringPiece msg)
+      : clusterId_(clusterId), termId_(termId), msg_(msg.toString()) {}
 
   int32_t size() const {
     return sizeof(ClusterID) + sizeof(TermID) + msg_.size();
@@ -52,7 +52,7 @@ struct Node {
   }
 
   /**
-   * @brief Add a record to current not
+   * @brief Add a record to current node
    *
    * @param rec Record to add
    * @return Whether operation succeed or not
@@ -267,8 +267,8 @@ class AtomicLogBuffer : public std::enable_shared_from_this<AtomicLogBuffer> {
    * @param clusterId Cluster id of log
    * @param msg Log message
    */
-  void push(LogID logId, TermID termId, ClusterID clusterId, std::string&& msg) {
-    push(logId, Record(clusterId, termId, std::move(msg)));
+  void push(LogID logId, TermID termId, ClusterID clusterId, folly::StringPiece msg) {
+    push(logId, Record(clusterId, termId, msg));
   }
 
   /**
@@ -327,7 +327,7 @@ class AtomicLogBuffer : public std::enable_shared_from_this<AtomicLogBuffer> {
   explicit AtomicLogBuffer(int32_t capacity) : capacity_(capacity) {}
 
   /**
-   * @brief Find the noe which contains the log with given id
+   * @brief Find the node which contains the log with given id
    *
    * @param logId Log it to seek
    * @return Node* Return the node contains the log, return nullptr if not found
diff --git a/src/kvstore/wal/FileBasedWal.cpp b/src/kvstore/wal/FileBasedWal.cpp
index 0e0b2af5165..91435b4955c 100644
--- a/src/kvstore/wal/FileBasedWal.cpp
+++ b/src/kvstore/wal/FileBasedWal.cpp
@@ -439,7 +439,10 @@ void FileBasedWal::scanLastWal(WalFileInfoPtr info, LogID firstId) {
   close(fd);
 }
 
-bool FileBasedWal::appendLogInternal(LogID id, TermID term, ClusterID cluster, std::string msg) {
+bool FileBasedWal::appendLogInternal(LogID id,
+                                     TermID term,
+                                     ClusterID cluster,
+                                     folly::StringPiece msg) {
   if (lastLogId_ != 0 && firstLogId_ != 0 && id != lastLogId_ + 1) {
     VLOG(3) << idStr_ << "There is a gap in the log id. The last log id is " << lastLogId_
             << ", and the id being appended is " << id;
@@ -493,7 +496,7 @@ bool FileBasedWal::appendLogInternal(LogID id, TermID term, ClusterID cluster, s
     firstLogId_ = id;
   }
 
-  logBuffer_->push(id, term, cluster, std::move(msg));
+  logBuffer_->push(id, term, cluster, msg);
   return true;
 }
 
@@ -502,7 +505,7 @@ bool FileBasedWal::appendLog(LogID id, TermID term, ClusterID cluster, std::stri
     VLOG_EVERY_N(2, 1000) << idStr_ << "Failed to appendLogs because of no more space";
     return false;
   }
-  if (!appendLogInternal(id, term, cluster, std::move(msg))) {
+  if (!appendLogInternal(id, term, cluster, folly::StringPiece(msg))) {
     VLOG(3) << "Failed to append log for logId " << id;
     return false;
   }
@@ -515,8 +518,7 @@ bool FileBasedWal::appendLogs(LogIterator& iter) {
     return false;
   }
   for (; iter.valid(); ++iter) {
-    if (!appendLogInternal(
-            iter.logId(), iter.logTerm(), iter.logSource(), iter.logMsg().toString())) {
+    if (!appendLogInternal(iter.logId(), iter.logTerm(), iter.logSource(), iter.logMsg())) {
       VLOG(3) << idStr_ << "Failed to append log for logId " << iter.logId();
       return false;
     }
diff --git a/src/kvstore/wal/FileBasedWal.h b/src/kvstore/wal/FileBasedWal.h
index 296767b314b..925a46c83bd 100644
--- a/src/kvstore/wal/FileBasedWal.h
+++ b/src/kvstore/wal/FileBasedWal.h
@@ -37,7 +37,7 @@ struct FileBasedWalInfo {
   PartitionID partId_;
 };
 
-using PreProcessor = folly::Function<bool(LogID, TermID, ClusterID, const std::string& log)>;
+using PreProcessor = folly::Function<bool(LogID, TermID, ClusterID, folly::StringPiece)>;
 
 class FileBasedWal final : public Wal, public std::enable_shared_from_this<FileBasedWal> {
   FRIEND_TEST(FileBasedWal, TTLTest);
@@ -247,7 +247,7 @@ class FileBasedWal final : public Wal, public std::enable_shared_from_this<FileB
    * @param msg Log messgage to append
    * @return Wheter append succeed
    */
-  bool appendLogInternal(LogID id, TermID term, ClusterID cluster, std::string msg);
+  bool appendLogInternal(LogID id, TermID term, ClusterID cluster, folly::StringPiece msg);
 
  private:
   using WalFiles = std::map<LogID, WalFileInfoPtr>;
diff --git a/src/kvstore/wal/test/FileBasedWalTest.cpp b/src/kvstore/wal/test/FileBasedWalTest.cpp
index a51589eecb5..10aeed22f86 100644
--- a/src/kvstore/wal/test/FileBasedWalTest.cpp
+++ b/src/kvstore/wal/test/FileBasedWalTest.cpp
@@ -41,7 +41,7 @@ TEST(FileBasedWal, AppendLogs) {
   TempDir walDir("/tmp/testWal.XXXXXX");
 
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -56,7 +56,7 @@ TEST(FileBasedWal, AppendLogs) {
 
   // Now let's open it to read
   wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(10, wal->lastLogId());
@@ -82,7 +82,7 @@ TEST(FileBasedWal, CacheOverflow) {
 
   TempDir walDir("/tmp/testWal.XXXXXX");
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -103,7 +103,7 @@ TEST(FileBasedWal, CacheOverflow) {
 
   // Now let's open it to read
   wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
 
@@ -130,7 +130,7 @@ TEST(FileBasedWal, Rollback) {
 
   TempDir walDir("/tmp/testWal.XXXXXX");
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -204,7 +204,7 @@ TEST(FileBasedWal, RollbackThenReopen) {
 
   TempDir walDir("/tmp/testWal.XXXXXX");
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -228,7 +228,7 @@ TEST(FileBasedWal, RollbackThenReopen) {
 
   // Now let's open it to read
   wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(800, wal->lastLogId());
@@ -255,7 +255,7 @@ TEST(FileBasedWal, RollbackToZero) {
 
   TempDir walDir("/tmp/testWal.XXXXXX");
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   ASSERT_EQ(0, wal->lastLogId());
@@ -294,7 +294,7 @@ TEST(FileBasedWal, BackAndForth) {
 
   TempDir walDir("/tmp/testWal.XXXXXX");
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   ASSERT_EQ(0, wal->lastLogId());
@@ -333,7 +333,7 @@ TEST(FileBasedWal, TTLTest) {
   policy.bufferSize = 128;
   policy.fileSize = 1024;
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -357,7 +357,7 @@ TEST(FileBasedWal, TTLTest) {
   {
     // Now let's open it to read
     wal = FileBasedWal::getWal(
-        walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+        walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
           return true;
         });
     EXPECT_EQ(200, wal->lastLogId());
@@ -384,7 +384,7 @@ TEST(FileBasedWal, TTLTest) {
   {
     // Now let's open it to read
     wal = FileBasedWal::getWal(
-        walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+        walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
           return true;
         });
     EXPECT_EQ(200, wal->lastLogId());
@@ -408,7 +408,7 @@ TEST(FileBasedWal, CheckLastWalTest) {
   TempDir walDir("/tmp/testWal.XXXXXX");
 
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   {
@@ -436,7 +436,7 @@ TEST(FileBasedWal, CheckLastWalTest) {
 
     // Now let's open it to read
     wal = FileBasedWal::getWal(
-        walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+        walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
           return true;
         });
     EXPECT_EQ(999, wal->lastLogId());
@@ -461,7 +461,7 @@ TEST(FileBasedWal, CheckLastWalTest) {
 
     // Now let's open it to read
     wal = FileBasedWal::getWal(
-        walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+        walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
           return true;
         });
     EXPECT_EQ(expected, wal->lastLogId());
@@ -478,7 +478,7 @@ TEST(FileBasedWal, CheckLastWalTest) {
 
     // Now let's open it to read
     wal = FileBasedWal::getWal(
-        walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+        walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
           return true;
         });
     EXPECT_EQ(expected, wal->lastLogId());
@@ -496,7 +496,7 @@ TEST(FileBasedWal, CheckLastWalTest) {
 
     // Now let's open it to read
     wal = FileBasedWal::getWal(
-        walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+        walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
           return true;
         });
     EXPECT_EQ(1000, wal->lastLogId());
@@ -509,7 +509,7 @@ TEST(FileBasedWal, LinkTest) {
   FileBasedWalPolicy policy;
   policy.fileSize = 1024 * 512;
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -540,7 +540,7 @@ TEST(FileBasedWal, CleanWalBeforeIdTest) {
   FileBasedWalPolicy policy;
   policy.fileSize = 1024 * 10;
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   for (LogID i = 1; i <= 1000; i++) {
@@ -576,7 +576,7 @@ TEST(FileBasedWal, getLogTermTest) {
   policy.bufferSize = 1024L * 1024L;
 
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
 
@@ -596,7 +596,7 @@ TEST(FileBasedWal, getLogTermTest) {
 
   // Now let's open it to read
   wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(10, wal->getLogTerm(10));
diff --git a/src/kvstore/wal/test/WalFileIterTest.cpp b/src/kvstore/wal/test/WalFileIterTest.cpp
index 8f345a239ca..d677147d210 100644
--- a/src/kvstore/wal/test/WalFileIterTest.cpp
+++ b/src/kvstore/wal/test/WalFileIterTest.cpp
@@ -22,7 +22,7 @@ TEST(WalFileIter, SimpleReadTest) {
   TempDir walDir("/tmp/testWal.XXXXXX");
 
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());
@@ -53,7 +53,7 @@ TEST(WalFileIter, MultiFilesReadTest) {
   TempDir walDir("/tmp/testWal.XXXXXX");
 
   auto wal = FileBasedWal::getWal(
-      walDir.path(), info, policy, [](LogID, TermID, ClusterID, const std::string&) {
+      walDir.path(), info, policy, [](LogID, TermID, ClusterID, folly::StringPiece) {
         return true;
       });
   EXPECT_EQ(0, wal->lastLogId());