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diff --git a/src/rocksdb/db/logs_with_prep_tracker.h b/src/rocksdb/db/logs_with_prep_tracker.h
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+++ b/src/rocksdb/db/logs_with_prep_tracker.h
@@ -0,0 +1,62 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+#pragma once
+
+#include <cassert>
+#include <cstdint>
+#include <cstdlib>
+#include <mutex>
+#include <unordered_map>
+#include <vector>
+
+#include "rocksdb/rocksdb_namespace.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// This class is used to track the log files with outstanding prepare entries.
+class LogsWithPrepTracker {
+ public:
+  // Called when a transaction prepared in `log` has been committed or aborted.
+  void MarkLogAsHavingPrepSectionFlushed(uint64_t log);
+  // Called when a transaction is prepared in `log`.
+  void MarkLogAsContainingPrepSection(uint64_t log);
+  // Return the earliest log file with outstanding prepare entries.
+  uint64_t FindMinLogContainingOutstandingPrep();
+  size_t TEST_PreparedSectionCompletedSize() {
+    return prepared_section_completed_.size();
+  }
+  size_t TEST_LogsWithPrepSize() { return logs_with_prep_.size(); }
+
+ private:
+  // REQUIRES: logs_with_prep_mutex_ held
+  //
+  // sorted list of log numbers still containing prepared data.
+  // this is used by FindObsoleteFiles to determine which
+  // flushed logs we must keep around because they still
+  // contain prepared data which has not been committed or rolled back
+  struct LogCnt {
+    uint64_t log;  // the log number
+    uint64_t cnt;  // number of prepared sections in the log
+  };
+  std::vector<LogCnt> logs_with_prep_;
+  std::mutex logs_with_prep_mutex_;
+
+  // REQUIRES: prepared_section_completed_mutex_ held
+  //
+  // to be used in conjunction with logs_with_prep_.
+  // once a transaction with data in log L is committed or rolled back
+  // rather than updating logs_with_prep_ directly we keep track of that
+  // in prepared_section_completed_ which maps LOG -> instance_count. This helps
+  // avoiding contention between a commit thread and the prepare threads.
+  //
+  // when trying to determine the minimum log still active we first
+  // consult logs_with_prep_. while that root value maps to
+  // an equal value in prepared_section_completed_ we erase the log from
+  // both logs_with_prep_ and prepared_section_completed_.
+  std::unordered_map<uint64_t, uint64_t> prepared_section_completed_;
+  std::mutex prepared_section_completed_mutex_;
+};
+}  // namespace ROCKSDB_NAMESPACE