Add OpenLedger::empty

src/ripple/app/ledger/OpenLedger.h

@@ -73,6 +73,22 @@ public:
             Config const& config, CachedSLEs& cache,
                 beast::Journal journal);
 
+    /** Returns `true` if there are no transactions.
+
+        The behavior of ledger closing can be different
+        depending on whether or not transactions exist
+        in the open ledger.
+
+        @note The value returned is only meaningful for
+              that specific instant in time. An open,
+              empty ledger can become non empty from
+              subsequent modifications. Caller is
+              responsible for synchronizing the meaning of
+              the return value.
+    */
+    bool
+    empty() const;
+
     /** Returns a view to the current open ledger.
 
         Thread safety:

src/ripple/app/ledger/impl/OpenLedger.cpp

@@ -36,6 +36,14 @@ OpenLedger::OpenLedger(std::shared_ptr<
 {
 }
 
+bool
+OpenLedger::empty() const
+{
+    std::lock_guard<
+        std::mutex> lock(modify_mutex_);
+    return current_->txCount() != 0;
+}
+
 std::shared_ptr<ReadView const>
 OpenLedger::current() const
 {