Bug fixes

* Handle empty ranges in initial download
* Don't skip records in last marker
* Add identifier for timed out Cassandra writes

src/backend/CassandraBackend.cpp

@@ -16,8 +16,8 @@ processAsyncWriteResponse(T& requestParams, CassFuture* fut, F func)
             lround(std::pow(2, std::min(10u, requestParams.currentRetries))));
         BOOST_LOG_TRIVIAL(error)
             << "ERROR!!! Cassandra write error: " << rc << ", "
-            << cass_error_desc(rc) << ", retrying in " << wait.count()
-            << " milliseconds";
+            << cass_error_desc(rc) << " id= " << requestParams.toString()
+            << ", retrying in " << wait.count() << " milliseconds";
         ++requestParams.currentRetries;
         std::shared_ptr<boost::asio::steady_timer> timer =
             std::make_shared<boost::asio::steady_timer>(
@@ -52,9 +52,14 @@ struct WriteCallbackData
     std::function<void(WriteCallbackData<T, B>&, bool)> retry;
     uint32_t currentRetries;
     std::atomic<int> refs = 1;
+    std::string id;
 
-    WriteCallbackData(CassandraBackend const* b, T&& d, B bind)
-        : backend(b), data(std::move(d))
+    WriteCallbackData(
+        CassandraBackend const* b,
+        T&& d,
+        B bind,
+        std::string const& identifier)
+        : backend(b), data(std::move(d)), id(identifier)
     {
         retry = [bind, this](auto& params, bool isRetry) {
             auto statement = bind(params);
@@ -83,6 +88,12 @@ struct WriteCallbackData
     virtual ~WriteCallbackData()
     {
     }
+
+    std::string
+    toString()
+    {
+        return id;
+    }
 };
 template <class T, class B>
 struct BulkWriteCallbackData : public WriteCallbackData<T, B>
@@ -97,7 +108,7 @@ struct BulkWriteCallbackData : public WriteCallbackData<T, B>
         std::atomic_int& r,
         std::mutex& m,
         std::condition_variable& c)
-        : WriteCallbackData<T, B>(b, std::move(d), bind)
+        : WriteCallbackData<T, B>(b, std::move(d), bind, "bulk")
         , numRemaining(r)
         , mtx(m)
         , cv(c)
@@ -124,9 +135,13 @@ struct BulkWriteCallbackData : public WriteCallbackData<T, B>
 
 template <class T, class B>
 void
-makeAndExecuteAsyncWrite(CassandraBackend const* b, T&& d, B bind)
+makeAndExecuteAsyncWrite(
+    CassandraBackend const* b,
+    T&& d,
+    B bind,
+    std::string const& id)
 {
-    auto* cb = new WriteCallbackData(b, std::move(d), bind);
+    auto* cb = new WriteCallbackData(b, std::move(d), bind, id);
     cb->start();
 }
 template <class T, class B>
@@ -153,14 +168,17 @@ CassandraBackend::doWriteLedgerObject(
     BOOST_LOG_TRIVIAL(trace) << "Writing ledger object to cassandra";
     if (range)
         makeAndExecuteAsyncWrite(
-            this, std::move(std::make_tuple(seq, key)), [this](auto& params) {
+            this,
+            std::move(std::make_tuple(seq, key)),
+            [this](auto& params) {
                 auto& [sequence, key] = params.data;
 
                 CassandraStatement statement{insertDiff_};
                 statement.bindNextInt(sequence);
                 statement.bindNextBytes(key);
                 return statement;
-            });
+            },
+            "ledger_diff");
     makeAndExecuteAsyncWrite(
         this,
         std::move(std::make_tuple(std::move(key), seq, std::move(blob))),
@@ -172,7 +190,8 @@ CassandraBackend::doWriteLedgerObject(
             statement.bindNextInt(sequence);
             statement.bindNextBytes(blob);
             return statement;
-        });
+        },
+        "ledger_object");
 }
 void
 CassandraBackend::writeSuccessor(
@@ -183,8 +202,8 @@ CassandraBackend::writeSuccessor(
     BOOST_LOG_TRIVIAL(trace)
         << "Writing successor. key = " << key
         << " seq = " << std::to_string(seq) << " successor = " << successor;
-    assert(key.size());
-    assert(successor.size());
+    assert(key.size() != 0);
+    assert(successor.size() != 0);
     makeAndExecuteAsyncWrite(
         this,
         std::move(std::make_tuple(std::move(key), seq, std::move(successor))),
@@ -196,7 +215,8 @@ CassandraBackend::writeSuccessor(
             statement.bindNextInt(sequence);
             statement.bindNextBytes(successor);
             return statement;
-        });
+        },
+        "successor");
 }
 void
 CassandraBackend::writeLedger(
@@ -212,7 +232,8 @@ CassandraBackend::writeLedger(
             statement.bindNextInt(sequence);
             statement.bindNextBytes(header);
             return statement;
-        });
+        },
+        "ledger");
     makeAndExecuteAsyncWrite(
         this,
         std::move(std::make_tuple(ledgerInfo.hash, ledgerInfo.seq)),
@@ -222,7 +243,8 @@ CassandraBackend::writeLedger(
             statement.bindNextBytes(hash);
             statement.bindNextInt(sequence);
             return statement;
-        });
+        },
+        "ledger_hash");
     ledgerSequence_ = ledgerInfo.seq;
 }
 void
@@ -247,7 +269,8 @@ CassandraBackend::writeAccountTransactions(
                     statement.bindNextIntTuple(lgrSeq, txnIdx);
                     statement.bindNextBytes(hash);
                     return statement;
-                });
+                },
+                "account_tx");
         }
     }
 }
@@ -263,12 +286,15 @@ CassandraBackend::writeTransaction(
     std::string hashCpy = hash;
 
     makeAndExecuteAsyncWrite(
-        this, std::move(std::make_pair(seq, hash)), [this](auto& params) {
+        this,
+        std::move(std::make_pair(seq, hash)),
+        [this](auto& params) {
             CassandraStatement statement{insertLedgerTransaction_};
             statement.bindNextInt(params.data.first);
             statement.bindNextBytes(params.data.second);
             return statement;
-        });
+        },
+        "ledger_transaction");
     makeAndExecuteAsyncWrite(
         this,
         std::move(std::make_tuple(
@@ -286,7 +312,8 @@ CassandraBackend::writeTransaction(
             statement.bindNextBytes(transaction);
             statement.bindNextBytes(metadata);
             return statement;
-        });
+        },
+        "transaction");
 }
 
 std::optional<LedgerRange>