Revert "Asynchronously write batches to NuDB. (XRPLF#4503)" (XRPLF#4882)

This reverts commit 1d9db1b.

This improves the stability of online deletion.

src/ripple/nodestore/Types.h

@@ -36,9 +36,8 @@ enum {
  // This sets a limit on the maximum number of writes
  // in a batch. Actual usage can be twice this since
  // we have a new batch growing as we write the old.
- // The main goal is to avoid delays while persisting the ledger.
  //
- batchWriteLimitSize = 262144
+ batchWriteLimitSize = 65536
 };
 
 /** Return codes from Backend operations. */

src/ripple/nodestore/backend/NuDBFactory.cpp

@@ -20,7 +20,6 @@
 #include <ripple/basics/contract.h>
 #include <ripple/nodestore/Factory.h>
 #include <ripple/nodestore/Manager.h>
-#include <ripple/nodestore/impl/BatchWriter.h>
 #include <ripple/nodestore/impl/DecodedBlob.h>
 #include <ripple/nodestore/impl/EncodedBlob.h>
 #include <ripple/nodestore/impl/codec.h>
@@ -36,7 +35,7 @@
 namespace ripple {
 namespace NodeStore {
 
-class NuDBBackend : public Backend, public BatchWriter::Callback
+class NuDBBackend : public Backend
 {
 public:
  static constexpr std::uint64_t currentType = 1;
@@ -47,7 +46,6 @@ class NuDBBackend : public Backend, public BatchWriter::Callback
 
  beast::Journal const j_;
  size_t const keyBytes_;
- BatchWriter batch_;
  std::size_t const burstSize_;
  std::string const name_;
  nudb::store db_;
@@ -62,7 +60,6 @@ class NuDBBackend : public Backend, public BatchWriter::Callback
  beast::Journal journal)
  : j_(journal)
  , keyBytes_(keyBytes)
- , batch_(*this, scheduler)
  , burstSize_(burstSize)
  , name_(get(keyValues, "path"))
  , deletePath_(false)
@@ -82,7 +79,6 @@ class NuDBBackend : public Backend, public BatchWriter::Callback
  beast::Journal journal)
  : j_(journal)
  , keyBytes_(keyBytes)
- , batch_(*this, scheduler)
  , burstSize_(burstSize)
  , name_(get(keyValues, "path"))
  , db_(context)
@@ -266,7 +262,13 @@ class NuDBBackend : public Backend, public BatchWriter::Callback
  void
  store(std::shared_ptr<NodeObject> const& no) override
  {
- batch_.store(no);
+ BatchWriteReport report;
+ report.writeCount = 1;
+ auto const start = std::chrono::steady_clock::now();
+ do_insert(no);
+ report.elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(
+ std::chrono::steady_clock::now() - start);
+ scheduler_.onBatchWrite(report);
  }
 
  void
@@ -327,7 +329,7 @@ class NuDBBackend : public Backend, public BatchWriter::Callback
  int
  getWriteLoad() override
  {
- return batch_.getWriteLoad();
+ return 0;
  }
 
  void
@@ -355,12 +357,6 @@ class NuDBBackend : public Backend, public BatchWriter::Callback
  Throw<nudb::system_error>(ec);
  }
 
- void
- writeBatch(Batch const& batch) override
- {
- storeBatch(batch);
- }
-
  int
  fdRequired() const override
  {