From 291f0425e2fb18fe68bdde2f0aebee81dd9f4e44 Mon Sep 17 00:00:00 2001
From: Matej Ferencevic <matej.ferencevic@memgraph.io>
Date: Thu, 2 May 2019 14:40:43 +0200
Subject: [PATCH] Use SLK for Raft log

Reviewers: msantl, ipaljak

Reviewed By: ipaljak

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D2007
---
 src/raft/raft_server.cpp | 78 ++++++++++++++++++++--------------------
 1 file changed, 38 insertions(+), 40 deletions(-)

diff --git a/src/raft/raft_server.cpp b/src/raft/raft_server.cpp
index 942508798..47ae27b28 100644
--- a/src/raft/raft_server.cpp
+++ b/src/raft/raft_server.cpp
@@ -1,6 +1,5 @@
 #include "raft/raft_server.hpp"
 
-#include <kj/std/iostream.h>
 #include <algorithm>
 #include <chrono>
 #include <iostream>
@@ -17,6 +16,8 @@
 #include "durability/single_node_ha/snapshooter.hpp"
 #include "raft/exceptions.hpp"
 #include "rpc/serialization.hpp"
+#include "slk/streams.hpp"
+#include "utils/cast.hpp"
 #include "utils/exceptions.hpp"
 #include "utils/on_scope_exit.hpp"
 #include "utils/thread.hpp"
@@ -384,17 +385,16 @@ std::optional<SnapshotMetadata> RaftServer::GetSnapshotMetadata() {
     return std::nullopt;
   }
 
-  ::capnp::MallocMessageBuilder message;
-  std::stringstream stream(std::ios_base::in | std::ios_base::out |
-                           std::ios_base::binary);
-  kj::std::StdInputStream std_stream(stream);
-  kj::BufferedInputStreamWrapper buffered_stream(std_stream);
-  stream << *opt_value;
-  readMessageCopy(buffered_stream, message);
-  capnp::SnapshotMetadata::Reader reader =
-      message.getRoot<capnp::SnapshotMetadata>().asReader();
+  auto &value = *opt_value;
+  slk::Reader reader(reinterpret_cast<const uint8_t *>(value.data()),
+                     value.size());
   SnapshotMetadata deserialized;
-  Load(&deserialized, reader);
+  try {
+    slk::Load(&deserialized, &reader);
+    reader.Finalize();
+  } catch (const slk::SlkReaderException &) {
+    return std::nullopt;
+  }
   return std::make_optional(deserialized);
 }
 
@@ -402,15 +402,14 @@ void RaftServer::PersistSnapshotMetadata(
     const SnapshotMetadata &snapshot_metadata) {
   std::stringstream stream(std::ios_base::in | std::ios_base::out |
                            std::ios_base::binary);
-  {
-    ::capnp::MallocMessageBuilder message;
-    capnp::SnapshotMetadata::Builder builder =
-        message.initRoot<capnp::SnapshotMetadata>();
-    Save(snapshot_metadata, &builder);
-    kj::std::StdOutputStream std_stream(stream);
-    kj::BufferedOutputStreamWrapper buffered_stream(std_stream);
-    writeMessage(buffered_stream, message);
-  }
+  slk::Builder builder(
+      [&stream](const uint8_t *data, size_t size, bool have_more) {
+        for (size_t i = 0; i < size; ++i) {
+          stream << utils::MemcpyCast<char>(data[i]);
+        }
+      });
+  slk::Save(snapshot_metadata, &builder);
+  builder.Finalize();
   disk_storage_.Put(kSnapshotMetadataKey, stream.str());
 }
 
@@ -1226,31 +1225,30 @@ std::string RaftServer::LogEntryKey(uint64_t index) {
 std::string RaftServer::SerializeLogEntry(const LogEntry &log_entry) {
   std::stringstream stream(std::ios_base::in | std::ios_base::out |
                            std::ios_base::binary);
-  {
-    ::capnp::MallocMessageBuilder message;
-    capnp::LogEntry::Builder log_builder = message.initRoot<capnp::LogEntry>();
-    Save(log_entry, &log_builder);
-    kj::std::StdOutputStream std_stream(stream);
-    kj::BufferedOutputStreamWrapper buffered_stream(std_stream);
-    writeMessage(buffered_stream, message);
-  }
+  slk::Builder builder(
+      [&stream](const uint8_t *data, size_t size, bool have_more) {
+        for (size_t i = 0; i < size; ++i) {
+          stream << utils::MemcpyCast<char>(data[i]);
+        }
+      });
+  slk::Save(log_entry, &builder);
+  builder.Finalize();
   return stream.str();
 }
 
 LogEntry RaftServer::DeserializeLogEntry(
     const std::string &serialized_log_entry) {
-  ::capnp::MallocMessageBuilder message;
-  std::stringstream stream(std::ios_base::in | std::ios_base::out |
-                           std::ios_base::binary);
-  kj::std::StdInputStream std_stream(stream);
-  kj::BufferedInputStreamWrapper buffered_stream(std_stream);
-  stream << serialized_log_entry;
-  readMessageCopy(buffered_stream, message);
-  capnp::LogEntry::Reader log_reader =
-      message.getRoot<capnp::LogEntry>().asReader();
-  LogEntry deserialized_log;
-  Load(&deserialized_log, log_reader);
-  return deserialized_log;
+  slk::Reader reader(
+      reinterpret_cast<const uint8_t *>(serialized_log_entry.data()),
+      serialized_log_entry.size());
+  LogEntry deserialized;
+  try {
+    slk::Load(&deserialized, &reader);
+    reader.Finalize();
+  } catch (const slk::SlkReaderException &) {
+    LOG(FATAL) << "Couldn't load log from disk storage!";
+  }
+  return deserialized;
 }
 
 void RaftServer::ResetReplicationLog() {