Add write buffer from nuraft

src/Coordination/ReadBufferFromNuraftBuffer.h

@@ -0,0 +1,17 @@
+#pragma once
+#include <IO/ReadBufferFromMemory.h>
+
+#include <libnuraft/nuraft.hxx>
+
+namespace DB
+{
+
+class ReadBufferFromNuraftBuffer : public ReadBufferFromMemory
+{
+public:
+    explicit ReadBufferFromNuraftBuffer(nuraft::ptr<nuraft::buffer> buffer)
+        : ReadBufferFromMemory(buffer->data_begin(), buffer->size())
+    {}
+};
+
+}

src/Coordination/WriteBufferFromNuraftBuffer.cpp

@@ -0,0 +1,66 @@
+#include <Coordination/WriteBufferFromNuraftBuffer.h>
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int CANNOT_WRITE_AFTER_END_OF_BUFFER;
+}
+
+void WriteBufferFromNuraftBuffer::nextImpl()
+{
+    if (is_finished)
+        throw Exception("WriteBufferFromNuraftBuffer is finished", ErrorCodes::CANNOT_WRITE_AFTER_END_OF_BUFFER);
+
+    size_t old_size = buffer->size();
+    /// pos may not be equal to vector.data() + old_size, because WriteBuffer::next() can be used to flush data
+    size_t pos_offset = pos - reinterpret_cast<Position>(buffer->data_begin());
+    nuraft::ptr<nuraft::buffer> new_buffer = nuraft::buffer::alloc(old_size * size_multiplier);
+    memcpy(new_buffer->data_begin(), buffer->data_begin(), buffer->size());
+    buffer = new_buffer;
+    internal_buffer = Buffer(reinterpret_cast<Position>(buffer->data_begin() + pos_offset), reinterpret_cast<Position>(buffer->data_begin() + buffer->size()));
+    working_buffer = internal_buffer;
+}
+
+WriteBufferFromNuraftBuffer::WriteBufferFromNuraftBuffer()
+    : WriteBuffer(nullptr, 0)
+{
+    buffer = nuraft::buffer::alloc(initial_size);
+    set(reinterpret_cast<Position>(buffer->data_begin()), buffer->size());
+}
+
+void WriteBufferFromNuraftBuffer::finalize()
+{
+    if (is_finished)
+        return;
+
+    is_finished = true;
+    size_t real_size = position() - reinterpret_cast<Position>(buffer->data_begin());
+    nuraft::ptr<nuraft::buffer> new_buffer = nuraft::buffer::alloc(real_size);
+    memcpy(new_buffer->data_begin(), buffer->data_begin(), real_size);
+    buffer = new_buffer;
+
+    /// Prevent further writes.
+    set(nullptr, 0);
+}
+
+nuraft::ptr<nuraft::buffer> WriteBufferFromNuraftBuffer::getBuffer()
+{
+    finalize();
+    return buffer;
+}
+
+ WriteBufferFromNuraftBuffer::~WriteBufferFromNuraftBuffer()
+{
+    try
+    {
+        finalize();
+    }
+    catch (...)
+    {
+        tryLogCurrentException(__PRETTY_FUNCTION__);
+    }
+}
+
+}

src/Coordination/WriteBufferFromNuraftBuffer.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <IO/WriteBuffer.h>
+#include <libnuraft/nuraft.hxx>
+
+namespace DB
+{
+
+class WriteBufferFromNuraftBuffer : public WriteBuffer
+{
+private:
+    nuraft::ptr<nuraft::buffer> buffer;
+    bool is_finished = false;
+
+    static constexpr size_t initial_size = 32;
+    static constexpr size_t size_multiplier = 2;
+
+    void nextImpl() override;
+
+public:
+    WriteBufferFromNuraftBuffer();
+
+    void finalize() override final;
+    nuraft::ptr<nuraft::buffer> getBuffer();
+    bool isFinished() const { return is_finished; }
+
+    ~WriteBufferFromNuraftBuffer() override;
+};
+
+}

src/Coordination/tests/gtest_for_build.cpp

@@ -4,6 +4,10 @@
 #include <Coordination/InMemoryStateManager.h>
 #include <Coordination/SummingStateMachine.h>
 #include <Coordination/LoggerWrapper.h>
+#include <Coordination/WriteBufferFromNuraftBuffer.h>
+#include <Coordination/ReadBufferFromNuraftBuffer.h>
+#include <Common/ZooKeeper/ZooKeeperCommon.h>
+#include <Common/ZooKeeper/ZooKeeperIO.h>
 #include <Common/Exception.h>
 #include <libnuraft/nuraft.hxx>
 #include <thread>
@@ -26,6 +30,39 @@ TEST(CoordinationTest, BuildTest)
     EXPECT_EQ(1, 1);
 }
 
+TEST(CoordinationTest, BufferSerde)
+{
+    Coordination::ZooKeeperRequestPtr request = Coordination::ZooKeeperRequestFactory::instance().get(Coordination::OpNum::Get);
+    request->xid = 3;
+    dynamic_cast<Coordination::ZooKeeperGetRequest *>(request.get())->path = "/path/value";
+
+    DB::WriteBufferFromNuraftBuffer wbuf;
+    request->write(wbuf);
+    auto nuraft_buffer = wbuf.getBuffer();
+    EXPECT_EQ(nuraft_buffer->size(), 28);
+
+    DB::ReadBufferFromNuraftBuffer rbuf(nuraft_buffer);
+
+    int32_t length;
+    Coordination::read(length, rbuf);
+    EXPECT_EQ(length + sizeof(length), nuraft_buffer->size());
+
+    int32_t xid;
+    Coordination::read(xid, rbuf);
+    EXPECT_EQ(xid, request->xid);
+
+    Coordination::OpNum opnum;
+    Coordination::read(opnum, rbuf);
+
+    Coordination::ZooKeeperRequestPtr request_read = Coordination::ZooKeeperRequestFactory::instance().get(opnum);
+    request_read->xid = xid;
+    request_read->readImpl(rbuf);
+
+    EXPECT_EQ(request_read->getOpNum(), Coordination::OpNum::Get);
+    EXPECT_EQ(request_read->xid, 3);
+    EXPECT_EQ(dynamic_cast<Coordination::ZooKeeperGetRequest *>(request_read.get())->path, "/path/value");
+}
+
 struct SummingRaftServer
 {
     SummingRaftServer(int server_id_, const std::string & hostname_, int port_)