Repo created

libs/coding/buffered_file_writer.cpp

@@ -0,0 +1,75 @@
+#include "coding/buffered_file_writer.hpp"
+
+#include "coding/internal/file_data.hpp"
+
+#include "base/assert.hpp"
+
+BufferedFileWriter::BufferedFileWriter(std::string const & fileName, Op operation /* = OP_WRITE_TRUNCATE */,
+                                       size_t bufferSize /*  = 4096 */)
+  : FileWriter(fileName, operation)
+{
+  CHECK_GREATER(bufferSize, 0, ());
+  m_buf.reserve(bufferSize);
+}
+
+BufferedFileWriter::~BufferedFileWriter() noexcept(false)
+{
+  DropBuffer();
+}
+
+void BufferedFileWriter::Seek(uint64_t pos)
+{
+  DropBuffer();
+  FileWriter::Seek(pos);
+}
+
+uint64_t BufferedFileWriter::Pos() const
+{
+  return FileWriter::Pos() + m_buf.size();
+}
+
+void BufferedFileWriter::Write(void const * p, size_t size)
+{
+  // Need to use pointer arithmetic.
+  auto src = static_cast<uint8_t const *>(p);
+
+  while (size >= m_buf.capacity() - m_buf.size())
+  {
+    if (m_buf.empty())
+    {
+      FileWriter::Write(src, m_buf.capacity());
+      src += m_buf.capacity();
+      size -= m_buf.capacity();
+    }
+    else
+    {
+      auto const copyCount = m_buf.capacity() - m_buf.size();
+      std::copy(src, src + copyCount, std::back_inserter(m_buf));
+      DropBuffer();
+      src += copyCount;
+      size -= copyCount;
+    }
+  }
+
+  std::copy(src, src + size, std::back_inserter(m_buf));
+}
+
+uint64_t BufferedFileWriter::Size() const
+{
+  return FileWriter::Size() + m_buf.size();
+}
+
+void BufferedFileWriter::Flush()
+{
+  DropBuffer();
+  FileWriter::Flush();
+}
+
+void BufferedFileWriter::DropBuffer()
+{
+  if (m_buf.empty())
+    return;
+
+  FileWriter::Write(m_buf.data(), m_buf.size());
+  m_buf.clear();
+}