Implement WinRandomRW file and improve code reuse (#1388)

include/rocksdb/env.h

@@ -504,15 +504,16 @@ class WritableFile {
   virtual ~WritableFile();
 
   // Indicates if the class makes use of unbuffered I/O
+  // If false you must pass aligned buffer to Write()
   virtual bool UseOSBuffer() const {
     return true;
   }
 
   const size_t c_DefaultPageSize = 4 * 1024;
 
-  // This is needed when you want to allocate
-  // AlignedBuffer for use with file I/O classes
-  // Used for unbuffered file I/O when UseOSBuffer() returns false
+  // Use the returned alignment value to allocate
+  // aligned buffer for Write() when UseOSBuffer()
+  // returns false
   virtual size_t GetRequiredBufferAlignment() const {
     return c_DefaultPageSize;
   }
@@ -664,7 +665,34 @@ class RandomRWFile {
   RandomRWFile() {}
   virtual ~RandomRWFile() {}
 
+  // Indicates if the class makes use of unbuffered I/O
+  // If false you must pass aligned buffer to Write()
+  virtual bool UseOSBuffer() const {
+    return true;
+  }
+
+  const size_t c_DefaultPageSize = 4 * 1024;
+
+  // Use the returned alignment value to allocate
+  // aligned buffer for Write() when UseOSBuffer()
+  // returns false
+  virtual size_t GetRequiredBufferAlignment() const {
+    return c_DefaultPageSize;
+  }
+
+  // Used by the file_reader_writer to decide if the ReadAhead wrapper
+  // should simply forward the call and do not enact read_ahead buffering or locking.
+  // The implementation below takes care of reading ahead
+  virtual bool ShouldForwardRawRequest() const {
+    return false;
+  }
+
+  // For cases when read-ahead is implemented in the platform dependent
+  // layer. This is when ShouldForwardRawRequest() returns true.
+  virtual void EnableReadAhead() {}
+
   // Write bytes in `data` at  offset `offset`, Returns Status::OK() on success.
+  // Pass aligned buffer when UseOSBuffer() returns false.
   virtual Status Write(uint64_t offset, const Slice& data) = 0;
 
   // Read up to `n` bytes starting from offset `offset` and store them in
@@ -681,7 +709,6 @@ class RandomRWFile {
 
   virtual Status Close() = 0;
 
- private:
   // No copying allowed
   RandomRWFile(const RandomRWFile&) = delete;
   RandomRWFile& operator=(const RandomRWFile&) = delete;

port/win/env_win.cc

@@ -293,6 +293,50 @@ Status WinEnvIO::NewWritableFile(const std::string& fname,
   return s;
 }
 
+Status WinEnvIO::NewRandomRWFile(const std::string & fname,
+  unique_ptr<RandomRWFile>* result, const EnvOptions & options) {
+
+  Status s;
+
+  // Open the file for read-only random access
+  // Random access is to disable read-ahead as the system reads too much data
+  DWORD desired_access = GENERIC_READ | GENERIC_WRITE;
+  DWORD shared_mode = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE;
+  DWORD creation_disposition = OPEN_ALWAYS; // Create if necessary or open existing
+  DWORD file_flags = FILE_FLAG_RANDOM_ACCESS;
+
+  if (!options.use_os_buffer) {
+    file_flags |= FILE_FLAG_NO_BUFFERING;
+  }
+
+  /// Shared access is necessary for corruption test to pass
+  // almost all tests would work with a possible exception of fault_injection
+  HANDLE hFile = 0;
+  {
+    IOSTATS_TIMER_GUARD(open_nanos);
+    hFile =
+      CreateFileA(fname.c_str(),
+        desired_access,
+        shared_mode,
+        NULL, // Security attributes
+        creation_disposition,
+        file_flags,
+        NULL);
+  }
+
+  if (INVALID_HANDLE_VALUE == hFile) {
+    auto lastError = GetLastError();
+    return IOErrorFromWindowsError(
+      "NewRandomRWFile failed to Create/Open: " + fname, lastError);
+  }
+
+  UniqueCloseHandlePtr fileGuard(hFile, CloseHandleFunc);
+  result->reset(new WinRandomRWFile(fname, hFile, page_size_, options));
+  fileGuard.release();
+
+  return s;
+}
+
 Status WinEnvIO::NewDirectory(const std::string& name,
   std::unique_ptr<Directory>* result) {
   Status s;
@@ -868,6 +912,11 @@ Status WinEnv::NewWritableFile(const std::string& fname,
   return winenv_io_.NewWritableFile(fname, result, options);
 }
 
+Status WinEnv::NewRandomRWFile(const std::string & fname,
+  unique_ptr<RandomRWFile>* result, const EnvOptions & options) {
+  return winenv_io_.NewRandomRWFile(fname, result, options);
+}
+
 Status WinEnv::NewDirectory(const std::string& name,
   std::unique_ptr<Directory>* result) {
   return winenv_io_.NewDirectory(name, result);

port/win/env_win.h

@@ -92,6 +92,11 @@ public:
     std::unique_ptr<WritableFile>* result,
     const EnvOptions& options);
 
+  // The returned file will only be accessed by one thread at a time.
+  virtual Status NewRandomRWFile(const std::string& fname,
+    unique_ptr<RandomRWFile>* result,
+    const EnvOptions& options);
+
   virtual Status NewDirectory(const std::string& name,
     std::unique_ptr<Directory>* result);
 
@@ -188,6 +193,11 @@ public:
     std::unique_ptr<WritableFile>* result,
     const EnvOptions& options) override;
 
+  // The returned file will only be accessed by one thread at a time.
+  Status NewRandomRWFile(const std::string& fname,
+    unique_ptr<RandomRWFile>* result,
+    const EnvOptions& options) override;
+
   Status NewDirectory(const std::string& name,
     std::unique_ptr<Directory>* result) override;
 

port/win/io_win.cc

@@ -155,10 +155,12 @@ size_t GetUniqueIdFromFile(HANDLE hFile, char* id, size_t max_size) {
   return static_cast<size_t>(rid - id);
 }
 
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// WinMmapReadableFile
+
 WinMmapReadableFile::WinMmapReadableFile(const std::string& fileName, HANDLE hFile, HANDLE hMap,
   const void* mapped_region, size_t length)
-  : fileName_(fileName),
-  hFile_(hFile),
+  : WinFileData(fileName, hFile, false),
   hMap_(hMap),
   mapped_region_(mapped_region),
   length_(length) {}
@@ -169,9 +171,6 @@ WinMmapReadableFile::~WinMmapReadableFile() {
 
   ret = ::CloseHandle(hMap_);
   assert(ret);
-
-  ret = ::CloseHandle(hFile_);
-  assert(ret);
 }
 
 Status WinMmapReadableFile::Read(uint64_t offset, size_t n, Slice* result,
@@ -180,7 +179,7 @@ Status WinMmapReadableFile::Read(uint64_t offset, size_t n, Slice* result,
 
   if (offset > length_) {
     *result = Slice();
-    return IOError(fileName_, EINVAL);
+    return IOError(filename_, EINVAL);
   } else if (offset + n > length_) {
     n = length_ - offset;
   }
@@ -197,6 +196,10 @@ size_t WinMmapReadableFile::GetUniqueId(char* id, size_t max_size) const {
   return GetUniqueIdFromFile(hFile_, id, max_size);
 }
 
+///////////////////////////////////////////////////////////////////////////////
+/// WinMmapFile
+
+
 // Can only truncate or reserve to a sector size aligned if
 // used on files that are opened with Unbuffered I/O
 Status WinMmapFile::TruncateFile(uint64_t toSize) {
@@ -302,8 +305,7 @@ Status WinMmapFile::PreallocateInternal(uint64_t spaceToReserve) {
 
 WinMmapFile::WinMmapFile(const std::string& fname, HANDLE hFile, size_t page_size,
   size_t allocation_granularity, const EnvOptions& options)
-  : filename_(fname),
-  hFile_(hFile),
+  : WinFileData(fname, hFile, false),
   hMap_(NULL),
   page_size_(page_size),
   allocation_granularity_(allocation_granularity),
@@ -515,16 +517,16 @@ size_t WinMmapFile::GetUniqueId(char* id, size_t max_size) const {
   return GetUniqueIdFromFile(hFile_, id, max_size);
 }
 
+//////////////////////////////////////////////////////////////////////////////////
+// WinSequentialFile
+
 WinSequentialFile::WinSequentialFile(const std::string& fname, HANDLE f,
   const EnvOptions& options)
-  : filename_(fname),
-  file_(f),
-  use_os_buffer_(options.use_os_buffer)
+  : WinFileData(fname, f, options.use_os_buffer)
 {}
 
 WinSequentialFile::~WinSequentialFile() {
-  assert(file_ != INVALID_HANDLE_VALUE);
-  CloseHandle(file_);
+  assert(hFile_ != INVALID_HANDLE_VALUE);
 }
 
 Status WinSequentialFile::Read(size_t n, Slice* result, char* scratch) {
@@ -540,7 +542,7 @@ Status WinSequentialFile::Read(size_t n, Slice* result, char* scratch) {
 
   DWORD bytesToRead = static_cast<DWORD>(n); //cast is safe due to the check above
   DWORD bytesRead = 0;
-  BOOL ret = ReadFile(file_, scratch, bytesToRead, &bytesRead, NULL);
+  BOOL ret = ReadFile(hFile_, scratch, bytesToRead, &bytesRead, NULL);
   if (ret == TRUE) {
     r = bytesRead;
   } else {
@@ -561,7 +563,7 @@ Status WinSequentialFile::Skip(uint64_t n) {
 
   LARGE_INTEGER li;
   li.QuadPart = static_cast<int64_t>(n); //cast is safe due to the check above
-  BOOL ret = SetFilePointerEx(file_, li, NULL, FILE_CURRENT);
+  BOOL ret = SetFilePointerEx(hFile_, li, NULL, FILE_CURRENT);
   if (ret == FALSE) {
     return IOErrorFromWindowsError(filename_, GetLastError());
   }
@@ -572,14 +574,31 @@ Status WinSequentialFile::InvalidateCache(size_t offset, size_t length) {
   return Status::OK();
 }
 
-SSIZE_T WinRandomAccessFile::ReadIntoBuffer(uint64_t user_offset, uint64_t first_page_start,
+//////////////////////////////////////////////////////////////////////////////////////////////////
+/// WinRandomAccessBase
+
+// Helper
+void CalculateReadParameters(size_t alignment, uint64_t offset,
+  size_t bytes_requested,
+  size_t& actual_bytes_toread,
+  uint64_t& first_page_start) {
+
+  first_page_start = TruncateToPageBoundary(alignment, offset);
+  const uint64_t last_page_start =
+    TruncateToPageBoundary(alignment, offset + bytes_requested - 1);
+  actual_bytes_toread = (last_page_start - first_page_start) + alignment;
+}
+
+SSIZE_T WinRandomAccessImpl::ReadIntoBuffer(uint64_t user_offset,
+  uint64_t first_page_start,
   size_t bytes_to_read, size_t& left,
   AlignedBuffer& buffer, char* dest) const {
   assert(buffer.CurrentSize() == 0);
   assert(buffer.Capacity() >= bytes_to_read);
 
   SSIZE_T read =
-    PositionedReadInternal(buffer.Destination(), bytes_to_read, first_page_start);
+    PositionedReadInternal(buffer.Destination(), bytes_to_read,
+      first_page_start);
 
   if (read > 0) {
     buffer.Size(read);
@@ -597,7 +616,8 @@ SSIZE_T WinRandomAccessFile::ReadIntoBuffer(uint64_t user_offset, uint64_t first
   return read;
 }
 
-SSIZE_T WinRandomAccessFile::ReadIntoOneShotBuffer(uint64_t user_offset, uint64_t first_page_start,
+SSIZE_T WinRandomAccessImpl::ReadIntoOneShotBuffer(uint64_t user_offset,
+  uint64_t first_page_start,
   size_t bytes_to_read, size_t& left,
   char* dest) const {
   AlignedBuffer bigBuffer;
@@ -608,7 +628,7 @@ SSIZE_T WinRandomAccessFile::ReadIntoOneShotBuffer(uint64_t user_offset, uint64_
     bigBuffer, dest);
 }
 
-SSIZE_T WinRandomAccessFile::ReadIntoInstanceBuffer(uint64_t user_offset,
+SSIZE_T WinRandomAccessImpl::ReadIntoInstanceBuffer(uint64_t user_offset,
   uint64_t first_page_start,
   size_t bytes_to_read, size_t& left,
   char* dest) const {
@@ -622,52 +642,35 @@ SSIZE_T WinRandomAccessFile::ReadIntoInstanceBuffer(uint64_t user_offset,
   return read;
 }
 
-void WinRandomAccessFile::CalculateReadParameters(uint64_t offset, size_t bytes_requested,
-  size_t& actual_bytes_toread,
-  uint64_t& first_page_start) const {
-
-  const size_t alignment = buffer_.Alignment();
-
-  first_page_start = TruncateToPageBoundary(alignment, offset);
-  const uint64_t last_page_start =
-    TruncateToPageBoundary(alignment, offset + bytes_requested - 1);
-  actual_bytes_toread = (last_page_start - first_page_start) + alignment;
-}
-
-SSIZE_T WinRandomAccessFile::PositionedReadInternal(char* src, size_t numBytes,
+SSIZE_T WinRandomAccessImpl::PositionedReadInternal(char* src,
+  size_t numBytes,
   uint64_t offset) const {
-  return pread(hFile_, src, numBytes, offset);
+  return pread(file_base_->GetFileHandle(), src, numBytes, offset);
 }
 
-WinRandomAccessFile::WinRandomAccessFile(const std::string& fname, HANDLE hFile, size_t alignment,
-    const EnvOptions& options)
-    : filename_(fname),
-    hFile_(hFile),
-    use_os_buffer_(options.use_os_buffer),
+inline
+WinRandomAccessImpl::WinRandomAccessImpl(WinFileData* file_base,
+  size_t alignment,
+  const EnvOptions& options) :
+    file_base_(file_base),
     read_ahead_(false),
     compaction_readahead_size_(options.compaction_readahead_size),
     random_access_max_buffer_size_(options.random_access_max_buffer_size),
     buffer_(),
     buffered_start_(0) {
+
   assert(!options.use_mmap_reads);
 
   // Unbuffered access, use internal buffer for reads
-  if (!use_os_buffer_) {
+  if (!file_base_->UseOSBuffer()) {
     // Do not allocate the buffer either until the first request or
     // until there is a call to allocate a read-ahead buffer
     buffer_.Alignment(alignment);
   }
 }
 
-WinRandomAccessFile::~WinRandomAccessFile() {
-  if (hFile_ != NULL && hFile_ != INVALID_HANDLE_VALUE) {
-    ::CloseHandle(hFile_);
-  }
-}
-
-void WinRandomAccessFile::EnableReadAhead() { this->Hint(SEQUENTIAL); }
-
-Status WinRandomAccessFile::Read(uint64_t offset, size_t n, Slice* result,
+inline
+Status WinRandomAccessImpl::ReadImpl(uint64_t offset, size_t n, Slice* result,
   char* scratch) const {
 
   Status s;
@@ -683,14 +686,15 @@ Status WinRandomAccessFile::Read(uint64_t offset, size_t n, Slice* result,
   // When in unbuffered mode we need to do the following changes:
   // - use our own aligned buffer
   // - always read at the offset of that is a multiple of alignment
-  if (!use_os_buffer_) {
+  if (!file_base_->UseOSBuffer()) {
 
     uint64_t first_page_start = 0;
     size_t actual_bytes_toread = 0;
     size_t bytes_requested = left;
 
     if (!read_ahead_ && random_access_max_buffer_size_ == 0) {
-      CalculateReadParameters(offset, bytes_requested, actual_bytes_toread,
+      CalculateReadParameters(buffer_.Alignment(), offset, bytes_requested,
+        actual_bytes_toread,
         first_page_start);
 
       assert(actual_bytes_toread > 0);
@@ -723,7 +727,8 @@ Status WinRandomAccessFile::Read(uint64_t offset, size_t n, Slice* result,
           bytes_requested = compaction_readahead_size_;
         }
 
-        CalculateReadParameters(offset, bytes_requested, actual_bytes_toread,
+        CalculateReadParameters(buffer_.Alignment(), offset, bytes_requested,
+          actual_bytes_toread,
           first_page_start);
 
         assert(actual_bytes_toread > 0);
@@ -757,20 +762,25 @@ Status WinRandomAccessFile::Read(uint64_t offset, size_t n, Slice* result,
     }
   }
 
-  *result = Slice(scratch, (r < 0) ? 0 : n - left);
-
   if (r < 0) {
-    s = IOErrorFromLastWindowsError(filename_);
+    auto lastError = GetLastError();
+    // Posix impl wants to treat reads from beyond
+    // of the file as OK.
+    if(lastError != ERROR_HANDLE_EOF) {
+      s = IOErrorFromWindowsError(file_base_->GetName(), lastError);
     }
-  return s;
   }
 
-bool WinRandomAccessFile::ShouldForwardRawRequest() const {
-  return true;
+  *result = Slice(scratch, (r < 0) ? 0 : n - left);
+
+  return s;
 }
 
-void WinRandomAccessFile::Hint(AccessPattern pattern) {
-  if (pattern == SEQUENTIAL && !use_os_buffer_ &&
+inline
+void WinRandomAccessImpl::HintImpl(RandomAccessFile::AccessPattern pattern) {
+
+  if (pattern == RandomAccessFile::SEQUENTIAL &&
+    !file_base_->UseOSBuffer() &&
     compaction_readahead_size_ > 0) {
     std::lock_guard<std::mutex> lg(buffer_mut_);
     if (!read_ahead_) {
@@ -785,60 +795,76 @@ void WinRandomAccessFile::Hint(AccessPattern pattern) {
   }
 }
 
-Status WinRandomAccessFile::InvalidateCache(size_t offset, size_t length) {
-  return Status::OK();
+///////////////////////////////////////////////////////////////////////////////////////////////////
+/// WinRandomAccessFile
+
+WinRandomAccessFile::WinRandomAccessFile(const std::string& fname, HANDLE hFile, size_t alignment,
+  const EnvOptions& options) :
+  WinFileData(fname, hFile, options.use_os_buffer),
+  WinRandomAccessImpl(this, alignment, options) {
 }
 
-size_t WinRandomAccessFile::GetUniqueId(char* id, size_t max_size) const {
-  return GetUniqueIdFromFile(hFile_, id, max_size);
+WinRandomAccessFile::~WinRandomAccessFile() {
 }
 
-Status WinWritableFile::PreallocateInternal(uint64_t spaceToReserve) {
-  return fallocate(filename_, hFile_, spaceToReserve);
+Status WinRandomAccessFile::Read(uint64_t offset, size_t n, Slice* result,
+  char* scratch) const {
+  return ReadImpl(offset, n, result, scratch);
 }
 
-WinWritableFile::WinWritableFile(const std::string& fname, HANDLE hFile, size_t alignment,
-    size_t capacity, const EnvOptions& options)
-    : filename_(fname),
-    hFile_(hFile),
-    use_os_buffer_(options.use_os_buffer),
-    alignment_(alignment),
-    filesize_(0),
-    reservedsize_(0) {
-  assert(!options.use_mmap_writes);
+void WinRandomAccessFile::EnableReadAhead() {
+  HintImpl(SEQUENTIAL);
 }
 
-WinWritableFile::~WinWritableFile() {
-  if (NULL != hFile_ && INVALID_HANDLE_VALUE != hFile_) {
-    WinWritableFile::Close();
+bool WinRandomAccessFile::ShouldForwardRawRequest() const {
+  return true;
 }
+
+void WinRandomAccessFile::Hint(AccessPattern pattern) {
+  HintImpl(pattern);
 }
 
-  // Indicates if the class makes use of unbuffered I/O
-bool WinWritableFile::UseOSBuffer() const {
-  return use_os_buffer_;
+Status WinRandomAccessFile::InvalidateCache(size_t offset, size_t length) {
+  return Status::OK();
 }
 
-size_t WinWritableFile::GetRequiredBufferAlignment() const {
-  return alignment_;
+size_t WinRandomAccessFile::GetUniqueId(char* id, size_t max_size) const {
+  return GetUniqueIdFromFile(GetFileHandle(), id, max_size);
 }
 
-Status WinWritableFile::Append(const Slice& data) {
+/////////////////////////////////////////////////////////////////////////////
+// WinWritableImpl
+//
+
+inline
+Status WinWritableImpl::PreallocateInternal(uint64_t spaceToReserve) {
+  return fallocate(file_data_->GetName(), file_data_->GetFileHandle(), spaceToReserve);
+}
+
+WinWritableImpl::WinWritableImpl(WinFileData* file_data, size_t alignment)
+  : file_data_(file_data),
+  alignment_(alignment),
+  filesize_(0),
+  reservedsize_(0) {
+}
+
+Status WinWritableImpl::AppendImpl(const Slice& data) {
 
   // Used for buffered access ONLY
-  assert(use_os_buffer_);
+  assert(file_data_->UseOSBuffer());
   assert(data.size() < std::numeric_limits<DWORD>::max());
 
   Status s;
 
   DWORD bytesWritten = 0;
-  if (!WriteFile(hFile_, data.data(),
+  if (!WriteFile(file_data_->GetFileHandle(), data.data(),
     static_cast<DWORD>(data.size()), &bytesWritten, NULL)) {
     auto lastError = GetLastError();
     s = IOErrorFromWindowsError(
-      "Failed to WriteFile: " + filename_,
+      "Failed to WriteFile: " + file_data_->GetName(),
       lastError);
-  } else {
+  }
+  else {
     assert(size_t(bytesWritten) == data.size());
     filesize_ += data.size();
   }
@@ -846,86 +872,77 @@ Status WinWritableFile::Append(const Slice& data) {
   return s;
 }
 
-Status WinWritableFile::PositionedAppend(const Slice& data, uint64_t offset) {
+Status WinWritableImpl::PositionedAppendImpl(const Slice& data, uint64_t offset) {
   Status s;
 
-  SSIZE_T ret = pwrite(hFile_, data.data(), data.size(), offset);
+  SSIZE_T ret = pwrite(file_data_->GetFileHandle(), data.data(), data.size(), offset);
 
   // Error break
   if (ret < 0) {
     auto lastError = GetLastError();
     s = IOErrorFromWindowsError(
-      "Failed to pwrite for: " + filename_, lastError);
-  } else {
-    // With positional write it is not clear at all
-    // if this actually extends the filesize
+      "Failed to pwrite for: " + file_data_->GetName(), lastError);
+  }
+  else {
     assert(size_t(ret) == data.size());
-    filesize_ += data.size();
+    // For sequential write this would be simple 
+    // size extension by data.size()
+    uint64_t write_end = offset + data.size();
+    if (write_end >= filesize_) {
+      filesize_ = write_end;
+    }
   }
   return s;
 }
 
 // Need to implement this so the file is truncated correctly
 // when buffered and unbuffered mode
-Status WinWritableFile::Truncate(uint64_t size) {
-  Status s = ftruncate(filename_, hFile_, size);
+inline
+Status WinWritableImpl::TruncateImpl(uint64_t size) {
+  Status s = ftruncate(file_data_->GetName(), file_data_->GetFileHandle(),
+    size);
   if (s.ok()) {
     filesize_ = size;
   }
   return s;
 }
 
-Status WinWritableFile::Close() {
+Status WinWritableImpl::CloseImpl() {
 
   Status s;
 
-  assert(INVALID_HANDLE_VALUE != hFile_);
+  auto hFile = file_data_->GetFileHandle();
+  assert(INVALID_HANDLE_VALUE != hFile);
 
-  if (fsync(hFile_) < 0) {
+  if (fsync(hFile) < 0) {
     auto lastError = GetLastError();
-    s = IOErrorFromWindowsError("fsync failed at Close() for: " + filename_,
+    s = IOErrorFromWindowsError("fsync failed at Close() for: " +
+      file_data_->GetName(),
       lastError);
   }
 
-  if (FALSE == ::CloseHandle(hFile_)) {
+  if(!file_data_->CloseFile()) {
     auto lastError = GetLastError();
-    s = IOErrorFromWindowsError("CloseHandle failed for: " + filename_,
+    s = IOErrorFromWindowsError("CloseHandle failed for: " + file_data_->GetName(),
       lastError);
   }
-
-  hFile_ = INVALID_HANDLE_VALUE;
   return s;
 }
 
-  // write out the cached data to the OS cache
-  // This is now taken care of the WritableFileWriter
-Status WinWritableFile::Flush() {
-  return Status::OK();
-}
-
-Status WinWritableFile::Sync() {
+Status WinWritableImpl::SyncImpl() {
   Status s;
   // Calls flush buffers
-  if (fsync(hFile_) < 0) {
+  if (fsync(file_data_->GetFileHandle()) < 0) {
     auto lastError = GetLastError();
-    s = IOErrorFromWindowsError("fsync failed at Sync() for: " + filename_,
+    s = IOErrorFromWindowsError("fsync failed at Sync() for: " + 
+      file_data_->GetName(),
       lastError);
   }
   return s;
 }
 
-Status WinWritableFile::Fsync() { return Sync(); }
-
-uint64_t WinWritableFile::GetFileSize() {
-  // Double accounting now here with WritableFileWriter
-  // and this size will be wrong when unbuffered access is used
-  // but tests implement their own writable files and do not use WritableFileWrapper
-  // so we need to squeeze a square peg through
-  // a round hole here.
-  return filesize_;
-}
 
-Status WinWritableFile::Allocate(uint64_t offset, uint64_t len) {
+Status WinWritableImpl::AllocateImpl(uint64_t offset, uint64_t len) {
   Status status;
   TEST_KILL_RANDOM("WinWritableFile::Allocate", rocksdb_kill_odds);
 
@@ -946,18 +963,135 @@ Status WinWritableFile::Allocate(uint64_t offset, uint64_t len) {
   return status;
 }
 
+
+////////////////////////////////////////////////////////////////////////////////
+/// WinWritableFile
+
+WinWritableFile::WinWritableFile(const std::string& fname, HANDLE hFile, size_t alignment,
+    size_t /* capacity */, const EnvOptions& options)
+    : WinFileData(fname, hFile, options.use_os_buffer),
+  WinWritableImpl(this, alignment) {
+
+  assert(!options.use_mmap_writes);
+}
+
+WinWritableFile::~WinWritableFile() {
+}
+
+  // Indicates if the class makes use of unbuffered I/O
+bool WinWritableFile::UseOSBuffer() const {
+  return WinFileData::UseOSBuffer();
+}
+
+size_t WinWritableFile::GetRequiredBufferAlignment() const {
+  return GetAlignement();
+}
+
+Status WinWritableFile::Append(const Slice& data) {
+  return AppendImpl(data);
+}
+
+Status WinWritableFile::PositionedAppend(const Slice& data, uint64_t offset) {
+  return PositionedAppendImpl(data, offset);
+}
+
+// Need to implement this so the file is truncated correctly
+// when buffered and unbuffered mode
+Status WinWritableFile::Truncate(uint64_t size) {
+  return TruncateImpl(size);
+}
+
+Status WinWritableFile::Close() {
+  return CloseImpl();
+}
+
+  // write out the cached data to the OS cache
+  // This is now taken care of the WritableFileWriter
+Status WinWritableFile::Flush() {
+  return Status::OK();
+}
+
+Status WinWritableFile::Sync() {
+  return SyncImpl();
+}
+
+Status WinWritableFile::Fsync() { 
+  return SyncImpl();
+}
+
+uint64_t WinWritableFile::GetFileSize() {
+  return GetFileSizeImpl();
+}
+
+Status WinWritableFile::Allocate(uint64_t offset, uint64_t len) {
+  return AllocateImpl(offset, len);
+}
+
 size_t WinWritableFile::GetUniqueId(char* id, size_t max_size) const {
-  return GetUniqueIdFromFile(hFile_, id, max_size);
+  return GetUniqueIdFromFile(GetFileHandle(), id, max_size);
+}
+
+/////////////////////////////////////////////////////////////////////////
+/// WinRandomRWFile
+
+WinRandomRWFile::WinRandomRWFile(const std::string& fname, HANDLE hFile, size_t alignment,
+  const EnvOptions& options) :
+  WinFileData(fname, hFile, options.use_os_buffer),
+  WinRandomAccessImpl(this, alignment, options),
+  WinWritableImpl(this, alignment) {
+
+}
+
+bool WinRandomRWFile::UseOSBuffer() const {
+  return WinFileData::UseOSBuffer();
 }
 
+size_t WinRandomRWFile::GetRequiredBufferAlignment() const {
+  return GetAlignement();
+}
+
+bool WinRandomRWFile::ShouldForwardRawRequest() const {
+  return true;
+}
+
+void WinRandomRWFile::EnableReadAhead() {
+  HintImpl(RandomAccessFile::SEQUENTIAL);
+}
+
+Status WinRandomRWFile::Write(uint64_t offset, const Slice & data) {
+  return PositionedAppendImpl(data, offset);
+}
+
+Status WinRandomRWFile::Read(uint64_t offset, size_t n, Slice * result, 
+  char * scratch) const {
+  return ReadImpl(offset, n, result, scratch);
+}
+
+Status WinRandomRWFile::Flush() {
+  return Status::OK();
+}
+
+Status WinRandomRWFile::Sync() {
+  return SyncImpl();
+}
+
+Status WinRandomRWFile::Close() {
+  return CloseImpl();
+}
+
+//////////////////////////////////////////////////////////////////////////
+/// WinDirectory
+
 Status WinDirectory::Fsync() { return Status::OK(); }
 
+//////////////////////////////////////////////////////////////////////////
+/// WinFileLock
+
 WinFileLock::~WinFileLock() {
   BOOL ret = ::CloseHandle(hFile_);
   assert(ret);
 }
 
-
 }
 }
 

port/win/io_win.h

@@ -68,10 +68,58 @@ Status ftruncate(const std::string& filename, HANDLE hFile,
 
 size_t GetUniqueIdFromFile(HANDLE hFile, char* id, size_t max_size);
 
-// mmap() based random-access
-class WinMmapReadableFile : public RandomAccessFile {
-  const std::string fileName_;
+class WinFileData {
+protected:
+
+  const std::string filename_;
   HANDLE hFile_;
+  // There is no equivalent of advising away buffered pages as in posix.
+  // To implement this flag we would need to do unbuffered reads which
+  // will need to be aligned (not sure there is a guarantee that the buffer
+  // passed in is aligned).
+  // Hence we currently ignore this flag. It is used only in a few cases
+  // which should not be perf critical.
+  // If perf evaluation finds this to be a problem, we can look into
+  // implementing this.
+  const bool use_os_buffer_;
+
+public:
+
+  // We want this class be usable both for inheritance (prive
+  // or protected) and for containment so __ctor and __dtor public
+  WinFileData(const std::string& filename, HANDLE hFile, bool use_os_buffer) :
+    filename_(filename), hFile_(hFile), use_os_buffer_(use_os_buffer)
+  {}
+
+  virtual ~WinFileData() {
+    this->CloseFile();
+  }
+
+  bool CloseFile() {
+
+    bool result = true;
+
+    if (hFile_ != NULL && hFile_ != INVALID_HANDLE_VALUE) {
+      result = ::CloseHandle(hFile_);
+      assert(result);
+      hFile_ = NULL;
+    }
+    return result;
+  }
+
+  const std::string& GetName() const { return filename_; }
+
+  HANDLE GetFileHandle() const { return hFile_; }
+
+  bool UseOSBuffer() const { return use_os_buffer_; }
+
+  WinFileData(const WinFileData&) = delete;
+  WinFileData& operator=(const WinFileData&) = delete;
+};
+
+
+// mmap() based random-access
+class WinMmapReadableFile : private WinFileData, public RandomAccessFile {
   HANDLE hMap_;
 
   const void* mapped_region_;
@@ -84,6 +132,9 @@ public:
 
   ~WinMmapReadableFile();
 
+  WinMmapReadableFile(const WinMmapReadableFile&) = delete;
+  WinMmapReadableFile& operator=(const WinMmapReadableFile&) = delete;
+
   virtual Status Read(uint64_t offset, size_t n, Slice* result,
     char* scratch) const override;
 
@@ -96,10 +147,8 @@ public:
 // data to the file.  This is safe since we either properly close the
 // file before reading from it, or for log files, the reading code
 // knows enough to skip zero suffixes.
-class WinMmapFile : public WritableFile {
+class WinMmapFile : private WinFileData, public WritableFile {
 private:
-  const std::string filename_;
-  HANDLE hFile_;
   HANDLE hMap_;
 
   const size_t page_size_;  // We flush the mapping view in page_size
@@ -142,6 +191,9 @@ public:
 
   ~WinMmapFile();
 
+  WinMmapFile(const WinMmapFile&) = delete;
+  WinMmapFile& operator=(const WinMmapFile&) = delete;
+
   virtual Status Append(const Slice& data) override;
 
   // Means Close() will properly take care of truncate
@@ -174,27 +226,16 @@ public:
   virtual size_t GetUniqueId(char* id, size_t max_size) const override;
 };
 
-class WinSequentialFile : public SequentialFile {
-private:
-  const std::string filename_;
-  HANDLE file_;
-
-  // There is no equivalent of advising away buffered pages as in posix.
-  // To implement this flag we would need to do unbuffered reads which
-  // will need to be aligned (not sure there is a guarantee that the buffer
-  // passed in is aligned).
-  // Hence we currently ignore this flag. It is used only in a few cases
-  // which should not be perf critical.
-  // If perf evaluation finds this to be a problem, we can look into
-  // implementing this.
-  bool use_os_buffer_;
-
+class WinSequentialFile : private WinFileData, public SequentialFile {
 public:
   WinSequentialFile(const std::string& fname, HANDLE f,
     const EnvOptions& options);
 
   ~WinSequentialFile();
 
+  WinSequentialFile(const WinSequentialFile&) = delete;
+  WinSequentialFile& operator=(const WinSequentialFile&) = delete;
+
   virtual Status Read(size_t n, Slice* result, char* scratch) override;
 
   virtual Status Skip(uint64_t n) override;
@@ -202,11 +243,10 @@ public:
   virtual Status InvalidateCache(size_t offset, size_t length) override;
 };
 
-// pread() based random-access
-class WinRandomAccessFile : public RandomAccessFile {
-  const std::string filename_;
-  HANDLE hFile_;
-  const bool use_os_buffer_;
+class WinRandomAccessImpl {
+protected:
+
+  WinFileData* file_base_;
   bool         read_ahead_;
   const size_t compaction_readahead_size_;
   const size_t random_access_max_buffer_size_;
@@ -215,6 +255,10 @@ class WinRandomAccessFile : public RandomAccessFile {
   mutable uint64_t
     buffered_start_;  // file offset set that is currently buffered
 
+  // Override for behavior change when creating a custom env
+  virtual SSIZE_T PositionedReadInternal(char* src, size_t numBytes,
+    uint64_t offset) const;
+
     /*
     * The function reads a requested amount of bytes into the specified aligned
     * buffer Upon success the function sets the length of the buffer to the
@@ -237,6 +281,7 @@ class WinRandomAccessFile : public RandomAccessFile {
     * @buffer - buffer to use
     * @dest - user supplied buffer
     */
+
   SSIZE_T ReadIntoBuffer(uint64_t user_offset, uint64_t first_page_start,
     size_t bytes_to_read, size_t& left,
     AlignedBuffer& buffer, char* dest) const;
@@ -250,13 +295,27 @@ class WinRandomAccessFile : public RandomAccessFile {
     size_t bytes_to_read, size_t& left,
     char* dest) const;
 
-  void CalculateReadParameters(uint64_t offset, size_t bytes_requested,
-    size_t& actual_bytes_toread,
-    uint64_t& first_page_start) const;
+  WinRandomAccessImpl(WinFileData* file_base, size_t alignment,
+    const EnvOptions& options);
 
-  // Override for behavior change
-  virtual SSIZE_T PositionedReadInternal(char* src, size_t numBytes,
-     uint64_t offset) const;
+  virtual ~WinRandomAccessImpl() {}
+
+public:
+
+  WinRandomAccessImpl(const WinRandomAccessImpl&) = delete;
+  WinRandomAccessImpl& operator=(const WinRandomAccessImpl&) = delete;
+
+
+  Status ReadImpl(uint64_t offset, size_t n, Slice* result,
+    char* scratch) const;
+
+  void HintImpl(RandomAccessFile::AccessPattern pattern);
+};
+
+// pread() based random-access
+class WinRandomAccessFile : private WinFileData, 
+  protected WinRandomAccessImpl, // Want to be able to override PositionedReadInternal
+  public RandomAccessFile {
 
 public:
   WinRandomAccessFile(const std::string& fname, HANDLE hFile, size_t alignment,
@@ -291,18 +350,55 @@ public:
 // the tail for the next write OR for Close() at which point we pad with zeros.
 // No padding is required for
 // buffered access.
-class WinWritableFile : public WritableFile {
-private:
-  const std::string filename_;
-  HANDLE            hFile_;
-  const bool        use_os_buffer_;  // Used to indicate unbuffered access, the file
+class WinWritableImpl {
+protected:
+
+  WinFileData*      file_data_;
   const uint64_t    alignment_;
-  // must be opened as unbuffered if false
   uint64_t          filesize_;      // How much data is actually written disk
   uint64_t          reservedsize_;  // how far we have reserved space
 
   virtual Status PreallocateInternal(uint64_t spaceToReserve);
 
+  WinWritableImpl(WinFileData* file_data, size_t alignment);
+
+  ~WinWritableImpl() {}
+
+  uint64_t GetAlignement() const { return alignment_; }
+
+  Status AppendImpl(const Slice& data);
+
+  // Requires that the data is aligned as specified by GetRequiredBufferAlignment()
+  Status PositionedAppendImpl(const Slice& data, uint64_t offset);
+
+  Status TruncateImpl(uint64_t size);
+
+  Status CloseImpl();
+
+  Status SyncImpl();
+
+  uint64_t GetFileSizeImpl() {
+    // Double accounting now here with WritableFileWriter
+    // and this size will be wrong when unbuffered access is used
+    // but tests implement their own writable files and do not use WritableFileWrapper
+    // so we need to squeeze a square peg through
+    // a round hole here.
+    return filesize_;
+  }
+
+  Status AllocateImpl(uint64_t offset, uint64_t len);
+
+public:
+
+  WinWritableImpl(const WinWritableImpl&) = delete;
+  WinWritableImpl& operator=(const WinWritableImpl&) = delete;
+};
+
+
+class WinWritableFile : private WinFileData,
+  protected WinWritableImpl,
+  public WritableFile {
+
 public:
   WinWritableFile(const std::string& fname, HANDLE hFile, size_t alignment,
     size_t capacity, const EnvOptions& options);
@@ -310,12 +406,14 @@ public:
   ~WinWritableFile();
 
   // Indicates if the class makes use of unbuffered I/O
+  // Use PositionedAppend
   virtual bool UseOSBuffer() const override;
 
   virtual size_t GetRequiredBufferAlignment() const override;
 
   virtual Status Append(const Slice& data) override;
 
+  // Requires that the data is aligned as specified by GetRequiredBufferAlignment()
   virtual Status PositionedAppend(const Slice& data, uint64_t offset) override;
 
   // Need to implement this so the file is truncated correctly
@@ -339,6 +437,57 @@ public:
   virtual size_t GetUniqueId(char* id, size_t max_size) const override;
 };
 
+
+class WinRandomRWFile : private WinFileData,
+  protected WinRandomAccessImpl,
+  protected WinWritableImpl,
+  public RandomRWFile {
+
+public:
+
+  WinRandomRWFile(const std::string& fname, HANDLE hFile, size_t alignment,
+    const EnvOptions& options);
+
+  ~WinRandomRWFile() {}
+
+  // Indicates if the class makes use of unbuffered I/O
+  // If false you must pass aligned buffer to Write()
+  virtual bool UseOSBuffer() const override;
+
+  // Use the returned alignment value to allocate
+  // aligned buffer for Write() when UseOSBuffer()
+  // returns false
+  virtual size_t GetRequiredBufferAlignment() const override;
+
+  // Used by the file_reader_writer to decide if the ReadAhead wrapper
+  // should simply forward the call and do not enact read_ahead buffering or locking.
+  // The implementation below takes care of reading ahead
+  virtual bool ShouldForwardRawRequest() const override;
+
+  // For cases when read-ahead is implemented in the platform dependent
+  // layer. This is when ShouldForwardRawRequest() returns true.
+  virtual void EnableReadAhead() override;
+
+  // Write bytes in `data` at  offset `offset`, Returns Status::OK() on success.
+  // Pass aligned buffer when UseOSBuffer() returns false.
+  virtual Status Write(uint64_t offset, const Slice& data) override;
+
+  // Read up to `n` bytes starting from offset `offset` and store them in
+  // result, provided `scratch` size should be at least `n`.
+  // Returns Status::OK() on success.
+  virtual Status Read(uint64_t offset, size_t n, Slice* result,
+    char* scratch) const override;
+
+  virtual Status Flush() override;
+
+  virtual Status Sync() override;
+
+  virtual Status Fsync() { return Sync(); }
+
+  virtual Status Close() override;
+};
+
+
 class WinDirectory : public Directory {
 public:
   WinDirectory() {}