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rocksdb/port/win/io_win.h

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <rocksdb/Status.h>
#include <rocksdb/env.h>
#include "util/aligned_buffer.h"
#include <string>
#include <stdint.h>
#include <Windows.h>
#include <mutex>
namespace rocksdb {
namespace port {
std::string GetWindowsErrSz(DWORD err);
inline Status IOErrorFromWindowsError(const std::string& context, DWORD err) {
return (err == ERROR_HANDLE_DISK_FULL) ?
Status::NoSpace(context, GetWindowsErrSz(err)) :
Status::IOError(context, GetWindowsErrSz(err));
}
inline Status IOErrorFromLastWindowsError(const std::string& context) {
return IOErrorFromWindowsError(context, GetLastError());
}
inline Status IOError(const std::string& context, int err_number) {
return (err_number == ENOSPC) ?
Status::NoSpace(context, strerror(err_number)) :
Status::IOError(context, strerror(err_number));
}
// Note the below two do not set errno because they are used only here in this
// file
// on a Windows handle and, therefore, not necessary. Translating GetLastError()
// to errno
// is a sad business
inline int fsync(HANDLE hFile) {
if (!FlushFileBuffers(hFile)) {
return -1;
}
return 0;
}
SSIZE_T pwrite(HANDLE hFile, const char* src, size_t numBytes,
uint64_t offset);
SSIZE_T pread(HANDLE hFile, char* src, size_t numBytes, uint64_t offset);
Status fallocate(const std::string& filename, HANDLE hFile,
uint64_t to_size);
Status ftruncate(const std::string& filename, HANDLE hFile,
uint64_t toSize);
size_t GetUniqueIdFromFile(HANDLE hFile, char* id, size_t max_size);
// mmap() based random-access
class WinMmapReadableFile : public RandomAccessFile {
const std::string fileName_;
HANDLE hFile_;
HANDLE hMap_;
const void* mapped_region_;
const size_t length_;
public:
// mapped_region_[0,length-1] contains the mmapped contents of the file.
WinMmapReadableFile(const std::string& fileName, HANDLE hFile, HANDLE hMap,
const void* mapped_region, size_t length);
~WinMmapReadableFile();
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const override;
virtual Status InvalidateCache(size_t offset, size_t length) override;
virtual size_t GetUniqueId(char* id, size_t max_size) const override;
};
// We preallocate and use memcpy to append new
// 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 {
private:
const std::string filename_;
HANDLE hFile_;
HANDLE hMap_;
const size_t page_size_; // We flush the mapping view in page_size
// increments. We may decide if this is a memory
// page size or SSD page size
const size_t
allocation_granularity_; // View must start at such a granularity
size_t reserved_size_; // Preallocated size
size_t mapping_size_; // The max size of the mapping object
// we want to guess the final file size to minimize the remapping
size_t view_size_; // How much memory to map into a view at a time
char* mapped_begin_; // Must begin at the file offset that is aligned with
// allocation_granularity_
char* mapped_end_;
char* dst_; // Where to write next (in range [mapped_begin_,mapped_end_])
char* last_sync_; // Where have we synced up to
uint64_t file_offset_; // Offset of mapped_begin_ in file
// Do we have unsynced writes?
bool pending_sync_;
// Can only truncate or reserve to a sector size aligned if
// used on files that are opened with Unbuffered I/O
Status TruncateFile(uint64_t toSize);
Status UnmapCurrentRegion();
Status MapNewRegion();
virtual Status PreallocateInternal(uint64_t spaceToReserve);
public:
WinMmapFile(const std::string& fname, HANDLE hFile, size_t page_size,
size_t allocation_granularity, const EnvOptions& options);
~WinMmapFile();
virtual Status Append(const Slice& data) override;
// Means Close() will properly take care of truncate
// and it does not need any additional information
virtual Status Truncate(uint64_t size) override;
virtual Status Close() override;
virtual Status Flush() override;
// Flush only data
virtual Status Sync() override;
/**
* Flush data as well as metadata to stable storage.
*/
virtual Status Fsync() override;
/**
* Get the size of valid data in the file. This will not match the
* size that is returned from the filesystem because we use mmap
* to extend file by map_size every time.
*/
virtual uint64_t GetFileSize() override;
virtual Status InvalidateCache(size_t offset, size_t length) override;
virtual Status Allocate(uint64_t offset, uint64_t len) override;
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_;
public:
WinSequentialFile(const std::string& fname, HANDLE f,
const EnvOptions& options);
~WinSequentialFile();
virtual Status Read(size_t n, Slice* result, char* scratch) override;
virtual Status Skip(uint64_t n) override;
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_;
bool read_ahead_;
const size_t compaction_readahead_size_;
const size_t random_access_max_buffer_size_;
mutable std::mutex buffer_mut_;
mutable AlignedBuffer buffer_;
mutable uint64_t
buffered_start_; // file offset set that is currently buffered
/*
* 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
* amount of bytes actually read even though it might be less than actually
* requested. It then copies the amount of bytes requested by the user (left)
* to the user supplied buffer (dest) and reduces left by the amount of bytes
* copied to the user buffer
*
* @user_offset [in] - offset on disk where the read was requested by the user
* @first_page_start [in] - actual page aligned disk offset that we want to
* read from
* @bytes_to_read [in] - total amount of bytes that will be read from disk
* which is generally greater or equal to the amount
* that the user has requested due to the
* either alignment requirements or read_ahead in
* effect.
* @left [in/out] total amount of bytes that needs to be copied to the user
* buffer. It is reduced by the amount of bytes that actually
* copied
* @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;
SSIZE_T ReadIntoOneShotBuffer(uint64_t user_offset, uint64_t first_page_start,
size_t bytes_to_read, size_t& left,
char* dest) const;
SSIZE_T ReadIntoInstanceBuffer(uint64_t user_offset,
uint64_t first_page_start,
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;
// Override for behavior change
virtual SSIZE_T PositionedReadInternal(char* src, size_t numBytes,
uint64_t offset) const;
public:
WinRandomAccessFile(const std::string& fname, HANDLE hFile, size_t alignment,
const EnvOptions& options);
~WinRandomAccessFile();
virtual void EnableReadAhead() override;
virtual Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const override;
virtual bool ShouldForwardRawRequest() const override;
virtual void Hint(AccessPattern pattern) override;
virtual Status InvalidateCache(size_t offset, size_t length) override;
virtual size_t GetUniqueId(char* id, size_t max_size) const override;
};
// This is a sequential write class. It has been mimicked (as others) after
// the original Posix class. We add support for unbuffered I/O on windows as
// well
// we utilize the original buffer as an alignment buffer to write directly to
// file with no buffering.
// No buffering requires that the provided buffer is aligned to the physical
// sector size (SSD page size) and
// that all SetFilePointer() operations to occur with such an alignment.
// We thus always write in sector/page size increments to the drive and leave
// 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
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);
public:
WinWritableFile(const std::string& fname, HANDLE hFile, size_t alignment,
size_t capacity, const EnvOptions& options);
~WinWritableFile();
// Indicates if the class makes use of unbuffered I/O
virtual bool UseOSBuffer() const override;
virtual size_t GetRequiredBufferAlignment() const override;
virtual Status Append(const Slice& data) override;
virtual Status PositionedAppend(const Slice& data, uint64_t offset) override;
// Need to implement this so the file is truncated correctly
// when buffered and unbuffered mode
virtual Status Truncate(uint64_t size) override;
virtual Status Close() override;
// write out the cached data to the OS cache
// This is now taken care of the WritableFileWriter
virtual Status Flush() override;
virtual Status Sync() override;
virtual Status Fsync() override;
virtual uint64_t GetFileSize() override;
virtual Status Allocate(uint64_t offset, uint64_t len) override;
virtual size_t GetUniqueId(char* id, size_t max_size) const override;
};
class WinDirectory : public Directory {
public:
WinDirectory() {}
virtual Status Fsync() override;
};
class WinFileLock : public FileLock {
public:
explicit WinFileLock(HANDLE hFile) : hFile_(hFile) {
assert(hFile != NULL);
assert(hFile != INVALID_HANDLE_VALUE);
}
~WinFileLock();
private:
HANDLE hFile_;
};
}
}