OnDiskCommon.h

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//===- OnDiskCommon.h -------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_LIB_CAS_ONDISKCOMMON_H
#define LLVM_LIB_CAS_ONDISKCOMMON_H
 
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include <chrono>
 
namespace llvm::cas::ondisk {
 
/// Thread-safe alternative to \c sys::fs::lockFile. This does not support all
/// the platforms that \c sys::fs::lockFile does, so keep it in the CAS library
/// for now.
std::error_code lockFileThreadSafe(int FD, llvm::sys::fs::LockKind Kind);
 
/// Thread-safe alternative to \c sys::fs::unlockFile. This does not support all
/// the platforms that \c sys::fs::lockFile does, so keep it in the CAS library
/// for now.
std::error_code unlockFileThreadSafe(int FD);
 
/// Thread-safe alternative to \c sys::fs::tryLockFile. This does not support
/// all the platforms that \c sys::fs::lockFile does, so keep it in the CAS
/// library for now.
std::error_code tryLockFileThreadSafe(
    int FD, std::chrono::milliseconds Timeout = std::chrono::milliseconds(0),
    llvm::sys::fs::LockKind Kind = llvm::sys::fs::LockKind::Exclusive);
 
/// Allocate space for the file \p FD on disk, if the filesystem supports it.
///
/// On filesystems that support this operation, this ensures errors such as
/// \c std::errc::no_space_on_device are detected before we write data.
///
/// \returns the new size of the file, or an \c Error.
Expected<size_t> preallocateFileTail(int FD, size_t CurrentSize,
                                     size_t NewSize);
 
} // namespace llvm::cas::ondisk
 
#endif // LLVM_LIB_CAS_ONDISKCOMMON_H