Files
llvm-project/llvm/lib/CAS/BuiltinObjectHasher.cpp
Argyrios Kyrtzidis 60ecb37896 [llvm/CAS] Add file-based APIs to OnDiskGraphDB (#179782)
These allow performing optimizations that reduce I/O and disk space
consumption. For example, when applicable, a file can be cloned directly
into the database directory, instead of needing to load it in memory and
then copy its contents into a new file.

These APIs are then used to optimize importing data from an upstream DB
by using file cloning where applicable.
2026-02-06 13:27:24 -08:00

52 lines
1.7 KiB
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//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/CAS/BuiltinObjectHasher.h"
#include "llvm/Support/BLAKE3.h"
using namespace llvm;
using namespace llvm::cas;
template <class HasherT>
Expected<typename BuiltinObjectHasher<HasherT>::HashT>
BuiltinObjectHasher<HasherT>::hashFile(StringRef FilePath) {
BuiltinObjectHasher H;
H.updateSize(0); // 0 refs
sys::fs::file_t FD;
if (Error E = sys::fs::openNativeFileForRead(FilePath).moveInto(FD))
return E;
sys::fs::file_status Status;
std::error_code EC = sys::fs::status(FD, Status);
if (EC)
return createFileError(FilePath, EC);
// FIXME: Do we need to add a hash of the data size? If we remove that we can
// avoid needing to read the file size before reading the file contents.
H.updateSize(Status.getSize());
size_t ChunkSize = sys::fs::DefaultReadChunkSize;
SmallVector<char, 0> Buffer;
Buffer.resize_for_overwrite(ChunkSize);
for (;;) {
Expected<size_t> ReadBytes =
sys::fs::readNativeFile(FD, MutableArrayRef(Buffer.begin(), ChunkSize));
if (!ReadBytes)
return ReadBytes.takeError();
if (*ReadBytes == 0)
break;
H.Hasher.update(toStringRef(ArrayRef(Buffer).take_front(*ReadBytes)));
}
return H.finish();
}
// Provide the definition for when using the BLAKE3 hasher.
template Expected<BuiltinObjectHasher<BLAKE3>::HashT>
BuiltinObjectHasher<BLAKE3>::hashFile(StringRef FilePath);