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// Copyright 2023 Huawei Cloud Computing Technology Co., Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef INCLUDED_SRC_BUILDTOOL_FILE_SYSTEM_OBJECT_CAS_HPP
#define INCLUDED_SRC_BUILDTOOL_FILE_SYSTEM_OBJECT_CAS_HPP
#include <filesystem>
#include <functional>
#include <optional>
#include <string>
#include <utility> // std::move
#include "gsl/gsl"
#include "src/buildtool/common/artifact_digest.hpp"
#include "src/buildtool/common/artifact_digest_factory.hpp"
#include "src/buildtool/crypto/hash_function.hpp"
#include "src/buildtool/file_system/file_storage.hpp"
#include "src/buildtool/file_system/file_system_manager.hpp"
#include "src/buildtool/file_system/object_type.hpp"
#include "src/buildtool/logging/log_level.hpp"
#include "src/buildtool/logging/logger.hpp"
/// \brief CAS for storing objects as plain blobs.
/// Automatically computes the digest for storing a blob from file path/bytes.
/// The actual object type is given as a template parameter. Depending on the
/// object type, files written to the file system may have different properties
/// (e.g., the x-bit set) or the digest may be computed differently (e.g., tree
/// digests in non-compatible mode). Supports custom "exists callback", which
/// is used to check blob existence before every read and write operation.
/// \tparam kType The object type to store as blob.
template <ObjectType kType>
class ObjectCAS {
public:
/// \brief Callback type for checking blob existence.
/// \returns true if a blob for the given digest exists at the given path.
using ExistsFunc = std::function<bool(ArtifactDigest const&,
std::filesystem::path const&)>;
/// \brief Create new object CAS in store_path directory.
/// The optional "exists callback" is used to check blob existence before
/// every read and write operation. It promises that a blob for the given
/// digest exists at the given path if true was returned.
/// \param store_path The path to use for storing blobs.
/// \param exists (optional) Function for checking blob existence.
explicit ObjectCAS(
HashFunction hash_function,
std::filesystem::path const& store_path,
std::optional<gsl::not_null<ExistsFunc>> exists = std::nullopt)
: file_store_{store_path},
exists_{exists.has_value() ? std::move(exists)->get()
: kDefaultExists},
hash_function_{hash_function} {}
ObjectCAS(ObjectCAS const&) = delete;
ObjectCAS(ObjectCAS&&) = delete;
auto operator=(ObjectCAS const&) -> ObjectCAS& = delete;
auto operator=(ObjectCAS&&) -> ObjectCAS& = delete;
~ObjectCAS() noexcept = default;
/// \brief Obtain path to the storage root.
[[nodiscard]] auto StorageRoot() const noexcept
-> std::filesystem::path const& {
return file_store_.StorageRoot();
}
/// \brief Store blob from bytes.
/// \param bytes The bytes do create the blob from.
/// \returns Digest of the stored blob or nullopt in case of error.
[[nodiscard]] auto StoreBlobFromBytes(std::string const& bytes)
const noexcept -> std::optional<ArtifactDigest> {
return StoreBlob(bytes, /*is_owner=*/true);
}
/// \brief Store blob from file path.
/// \param file_path The path of the file to store as blob.
/// \param is_owner Indicates ownership for optimization (hardlink).
/// \returns Digest of the stored blob or nullopt in case of error.
[[nodiscard]] auto StoreBlobFromFile(std::filesystem::path const& file_path,
bool is_owner = false) const noexcept
-> std::optional<ArtifactDigest> {
return StoreBlob(file_path, is_owner);
}
/// \brief Get path to blob.
/// \param digest Digest of the blob to lookup.
/// \returns Path to blob if found or nullopt otherwise.
[[nodiscard]] auto BlobPath(ArtifactDigest const& digest) const noexcept
-> std::optional<std::filesystem::path> {
auto const& id = digest.hash();
auto blob_path = file_store_.GetPath(id);
if (not IsAvailable(digest, blob_path)) {
logger_.Emit(LogLevel::Trace, "Blob not found {}", id);
return std::nullopt;
}
return blob_path;
}
private:
// For `Tree` the underlying storage type is non-executable file.
static constexpr ObjectType kStorageType =
IsTreeObject(kType) ? ObjectType::File : kType;
Logger logger_{std::string{"ObjectCAS"} + ToChar(kType)};
FileStorage<kStorageType, StoreMode::FirstWins, /*kSetEpochTime=*/true>
file_store_;
gsl::not_null<ExistsFunc> exists_;
HashFunction hash_function_;
/// Default callback for checking blob existence.
static inline ExistsFunc const kDefaultExists = [](auto const& /*digest*/,
auto const& path) {
return FileSystemManager::IsFile(path);
};
[[nodiscard]] auto CreateDigest(std::string const& bytes) const noexcept
-> std::optional<ArtifactDigest> {
return ArtifactDigestFactory::HashDataAs<kType>(hash_function_, bytes);
}
[[nodiscard]] auto CreateDigest(std::filesystem::path const& file_path)
const noexcept -> std::optional<ArtifactDigest> {
return ArtifactDigestFactory::HashFileAs<kType>(hash_function_,
file_path);
}
[[nodiscard]] auto IsAvailable(
ArtifactDigest const& digest,
std::filesystem::path const& path) const noexcept -> bool {
try {
return std::invoke(exists_.get(), digest, path);
} catch (...) {
return false;
}
}
/// \brief Store blob from bytes to storage.
[[nodiscard]] auto StoreBlobData(std::string const& blob_id,
std::string const& bytes,
bool /*unused*/) const noexcept -> bool {
return file_store_.AddFromBytes(blob_id, bytes);
}
/// \brief Store blob from file path to storage.
[[nodiscard]] auto StoreBlobData(std::string const& blob_id,
std::filesystem::path const& file_path,
bool is_owner) const noexcept -> bool {
return file_store_.AddFromFile(blob_id, file_path, is_owner);
}
/// \brief Store blob from unspecified data to storage.
template <class T>
[[nodiscard]] auto StoreBlob(T const& data, bool is_owner) const noexcept
-> std::optional<ArtifactDigest> {
if (auto digest = CreateDigest(data)) {
auto const& id = digest->hash();
if (IsAvailable(*digest, file_store_.GetPath(id))) {
return digest;
}
if (StoreBlobData(id, data, is_owner)) {
return digest;
}
logger_.Emit(LogLevel::Debug, "Failed to store blob {}.", id);
}
logger_.Emit(LogLevel::Debug, "Failed to create digest.");
return std::nullopt;
}
};
#endif // INCLUDED_SRC_BUILDTOOL_FILE_SYSTEM_OBJECT_CAS_HPP
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