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// Copyright 2022 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_OTHER_TOOLS_OPS_MAPS_CRITICAL_GIT_OP_MAP_HPP
#define INCLUDED_SRC_OTHER_TOOLS_OPS_MAPS_CRITICAL_GIT_OP_MAP_HPP
#include <cstddef>
#include <filesystem>
#include <functional>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <unordered_map>
#include <utility>
#include "src/buildtool/multithreading/async_map_consumer.hpp"
#include "src/other_tools/git_operations/git_ops_types.hpp"
#include "src/utils/cpp/hash_combine.hpp"
#include "src/utils/cpp/path_hash.hpp"
using GitOpKeyMap = std::unordered_map<
GitOpType,
std::function<GitOpValue(GitOpParams const&,
AsyncMapConsumerLoggerPtr const&)>>;
struct GitOpKey {
GitOpParams params{"", ""}; /* key (with exceptions) */
GitOpType op_type{GitOpType::DEFAULT_OP}; /* key */
[[nodiscard]] auto operation(GitOpParams const& params,
AsyncMapConsumerLoggerPtr const& logger) const
-> GitOpValue {
return kMap.at(op_type)(params, logger);
}
[[nodiscard]] auto operator==(GitOpKey const& other) const -> bool {
return params == other.params && op_type == other.op_type;
}
private:
static GitOpKeyMap const kMap;
};
class CriticalGitOpGuard;
using CriticalGitOpGuardPtr = std::shared_ptr<CriticalGitOpGuard>;
using CriticalGitOpMap = AsyncMapConsumer<GitOpKey, GitOpValue>;
[[nodiscard]] auto CreateCriticalGitOpMap(
CriticalGitOpGuardPtr const& crit_git_op_ptr) -> CriticalGitOpMap;
/// \brief Class ensuring thread safety in critical Git operations.
/// By always storing the most recent operation to be executed, a chain of
/// operations can be created such that no thread is left in a blocking state.
/// Each repo has its own key, so the caller has to ensure the target_path
/// parameter provided is non-empty.
class CriticalGitOpGuard {
public:
[[nodiscard]] auto FetchAndSetCriticalKey(GitOpKey const& new_key)
-> std::optional<GitOpKey> {
// making sure only one thread at a time processes this section
std::scoped_lock<std::mutex> const lock(critical_key_mutex_);
// try emplace a new value
auto const canonical_path =
std::filesystem::weakly_canonical(new_key.params.target_path);
auto result = curr_critical_key_.try_emplace(canonical_path, new_key);
// If the insertion happens, there are no keys to wait for. std::nullopt
// is returned.
if (result.second) {
return std::nullopt;
}
// If insertion fails (the path is being processed), mark the path
// occupied by the new key, but return the previous key to inform
// the new task to wait for the previous operation to complete.
return std::exchange(result.first->second, new_key);
}
private:
std::unordered_map<std::filesystem::path, GitOpKey> curr_critical_key_;
std::mutex critical_key_mutex_;
};
namespace std {
template <>
struct hash<GitOpParams> {
[[nodiscard]] auto operator()(GitOpParams const& ct) const noexcept
-> std::size_t {
size_t seed{};
hash_combine<std::filesystem::path>(&seed, ct.target_path);
hash_combine<std::string>(&seed, ct.git_hash);
return seed;
}
};
template <>
struct hash<GitOpKey> {
[[nodiscard]] auto operator()(GitOpKey const& ct) const noexcept
-> std::size_t {
size_t seed{};
hash_combine<GitOpParams>(&seed, ct.params);
hash_combine<>(&seed, ct.op_type);
return seed;
}
};
} // namespace std
#endif // INCLUDED_SRC_OTHER_TOOLS_OPS_MAPS_CRITICAL_GIT_OP_MAP_HPP
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