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// Copyright (C) 2021-2022 Joel Rosdahl and other contributors
//
// See doc/AUTHORS.adoc for a complete list of contributors.
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along with
// this program; if not, write to the Free Software Foundation, Inc., 51
// Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#pragma once
#include <storage/types.hpp>
#include <util/Bytes.hpp>
#include <third_party/nonstd/expected.hpp>
#include <third_party/nonstd/span.hpp>
#include <third_party/url.hpp>
#include <chrono>
#include <memory>
#include <optional>
#include <string>
#include <vector>
class Digest;
namespace storage::remote {
constexpr auto k_redacted_password = "********";
const auto k_default_connect_timeout = std::chrono::milliseconds{100};
const auto k_default_operation_timeout = std::chrono::milliseconds{10000};
// This class defines the API that a remote storage must implement.
class RemoteStorage
{
public:
class Backend
{
public:
struct Attribute
{
std::string key; // Key part.
std::string value; // Value part, percent-decoded.
std::string raw_value; // Value part, not percent-decoded.
};
struct Params
{
Url url;
std::vector<Attribute> attributes;
};
enum class Failure {
error, // Operation error, e.g. bad parameters or failed connection.
timeout, // Timeout, e.g. due to slow network or server.
};
class Failed : public std::runtime_error
{
public:
Failed(Failure failure);
Failed(const std::string& message, Failure failure = Failure::error);
Failure failure() const;
private:
Failure m_failure;
};
virtual ~Backend() = default;
// Get the value associated with `key`. Returns the value on success or
// std::nullopt if the entry is not present.
virtual nonstd::expected<std::optional<util::Bytes>, Failure>
get(const Digest& key) = 0;
// Put `value` associated to `key` in the storage. A true `only_if_missing`
// is a hint that the value does not have to be set if already present.
// Returns true if the entry was stored, otherwise false.
virtual nonstd::expected<bool, Failure>
put(const Digest& key,
nonstd::span<const uint8_t> value,
bool only_if_missing = false) = 0;
// Remove `key` and its associated value. Returns true if the entry was
// removed, otherwise false.
virtual nonstd::expected<bool, Failure> remove(const Digest& key) = 0;
// Determine whether an attribute is handled by the remote storage
// framework itself.
static bool is_framework_attribute(const std::string& name);
// Parse a timeout `value`, throwing `Failed` on error.
static std::chrono::milliseconds
parse_timeout_attribute(const std::string& value);
};
virtual ~RemoteStorage() = default;
// Create an instance of the backend. The instance is created just before the
// first call to a backend method, so the backend constructor can open a
// connection or similar right away if wanted. The method should throw
// `core::Fatal` on fatal configuration error or `Backend::Failed` on
// connection error or timeout.
virtual std::unique_ptr<Backend>
create_backend(const Backend::Params& parameters) const = 0;
// Redact secrets in backend parameters, if any.
virtual void redact_secrets(Backend::Params& parameters) const;
};
// --- Inline implementations ---
inline void
RemoteStorage::redact_secrets(RemoteStorage::Backend::Params& /*config*/) const
{
}
inline RemoteStorage::Backend::Failed::Failed(Failure failure)
: Failed("", failure)
{
}
inline RemoteStorage::Backend::Failed::Failed(const std::string& message,
Failure failure)
: std::runtime_error::runtime_error(message),
m_failure(failure)
{
}
inline RemoteStorage::Backend::Failure
RemoteStorage::Backend::Failed::failure() const
{
return m_failure;
}
} // namespace storage::remote
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