CCF/include/ccf/tx_id.h

127 строки
3.3 KiB
C++

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the Apache 2.0 License.
#pragma once
#include "ccf/ds/json.h"
#include <charconv>
#include <cstdint>
#define FMT_HEADER_ONLY
#include <fmt/format.h>
#include <nlohmann/json.hpp>
#include <optional>
#include <string>
#include <string_view>
namespace ccf
{
/** Transactions occur within a fixed View. Each View generally spans a range
* of transactions, though empty Views are also possible. The View is advanced
* by the consensus protocol during election of a new leader, and a single
* leader is assigned in each View.
*/
using View = uint64_t;
// No transactions occur in View 0.
constexpr View VIEW_UNKNOWN = 0;
/** Each transaction is assigned a unique incrementing SeqNo, maintained
* across View transitions. This matches the order in which transactions are
* applied, where a higher SeqNo means that a transaction executed later.
* SeqNos are unique during normal operation, but around elections it is
* possible for distinct transactions in separate Views to have the same
* SeqNo. Only one of these transactions will ever commit, and the others are
* ephemeral.
*/
using SeqNo = uint64_t;
// No transaction is assigned seqno 0.
constexpr SeqNo SEQNO_UNKNOWN = 0;
// The combination of View and SeqNo produce a unique TxID for each
// transaction executed by CCF.
struct TxID
{
View view;
SeqNo seqno;
std::string to_str() const
{
return std::to_string(view) + "." + std::to_string(seqno);
}
static std::optional<TxID> from_str(const std::string_view& sv)
{
const auto separator_idx = sv.find(".");
if (separator_idx == std::string_view::npos)
{
return std::nullopt;
}
TxID tx_id;
{
const auto view_sv = sv.substr(0, separator_idx);
const auto [p, ec] =
std::from_chars(view_sv.begin(), view_sv.end(), tx_id.view);
if (ec != std::errc() || p != view_sv.end())
{
return std::nullopt;
}
}
{
const auto seqno_sv = sv.substr(separator_idx + 1);
const auto [p, ec] =
std::from_chars(seqno_sv.begin(), seqno_sv.end(), tx_id.seqno);
if (ec != std::errc() || p != seqno_sv.end())
{
return std::nullopt;
}
}
return tx_id;
}
bool operator==(const TxID& other) const
{
return view == other.view && seqno == other.seqno;
}
};
// ADL-found functions used during JSON conversion and OpenAPI/JSON schema
// generation
inline void to_json(nlohmann::json& j, const TxID& tx_id)
{
j = tx_id.to_str();
}
inline void from_json(const nlohmann::json& j, TxID& tx_id)
{
if (!j.is_string())
{
throw JsonParseError(
fmt::format("Cannot parse TxID: Expected string, got {}", j.dump()));
}
const auto opt = TxID::from_str(j.get<std::string>());
if (!opt.has_value())
{
throw JsonParseError(fmt::format("Cannot parse TxID: {}", j.dump()));
}
tx_id = opt.value();
}
inline std::string schema_name(const TxID*)
{
return "TransactionId";
}
inline void fill_json_schema(nlohmann::json& schema, const TxID*)
{
schema["type"] = "string";
schema["pattern"] = "^[0-9]+\\.[0-9]+$";
}
}