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/*************************************************************************
*
* Copyright 2021 Realm Inc.
*
* 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.
*
**************************************************************************/
#pragma once
#include <atomic>
#include <cstdint>
#include <iosfwd>
#include <string>
#include "realm/error_codes.hpp"
#include "realm/string_data.hpp"
#include "realm/util/bind_ptr.hpp"
#include "realm/util/features.h"
namespace realm {
class REALM_NODISCARD Status {
public:
/*
* This is the best way to construct a Status that represents a non-error condition.
*/
static inline Status OK();
/*
* You can construct a Status from strings, C strings, and StringData's.
*/
Status(ErrorCodes::Error code, StringData reason);
Status(ErrorCodes::Error code, const std::string& reason);
Status(ErrorCodes::Error code, const char* reason);
/*
* Copying a Status is just copying an intrusive pointer - i.e. very cheap. Moving them is similarly cheap.
*/
inline Status(const Status& other);
inline Status& operator=(const Status& other);
inline Status(Status&& other) noexcept;
inline Status& operator=(Status&& other) noexcept;
inline bool is_ok() const noexcept;
inline const std::string& reason() const noexcept;
inline ErrorCodes::Error code() const noexcept;
inline StringData code_string() const noexcept;
/*
* This class is marked nodiscard so that we always handle errors. If there is a place where we need
* to explicitly ignore an error, you can call this function, which does nothing, to satisfy the compiler.
*/
void ignore() const noexcept {}
private:
Status() = default;
struct ErrorInfo {
mutable std::atomic<uint32_t> m_refs;
const ErrorCodes::Error m_code;
const std::string m_reason;
static util::bind_ptr<ErrorInfo> create(ErrorCodes::Error code, StringData reason);
protected:
template <typename>
friend class ::realm::util::bind_ptr;
inline void bind_ptr() const noexcept
{
m_refs.fetch_add(1, std::memory_order_relaxed);
}
inline void unbind_ptr() const noexcept
{
if (m_refs.fetch_sub(1, std::memory_order_acq_rel) == 1) {
delete this;
}
}
private:
ErrorInfo(ErrorCodes::Error code, StringData reason);
};
util::bind_ptr<ErrorInfo> m_error = {};
};
class ExceptionForStatus : public std::exception {
public:
const char* what() const noexcept final
{
return reason().c_str();
}
const Status& to_status() const
{
return m_status;
}
const std::string& reason() const noexcept
{
return m_status.reason();
}
ErrorCodes::Error code() const noexcept
{
return m_status.code();
}
StringData code_string() const noexcept
{
return m_status.code_string();
}
ExceptionForStatus(ErrorCodes::Error err, StringData str)
: m_status(err, str)
{
}
explicit ExceptionForStatus(Status status)
: m_status(std::move(status))
{
}
private:
Status m_status;
};
/*
* This will convert an exception in a catch(...) block into a Status. For ExceptionForStatus's, it returns the
* status held in the exception directly. Otherwise it returns a status with an UnknownError error code and a
* reason string holding the exception type and message.
*
* Currently this works for exceptions that derive from std::exception or ExceptionForStatus only.
*/
Status exception_to_status() noexcept;
std::ostream& operator<<(std::ostream& out, const Status& val);
inline bool operator==(const Status& lhs, const Status& rhs) noexcept
{
return lhs.code() == rhs.code();
}
inline bool operator!=(const Status& lhs, const Status& rhs) noexcept
{
return lhs.code() != rhs.code();
}
inline bool operator==(const Status& lhs, ErrorCodes::Error rhs) noexcept
{
return lhs.code() == rhs;
}
inline bool operator!=(const Status& lhs, ErrorCodes::Error rhs) noexcept
{
return lhs.code() != rhs;
}
inline Status Status::OK()
{
// Returns a status with m_error set to nullptr.
return Status{};
}
inline Status::Status(const Status& other)
: m_error(other.m_error)
{
}
inline Status& Status::operator=(const Status& other)
{
m_error = other.m_error;
return *this;
}
inline Status::Status(Status&& other) noexcept
: m_error(std::move(other.m_error))
{
}
inline Status& Status::operator=(Status&& other) noexcept
{
m_error = std::move(other.m_error);
return *this;
}
inline bool Status::is_ok() const noexcept
{
return !m_error;
}
inline const std::string& Status::reason() const noexcept
{
static const std::string empty;
return m_error ? m_error->m_reason : empty;
}
inline ErrorCodes::Error Status::code() const noexcept
{
return m_error ? m_error->m_code : ErrorCodes::OK;
}
inline StringData Status::code_string() const noexcept
{
return ErrorCodes::error_string(code());
}
} // namespace realm
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