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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// A Status encapsulates the result of an operation. It may indicate success,
// or it may indicate an error with an associated error message.
//
// Multiple threads can invoke const methods on a Status without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same Status must use
// external synchronization.
#ifndef STORAGE_LEVELDB_INCLUDE_STATUS_H_
#define STORAGE_LEVELDB_INCLUDE_STATUS_H_
#include <algorithm>
#include <string>
#include "leveldb/export.h"
#include "leveldb/slice.h"
namespace leveldb {
class LEVELDB_EXPORT Status {
public:
// Create a success status.
Status() noexcept : state_(nullptr) {}
~Status() { delete[] state_; }
Status(const Status& rhs);
Status& operator=(const Status& rhs);
Status(Status&& rhs) noexcept : state_(rhs.state_) { rhs.state_ = nullptr; }
Status& operator=(Status&& rhs) noexcept;
// Return a success status.
static Status OK() { return Status(); }
// Return error status of an appropriate type.
static Status NotFound(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kNotFound, msg, msg2);
}
static Status Corruption(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kCorruption, msg, msg2);
}
static Status NotSupported(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kNotSupported, msg, msg2);
}
static Status InvalidArgument(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kInvalidArgument, msg, msg2);
}
static Status IOError(const Slice& msg, const Slice& msg2 = Slice()) {
return Status(kIOError, msg, msg2);
}
// Returns true iff the status indicates success.
bool ok() const { return (state_ == nullptr); }
// Returns true iff the status indicates a NotFound error.
bool IsNotFound() const { return code() == kNotFound; }
// Returns true iff the status indicates a Corruption error.
bool IsCorruption() const { return code() == kCorruption; }
// Returns true iff the status indicates an IOError.
bool IsIOError() const { return code() == kIOError; }
// Returns true iff the status indicates a NotSupportedError.
bool IsNotSupportedError() const { return code() == kNotSupported; }
// Returns true iff the status indicates an InvalidArgument.
bool IsInvalidArgument() const { return code() == kInvalidArgument; }
// Return a string representation of this status suitable for printing.
// Returns the string "OK" for success.
std::string ToString() const;
private:
enum Code {
kOk = 0,
kNotFound = 1,
kCorruption = 2,
kNotSupported = 3,
kInvalidArgument = 4,
kIOError = 5
};
Code code() const {
return (state_ == nullptr) ? kOk : static_cast<Code>(state_[4]);
}
Status(Code code, const Slice& msg, const Slice& msg2);
static const char* CopyState(const char* s);
// OK status has a null state_. Otherwise, state_ is a new[] array
// of the following form:
// state_[0..3] == length of message
// state_[4] == code
// state_[5..] == message
const char* state_;
};
inline Status::Status(const Status& rhs) {
state_ = (rhs.state_ == nullptr) ? nullptr : CopyState(rhs.state_);
}
inline Status& Status::operator=(const Status& rhs) {
// The following condition catches both aliasing (when this == &rhs),
// and the common case where both rhs and *this are ok.
if (state_ != rhs.state_) {
delete[] state_;
state_ = (rhs.state_ == nullptr) ? nullptr : CopyState(rhs.state_);
}
return *this;
}
inline Status& Status::operator=(Status&& rhs) noexcept {
std::swap(state_, rhs.state_);
return *this;
}
} // namespace leveldb
#endif // STORAGE_LEVELDB_INCLUDE_STATUS_H_
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