rocksdb/include/rocksdb/status.h

// Copyright (c) 2013, Facebook, Inc.  All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
// 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_ROCKSDB_INCLUDE_STATUS_H_
#define STORAGE_ROCKSDB_INCLUDE_STATUS_H_

#include <string>
#include "rocksdb/slice.h"

namespace rocksdb {

class Status {
 public:
  // Create a success status.
  Status() : code_(kOk), state_(nullptr) { }
  ~Status() { delete[] state_; }

  // Copy the specified status.
  Status(const Status& s);
  void operator=(const Status& s);

  // 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);
  }
  // Fast path for not found without malloc;
  static Status NotFound() {
    return Status(kNotFound);
  }
  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);
  }
  static Status MergeInProgress(const Slice& msg, const Slice& msg2 = Slice()) {
    return Status(kMergeInProgress, msg, msg2);
  }
  static Status Incomplete(const Slice& msg, const Slice& msg2 = Slice()) {
    return Status(kIncomplete, msg, msg2);
  }
  static Status ShutdownInProgress(const Slice& msg,
                                   const Slice& msg2 = Slice()) {
    return Status(kShutdownInProgress, msg, msg2);
  }

  // Returns true iff the status indicates success.
  bool ok() const { return code() == kOk; }

  // 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 a NotSupported error.
  bool IsNotSupported() const { return code() == kNotSupported; }

  // Returns true iff the status indicates an InvalidArgument error.
  bool IsInvalidArgument() const { return code() == kInvalidArgument; }

  // Returns true iff the status indicates an IOError.
  bool IsIOError() const { return code() == kIOError; }

  // Returns true iff the status indicates an MergeInProgress.
  bool IsMergeInProgress() const { return code() == kMergeInProgress; }

  // Returns true iff the status indicates Incomplete
  bool IsIncomplete() const { return code() == kIncomplete; }

  // Returns true iff the status indicates Incomplete
  bool IsShutdownInProgress() const { return code() == kShutdownInProgress; }

  // 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,
    kMergeInProgress = 6,
    kIncomplete = 7,
    kShutdownInProgress = 8
  };

  // A nullptr state_ (which is always the case for OK) means the message
  // is empty.
  // of the following form:
  //    state_[0..3] == length of message
  //    state_[4..]  == message
  Code code_;
  const char* state_;

  Code code() const {
    return code_;
  }
  explicit Status(Code code) : code_(code), state_(nullptr) { }
  Status(Code code, const Slice& msg, const Slice& msg2);
  static const char* CopyState(const char* s);
};

inline Status::Status(const Status& s) {
  code_ = s.code_;
  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
}
inline void Status::operator=(const Status& s) {
  // The following condition catches both aliasing (when this == &s),
  // and the common case where both s and *this are ok.
  code_ = s.code_;
  if (state_ != s.state_) {
    delete[] state_;
    state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
  }
}

}  // namespace rocksdb

#endif  // STORAGE_ROCKSDB_INCLUDE_STATUS_H_