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