05e8854085
Summary: This diff introduces a new Merge operation into rocksdb. The purpose of this review is mostly getting feedback from the team (everyone please) on the design. Please focus on the four files under include/leveldb/, as they spell the client visible interface change. include/leveldb/db.h include/leveldb/merge_operator.h include/leveldb/options.h include/leveldb/write_batch.h Please go over local/my_test.cc carefully, as it is a concerete use case. Please also review the impelmentation files to see if the straw man implementation makes sense. Note that, the diff does pass all make check and truly supports forward iterator over db and a version of Get that's based on iterator. Future work: - Integration with compaction - A raw Get implementation I am working on a wiki that explains the design and implementation choices, but coding comes just naturally and I think it might be a good idea to share the code earlier. The code is heavily commented. Test Plan: run all local tests Reviewers: dhruba, heyongqiang Reviewed By: dhruba CC: leveldb, zshao, sheki, emayanke, MarkCallaghan Differential Revision: https://reviews.facebook.net/D9651
120 lines
3.9 KiB
C++
120 lines
3.9 KiB
C++
// 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 <string>
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#include "leveldb/slice.h"
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namespace leveldb {
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class Status {
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public:
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// Create a success status.
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Status() : state_(nullptr) { }
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~Status() { delete[] state_; }
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// Copy the specified status.
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Status(const Status& s);
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void operator=(const Status& s);
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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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static Status MergeInProgress(const Slice& msg, const Slice& msg2 = Slice()) {
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return Status(kMergeInProgress, 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 a NotSupported error.
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bool IsNotSupported() const { return code() == kNotSupported; }
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// Returns true iff the status indicates an InvalidArgument error.
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bool IsInvalidArgument() const { return code() == kInvalidArgument; }
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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 an MergeInProgress.
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bool IsMergeInProgress() const { return code() == kMergeInProgress; }
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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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// OK status has a nullptr 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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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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kMergeInProgress = 6
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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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};
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inline Status::Status(const Status& s) {
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state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
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}
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inline void Status::operator=(const Status& s) {
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// The following condition catches both aliasing (when this == &s),
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// and the common case where both s and *this are ok.
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if (state_ != s.state_) {
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delete[] state_;
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state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
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}
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}
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_INCLUDE_STATUS_H_
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