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// @file key.h class(es) representing individual keys in a btree
/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/jsobj.h"
#include "mongo/util/debug_util.h"
namespace mongo {
/** Key class for precomputing a small format index key that is denser than a traditional BSONObj.
KeyBson is a legacy wrapper implementation for old BSONObj style keys for v:0 indexes.
KeyV1 is the new implementation.
*/
class KeyBson /* "KeyV0" */ {
public:
KeyBson() {}
explicit KeyBson(const char* keyData) : _o(keyData) {}
explicit KeyBson(const BSONObj& obj) : _o(obj) {}
int woCompare(const KeyBson& r, const Ordering& o) const;
BSONObj toBson() const {
return _o;
}
std::string toString() const {
return _o.toString();
}
int dataSize() const {
return _o.objsize();
}
const char* data() const {
return _o.objdata();
}
BSONElement _firstElement() const {
return _o.firstElement();
}
bool isCompactFormat() const {
return false;
}
bool woEqual(const KeyBson& r) const;
void assign(const KeyBson& rhs) {
*this = rhs;
}
bool isValid() const {
return true;
}
private:
BSONObj _o;
};
class KeyV1Owned;
// corresponding to BtreeData_V1
class KeyV1 {
// disallowed just to make people be careful as we don't own the buffer
void operator=(const KeyV1&);
// disallowed as this is not a great idea as KeyV1Owned likely will go out of scope
KeyV1(const KeyV1Owned&);
public:
KeyV1() {
_keyData = 0;
}
~KeyV1() {
DEV _keyData = (const unsigned char*)1;
}
KeyV1(const KeyV1& rhs) : _keyData(rhs._keyData) {
dassert(_keyData > (const unsigned char*)1);
}
// explicit version of operator= to be safe
void assign(const KeyV1& rhs) {
_keyData = rhs._keyData;
}
/** @param keyData can be a buffer containing data in either BSON format, OR in KeyV1 format.
when BSON, we are just a wrapper
*/
explicit KeyV1(const char* keyData) : _keyData((unsigned char*)keyData) {}
int woCompare(const KeyV1& r, const Ordering& o) const;
bool woEqual(const KeyV1& r) const;
BSONObj toBson() const;
std::string toString() const {
return toBson().toString();
}
/** get the key data we want to store in the btree bucket */
const char* data() const {
return (const char*)_keyData;
}
/** @return size of data() */
int dataSize() const;
/** only used by geo, which always has bson keys */
BSONElement _firstElement() const {
return bson().firstElement();
}
bool isCompactFormat() const {
return *_keyData != IsBSON;
}
bool isValid() const {
return _keyData > (const unsigned char*)1;
}
protected:
enum { IsBSON = 0xff };
const unsigned char* _keyData;
BSONObj bson() const {
dassert(!isCompactFormat());
return BSONObj((const char*)_keyData + 1);
}
private:
int compareHybrid(const KeyV1& right, const Ordering& order) const;
};
class KeyV1Owned : public KeyV1 {
void operator=(const KeyV1Owned&);
public:
/** @obj a BSON object to be translated to KeyV1 format. If the object isn't
representable in KeyV1 format (which happens, intentionally, at times)
it will stay as bson herein.
*/
KeyV1Owned(const BSONObj& obj);
/** makes a copy (memcpy's the whole thing) */
KeyV1Owned(const KeyV1& rhs);
private:
StackBufBuilder b;
void traditional(const BSONObj& obj); // store as traditional bson not as compact format
};
};
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