112 lines
4.2 KiB
C++
112 lines
4.2 KiB
C++
// @file key.h class(es) representing individual keys in a btree
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/**
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* Copyright (C) 2011 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "jsobj.h"
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namespace mongo {
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/** Key class for precomputing a small format index key that is denser than a traditional BSONObj.
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KeyBson is a legacy wrapper implementation for old BSONObj style keys for v:0 indexes.
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KeyV1 is the new implementation.
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*/
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class KeyBson /* "KeyV0" */ {
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public:
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KeyBson() { }
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explicit KeyBson(const char *keyData) : _o(keyData) { }
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explicit KeyBson(const BSONObj& obj) : _o(obj) { }
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int woCompare(const KeyBson& r, const Ordering &o) const;
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BSONObj toBson() const { return _o; }
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string toString() const { return _o.toString(); }
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int dataSize() const { return _o.objsize(); }
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const char * data() const { return _o.objdata(); }
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BSONElement _firstElement() const { return _o.firstElement(); }
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bool isCompactFormat() const { return false; }
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bool woEqual(const KeyBson& r) const;
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void assign(const KeyBson& rhs) { *this = rhs; }
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private:
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BSONObj _o;
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};
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class KeyV1Owned;
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// corresponding to BtreeData_V1
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class KeyV1 {
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void operator=(const KeyV1&); // disallowed just to make people be careful as we don't own the buffer
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KeyV1(const KeyV1Owned&); // disallowed as this is not a great idea as KeyV1Owned likely will go out of scope
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public:
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KeyV1() { _keyData = 0; }
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~KeyV1() { DEV _keyData = (const unsigned char *) 1; }
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KeyV1(const KeyV1& rhs) : _keyData(rhs._keyData) {
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dassert( _keyData > (const unsigned char *) 1 );
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}
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// explicit version of operator= to be safe
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void assign(const KeyV1& rhs) {
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_keyData = rhs._keyData;
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}
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/** @param keyData can be a buffer containing data in either BSON format, OR in KeyV1 format.
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when BSON, we are just a wrapper
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*/
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explicit KeyV1(const char *keyData) : _keyData((unsigned char *) keyData) { }
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int woCompare(const KeyV1& r, const Ordering &o) const;
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bool woEqual(const KeyV1& r) const;
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BSONObj toBson() const;
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string toString() const { return toBson().toString(); }
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/** get the key data we want to store in the btree bucket */
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const char * data() const { return (const char *) _keyData; }
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/** @return size of data() */
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int dataSize() const;
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/** only used by geo, which always has bson keys */
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BSONElement _firstElement() const { return bson().firstElement(); }
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bool isCompactFormat() const { return *_keyData != IsBSON; }
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protected:
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enum { IsBSON = 0xff };
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const unsigned char *_keyData;
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BSONObj bson() const {
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dassert( !isCompactFormat() );
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return BSONObj((const char *) _keyData+1);
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}
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private:
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int compareHybrid(const KeyV1& right, const Ordering& order) const;
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};
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class KeyV1Owned : public KeyV1 {
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KeyV1Owned(const KeyV1Owned&); // not copyable -- StackBufBuilder is not copyable and that owns our buffer
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void operator=(const KeyV1Owned&);
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public:
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/** @obj a BSON object to be translated to KeyV1 format. If the object isn't
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representable in KeyV1 format (which happens, intentionally, at times)
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it will stay as bson herein.
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*/
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KeyV1Owned(const BSONObj& obj);
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private:
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StackBufBuilder b;
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void traditional(const BSONObj& obj); // store as traditional bson not as compact format
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};
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};
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