mongo::BucketBasics Class Reference

#include <btree.h>

Inheritance diagram for mongo::BucketBasics:

[legend]

List of all members.

Public Member Functions
void	assertValid (const BSONObj &orderObj, bool force=false) const
void	assertValid (const Ordering &order, bool force=false) const
void	assertWritable ()
const DiskLoc	getNextChild () const
const KeyNode	keyNode (int i) const
int	nKeys () const
Static Public Member Functions
static int	bodySize ()
static int	headerSize ()
Protected Types
enum	Flags { Packed = 1 }
Protected Member Functions
int	_alloc (int bytes)
void	_delKeyAtPos (int keypos, bool mayEmpty=false)
void	_pack (const DiskLoc thisLoc, const Ordering &order, int &refPos) const
void	_packReadyForMod (const Ordering &order, int &refPos)
bool	_pushBack (const DiskLoc recordLoc, const BSONObj &key, const Ordering &order, const DiskLoc prevChild)
void	_shape (int level, stringstream &) const
void	_unalloc (int bytes)
bool	basicInsert (const DiskLoc thisLoc, int &keypos, const DiskLoc recordLoc, const BSONObj &key, const Ordering &order) const
DiskLoc &	childForPos (int p)
const DiskLoc &	childForPos (int p) const
char *	dataAt (short ofs)
void	dropFront (int nDrop, const Ordering &order, int &refPos)
void	init ()
_KeyNode &	k (int i)
const _KeyNode &	k (int i) const
void	markUnused (int keypos)
bool	mayDropKey (int index, int refPos) const
int	packedDataSize (int refPos) const
void	popBack (DiskLoc &recLoc, BSONObj &key)
void	pushBack (const DiskLoc recordLoc, const BSONObj &key, const Ordering &order, const DiskLoc prevChild)
void	reserveKeysFront (int nAdd)
void	setKey (int i, const DiskLoc recordLoc, const BSONObj &key, const DiskLoc prevChildBucket)
void	setNotPacked ()
void	setPacked ()
int	Size () const
int	splitPos (int keypos) const
DiskLoc &	tempNext ()
const DiskLoc &	tempNext () const
int	totalDataSize () const
void	truncateTo (int N, const Ordering &order, int &refPos)
Friends
class	BtreeBuilder
class	KeyNode

---

Detailed Description

This class is all about the storage management

Const member functions of this class are those which may be called on an object for which writing has not been signaled. Non const member functions may only be called on objects for which writing has been signaled. Note that currently some const functions write to the underlying memory representation of this bucket using optimized methods to signal write operations.

DiskLoc parameters that may shadow references within the btree should be passed by value rather than by reference to non const member functions or const member functions which may perform writes. This way a callee need not worry that write operations will change or invalidate its arguments.

The current policy for dealing with bson arguments is the opposite of what is described above for DiskLoc arguments. We do not want to want to copy bson into memory as an intermediate step for btree changes, so if bson is to be moved it must be copied to the new location before the old location is invalidated.

Definition at line 120 of file btree.h.

---

Member Enumeration Documentation

enum mongo::BucketBasics::Flags [protected]

Enumerator:

Packed

Definition at line 191 of file btree.h.

---

Member Function Documentation

int mongo::BucketBasics::_alloc

(

int

bytes

)

[protected]

void mongo::BucketBasics::_delKeyAtPos	(	int	keypos,
		bool	mayEmpty = false
	)			[protected]

void mongo::BucketBasics::_pack	(	const DiskLoc	thisLoc,
		const Ordering &	order,
		int &	refPos
	)			const [protected]

Pack the bucket to reclaim space from invalidated memory. is an index in the bucket which will may be updated if we delete keys from the bucket This function may cast away const and perform a write.

void mongo::BucketBasics::_packReadyForMod	(	const Ordering &	order,
		int &	refPos
	)			[protected]

Pack when already writable

bool mongo::BucketBasics::_pushBack	(	const DiskLoc	recordLoc,
		const BSONObj &	key,
		const Ordering &	order,
		const DiskLoc	prevChild
	)			[protected]

Returns:

true if works, false if not enough space

void mongo::BucketBasics::_shape	(	int	level,
		stringstream &
	)			const [protected]

void mongo::BucketBasics::_unalloc

(

int

bytes

)

[protected]

void mongo::BucketBasics::assertValid	(	const BSONObj &	orderObj,
		bool	force = false
	)			const [inline]

Definition at line 128 of file btree.h.

void mongo::BucketBasics::assertValid	(	const Ordering &	order,
		bool	force = false
	)			const

void mongo::BucketBasics::assertWritable

(

)

assert write intent declared for this bucket already

bool mongo::BucketBasics::basicInsert	(	const DiskLoc	thisLoc,
		int &	keypos,
		const DiskLoc	recordLoc,
		const BSONObj &	key,
		const Ordering &	order
	)			const [protected]

Returns:

false if node is full and must be split is where to insert -- inserted before that key #. so keypos=0 is the leftmost one. keypos will be updated if keys are moved as a result of pack() This function will modify the btree bucket memory representation even though it is marked const.

static int mongo::BucketBasics::bodySize

(

)

[inline, static]

Definition at line 145 of file btree.h.

DiskLoc& mongo::BucketBasics::childForPos

(

int

p

)

[inline, protected]

Definition at line 194 of file btree.h.

const DiskLoc& mongo::BucketBasics::childForPos

(

int

p

)

const [inline, protected]

Definition at line 193 of file btree.h.

char* mongo::BucketBasics::dataAt

(

short

ofs

)

[inline, protected]

Definition at line 152 of file btree.h.

void mongo::BucketBasics::dropFront	(	int	nDrop,
		const Ordering &	order,
		int &	refPos
	)			[protected]

drop specified number of keys from beginning of key array, and pack

const DiskLoc mongo::BucketBasics::getNextChild

(

)

const [inline]

Definition at line 149 of file btree.h.

static int mongo::BucketBasics::headerSize

(

)

[inline, static]

Definition at line 141 of file btree.h.

void mongo::BucketBasics::init

(

)

[protected]

_KeyNode& mongo::BucketBasics::k

(

int

i

)

[inline, protected]

Definition at line 234 of file btree.h.

const _KeyNode& mongo::BucketBasics::k

(

int

i

)

const [inline, protected]

Definition at line 233 of file btree.h.

const KeyNode mongo::BucketBasics::keyNode

(

int

i

)

const [inline]

Returns:

KeyNode for key at index i. The KeyNode will become invalid if the key is moved or reassigned, or if the node is packed.

Definition at line 134 of file btree.h.

void mongo::BucketBasics::markUnused

(

int

keypos

)

[protected]

bool mongo::BucketBasics::mayDropKey	(	int	index,
		int	refPos
	)			const [protected]

Returns:

true if the key may be dropped by pack()

int mongo::BucketBasics::nKeys

(

)

const [inline]

Definition at line 148 of file btree.h.

int mongo::BucketBasics::packedDataSize

(

int

refPos

)

const [protected]

Returns:

the size of non header data in this bucket if we were to call pack().

void mongo::BucketBasics::popBack	(	DiskLoc &	recLoc,
		BSONObj &	key
	)			[protected]

This is a special purpose function used by BtreeBuilder. The interface is quite dangerous if you're not careful. The bson key returned here points to bucket memory that has been invalidated but not yet reclaimed.

TODO Maybe this could be replaced with two functions, one which returns the last key without deleting it and another which simply deletes the last key. Then the caller would have enough control to ensure proper memory integrity.

void mongo::BucketBasics::pushBack	(	const DiskLoc	recordLoc,
		const BSONObj &	key,
		const Ordering &	order,
		const DiskLoc	prevChild
	)			[inline, protected]

Definition at line 167 of file btree.h.

void mongo::BucketBasics::reserveKeysFront

(

int

nAdd

)

[protected]

Adds new entries to beginning of key array, shifting existing entries to the right. After this is called, setKey() must be called on all the newly created entries in the key array.

void mongo::BucketBasics::setKey	(	int	i,
		const DiskLoc	recordLoc,
		const BSONObj &	key,
		const DiskLoc	prevChildBucket
	)			[protected]

Sets an existing key using the given parameters. index of key to set

void mongo::BucketBasics::setNotPacked

(

)

[inline, protected]

Definition at line 215 of file btree.h.

void mongo::BucketBasics::setPacked

(

)

[inline, protected]

Definition at line 216 of file btree.h.

int mongo::BucketBasics::Size

(

)

const [protected]

int mongo::BucketBasics::splitPos

(

int

keypos

)

const [protected]

Returns:

the key position where a split should occur on insert

DiskLoc& mongo::BucketBasics::tempNext

(

)

[inline, protected]

Definition at line 229 of file btree.h.

const DiskLoc& mongo::BucketBasics::tempNext

(

)

const [inline, protected]

BtreeBuilder uses the parent var as a temp place to maintain a linked list chain. we use tempNext() when we do that to be less confusing. (one might have written a union in C)

Definition at line 228 of file btree.h.

int mongo::BucketBasics::totalDataSize

(

)

const [protected]

void mongo::BucketBasics::truncateTo	(	int	N,
		const Ordering &	order,
		int &	refPos
	)			[protected]

---

Friends And Related Function Documentation

friend class BtreeBuilder [friend]

Definition at line 121 of file btree.h.

friend class KeyNode [friend]

Definition at line 122 of file btree.h.

---

The documentation for this class was generated from the following file:

• btree.h