ssm_sort::skey_t Class Reference
[Sorting]

Collaboration diagram for ssm_sort::skey_t:

[legend]List of all members.

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Detailed Description

The result of a CSKF function.

This is a handle on a key. The key might reside in scratch memory or in the buffer pool. This class provides a generic API for using such a key.

The attributes are:

• pointer to start of key (method ptr())
• length of key (method size())
• length of contiguous portion of key (method contig_length())
• location (in buffer pool or scratch memory) (method is_in_obj())
• sub-location (in buffer pool: in record header or body) (method is_in_hdr())
• the heap allocator (factory_t) used to allocate buffers if this refers to a key in scratch memory.

Generally only the constructor is used by a CSKF callback function, and the idiom used (indeed, the only way it can be populated) is placement new as follows:

using namespace ssm_sort;
w_rc_t 
exampleCSKF(
    const rid_t&         rid,
    const object_t&      obj,
    key_cookie_t         ,  
    factory_t&           f,
    skey_t*              out
)
{
    {
    // this shows how to create an skey_t from the entire header of the
    // incoming object_t, whether the object is in the buffer pool or
    // in scratch memory:
    smsize_t length = obj.hdr_size();
    smsize_t offset = 0;
    bool     in_hdr = true;
    new(out) skey_t(obj, offset, length, in_hdr);
    }

    {
    // this shows how to create an skey_t from the last 3 bytes of the
    // body of the incoming object_t, whether the 
    // object is in the buffer pool or in scratch memory:
    smsize_t length = 3;
    smsize_t offset = obj.body_size() - length;
    bool     in_hdr = false;
    new(out) skey_t(obj, offset, length, in_hdr);
    }

    {
    // this shows how to create an skey_t derived from the record id
    int val = rid.pid.page;
    smsize_t length = sizeof(val);
    smsize_t offset = 0;
    void *buf = f.allocfunc(length);
    memcpy(&buf, &val, sizeof(val));
    new(out) skey_t(buf, offset, length, f);
    }

    return RCOK;
}

Definition at line 502 of file sort_s.h.

Public Member Functions
NORET	skey_t (const object_t &o, smsize_t offset, smsize_t len, bool in_hdr)
	Construct from a key in the buffer pool.
NORET	skey_t (void *buf, smsize_t offset, smsize_t len, factory_t &f)
	Construct from a key in scratch memory.
NORET	~skey_t ()
smsize_t	size () const
	Length of entire key.
bool	is_valid () const
	True if this structure is populated (points to a key).
bool	is_in_obj () const
	True if key is in the buffer pool.
bool	consistent_with_object (const object_t &o) const
	True unless this key is for an object other than o.
bool	is_in_hdr () const
	True if key is in buffer pool and is in record header.
const void *	ptr (smsize_t offset) const
	Pointer into byte at offset in key.
void	freespace ()
	Using its factory, free space allocated for the in-scratch-memory buffer.
void	assert_nobuffers () const
	Asserts that no heap memory is held by this or its object_t.
smsize_t	contig_length () const
	Pinned amount of the key.
w_rc_t	copy_out (vec_t &dest) const
	Copies key into vector (which must have pre-allocated space).
Protected Member Functions
NORET	skey_t ()
void	_construct (const object_t *o, smsize_t off, smsize_t l, bool h)
void	_construct (const void *buf, smsize_t off, smsize_t l, factory_t *f)
Protected Attributes
const object_t *	_obj
smsize_t	_offset

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Constructor & Destructor Documentation

NORET ssm_sort::skey_t::skey_t	(	const object_t &	o,
		smsize_t	offset,
		smsize_t	len,
		bool	in_hdr
	)			[inline]

Construct from a key in the buffer pool.

Parameters:

[in]	o	structure describing the key location
[in]	offset	offset from record header or body where key starts
[in]	len	length of entire key
[in]	in_hdr	true if key is in record header, false if in body

Definition at line 513 of file sort_s.h.

NORET ssm_sort::skey_t::skey_t	(	void *	buf,
		smsize_t	offset,
		smsize_t	len,
		factory_t &	f
	)			[inline]

Construct from a key in scratch memory.

Parameters:

[in]	buf	scratch memory buffer
[in]	offset	offset from buf where key starts
[in]	len	length of entire key
[in]	f	factory used to allocate the buffer

Definition at line 532 of file sort_s.h.

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Member Function Documentation

bool ssm_sort::skey_t::consistent_with_object

(

const object_t &

o

)

const [inline]

True unless this key is for an object other than o.

Used for assertions in sort code.

Definition at line 562 of file sort_s.h.

References _obj.

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

• src/sm/sort_s.h

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