block_prefetcher< block_type, bid_iterator_type > Class Template Reference

Encapsulates asynchronous prefetching engine. More...

#include <block_prefetcher.h>

Collaboration diagram for block_prefetcher< block_type, bid_iterator_type >:

Public Member Functions
	block_prefetcher (bid_iterator_type _cons_begin, bid_iterator_type _cons_end, int_type *_pref_seq, int_type _prefetch_buf_size, completion_handler do_after_fetch=default_completion_handler())
	Constructs an object and immediately starts prefetching. More...
block_type *	pull_block ()
	Pulls next unconsumed block from the consumption sequence. More...
bool	block_consumed (block_type *&buffer)
	Exchanges buffers between prefetcher and application. More...
bool	empty () const
unsigned_type	pos () const
	~block_prefetcher ()
	Frees used memory. More...

Protected Member Functions
block_type *	wait (int_type iblock)

Protected Attributes
bid_iterator_type	consume_seq_begin
bid_iterator_type	consume_seq_end
unsigned_type	seq_length
int_type *	prefetch_seq
unsigned_type	nextread
unsigned_type	nextconsume
const int_type	nreadblocks
block_type *	read_buffers
request_ptr *	read_reqs
bid_type *	read_bids
onoff_switch *	completed
int_type *	pref_buffer
completion_handler	do_after_fetch

Detailed Description

template<typename block_type, typename bid_iterator_type>
class block_prefetcher< block_type, bid_iterator_type >

Encapsulates asynchronous prefetching engine.

block_prefetcher overlaps I/Os with consumption of read data. Utilizes optimal asynchronous prefetch scheduling (by Peter Sanders et.al.)

Constructor & Destructor Documentation

template<typename block_type , typename bid_iterator_type >

block_prefetcher< block_type, bid_iterator_type >::block_prefetcher ( bid_iterator_type  _cons_begin, bid_iterator_type  _cons_end, int_type *  _pref_seq, int_type  _prefetch_buf_size, completion_handler  do_after_fetch = default_completion_handler()  )

inline

Constructs an object and immediately starts prefetching.

Parameters

_cons_begin	bid_iterator pointing to the bid of the first block to be consumed
_cons_end	bid_iterator pointing to the bid of the ( last + 1 ) block of consumption sequence
_pref_seq	gives the prefetch order, is a pointer to the integer array that contains the indices of the blocks in the consumption sequence
_prefetch_buf_size	amount of prefetch buffers to use

template<typename block_type , typename bid_iterator_type >

block_prefetcher< block_type, bid_iterator_type >::~block_prefetcher ( )

inline

Frees used memory.

References request_interface::wait().

Member Function Documentation

template<typename block_type , typename bid_iterator_type >

bool block_prefetcher< block_type, bid_iterator_type >::block_consumed ( block_type *&  buffer )

inline

Exchanges buffers between prefetcher and application.

Parameters

buffer

pointer to the consumed buffer. After call if return value is true buffer contains valid pointer to the next unconsumed prefetched buffer.

Remarks

parameter buffer must be value returned by pull_block() or block_consumed() methods

Returns

false if there are no blocks to prefetch left, true if consumption sequence is not emptied

References request_interface::wait().

Referenced by buf_istream< BlkTp_, BIDIteratorTp_ >::operator++(), and buf_istream< BlkTp_, BIDIteratorTp_ >::operator>>().

template<typename block_type , typename bid_iterator_type >

block_type* block_prefetcher< block_type, bid_iterator_type >::pull_block ( )

inline

Pulls next unconsumed block from the consumption sequence.

Returns

Pointer to the already prefetched block from the internal buffer pool

Referenced by buf_istream< BlkTp_, BIDIteratorTp_ >::buf_istream().

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

• block_prefetcher.h