Virtualization of a block of data. Holds information for allocating and swapping. To use in cooperation with block_scheduler. More...

#include <block_scheduler.h>

Inheritance diagram for stxxl::swappable_block< ValueType, BlockSize >:

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Collaboration diagram for stxxl::swappable_block< ValueType, BlockSize >:

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List of all members.

Public Types
typedef typed_block < raw_block_size, ValueType >	internal_block_type
typedef internal_block_type::bid_type	external_block_type
Public Member Functions
	swappable_block ()
	Create in uninitialized state.
	~swappable_block ()
bool	is_internal () const
	If it has an internal_block. The internal_block implicitly holds valid data.
bool	is_dirty () const
	If the external_block does not hold valid data.
bool	has_external_block () const
	If it has an external_block.
bool	is_external () const
	If it has an external_block that holds valid data.
bool	is_acquired () const
	If it is acquired.
bool	is_evictable () const
	If it holds an internal_block but does not need it.
bool	is_initialized () const
	If it has some valid data (in- or external).
bool	make_dirty_if (const bool make_dirty)
	Invalidate external data if true.
internal_block_type &	acquire ()
	Acquire the block, i.e. add a reference. Has to be internal.
void	release ()
	Release the block, i.e. subduct a reference. Has to be acquired.
const internal_block_type &	get_internal_block () const
	Get a reference to the data-block. Has to be acquired.
internal_block_type &	get_internal_block ()
	Get a reference to the data-block. Has to be acquired.
void	fill_default ()
	Fill block with default data, is supposed to be overwritten by subclass. Has to be internal.
request_ptr	read_async (completion_handler on_cmpl=default_completion_handler())
	Read asyncronusly from external_block to internal_block. Has to be internal and have an external_block.
void	read_sync ()
	Read synchronously from external_block to internal_block. Has to be internal and have an external_block.
request_ptr	clean_async (completion_handler on_cmpl=default_completion_handler())
	Write asyncronusly from internal_block to external_block if necessary.
void	clean_sync ()
	Write synchronously from internal_block to external_block if necessary.
void	attach_internal_block (internal_block_type *iblock)
	Attach an internal_block, making the block internal. Has to be not internal.
internal_block_type *	detach_internal_block ()
	Detach the internal_block. Writes to external_block if necessary. Has to be evictable.
internal_block_type *	deinitialize ()
	Bring the block in uninitialized state, freeing external and internal memory. Returns a pointer to the internal_block, NULL if it had none.
void	initialize (external_block_type eblock)
	Set the external_block that holds the swappable_block's data. The block gets initialized with it.
external_block_type	extract_external_block ()
	Extract the swappable_blocks data in an external_block. The block gets uninitialized.
Protected Member Functions
void	get_external_block ()
void	free_external_block ()
Protected Attributes
external_block_type	external_data
internal_block_type *	internal_data
	external_data.valid if no associated space on disk
bool	dirty
int_type	reference_count
Static Protected Attributes
static const unsigned_type	raw_block_size = BlockSize * sizeof(ValueType)
static unsigned_type	disk_allocation_offset = 0

Detailed Description

template<typename ValueType, unsigned BlockSize>
class stxxl::swappable_block< ValueType, BlockSize >

Virtualization of a block of data. Holds information for allocating and swapping. To use in cooperation with block_scheduler.

A swappable_block can be uninitialized, i.e. it holds no data. When access is required, is has to be acquired first, and released afterwards, so it can be swapped in and out as required. If the stored data is no longer needed, it can get uninitialized, freeing both internal and external memory.

Template Parameters:

ValueType	type of contained objects (POD with no references to internal memory).
BlockSize	Number of objects in one block. BlockSize*sizeof(ValueType) must be divisible by 4096.

Definition at line 36 of file block_scheduler.h.