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ExhaustibleBlockDevice Class Reference

ExhaustibleBlockDevice Class Reference

Heap backed block device which simulates failures. More...

#include <ExhaustibleBlockDevice.h>

Inherits BlockDevice.

Public Member Functions

 ExhaustibleBlockDevice (BlockDevice *bd, uint32_t erase_cycles)
 Lifetime of the block device.
uint32_t get_erase_cycles (bd_addr_t addr) const
 Get the number of erase cycles remaining on a block.
void set_erase_cycles (bd_addr_t addr, uint32_t cycles)
 Set the number of erase cycles before failure.
virtual int init ()
 Initialize a block device.
virtual int deinit ()
 Deinitialize a block device.
virtual int sync ()
 Ensure data on storage is in sync with the driver.
virtual int read (void *buffer, bd_addr_t addr, bd_size_t size)
 Read blocks from a block device.
virtual int program (const void *buffer, bd_addr_t addr, bd_size_t size)
 Program blocks to a block device.
virtual int erase (bd_addr_t addr, bd_size_t size)
 Erase blocks on a block device.
virtual bd_size_t get_read_size () const
 Get the size of a readable block.
virtual bd_size_t get_program_size () const
 Get the size of a programmable block.
virtual bd_size_t get_erase_size () const
 Get the size of an erasable block.
virtual bd_size_t get_erase_size (bd_addr_t addr) const
 Get the size of an erasable block given address.
virtual int get_erase_value () const
 Get the value of storage when erased.
virtual bd_size_t size () const
 Get the total size of the underlying device.
virtual int trim (bd_addr_t addr, bd_size_t size)
 Mark blocks as no longer in use.
bool is_valid_read (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block read validity.
bool is_valid_program (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block program validity.
bool is_valid_erase (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block erase validity.

Detailed Description

Heap backed block device which simulates failures.

Similar to heap block device but sectors wear out and are no longer programmable after a configurable number of cycles.

Definition at line 34 of file ExhaustibleBlockDevice.h.


Constructor & Destructor Documentation

ExhaustibleBlockDevice ( BlockDevice bd,
uint32_t  erase_cycles 
)

Lifetime of the block device.

Parameters:
bdBlock device to back the ExhaustibleBlockDevice
erase_cyclesNumber of erase cycles before failure

Definition at line 21 of file ExhaustibleBlockDevice.cpp.


Member Function Documentation

int deinit (  ) [virtual]

Deinitialize a block device.

Returns:
0 on success or a negative error code on failure

Implements BlockDevice.

Definition at line 49 of file ExhaustibleBlockDevice.cpp.

int erase ( bd_addr_t  addr,
bd_size_t  size 
) [virtual]

Erase blocks on a block device.

The state of an erased block is undefined until it has been programmed, unless get_erase_value returns a non-negative byte value

Parameters:
addrAddress of block to begin erasing
sizeSize to erase in bytes, must be a multiple of erase block size
Returns:
0 on success, negative error code on failure

Reimplemented from BlockDevice.

Definition at line 78 of file ExhaustibleBlockDevice.cpp.

uint32_t get_erase_cycles ( bd_addr_t  addr ) const

Get the number of erase cycles remaining on a block.

Parameters:
addrAny address in the block being queried for erase cycles
Returns:
Number of erase cycles remaining
bd_size_t get_erase_size (  ) const [virtual]

Get the size of an erasable block.

Returns:
Size of an erasable block in bytes

Reimplemented from BlockDevice.

Definition at line 105 of file ExhaustibleBlockDevice.cpp.

bd_size_t get_erase_size ( bd_addr_t  addr ) const [virtual]

Get the size of an erasable block given address.

Parameters:
addrAddress within the erasable block
Returns:
Size of an erasable block in bytes
Note:
Must be a multiple of the program size

Reimplemented from BlockDevice.

Definition at line 110 of file ExhaustibleBlockDevice.cpp.

int get_erase_value (  ) const [virtual]

Get the value of storage when erased.

If get_erase_value returns a non-negative byte value, the underlying storage is set to that value when erased, and storage containing that value can be programmed without another erase.

Returns:
The value of storage when erased, or -1 if you can't rely on the value of erased storage

Reimplemented from BlockDevice.

Definition at line 115 of file ExhaustibleBlockDevice.cpp.

bd_size_t get_program_size (  ) const [virtual]

Get the size of a programmable block.

Returns:
Size of a programmable block in bytes

Implements BlockDevice.

Definition at line 100 of file ExhaustibleBlockDevice.cpp.

bd_size_t get_read_size (  ) const [virtual]

Get the size of a readable block.

Returns:
Size of a readable block in bytes

Implements BlockDevice.

Definition at line 95 of file ExhaustibleBlockDevice.cpp.

int init (  ) [virtual]

Initialize a block device.

Returns:
0 on success or a negative error code on failure

Implements BlockDevice.

Definition at line 31 of file ExhaustibleBlockDevice.cpp.

bool is_valid_erase ( bd_addr_t  addr,
bd_size_t  size 
) const [inherited]

Convenience function for checking block erase validity.

Parameters:
addrAddress of block to begin erasing
sizeSize to erase in bytes
Returns:
True if erase is valid for underlying block device

Definition at line 213 of file BlockDevice.h.

bool is_valid_program ( bd_addr_t  addr,
bd_size_t  size 
) const [inherited]

Convenience function for checking block program validity.

Parameters:
addrAddress of block to begin writing to
sizeSize to write in bytes
Returns:
True if program is valid for underlying block device

Definition at line 199 of file BlockDevice.h.

bool is_valid_read ( bd_addr_t  addr,
bd_size_t  size 
) const [inherited]

Convenience function for checking block read validity.

Parameters:
addrAddress of block to begin reading from
sizeSize to read in bytes
Returns:
True if read is valid for underlying block device

Definition at line 185 of file BlockDevice.h.

int program ( const void *  buffer,
bd_addr_t  addr,
bd_size_t  size 
) [virtual]

Program blocks to a block device.

The blocks must have been erased prior to being programmed

Parameters:
bufferBuffer of data to write to blocks
addrAddress of block to begin writing to
sizeSize to write in bytes, must be a multiple of program block size
Returns:
0 on success, negative error code on failure

Implements BlockDevice.

Definition at line 66 of file ExhaustibleBlockDevice.cpp.

int read ( void *  buffer,
bd_addr_t  addr,
bd_size_t  size 
) [virtual]

Read blocks from a block device.

Parameters:
bufferBuffer to read blocks into
addrAddress of block to begin reading from
sizeSize to read in bytes, must be a multiple of read block size
Returns:
0 on success, negative error code on failure

Implements BlockDevice.

Definition at line 61 of file ExhaustibleBlockDevice.cpp.

void set_erase_cycles ( bd_addr_t  addr,
uint32_t  cycles 
)

Set the number of erase cycles before failure.

Parameters:
addrAny address in the block being queried for erase cycles
cyclesErase cycles before the block malfunctions
bd_size_t size (  ) const [virtual]

Get the total size of the underlying device.

Returns:
Size of the underlying device in bytes

Implements BlockDevice.

Definition at line 120 of file ExhaustibleBlockDevice.cpp.

int sync (  ) [virtual]

Ensure data on storage is in sync with the driver.

Returns:
0 on success or a negative error code on failure

Reimplemented from BlockDevice.

Definition at line 56 of file ExhaustibleBlockDevice.cpp.

virtual int trim ( bd_addr_t  addr,
bd_size_t  size 
) [virtual, inherited]

Mark blocks as no longer in use.

This function provides a hint to the underlying block device that a region of blocks is no longer in use and may be erased without side effects. Erase must still be called before programming, but trimming allows flash-translation-layers to schedule erases when the device is not busy.

Parameters:
addrAddress of block to mark as unused
sizeSize to mark as unused in bytes, must be a multiple of erase block size
Returns:
0 on success, negative error code on failure

Definition at line 120 of file BlockDevice.h.