A specialized memory device that provides read and write caching for a target device.

Interface

Constructor

os_cache( const os_adapter& device , int wbuf , int rbuf )

Constructs a read/write cache for device using an internal write buffer of size wbuf (default os_cache::wbuf_size_limit ) bytes and an internal read buffer of size rbuf (default os_cache::rbuf_size_limit ) bytes.

Destructor

~os_cache()

Destroys this cache object after flushing its contents to the device.

(os_adapter)

operator os_adapter()

Returns the device adapter.

adapter

const os_adapter& adapter() const

Returns a constant reference to the device adapter.

bad

bool bad () const

Returns true if this device is in a bad state.

clear

void clear ()

Resets the state of this device.

close

bool close()

Returns true if this device successfully flushes the internal buffers and shuts down the chained device.

eof

bool eof () const

Returns true if this device is at EOF.

fail

bool fail () const

Returns true if this device is in a bad state or has reached EOF.

good

bool good() const

Returns true if this device is in a good state.

read

ssize_t read( const void* buffer , size_t bytes )

Reads up to the specified number of bytes of data into buffer from the cache or from the actual device if the cache is empty. Returns the number of bytes actually read or returns -1 if a failure occurs.

read_buffer_size

int read_buffer_size() const

Returns the size, in bytes, of the internal read buffer.

reset

void reset()

Resets the cache to a state as though it was just constructed..

seek

long seek( long offset , int seekdir )

Positions the cache and the chained device to be offset bytes from the position specified by seekdir (


    os_device::begin

, os_device::current , or os_device::end ). Returns the offset of the new position or returns -1 if the operation fails.

sync

bool sync()

Flushes the internal buffers of the cache and the chained device and returns true if successful.

write

ssize_t write( const void* buffer , size_t bytes )

Writes up to the specified number of bytes of data from buffer to the cache. Returns the number of bytes actually written or returns -1 if a failure occurs.

write_buffer_size

int write_buffer_size() const

Returns the size, in bytes, of the internal write buffer.

cache

Library

Declaration

Enums

Interface