Cache Layer Function Reference

Infrasctucture Cache Layer Function Reference

Cache Layer
The cache layer is used to save information to disk so that it is non-volatile across process or system crashes or reboots. nbsp; In other words, if a piece of data or a request absolutely HAS to get there, you better cache it. nbsp; Data may be added (cached) or deleted (uncached) randomly or read sequentially as a process starts up (restore). nbsp; Cache handles are integers in the range of 1 to 1*231, values less than 1 are used as error returns. nbsp; Each record in the cache has an 'id' (identifier) which is used to uncache the record. nbsp; Cached records may be variable in size.

cchCln nbsp; nbsp;

cchOpn nbsp; nbsp;

nbsp; nbsp;

cchWt nbsp; nbsp;

cchRd nbsp; nbsp;

cchUnch nbsp; nbsp;


int	cchCln( int cHndl )

Delete all records in cache and truncate the file. Returns zero.


int nbsp;	*cchOpn( char fileName )**

Opens a cache file for reading or writing. On success it returns an integer cache handle required by all other cache API calls. On error it returns ERR (-1).


>int	cchRd( int )


int nbsp;	cchWt( int cHndl )

Writes a record to the cache file represented by cHndl. The 'data' argument is a pointer to the data to be written , 'len' is the number of bytes to write and 'id' is a 32 bit record identifyer which must be used to retrieve the record. On success it returns the number of data bytes written. On error it returns ERR (-1).


int nbsp;	cchRd( int cHndl )

Reads a record sequentially, from the cache file represented by cHndl. The 'data' argument is a pointer to the data area, 'len' is a pointer to an integer to contain the number of bytes read. On success it returns the 'id' of the record retrieved. On error it returns ERR (-1).


int nbsp;	cchUnch( int cHndl, long id )

Remove a record from the cache file represented by cHndl. If the record was the last in the file the file is truncated. Returns zero.