dr_net_write

The dr_net_write function sends a response back to the requestor after constructing the full page with hdr, the content of the cached entry as the body (located using the key), and ftr. The hdr, ftr, or hdl can be NULL, but not all of them can be NULL. If hdl is NULL, no cache lookup is done; the caller must pass DR_NONE as the flag.

By default, this function refreshes the cache entry if it has expired by making a call to the ref function passed to dr_cache_init. If no cache entry is found with the specified key, this function adds a new cache entry by calling the ref function before sending out the response. However, if the DR_CHECK flag is passed in the flags parameter and if either the cache entry has expired or the cache entry corresponding to the key does not exist, dr_net_write does not send any data out. Instead, it returns with DR_EXPIR.

If ref (passed to dr_cache_init) is NULL, the DR_CHECK flag is not passed in the flags parameter, and the cache entry corresponding to the key has expired or does not exist, then dr_net_write fails with DR_ERROR. However, dr_net_write refreshes the cache if ref is not NULL and DR_CHECK is not passed.

If ref (passed to dr_cache_init) is NULL and the DR_CHECK flag is not passed but DR_IGNORE is passed and the entry is present in the cache, dr_net_write sends out the response even if the entry has expired. However, if the entry is not found, dr_net_write returns DR_ERROR.

If ref (passed to dr_cache_init) is not NULL and the DR_CHECK flag is not passed but DR_IGNORE is passed and the entry is present in the cache, dr_net_write sends out the response even if the entry has expired. However, if the entry is not found, dr_net_write calls the ref function and stores the new entry returned from ref before sending out the response.

Syntax

PRInt32 dr_net_write(DrHdl hdl, const char *key, PRUint32 klen, const char *hdr, 
                    const char *ftr, PRUint32 hlen, PRUint32 flen, 
                    PRIntervalTime timeout, PRUint32 flags, 
                    Request *rq, Session *sn);

Returns

IO_OKAY if successful.

IO_ERROR if an error occurs.

DR_ERROR if an error in cache handling occurs.

DR_EXPIR if the cache has expired.

Parameters

The following table describes parameters for the dr_net_write function.

Table 7–3 dr_net_write parameters

Parameter	Description
DrHdl hdl	Persistent handle created by the dr_cache_init function.
const char *key	Key to cache, search, or refresh.
PRUint32 klen	Length of the key in bytes.
const char *hdr	Any header data (which can be NULL).
const char *ftr	Any footer data (which can be NULL).
PRUint32 hlen	Length of the header data in bytes (which can be 0).
PRUint32 flen	Length of the footer data in bytes (which can be 0).
PRIntervalTime timeout	Timeout before this function aborts.
PRUint32 flags	ORed directives for this function (see the Flags table, below).
Request *rq	Pointer to the request.
Session *sn	Pointer to the session.

Flags

The following table describes flags for dr_net_write.

Table 7–4 Flags for dr_net_write

Flag	Description
DR_NONE	Specifies that no cache is used, so the function works as net_write does; DrHdl can be NULL.
DR_FORCE	Forces the cache to refresh, even if it has not expired.
DR_CHECK	Returns DR_EXPIR if the cache has expired; if the calling function has not provided a refresh function and this flag is not used, DR_ERROR is returned.
DR_IGNORE	Ignores cache expiration and sends out the cache entry even if it has expired.
DR_CNTLEN	Supplies the Content-Length header and does a PROTOCOL_START_RESPONSE.
DR_PROTO	Does a PROTOCOL_START_RESPONSE.

Example

if(dr_net_write(Dr, szFileName, iLenK, NULL, NULL, 0, 0, 0, 
                DR_CNTLEN | DR_PROTO, rq, sn) == IO_ERROR)
{
    return(REQ_EXIT);
}