Traffic Server Software Developers Kit

In the example below, suppose there is a cache hit and the cache returns a vconnection that enables you to read the document from cache. To do this, you need to prepare a buffer (cache_bufp) to hold the document; meanwhile, use INKVConnCachedObjectSizeGet to find out the actual size of the document (content_length). Then, issue INKVConnRead to read the document with the total data length required as content_length. Assume the following data:

    INKIOBuffer       cache_bufp = INKIOBufferCreate ();
    INKIOBufferReader cache_readerp = INKIOBufferReaderAlloc (out_bufp);
    INKVConn          cache_vconnp = NULL;
    INKVIO            cache_vio = NULL;
    int               content_length = 0;

In the INK_CACHE_OPEN_READ handler:

cache_vconnp = (INKVConn) data;
    INKVConnCachedObjectSizeGet (cache_vconnp, &content_length);
    cache_vio = INKVConnRead (cache_vconn, contp, cache_bufp, content_length);

In the INK_EVENT_VCONN_READ_READY handler:

(usual VCONN_READ_READY handler logic)
int nbytes = INKVIONBytesGet (cache_vio);
int ntodo  = INKVIONTodoGet (cache_vio);
int ndone  = INKVIONDoneGet (cache_vio);
(consume data in cache_bufp)
INKVIOReenable (cache_vio);

Do not try to get continuations or VIOs from INKVConn objects for cache vconnections. Also note that the following APIs can only be used on transformation vconnections and must not be used on cache vconnections or net vconnections:

APIs such as INKVConnRead, INKVConnWrite, INKVConnClose, INKVConnAbort, and INKVConnShutdown can be used on any kind of vconnections.

When you are finished:

INKCacheKeyDestroy (key);