The IO buffer data structure is the building block of the
vconnection abstraction. An IO buffer (INKIOBuffer)
is composed of a list of buffer blocks that point to buffer
data. Both the buffer block (INKIOBufferBlock) and
buffer data (INKIOBufferData) data structures are
reference-counted so that they can reside in multiple buffers at the
same time. This makes it extremely efficient to copy data from one IO
buffer to another via INKIOBufferCopy, since
Traffic Server must only copy pointers and adjust reference counts
appropriately and doesn't actually copy any data.
The IO buffer abstraction provides for a single writer and
multiple readers. In order for the readers to have no knowledge of each
other, they manipulate IO buffers through the
INKIOBufferReader data structure. Since only a
single writer is allowed, there is no corresponding
INKIOBufferWriter data structure. The writer simply
modifies the IO buffer directly. To see an example that illustrates how
to use IOBuffers, refer to the sample code in the description of INKIOBufferBlockReadStart.
Additional information about IO buffer functions:
The INKIOBufferReader data structure
tracks how much data in INKIOBuffer
has been read. It has an offset number of bytes that is the current
start point of a particular buffer reader (for every read operation
on an INKIOBuffer, you must allocate an INKIOBufferReader).
INKIOBuffer. To consume bytes that have been read, you must call
INKIOBufferConsume.