Clear the entire buffer, including durable buffer contents.
N.B. If this is done mid-session, then string and thread references
from prior to this point will become invalid - the underlying data
will be gone. To prevent this save buffer contents before clearing.

This is typically used when buffer contents were saved after the
preceding Stop.

Clear the non-durable portion of the buffer, retaining the durable
portion.

This is typically used when buffer contents were not saved after the
preceding Stop and the current contents are to be discarded.

Retain buffer contents. New trace data is added where the previous
trace run left off.

This is typically used when buffer contents were not saved after the
preceding Stop and the current contents are to be retained.

In oneshot mode there is only one buffer that is not reused. When the
buffer fills the provider just keeps dropping records, keeping a count,
and then when tracing stops the header is updated to record final
state.

In circular mode, the buffer is continually written to until tracing
stops. When the buffer fills older records are discarded as needed.

In streaming mode, the buffer is effectively split into two pieces.
When one half of the buffer fills the provider notifies the trace
manager via the provided fifo, and then starts filling the other half
of the buffer. When the buffer is saved, the manager responds via the
provided fifo. If trace manager hasn't saved the buffer in time, and
the other buffer fills, then the provider is required to drop records
until space becomes available.