[interface] Expand object interface to allow for polymorphic interfaces

We have several types of object interface at present (data-xfer, job
control, name resolution), and there is some duplication of
functionality between them.  For example, job_done(), job_kill() and
xfer_close() are almost isomorphic to each other.

This updated version of the object interface mechanism allows for each
interface to export an arbitrary list of supported operations.
Advantages include:

  Operations methods now receive a pointer to the object, rather than
  a pointer to the interface.  This allows an object to, for example,
  implement a single close() method that can handle close() operations
  from any of its exposed interfaces.

  The close() operation is implemented as a generic operation (rather
  than having specific variants for data-xfer, job control, etc.).
  This will allow functions such as monojob_wait() to be used to wait
  for e.g.  a name resolution to complete.

  The amount of boilerplate code required in objects is reduced, not
  least because it is no longer necessary to include per-interface
  methods that simply use container_of() to derive a pointer to the
  object and then tail-call to a common per-object method.

  The cost of adding new operations is reduced; adding a new data-xfer
  operation such as stat() no longer incurs the penalty of adding a
  .stat member to the operations table of all existing data-xfer
  interfaces.

The data-xfer, job control and name resolution interfaces have not yet
been updated to use the new interface mechanism, but the code will
still compile and run.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/include/ipxe/xfer.h b/src/include/ipxe/xfer.h
index ad41e932c..8a3f9bb1c 100644
--- a/src/include/ipxe/xfer.h
+++ b/src/include/ipxe/xfer.h
@@ -238,7 +238,7 @@ xfer_put ( struct xfer_interface *xfer ) {
  */
 static inline __attribute__ (( always_inline )) void
 xfer_plug ( struct xfer_interface *xfer, struct xfer_interface *dest ) {
-	plug ( &xfer->intf, &dest->intf );
+	intf_plug ( &xfer->intf, &dest->intf );
 }
 
 /**
@@ -249,7 +249,7 @@ xfer_plug ( struct xfer_interface *xfer, struct xfer_interface *dest ) {
  */
 static inline __attribute__ (( always_inline )) void
 xfer_plug_plug ( struct xfer_interface *a, struct xfer_interface *b ) {
-	plug_plug ( &a->intf, &b->intf );
+	intf_plug_plug ( &a->intf, &b->intf );
 }
 
 /**
@@ -259,7 +259,7 @@ xfer_plug_plug ( struct xfer_interface *a, struct xfer_interface *b ) {
  */
 static inline __attribute__ (( always_inline )) void
 xfer_unplug ( struct xfer_interface *xfer ) {
-	plug ( &xfer->intf, &null_xfer.intf );
+	intf_plug ( &xfer->intf, &null_xfer.intf );
 }
 
 /**