Modify data-xfer semantics: it is no longer necessary to call one of

request(), seek() or deliver_xxx() in order to start the data flow.
Autonomous generators must be genuinely autonomous (having their own
process), or otherwise arrange to be called.  TCP does this by
starting the retry timer immediately.

Add some debugging statements.

1 files changed, 61 insertions, 10 deletions

diff --git a/src/core/xfer.c b/src/core/xfer.c
index f2783f5b..54377c70 100644
--- a/src/core/xfer.c
+++ b/src/core/xfer.c
@@ -35,6 +35,8 @@
 void xfer_close ( struct xfer_interface *xfer, int rc ) {
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 
+	DBGC ( xfer, "XFER %p->%p close\n", xfer, dest );
+
 	dest->op->close ( dest, rc );
 	xfer_unplug ( xfer );
 	xfer_put ( dest );
@@ -52,7 +54,14 @@ int xfer_vredirect ( struct xfer_interface *xfer, int type, va_list args ) {
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 	int rc;
 
+	DBGC ( xfer, "XFER %p->%p redirect\n", xfer, dest );
+
 	rc = dest->op->vredirect ( dest, type, args );
+
+	if ( rc != 0 ) {
+		DBGC ( xfer, "XFER %p<-%p redirect: %s\n", xfer, dest,
+		       strerror ( rc ) );
+	}
 	xfer_put ( dest );
 	return rc;
 }
@@ -89,22 +98,20 @@ int xfer_request ( struct xfer_interface *xfer, off_t offset, int whence,
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 	int rc;
 
+	DBGC ( xfer, "XFER %p->%p request %s+%ld %zd\n", xfer, dest,
+	       whence_text ( whence ), offset, len );
+
 	rc = dest->op->request ( dest, offset, whence, len );
+
+	if ( rc != 0 ) {
+		DBGC ( xfer, "XFER %p<-%p request: %s\n", xfer, dest,
+		       strerror ( rc ) );
+	}
 	xfer_put ( dest );
 	return rc;
 }
 
 /**
- * Request all data
- *
- * @v xfer		Data transfer interface
- * @ret rc		Return status code
- */
-int xfer_request_all ( struct xfer_interface *xfer ) {
-	return xfer_request ( xfer, 0, SEEK_SET, ~( ( size_t ) 0 ) );
-}
-
-/**
  * Seek to position
  *
  * @v xfer		Data transfer interface
@@ -116,12 +123,34 @@ int xfer_seek ( struct xfer_interface *xfer, off_t offset, int whence ) {
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 	int rc;
 
+	DBGC ( xfer, "XFER %p->%p seek %s+%ld\n", xfer, dest,
+	       whence_text ( whence ), offset );
+
 	rc = dest->op->seek ( dest, offset, whence );
+
+	if ( rc != 0 ) {
+		DBGC ( xfer, "XFER %p<-%p seek: %s\n", xfer, dest,
+		       strerror ( rc ) );
+	}
 	xfer_put ( dest );
 	return rc;
 }
 
 /**
+ * Test to see if interface is ready to accept data
+ *
+ * @v xfer		Data transfer interface
+ * @ret rc		Return status code
+ *
+ * This test is optional; the data transfer interface may wish that it
+ * does not yet wish to accept data, but cannot prevent attempts to
+ * deliver data to it.
+ */
+int xfer_ready ( struct xfer_interface *xfer ) {
+	return xfer_seek ( xfer, 0, SEEK_CUR );
+}
+
+/**
  * Allocate I/O buffer
  *
  * @v xfer		Data transfer interface
@@ -132,7 +161,13 @@ struct io_buffer * xfer_alloc_iob ( struct xfer_interface *xfer, size_t len ) {
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 	struct io_buffer *iobuf;
 
+	DBGC ( xfer, "XFER %p->%p alloc_iob %zd\n", xfer, dest, len );
+
 	iobuf = dest->op->alloc_iob ( dest, len );
+
+	if ( ! iobuf ) {
+		DBGC ( xfer, "XFER %p<-%p alloc_iob failed\n", xfer, dest );
+	}
 	xfer_put ( dest );
 	return iobuf;
 }
@@ -148,7 +183,15 @@ int xfer_deliver_iob ( struct xfer_interface *xfer, struct io_buffer *iobuf ) {
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 	int rc;
 
+	DBGC ( xfer, "XFER %p->%p deliver_iob %zd\n", xfer, dest,
+	       iob_len ( iobuf ) );
+
 	rc = dest->op->deliver_iob ( dest, iobuf );
+
+	if ( rc != 0 ) {
+		DBGC ( xfer, "XFER %p<-%p deliver_iob: %s\n", xfer, dest,
+		       strerror ( rc ) );
+	}
 	xfer_put ( dest );
 	return rc;
 }
@@ -165,7 +208,15 @@ int xfer_deliver_raw ( struct xfer_interface *xfer,
 	struct xfer_interface *dest = xfer_get_dest ( xfer );
 	int rc;
 
+	DBGC ( xfer, "XFER %p->%p deliver_raw %p+%zd\n", xfer, dest,
+	       data, len );
+
 	rc = dest->op->deliver_raw ( dest, data, len );
+
+	if ( rc != 0 ) {
+		DBGC ( xfer, "XFER %p<-%p deliver_raw: %s\n", xfer, dest,
+		       strerror ( rc ) );
+	}
 	xfer_put ( dest );
 	return rc;
 }