paulo@0: /*
paulo@0:  * $Id: tx_layer.c,v 1.7 2004/03/24 06:37:30 hipnod Exp $
paulo@0:  *
paulo@0:  * Copyright (C) 2003 giFT project (gift.sourceforge.net)
paulo@0:  *
paulo@0:  * This program is free software; you can redistribute it and/or modify it
paulo@0:  * under the terms of the GNU General Public License as published by the
paulo@0:  * Free Software Foundation; either version 2, or (at your option) any
paulo@0:  * later version.
paulo@0:  *
paulo@0:  * This program is distributed in the hope that it will be useful, but
paulo@0:  * WITHOUT ANY WARRANTY; without even the implied warranty of
paulo@0:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
paulo@0:  * General Public License for more details.
paulo@0:  */
paulo@0: 
paulo@0: #include "gt_gnutella.h"
paulo@0: 
paulo@0: #include "io/tx_stack.h"
paulo@0: #include "io/tx_layer.h"
paulo@0: #include "io/io_buf.h"
paulo@0: 
paulo@0: /*****************************************************************************/
paulo@0: 
paulo@0: struct tx_layer *gt_tx_layer_new (GtTxStack *stack, const char *name,
paulo@0:                                   struct tx_layer_ops *ops)
paulo@0: {
paulo@0: 	struct tx_layer *tx;
paulo@0: 
paulo@0: 	if (!(tx = NEW (struct tx_layer)))
paulo@0: 		return NULL;
paulo@0: 
paulo@0: 	tx->ops         = ops;
paulo@0: 	tx->name        = name;
paulo@0: 	tx->stack       = stack;
paulo@0: 	tx->partial_buf = NULL;
paulo@0: 
paulo@0: 	if (!ops->init (tx))
paulo@0: 	{
paulo@0: 		free (tx);
paulo@0: 		return NULL;
paulo@0: 	}
paulo@0: 
paulo@0: 	return tx;
paulo@0: }
paulo@0: 
paulo@0: void gt_tx_layer_free (struct tx_layer *layer)
paulo@0: {
paulo@0: 	if (!layer)
paulo@0: 		return;
paulo@0: 
paulo@0: 	io_buf_free (layer->partial_buf);
paulo@0: 
paulo@0: 	layer->ops->destroy (layer);
paulo@0: 
paulo@0: 	FREE (layer);
paulo@0: }
paulo@0: 
paulo@0: /*****************************************************************************/
paulo@0: 
paulo@0: static tx_status_t queue_data (struct tx_layer *tx, struct io_buf *io_buf)
paulo@0: {
paulo@0: 	tx_status_t ret;
paulo@0: 
paulo@0: 	ret = tx->ops->queue (tx, io_buf);
paulo@0: 
paulo@0: 	/*
paulo@0: 	 * If the message didn't get completely written, buffer the partial
paulo@0: 	 * message buffer until it's finished.
paulo@0: 	 */
paulo@0: 	if (ret == TX_PARTIAL)
paulo@0: 	{
paulo@0: 		assert (io_buf_read_avail (io_buf) > 0);
paulo@0: 
paulo@0: 		tx->partial_buf = io_buf;
paulo@0: 		return TX_OK;
paulo@0: 	}
paulo@0: 
paulo@0: 	return ret;
paulo@0: }
paulo@0: 
paulo@0: /* send a message to the layer underneath this one */
paulo@0: tx_status_t gt_tx_layer_queue (struct tx_layer *tx, struct io_buf *io_buf)
paulo@0: {
paulo@0: 	struct tx_layer *lower = tx->lower;
paulo@0: 
paulo@0: 	if (lower->partial_buf)
paulo@0: 		return TX_FULL;
paulo@0: 
paulo@0: 	return queue_data (lower, io_buf);
paulo@0: }
paulo@0: 
paulo@0: /* let upper layer know we're writable and get data from it */
paulo@0: tx_status_t gt_tx_layer_ready (struct tx_layer *tx)
paulo@0: {
paulo@0: 	struct tx_layer *upper;
paulo@0: 	tx_status_t      ret;
paulo@0: 
paulo@0: 	upper = tx->upper;
paulo@0: 
paulo@0: 	/*
paulo@0: 	 * If there is a partially written buffer on the layer, try to finish it
paulo@0: 	 * off before asking for more data by pretending the upper layer tried to
paulo@0: 	 * write it.
paulo@0: 	 *
paulo@0: 	 * Doing this avoids a special case in each layer where a partial buffer
paulo@0: 	 * is kept set aside and checked before calling gt_tx_layer_ready(), leading
paulo@0: 	 * to less code.
paulo@0: 	 */
paulo@0: 	if (tx->partial_buf)
paulo@0: 	{
paulo@0: 		struct io_buf *io_buf = tx->partial_buf;
paulo@0: 
paulo@0: 		tx->partial_buf = NULL;
paulo@0: 
paulo@0: 		/* this ends up calling this layer's queue func */
paulo@0: 		ret = queue_data (tx, io_buf);
paulo@0: 
paulo@0: 		/*
paulo@0: 		 * Can't happen because layer wouldn't have invoked us.
paulo@0: 		 */
paulo@0: 		assert (ret != TX_FULL);
paulo@0: 		assert (ret != TX_EMPTY);
paulo@0: 
paulo@0: 		/*
paulo@0: 		 * Upper layer can't be safely invoked again, even if the partial
paulo@0: 		 * buffer was completed, because we don't know if the lower layer has
paulo@0: 		 * any more room.  So, the lower layer must reinvoke tx_layer_ready()
paulo@0: 		 * to write more data.
paulo@0: 		 */
paulo@0: 		return ret;
paulo@0: 	}
paulo@0: 
paulo@0: 	ret = upper->ops->ready (upper);
paulo@0: 	assert (ret != TX_FULL);
paulo@0: 
paulo@0: 	return ret;
paulo@0: }
paulo@0: 
paulo@0: /*****************************************************************************/
paulo@0: 
paulo@0: void gt_tx_layer_enable (struct tx_layer *layer)
paulo@0: {
paulo@0: 	layer->ops->enable (layer);
paulo@0: }
paulo@0: 
paulo@0: void gt_tx_layer_disable (struct tx_layer *layer)
paulo@0: {
paulo@0: 	layer->ops->disable (layer);
paulo@0: }