From a7cd4d6b10064d9e5db53c143045b0ad1b169e6e Mon Sep 17 00:00:00 2001
From: Sree Harsha Totakura <totakura@in.tum.de>
Date: Wed, 22 Feb 2012 20:43:12 +0000
Subject: [PATCH] -read operation sketch

---
 src/stream/stream_api.c      | 61 +++++++++++++++++++++++++++++-------
 src/stream/stream_protocol.h |  3 ++
 2 files changed, 53 insertions(+), 11 deletions(-)

diff --git a/src/stream/stream_api.c b/src/stream/stream_api.c
index 1c0eec878..ccb3d94b0 100644
--- a/src/stream/stream_api.c
+++ b/src/stream/stream_api.c
@@ -106,6 +106,7 @@ enum State
 /**
  * Functions of this type are called when a message is written
  *
+ * @param cls the closure from queue_message
  * @param socket the socket the written message was bound to
  */
 typedef void (*SendFinishCallback) (void *cls,
@@ -496,7 +497,7 @@ ack_task (void *cls,
                                                GNUNET_STREAM_AckMessage));
   ack_msg->header.header.type = htons (GNUNET_MESSAGE_TYPE_STREAM_ACK);
   ack_msg->bitmap = GNUNET_htonll (socket->ack_bitmap);
-  ack_msg->base_sequence_number = htonl (socket->write_sequence_number);
+  ack_msg->base_sequence_number = htonl (socket->read_sequence_number);
   ack_msg->receive_window_remaining = htonl (socket->receive_window_available);
 
   /* Request MESH for sending ACK */
@@ -652,18 +653,15 @@ handle_data (struct GNUNET_STREAM_Socket *socket,
       GNUNET_assert (NULL != socket->receive_buffer);
       /* check if the message's sequence number is greater than the one we are
          expecting */
-      if (ntohl (msg->sequence_number) - socket->read_sequence_number < 64)
-        {
-
-        }
-      else                      /* We are receiving a retransmitted message */
-        {
+      if (ntohl (msg->sequence_number) - socket->read_sequence_number >= 64)
+        {/* We are receiving a retransmitted message */
           GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                       "Message with sequence number %d retransmitted\n",
                       ntohl (socket->read_sequence_number));
           return GNUNET_YES;
         }
-      /* Copy Data to buffer and send acknowledgements */
+
+      /* Copy Data to buffer and send acknowledgement for this packet */
       size -= sizeof (struct GNUNET_STREAM_DataMessage);
       payload = &msg[1];
       memcpy (socket->receive_buffer 
@@ -1074,7 +1072,11 @@ server_handle_data (void *cls,
 {
   struct GNUNET_STREAM_Socket *socket = *tunnel_ctx;
 
-  return GNUNET_OK;
+  return handle_data (socket,
+                      tunnel,
+                      sender,
+                      (const struct GNUNET_STREAM_DataMessage *)message,
+                      atsi);
 }
 
 
@@ -1854,7 +1856,7 @@ GNUNET_STREAM_write (struct GNUNET_STREAM_Socket *socket,
   struct GNUNET_STREAM_DataMessage *data_msg;
   const void *sweep;
 
-  /* There is already a write request pending */
+  /* Return NULL if there is already a write request pending */
   if (NULL != socket->write_handle)
   {
     GNUNET_break (0);
@@ -1893,14 +1895,51 @@ GNUNET_STREAM_write (struct GNUNET_STREAM_Socket *socket,
         htons (GNUNET_MESSAGE_TYPE_STREAM_DATA);
       io_handle->messages[packet]->sequence_number =
         htons (socket->write_sequence_number++);
+
+      /* FIXME: Remove the fixed delay for ack deadline; Set it to the value
+         determined from RTT */
+      io_handle->messages[packet]->ack_deadline = 
+        GNUNET_TIME_relative_hton (GNUNET_TIME_relative_multiply 
+                                   (GNUNET_TIME_UNIT_SECONDS, 5));
       data_msg = io_handle->messages[packet];
+      /* Copy data from given buffer to the packet */
       memcpy (&data_msg[1],
               sweep,
               packet_size - sizeof (struct GNUNET_STREAM_DataMessage));
       sweep += packet_size - sizeof (struct GNUNET_STREAM_DataMessage);
     }
-
+  socket->write_handle = io_handle;
   write_data (socket);
 
   return io_handle;
 }
+
+
+/**
+ * Tries to read data from the stream
+ *
+ * @param socket the socket representing a stream
+ * @param timeout the timeout period
+ * @param proc function to call with data (once only)
+ * @param proc_cls the closure for proc
+ * @return handle to cancel the operation
+ */
+struct GNUNET_STREAM_IOHandle *
+GNUNET_STREAM_read (const struct GNUNET_STREAM_Socket *socket,
+                    struct GNUNET_TIME_Relative timeout,
+		    GNUNET_STREAM_DataProcessor proc,
+		    void *proc_cls)
+{
+  /* Check the bitmap for any holes */
+
+  /* Deem the data from the starting of the bitmap upto a hole as available
+  data */
+
+  /* Create an IO handle */
+
+  /* Call the Data processor with this available data */
+  
+  /* Update the read_sequence_number to the first hole in the bitmap */
+
+  /* Shift the bitmap so that the first hole is now at the start */
+}
diff --git a/src/stream/stream_protocol.h b/src/stream/stream_protocol.h
index 0c1987e5d..0d427bfa2 100644
--- a/src/stream/stream_protocol.h
+++ b/src/stream/stream_protocol.h
@@ -89,6 +89,9 @@ struct GNUNET_STREAM_DataMessage
    * Offset of the packet in the overall stream, modulo 2^32; allows
    * the receiver to calculate where in the destination buffer the
    * message should be placed.  In network byte order.
+   *
+   * FIXME: if all the packets except the last one are of constant size we
+   * don't need this anymore
    */
   uint32_t offset GNUNET_PACKED;
 
-- 
2.25.1