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Developer notes

These notes are for developers of the simulator (not for students).

Different from C++ version:

  • Graph is undirected graph

    • Thus: we do not need to add link (2, 1) after add link (1, 2)

  • Remove useless parameters

    1. Remove "bandwidth" and "latency" from a node
      • 0 ADD_NODE 1 1 1 -> 0 ADD_NODE 1 // as well as DELETE_NODE
    2. Remove "bandwidth" from a link
      • 0 ADD_LINK 1 2 10 10 -> 0 ADD_LINK 1 2 10 // as well as CHANGE_LINK. DELETE_LINK only has two parameters.

  • Remove some not interested commands 1. DRAW_TREE [ID] . Since I think after implementing DRAW_PATH, we can see if it is easy to implemented in

  • Remove useless function

    1. Remove "SendToNeighbor" function, only "SendToNeighbors" is useful. 1.1. I add "send to neighbor" function back. We can use it to confuse students. ( •̀ ω •́ )y
    2. Remove "GetNeighbors" function. Node can only know their neighbors by "link_has_been_updated"

  • Remove send_current_links() function

    • There is a logic bug in Minet Add_Link Logic, since it reused in both topo file and event file
    • There for, call Add_link in runtime will not call link_has_been_updated
    • Change:
      • remove send_current_links() function after load topology
      • Call link_has_been_updated after Add_Link
    • However, it will introduce a bug in send_to_neighors(). Because we many add many links in one seconds. And call simulator does not know correct neighbor set in the middle.
    • Solution:
      • Introduce a "SEND_LINK" event
      • Post two "SEND_LINK" event afters process ADD_LINK
      • Change cmp function of Event, "SEND_LINK" will run lastest at that second.

  • .topo files are eliminated. Instead, just put the topology definition at the beginning of the .event file.

Question

  • If message arrive time = message send time + latency, a problem comes
    • suppose latency A to B is 100, A send message 1 at time 0, and will arrive at time 100
    • however, a link change is called at time 10, latency updated to 20
    • A send message 2 at time 20
    • message 2 should arrive at time 40
    • Then, how about message 1? arrive at 100 or at 40, or at 30?
    • In minet, it set to 100

step options:

0. NORMAL
    only stop when a picture is 
1. SINGLE_STEP
    stop after an event
2. NO_STOP
    no stop at all

Log Level

0. logging.DEBUG (recommand when debugging)
1. logging.INFO (default)
2. Logging.WARNING

Layout options for graph

- spring_layout (default)
- https://networkx.github.io/documentation/stable/reference/drawing.html#layout