32.4 Loss Detection--The Class SRMinfo

A very small encapsulating class, entirely in C++, tracks a number of assorted state information. Each member of the group, , uses one SRMinfo block for every other member of the group.

An SRMinfo object about group member at , contains information about the session messages received by from . can use this information to compute its distance to .

If sends is active in sending data traffic, then the SRMinfo object will also contain information about the received data, including a bit vector indicating all packets received from .

The agent keeps a list of SRMinfo objects, one per group member, in its member variable, sip_. Its method, [int sender]get_state will return the object corresponding to that sender, possibly creating that object, if it did not already exist. The SRMinfo../ns-2/srm-state.h has two methods to access and set the bit vector, ,

The session message variables to access timing information are public; no encapsulating methods are provided. These are:

        int     lsess_;                   /* # of last session msg received /
        int     sendTime_;                /* Time sess. msg. # sent /
        int     recvTime_;                /* Time sess. msg. # received /
        double  distance_;

        /* Data messages */
        int     ldata_;                   /* # of last data msg sent /