README.md

How to Compile

1. Navigate to src/ folder by cd src
2. Delete class files using rm *.class
3. Compile by javac Simulation.java

How to Run

1. Regular run using java Simulation
2. Run with assertions using java -ea Simulation
3. Run with async-profiler using java -agentpath:/home/nitin/async-profiler-1.7-linux-x64/build/libasyncProfiler.so=start,file=profile.svg Simulator

Output

1. All logs are stored at logs/ which is in the same level as src/
2. Each run will generate a unique folder using System.currentTimeMillis() eg. 1588266314130/
3. Each invocation of run() of Simulation class will have a log file eg. 24_60/
4. A csv file (to generate plots) will be generated having results from all the Simulation.run() invocations.

Result Metrics

Definitions of plotted metrics:

1. Clustering overhead vs Vehicle density
   Defined as the ratio of total cloud formation packets transmitted vs total packets transmitted
2. Cloud formation time vs Vehicle density Formation time for a (fresh) cloud is the difference between leader recognising itself as leader and the request generation time
3. Leader changes vs Vehicle Speed
4. Requests Generated/Serviced/Queued vs Vehicle density Use a stacked column graph to verify thar requests are being full-filled by the leader.

Graphs are available at this Google Sheets link.

Benchmark

Following results were obtained using time java Simulator

Vehicle density	real	user	sys	Remarks	commit
(8,36,4)	36m7.589s	100m27.850s	29m24.983s	Full simulation first half	dfc6715
24	32m9.841s	82m49.220s	25m19.116s	Full simulation second half	dfc6715
24	5m15.805s	13m58.626s	4m5.868s	Single run	dfc6715
24	2m44.564s	7m15.348s	1m59.026s	Single run	perf-optimisation

Reference

1. CSMA pseudocode:

if (backoff == 0) {
    if channel is free {
        transmit
        backoff = 0
        cw = cw_base
    }
    else {
        cw *= 2
        if (cw < cw_max) {
            backoff = rand(cw) + 1
        }
        else {
            // could not transfer start all over again
        }
    }
}
else {
    if channel is free {
        decrement backoff
    }
}