Homework #7 /proc file system

CSE-381: Systems 2
Homework #7

Maximum Points: 35
Submission Instructions
This homework assignment must be turned-in electronically via Canvas. Ensure your
C++ source code is named MUID_hw7.cpp, where MUID is your Miami University
Unique ID. Ensure your program compiles without any warnings or style violations.
Ensure you thoroughly test operations of your program as indicated. Once you have
tested your implementation, upload the following onto Canvas:
1. The 1 C++ source file developed for this homework.
General Note: Upload each file associated with homework individually to Canvas. Do
not upload archive file formats such as zip/tar/gz/7zip/rar etc.
Objective
The objective of this homework is to:
• Do some self-research/learning
• Understand the use of /proc file system
• Review the use of server sockets for communication
• Extend a C++ program that can be used as a web server
• Develop a web server to run programs & monitor programs
Grading Rubric:
The program submitted for this homework must pass necessary base
case test(s) in order to qualify for earning any score at all.
Programs that do not meet base case requirements will be assigned
zero score!
Program that do not compile, have a method longer than 25 lines, or
just some skeleton code will be assigned zero score.
• See points set for each command and overall structure, organization, conciseness,
variable-names, etc. in the next page. If your methods are not concise points will be
deducted.
• -1 Points: for each warning generated by the compiler (warnings are most likely sources
of errors in C++ programs)
NOTE: Violating CSE programming style guidelines is a compiler error! Your program should
not have any style violations.
Background
The /proc file system is a logical view of internal data that is maintained by the Linux kernel
about a process. For a given process the kernel exposes a logical file called
/proc/[pid]/stat (where [pid ]is the process ID, e.g., /proc/235/stat). This stats
file contains a variety of statistics about the process that can be used to report runtime statistics
about the process. In this homework, you will be using the following 3 values as described in the
following URL: http://man7.org/linux/man-pages/man5/proc.5.html
Word number
in stats file
Logical name
for Value
Notes
14th word utime (float) Cumulative user time. This value must be divided by divide
by sysconf(_SC_CLK_TCK) to get value in seconds
15th word stime (float) Cumulative system time. This value must be divided by
divide by sysconf(_SC_CLK_TCK) to get value in
seconds
23rd word vsize (long) Current virtual memory size in bytes. This value must be
divided by 1000 to get memory size in KB.
Starter code
The starter code for this homework is just the solution for Exercise #9. Invest time to refresh
your memory by reviewing the starter code.
Requirements
Suitably extend (how you modify is up to you) the starter source code to perform the following
additional functionality:
1. Base case -- Run a program & record runtime statistics [22 points]: Run a specified
command with suitable arguments and return the output and runtime statistics in the
HTML format shown further below. Recording of runtime statistics is:
a. Outputs are sent line-by-line to the client using chunked encoding
b. Record and print runtime statistics every second by opening & reading
/proc/[pid]/stat
c. Reading and printing statistics each second for the duration of a child process can
be accomplished as suggested below:
int exitCode = 0;
while (waitpid(pid, &exitCode, WNOHANG) == 0) {
sleep(1); // sleep for 1 second.
// Record current statistics about the process.
}
d. It is best to run the above loop in a separate thread to record the necessary
statistics.
e. The recorded statistics is finally sent to the client as a big chunk at the end of
program execution. No special formatting was needed to get the
statistics/numbers to be printed as shown in expected outputs.
The base case is relatively straightforward with plenty of time to finish.
Consequently, if the base case does not operate as expected, as per the course policy,
the whole program will be assigned zero score.
2. Setup statistics to plot a chart [8 points]: If the genChart parameter (3rd parameter) to
the serveClient method is true, then the program should also generate the runtime
statistics as a JSON array in the following format:
[ second, utime+stime, vsize ]
See annotated HTML in base case output below for details.
Note: This output should use exactly the same statistics values from base case. Do not reread the stats file to generate the statistics in JSON output.
3. Code quality [5 points]: Five points in this homework are reserved for good code quality,
effective code reuse, and documentation (in the form of comments). These 5 points
would be the hardest to earn in this homework.
Functional testing
The supplied starter code already includes a simple test harness that will also be used for testing
and grading purposes. Several test inputs and expected output files are also supplied to
streamline your testing as shown below. The true/false flag (i.e., last command-line
argument) is used to enable/disable generation of JSON format used to plot charts.
$ ./hw7 base_case1_inputs.txt my_base_case1_output.txt false
$ diff my_base_case1_output.txt base_case1_expected_outputs.txt
Testing for graph case:
$ ./hw7 base_case1_inputs.txt my_graph_case1_output.txt true
$ diff my_graph_case1_output.txt graph_case1_expected_outputs.txt
Needless to add, the above diff commands will not produce any output if the outputs are
identical.
! Due to non-deterministic scheduling and multiple users on the machine, the CPU
time and virtual memory use could be a bit different in some cases. Minor
differences in values are acceptable.
Ensure you test with input files and corresponding expected outputs prior to submission.
Browser testing
You may test operation of your webserver running on os1.csi.miamioh.edu. A partial
screenshot is shown further below for your reference (you may have to use a different port
number instead of 4000).
Submit to Canvas
This homework assignment must be turned-in electronically via Canvas. Ensure your C++ source
files are named appropriately. Ensure your program compiles (without any warnings or style
errors) successfully. Ensure you have tested operations of your program as indicated. Once you
have tested your implementation, upload the following onto Canvas:
 The 1 C++ source file you developed for this homework
Upload all the necessary C++ source files to onto Canvas independently. Do not submit
zip/7zip/tar/gzip files. Upload each file independently.
Screenshot of browser test:
Output from program
Runtime statistics
Time (sec)
User time
System time
Memory (KB)
1
0.99
0
14336
2
1.99
0
14336
3
2.99
0
14336
4
3.36
0
22728
5
3.36
0
22728
6
3.36
0
31117
7
3.36
0
31117
8
3.36
0
47894
9
3.36
0
47894
10
3.45
0.54
14336
11
4.25
0.74
14336
12
5.25
0.74
14336
13
6.25
0.74
14336
14
6.56
0.74
22810
15
6.56
0.74
22810
16
6.56
0.74
39587
17
6.56
0.74
39587
18
6.56
0.74
73146
19
6.56
0.74
73146
20
6.69
1.29
39587
21
6.72
1.51
0