====== Week 9 ======

~~NOTOC~~

===== Assignment: Dining Java Philosophers =====

  * Assign 4 
    * {{ diningjavaphils.pdf |PDF}}
    * due: Tue, Mar 31, 11:59pm \\ \\

===== Channels (cont'd) =====

  * CSP, Occam, and Golang!
  * Peter Welch's slides introducing CSP and occam-pi (but we will use Go this semester!)
    * [[courses:cs377-202651:welch-lectures:top|Occam-pi Lecture Notes]]
    * Legoland: slides 83--end of {{courses:cs377-202651:welch-lectures:basics.pdf|basics.pdf}} 
      * remember: 
        * //everything// is a process in occam and CSP, and
        * processes must be composed (explicitly) in sequence (SEQ) or in parallel (PAR) \\ \\ 

/************
  * Rob Pike's Google I/O 2012 - Go Concurrency Patterns: https://youtu.be/f6kdp27TYZs
*************/

  * Go demo and starter code
    * copy from Marc's directory into your ''cs377'' course directory: <code>
$ cd ~/cs377
$ cd -r /home/mlsmith/cs377-examples/Go ./
</code>
    * you should see the following files in your local ''Go'' directory: <code>
$ ls
csp-dining-phils.go       deadlock.go  sort-pump.go
csp-dining-phils-orig.go  sieve.go
$ 
</code>


  * Demo and codewalk of ''csp-dining-philosophers.go''
    * Based on an implementation found [[https://github.com/thomas11/csp|here]] 
      * on the example given in section 5.3 of Hoare's [[https://dl.acm.org/doi/pdf/10.1145/359576.359585|1978 CSP paper]]
      * and diagrammed more closely to the implementation in the [[https://antares.sip.ucm.es/~luis/doctorado06-07/cspbook.pdf|CSP Book]] on p. 57
      * you can copy Marc's Go examples directory into your current directory with this command: <code>$ cp -r /home/mlsmith/cs377-examples/Go ./</code>
    * Go language features highlighted:
      * channels
      * select
    * Design basis for solution in Go: go routines (processes)
      * room (communicates with philosophers over channels)
        * for philosophers to enter/leave -- at most 4 at a time to prevent deadlocking, 5th philosopher blocks 
      * forks (communicate with philosophers over channels)
      * philosophers (communicate with forks over channels)
    * To run this program: <code>
$ go run csp-dining-philosophers.go
</code>
    * Nondeterminism
      * still!  
      * sources? 

  * Demo and codewalk: Sieve of Eratosthenes (Prime Number Sieve) ''sieve.go''
    * Go language features highlighted:
      * Only one looping construct in Go: for loop 
        * all three parts are optional: init statement, conditional expression, post statement
      * channel declarations in function headers
        * can specify syntactically whether channel is for reading from: <code><-chan</code> or writing to: <code>chan<-</code>
    * To run this program: <code>
$ go run sieve.go
</code> // // 

  * Assignment 5 posted
    * Sort Pump Gophers {{sort-pump.pdf|PDF}}
    * see a similar example in occam on slides 13--31 of PHW's replicators lecture notes which can be found [[courses:cs377-202651:welch-lectures:top|here]]
    * Due: Thu, April 14th