Week 10

Channels, CSP, and Go

Continuing from where we left off last week

Hoare's 1978 CSP paper: https://spinroot.com/courses/summer/Papers/hoare_1978.pdf
- Go implementation of examples from paper: https://godoc.org/github.com/thomas11/csp
Rob Pike's Google I/O 2012 - Go Concurrency Patterns: https://youtu.be/f6kdp27TYZs
Peter Welch's slides introducing CSP and occam-pi (but we will use Go this semester!)
- Occam-pi Lecture Notes
- today:
  - Objects Considered Harmful (slide 27 of motivation.pdf slides)
  - even though we won't be programming in occam-pi, I want to give you a flavor of it
  - because:
    - ultimate lightweight processes!
    - composition!
  - Legoland: slide 83-end of basics.pdf
Demo and codewalk of csp-dining-philosophers.go
- 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)
Demo and codewalk: Sieve of Eratosthenes (Prime Number Sieve)
- copy the sample code from my directory to yours:
  - cd into the directory where you have your sample Go code
  - cp -r /home/mlsmith/cs377-examples/Go/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:
      <-chan
      
      or writing to:
      
      chan<-
Assignment 5 posted
- Sort Pump Gophers PDF
- Due: Friday, April 19th