% lec 24: wrapup

# administrivia

Q&A Monday, 11:30-12:20, 560

final exam Wednesday, 2:30, here

everything: lectures/sections/exercises/hws/readings

including today's reading, minus Rust/JavaScript

# today's plan

what have we been doing for the last 10 weeks?

# course goals

programming: C/C++

systems: talk to the OS for fs/net/proc/thread/...

tools: make, gcc, gdb, valgrind, nc, ...

coding discipline

deal with uncertainty: debugging, learning, communication

curiosity

# C: a high-level assembler

designed to write OSes (Unix)

abstractions: fixed-width integers, pointers, structs, ...

control: compilers won't generate code you didn't write

"easy" to understand & tune performance

trade-off: easy to shoot oneself in the foot

# C++: a better C (or not)

tries to keep the good/low-level part

higher-level abstractions

encapsulation: class (members/methods), namespace

polymorphism: virtual functions & templates

(compare to function pointers & macros)

examples: `std::string` vs `char *`, `std::thread` vs pthreads

# programming beyond C/C++

performance vs safety: garbage collection, big integers?

choose language(s) that work best for your applications

real-world concerns: easy to hire? fit existing code bases?

keep an open mind: Rust, Go, Java, Racket, OCaml, Haskell, ...

# systems overview

this course: programming interface to the kernel

memory management, file systems, networking, threading

general principles

# systems: abstractions

naming: filenames, DNS, IP

file descriptors

# systems: virtualization

virtual address: mmap, processes

virtual processor: processes/threads

example: valgrind

# systems: layering

example: `FILE *`, fd, kernel, disk

example: HTTP, TCP, IP, link layer

caching (fsync)

interface (zero-copying)

# tools: make our life easier

segfaults: much worse when bugs don't segfault

valgrind: find memory leaks without it?

how to build tools & design tool-friendly systems/languages

example: Linux kernel

example: g vs ms

# coding discipline

know what (not) to use

less error-prone constructs

performance trade-off

example: `new`/`delete` vs `unique_ptr`

# communication

programming is _not_ everything

in: reading books/google/stackoverflow/manpages

out: giving talks & writing

# future courses

[341: programming langauges](http://courses.cs.washington.edu/courses/cse341/):
principles & foundations

[451: operating systems](http://courses.cs.washington.edu/courses/cse451/):
lowest level of software stack

[452: distributed systems](http://courses.cs.washington.edu/courses/cse452/):
time, failure, coordination

grad courses: 505, 550, 551, 552

# beyond 333

my humble advice

"perfect is the enemy of good": end-to-end first; then improve

get your hands dirty (e.g., big-endian hands-on, learn Go in 452)

know yourself: what you like & you are good at

# that's it

congratulations & good luck on the exam(s)!

big thanks to Sunjay, Renshu, Josue, Edward!

stay in touch: drop by 560, grab lunch, emails