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CS 241 Section (03/15/2012)

CS 241 Section (03/15/2012). MP6. This MP is simple: Create a ‘make’ utility. MP6. This MP is simple: Create a ‘make’ utility. What does ‘make’ do? Reads a ‘makefile’ Determines the tasks that are available to run based on dependency rules Run until all tasks are finished. MP6.

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CS 241 Section (03/15/2012)

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  1. CS 241 Section(03/15/2012)

  2. MP6 • This MP is simple: • Create a ‘make’ utility.

  3. MP6 • This MP is simple: • Create a ‘make’ utility. • What does ‘make’ do? • Reads a ‘makefile’ • Determines the tasks that are available to run based on dependency rules • Run until all tasks are finished

  4. MP6 job1: job2 job3    commandtoberun withargs    commandtoberun2 withargs job2:    othercommand job3:    finalcommand

  5. MP6 target job1: job2 job3    commandtoberun withargs    commandtoberun2 withargs job2:    othercommand job3:    finalcommand

  6. MP6 dependencies job1: job2 job3    commandtoberun withargs    commandtoberun2 withargs job2:    othercommand job3:    finalcommand

  7. MP6 job1: job2 job3    commandtoberun withargs    commandtoberun2 withargs job2:    othercommand job3:    finalcommand commands

  8. MP6 • We can show this graphically: …job1 depends on job2 and job3 being done. job2 job1 job3

  9. MP6 • In MP6, you will specify (with the –j # option) how many worker threads should run. • “-j 1”: Only one worker thread • “-j 2”: Two worker threads • “-j 100”: One hundred worker threads • Use getopt() to handle command-line options

  10. MP6 • If the makefile is ran with –j 2, then: [thread a]: job2 runs [thread b]: job3 runs [thread b]: job3 finishes [thread b]: idle, job1 not ready[thread a]: job2 finishes [thread a OR b]: job1 runs [thread a OR b]: job1 finishes [thread a AND b]: exit, all jobs done [main thread]: join threads, exit

  11. MP6 • We provide you some tools you can use, if you’d like: • queue.c: A queue data structure • parser.c: A parser for makefiles • parser_parse_makefile(…) takes function pointers as arguments that will be called when it reaches a key, dependency, or command.

  12. MP6 Parser Callbacks parsed_new_key(key=job1) parsed_dependency(key=job1, dep=job2) parsed_dependency(key=job1, dep=job3) parsed_command(key=job1, command=...) parsed_command(key=job1, command=...) parsed_new_key(key=job2) parsed_command(key=job2, command=...) parsed_new_key(key=job3) parsed_command(key=job3, command=...)

  13. MP6 • Some useful functions: • pthread_create(), pthread_join() • sem_init(), sem_wait(), sem_post(), sem_destroy() • system() • Does fork(), exec(), and wait() for you in one command! • Remember to check return values! You may find some weird things going on with semaphores if you don’t… Good luck!

  14. MP6 • Run a rule only if any dependency has a modification time more recent than the target. • You can get the modification time of a file using stat()

  15. Coding Examples • This week:ds/ds6/

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