resource sleeping_barber()
   import SRgetopt
   var ch : char
   var num_chairs : int := 5
   var num_customers : int := 10
   var cut_time : int := 2
   var grow_time : int := 4
   var run_time : int := 60

   # process command line options
   do (ch := getopt("hs:u:c:g:r:")) != optEOF ->
      if ch = 'h' ->
         write("Options:",
      "-s num_chairs -u num_customers -c cut_time -g grow_time -r run_time")
         printf("defaults: %10d %16d %11d %12d %11d\n",
            num_chairs, num_customers, cut_time, grow_time, run_time)
         stop(1)
      [] ch = 's' -> num_chairs := int(optarg)
      [] ch = 'u' -> num_customers := int(optarg)
      [] ch = 'c' -> cut_time := int(optarg)
      [] ch = 'g' -> grow_time := int(optarg)
      [] ch = 'r' -> run_time := int(optarg)
      [] else -> stop(1)
      fi
   od

   write("sleeping barber alive with")
   write("   num_chairs=", num_chairs)
   write("   num_customers=", num_customers)
   write("   cut_time=", cut_time)
   write("   grow_time=", grow_time)
   write("   run_time=", run_time)

   sem customers := 0
   sem barber := 0
   sem mutex := 1
   sem cutting := 0
   var waiting : int := 0

   procedure cut_hair()
      write("age=", age(), "Barber cutting hair")
      P(cutting)
      write("age=", age(), "Barber finished cutting")
   end cut_hair

   procedure get_haircut(j : int)
      var napping : int
      napping := int(random(1000*cut_time))
      write("age=", age(), "Customer", j, "haircut for", napping, "ms")
      nap(napping)
      write("age=", age(), "Customer", j, "finished haircut")
      V(cutting)
   end get_haircut

   process Barber
      write("Barber is alive")
      do true ->
         write("age=", age(), "Barber waiting for a customer")
         P(customers)
         P(mutex)
         waiting--
         V(barber)
         write("age=", age(), "Barber has customer, waiting=", waiting)
         V(mutex)
         cut_hair()
      od
   end Barber

   process Customer(j := 1 to num_customers)
      var napping : int
      write("Customer", j, "is alive")
      do true ->
         napping := int(random(1000*grow_time))
         write("age=", age(), "Customer", j, "growing", napping, "ms")
         nap(napping)
         write("age=", age(), "Customer", j, "needs a haircut")
         P(mutex)
         if (waiting < num_chairs) ->
            waiting++
            write("age=", age(), "Customer", j, "in room, waiting=", waiting)
            V(customers)
            V(mutex)
            P(barber)
            get_haircut(j)
         [] else ->
            write("age=", age(), "Customer", j, "room full, waiting=", waiting)
            V(mutex)
         fi
      od
   end Customer

   nap(1000*run_time); write("must stop now"); stop
end sleeping_barber

/* ............... Example compile and run(s)

% sr -v; sr -o sleeping_barber sleeping_barber.sr
SR version 2.3, October 1994
% ./sleeping_barber -h
Options: -s num_chairs -u num_customers -c cut_time -g grow_time -r run_time
defaults:          5               10           2            4          60
% ./sleeping_barber -s 3 -u 6 -c 2 -g 4 -r 10
sleeping barber alive with
   num_chairs= 3
   num_customers= 6
   cut_time= 2
   grow_time= 4
   run_time= 10
Barber is alive
age= 108 Barber waiting for a customer
Customer 1 is alive
age= 110 Customer 1 growing 3584 ms
Customer 2 is alive
age= 113 Customer 2 growing 108 ms
Customer 3 is alive
age= 115 Customer 3 growing 3231 ms
Customer 4 is alive
age= 117 Customer 4 growing 446 ms
Customer 5 is alive
age= 119 Customer 5 growing 3634 ms
Customer 6 is alive
age= 121 Customer 6 growing 2699 ms
age= 226 Customer 2 needs a haircut
age= 227 Customer 2 in room, waiting= 1
age= 229 Barber has customer, waiting= 0
age= 230 Barber cutting hair
age= 232 Customer 2 haircut for 1985 ms
age= 566 Customer 4 needs a haircut
age= 568 Customer 4 in room, waiting= 1
age= 2226 Customer 2 finished haircut
age= 2227 Customer 2 growing 943 ms
age= 2229 Barber finished cutting
age= 2230 Barber waiting for a customer
age= 2231 Barber has customer, waiting= 0
age= 2233 Barber cutting hair
age= 2234 Customer 4 haircut for 1496 ms
age= 2827 Customer 6 needs a haircut
age= 2828 Customer 6 in room, waiting= 1
age= 3176 Customer 2 needs a haircut
age= 3177 Customer 2 in room, waiting= 2
age= 3356 Customer 3 needs a haircut
age= 3357 Customer 3 in room, waiting= 3
age= 3696 Customer 1 needs a haircut
age= 3697 Customer 1 room full, waiting= 3
age= 3699 Customer 1 growing 2582 ms
age= 3736 Customer 4 finished haircut
age= 3737 Customer 4 growing 1426 ms
age= 3739 Barber finished cutting
age= 3740 Barber waiting for a customer
age= 3741 Barber has customer, waiting= 2
age= 3743 Barber cutting hair
age= 3744 Customer 6 haircut for 380 ms
age= 3756 Customer 5 needs a haircut
age= 3757 Customer 5 in room, waiting= 3
age= 4126 Customer 6 finished haircut
age= 4127 Customer 6 growing 2008 ms
age= 4129 Barber finished cutting
age= 4131 Barber waiting for a customer
age= 4132 Barber has customer, waiting= 2
age= 4134 Barber cutting hair
age= 4135 Customer 2 haircut for 1955 ms
age= 5166 Customer 4 needs a haircut
age= 5167 Customer 4 in room, waiting= 3
age= 6096 Customer 2 finished haircut
age= 6097 Customer 2 growing 2105 ms
age= 6099 Barber finished cutting
age= 6101 Barber waiting for a customer
age= 6102 Barber has customer, waiting= 2
age= 6103 Barber cutting hair
age= 6105 Customer 3 haircut for 274 ms
age= 6146 Customer 6 needs a haircut
age= 6147 Customer 6 in room, waiting= 3
age= 6286 Customer 1 needs a haircut
age= 6287 Customer 1 room full, waiting= 3
age= 6288 Customer 1 growing 1830 ms
age= 6386 Customer 3 finished haircut
age= 6387 Customer 3 growing 1992 ms
age= 6389 Barber finished cutting
age= 6390 Barber waiting for a customer
age= 6391 Barber has customer, waiting= 2
age= 6393 Barber cutting hair
age= 6394 Customer 5 haircut for 278 ms
age= 6676 Customer 5 finished haircut
age= 6677 Customer 5 growing 935 ms
age= 6679 Barber finished cutting
age= 6680 Barber waiting for a customer
age= 6681 Barber has customer, waiting= 1
age= 6683 Barber cutting hair
age= 6684 Customer 4 haircut for 1163 ms
age= 7616 Customer 5 needs a haircut
age= 7617 Customer 5 in room, waiting= 2
age= 7856 Customer 4 finished haircut
age= 7857 Customer 4 growing 1190 ms
age= 7859 Barber finished cutting
age= 7860 Barber waiting for a customer
age= 7862 Barber has customer, waiting= 1
age= 7863 Barber cutting hair
age= 7864 Customer 6 haircut for 1292 ms
age= 8126 Customer 1 needs a haircut
age= 8127 Customer 1 in room, waiting= 2
age= 8206 Customer 2 needs a haircut
age= 8207 Customer 2 in room, waiting= 3
age= 8386 Customer 3 needs a haircut
age= 8387 Customer 3 room full, waiting= 3
age= 8388 Customer 3 growing 1814 ms
age= 9056 Customer 4 needs a haircut
age= 9057 Customer 4 room full, waiting= 3
age= 9058 Customer 4 growing 2238 ms
age= 9166 Customer 6 finished haircut
age= 9167 Customer 6 growing 3672 ms
age= 9170 Barber finished cutting
age= 9171 Barber waiting for a customer
age= 9172 Barber has customer, waiting= 2
age= 9174 Barber cutting hair
age= 9175 Customer 5 haircut for 1182 ms
must stop now
                                              */