##-
# Author: Brian Tiffin
# Dedicated to the public domain
#
# Date: September 2016
# Modified: 2016-10-13/22:57-0400
##+
#
# thread.icn, Demonstrate thread messaging
#
# requires Concurrency build of Unicon
#
procedure main()
    pr := create producerRace()
    cr := create consumerRace(pr)
    pTr := spawn(pr)
    cTr := spawn(cr)
    every wait(pTr | cTr)
    write("racing producer/consumer complete")
    write()

    p := create producer()
    c := create consumer(p)
    pT := spawn(p)
    cT := spawn(c)
    every wait(pT | cT)
    write("main complete")
end

#
# This code can easily trigger incorrect results due to a race condition
#

# send messages to the thread out-box
procedure producerRace()
    write("producer entry")
    every !6@>
end

# receive messages from the out-box of the producer thread
procedure consumerRace(T)
    write("consumer entry")
    while write(<@T)
end

# What follows is the suggested update from Jafar
# It alleviates the race condition where consumerRace
# can complete before the producerRace even starts
#
# an original capture:
#
# JMBPro:proj jafar$ ./thrd
# producer entry
# consumer entry
# racing producer/consumer complete

#
# This is the better code...
#
 
# send messages to the thread out-box
procedure producer()
    write("synch producer entry")
    every !6@>
    # produce &null (&null@>)  to signal the end
    @>
end

# receive messages from the out-box of the producer thread
procedure consumer(T)
    write("blocking consumer entry")
    # blocking receive. 
    while write(\<<@T)
end