June 2018 Update

Task/Dining-philosophers/Julia/dining-philosophers.julia

@@ -0,0 +1,83 @@
+mutable struct Philosopher
+    name::String
+    hungry::Bool
+    righthanded::Bool
+    rightforkheld::Channel
+    leftforkheld::Channel
+    function Philosopher(name, leftfork, rightfork)
+        this = new()
+        this.name = name
+        this.hungry = rand([false, true]) # not specified so start as either
+        this.righthanded   = (name == "Aristotle") ? false : true
+        this.leftforkheld  = leftfork
+        this.rightforkheld = rightfork
+        this
+    end
+end
+
+mutable struct FiveForkTable
+    fork51::Channel
+    fork12::Channel
+    fork23::Channel
+    fork34::Channel
+    fork45::Channel
+    function FiveForkTable()
+        this = new()
+        this.fork51 = Channel(1); put!(this.fork51, "fork") # start with one fork per channel
+        this.fork12 = Channel(1); put!(this.fork12, "fork")
+        this.fork23 = Channel(1); put!(this.fork23, "fork")
+        this.fork34 = Channel(1); put!(this.fork34, "fork")
+        this.fork45 = Channel(1); put!(this.fork45, "fork")
+        this
+    end
+end
+
+
+table = FiveForkTable();
+tasks = [Philosopher("Aristotle", table.fork12, table.fork51),
+         Philosopher("Kant", table.fork23, table.fork12),
+         Philosopher("Spinoza", table.fork34, table.fork23),
+         Philosopher("Marx", table.fork45, table.fork34),
+         Philosopher("Russell", table.fork51, table.fork45)]
+
+function dine(t,p)
+    if p.righthanded
+       take!(p.rightforkheld); println("$(p.name) takes right fork")
+       take!(p.leftforkheld); println("$(p.name) takes left fork")
+    else
+       take!(p.leftforkheld); println("$(p.name) takes left fork")
+       take!(p.rightforkheld); println("$(p.name) takes right fork")
+    end
+end
+
+function leavetothink(t, p)
+    put!(p.rightforkheld, "fork"); println("$(p.name) puts down right fork")
+    put!(p.leftforkheld, "fork");  println("$(p.name) puts down left fork")
+end
+
+contemplate(t) = sleep(t)
+
+function dophil(p, t, fullaftersecs=2.0, hungryaftersecs=10.0)
+    while true
+        if p.hungry
+            println("$(p.name) is hungry")
+            dine(table, p)
+            sleep(fullaftersecs)
+            p.hungry = false
+            leavetothink(t, p)
+        else
+            println("$(p.name) is out of the dining room for now.")
+            contemplate(hungryaftersecs)
+            p.hungry = true
+        end
+    end
+end
+
+function runall(tasklist)
+    for p in tasklist
+        @async dophil(p, table)
+    end
+    while true begin sleep(5) end end
+end
+
+runall(tasks)