Sync

Task/Checkpoint-synchronization/Haskell/checkpoint-synchronization-3.hs

@@ -0,0 +1,28 @@
+global nWorkers, workers, cv
+
+procedure main(A)
+    nWorkers := integer(A[1]) | 3
+    cv  := condvar()
+    every put(workers := [], worker(!nWorkers))
+    every wait(!workers)
+end
+
+procedure worker(n)
+    return thread every !3 do {       # Union limits each worker to 3 pieces
+        write(n," is working")
+        delay(?3 * 1000)
+        write(n," is done")
+        countdown()
+        }
+end
+
+procedure countdown()
+    critical cv: {
+        if (nWorkers -:= 1) <= 0 then {
+            write("\t\tAll done")
+            nWorkers := *workers
+            return (unlock(cv),signal(cv, 0))
+            }
+        wait(cv)
+        }
+end