Initial data commit

Task/Mutex/Shale/mutex.shale

@@ -0,0 +1,30 @@
+#!/usr/local/bin/shale
+
+thread library    // POSIX threads, mutexes and semaphores
+time library      // We use its sleep function here.
+
+// The threead code which will lock the mutex, print a message,
+// then unlock the mutex.
+threadCode dup var {
+  arg dup var swap =
+
+  stop lock thread::()
+  arg "Thread %d has the mutex\n" printf
+  stop unlock thread::()
+} =
+
+stop mutex thread::()   // Create the mutex.
+stop lock thread::()    // Lock it until we've started the threads.
+
+// Now create a few threads that will also try to lock the mutex.
+1 threadCode create thread::()
+2 threadCode create thread::()
+3 threadCode create thread::()
+4 threadCode create thread::()
+// The threads are all waiting to acquire the mutex.
+
+"Main thread unlocking the mutex now..." println
+stop unlock thread::()
+
+// Wait a bit to let the threads do their stuff.
+1000 sleep time::()   // milliseconds