#!/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