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Threads
The following are exported by the THREADS structure.
(WITH-MULTITASKING thunk)
Initializes for multitasking, then starts up a thread for the execution
of <thunk>. That thread and all others created will run in the dynamic
context of the call to with-multitasking. The call to with-multitasking
finally returns only when the scheduler runs out of things to do.
(SPAWN thunk) => thread
Create and schedule a new thread that will execute <thunk>.
(MAKE-LOCK) => lock
(WITH-LOCK lock thunk) => whatever <thunk> returns
(OBTAIN-LOCK lock)
(RELEASE-LOCK lock)
Locks are semaphores.
(MAKE-CONDVAR) => condvar
(CONDVAR-REF condvar) => value of condvar
(CONDVAR-SET! condvar value)
Condition Variables; attempts to reference a condition variable before
it has been set cause the referencing thread to block. Setting a
condition variable to two different values is an error.
(RELINQUISH-TIMESLICE)
Let other threads run for a while.
ONE-SECOND
The number of time units in one second.
(SLEEP time)
Sleep for <time> time units.
(TIME) => integer
The current time in time units.
(WITH-INTERRUPTS-INHIBITED thunk) => whatever <thunk> returns
(WITH-INTERRUPTS-ALLOWED thunk) => whatever <thunk> returns
Execute the thunk with or without interrupts. Interrupts are normally
enabled.
(THREAD-READ-CHAR port) => character or EOF
(THREAD-PEEK-CHAR port) => character or EOF
(READ-CHAR-WITH-TIMEOUT port time) => character or EOF or 'TIMEOUT
Read and peek for characters letting other threads run util a character
is available. READ-CHAR-WITH-TIMEOUT will return the symbol TIMEOUT if
<time> time units go by without a character being available.
(THREAD? thing)
#T if thing is a thread, #F otherwise.
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Debugging utilities:
(CURRENT-THREAD)
(TERMINATE-CURRENT-THREAD)
(KILL-THREAD thread)
(START-THREAD thread)
(STOP-THREAD thread)
(INTERRUPT-THREAD thread thunk)
Interrupt <thread> and make it execute <thunk> before continuing.
(ACTIVE-THREADS)
Returns a list containing all currently active threads.
(KILL-CONDVAR condvar)
Kill all threads waiting for <condvar>.
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The MORE-THREADS structure defines a command ,START-THREADS that
starts the scheduler with the command loop as its initial thread.
For example:
> ,load-package more-threads
[more-threads ...]
> ,open threads
> ,start-threads
Multitasking started
> (define (foo) (sleep one-second) (display "Hi") (newline) (foo))
> (define th (spawn foo))
> th
Hi
'#{Thread 1}
> (let loop () (loop))
Hi
Hi
Hi
Hi
Interrupt: keyboard
1>
> th
Hi
'#{Thread 1}
> (kill-thread th)
#t
> th
'#{Thread 1}
>
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Original by RK, 18 Nov 1993.
Sample transcript added by JAR, 5 Dec 1993.
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.