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83 lines
2.1 KiB
83 lines
2.1 KiB
6 years ago
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(in-package #:async-tools)
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(defun val (v) v)
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(defun sexpr-reader (stream char &key (func 'val))
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"Read next token only if S expression, else return as is"
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(if (char= (peek-char t stream t nil t) #\()
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(values (funcall func (read stream t nil t)) t)
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(let ((*readtable* (copy-readtable)))
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(set-macro-character char nil)
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(values (read-from-string (concatenate 'string (string char) (write-to-string (read stream t nil t)))) nil))))
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(defun async-reader (stream char)
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(multiple-value-bind (thing okay) (sexpr-reader stream char)
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(if okay
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(cons 'async (list thing))
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thing)))
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(defstruct promise
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thread
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value
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ended)
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(defmacro async (&body form)
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"Run body in seperate thread, returns promise."
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`(let ((end (make-promise)))
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(setf (promise-value end) nil)
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(setf (promise-ended end) nil)
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(setf (promise-thread end)
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(bt:make-thread
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#'(lambda ()
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(setf (promise-value end) (progn ,@form))
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(setf (promise-ended end) t))))
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end))
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(defun wait (promise)
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"Wait for promise to complete, returns the last value evaluated and T if the thread exited cleanly"
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(bt:join-thread (promise-thread promise))
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(value promise))
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(defun alive? (promise)
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"Is the thread alive?"
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(bt:thread-alive-p (promise-thread promise)))
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(defun value (promise)
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"The current value of the promise and T if the thread exited cleanly, (returns nil nil if it has not terminated yet)"
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(values (promise-value promise) (clean? promise)))
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(defun ended? (promise)
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"Has the promise completed?"
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(promise-ended promise))
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(defun thread (promise)
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"The thread for the promise"
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(promise-thread promise))
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(defun clean? (promise)
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"Did the thread exit, and did it do so cleanly?"
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(and (ended? promise) (not (alive? promise))))
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(defun kill (promise)
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"Kill thread. Unclean exit."
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(bt:destroy-thread (promise-thread promise)))
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(mapc 'export '(
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promise
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promise-p
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wait
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alive?
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thread
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value
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ended?
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clean?
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async))
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(defmacro enable-reader ()
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"Turn on reader macroi $(form) to run (async form)"
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'(eval-when (:compile-toplevel :load-toplevel :execute)
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(set-macro-character #\$ 'async-reader)))
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(export 'enable-reader)
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