145 lines
2.6 KiB
Racket
145 lines
2.6 KiB
Racket
#lang scribble/manual
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@(require (for-label racket))
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@title{Condition}
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@section{categories}
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Scheduling
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Block the execution of a thread
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@section{CLASSMETHODS}
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@section{method}
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new
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Create a new instance, set the strong::test:: variable.
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@section{INSTANCEMETHODS}
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@section{method}
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test
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Answer whether the condition will block or not (boolean).
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@section{method}
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wait
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Wait until the condition is true and signalled. This only works in a Routine. This method yields a symbol (\hang), so that the clock doesn't reschedule the Routine.
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@racketblock[
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c = Condition(false); fork { 0.5.wait; "started ...".postln; c.wait; "... and finished.".postln };
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c.test = true;
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c.signal;
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::
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]
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@section{method}
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hang
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Wait for strong::value:: time, regardless of test. This only works in a Routine. This method yields a symbol (\hang), so that the clock doesn't reschedule the Routine.
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@racketblock[
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c = Condition.new; fork { 0.5.wait; "started ...".postln; c.hang; "... and finished.".postln };
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c.unhang;
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::
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]
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@section{method}
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signal
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If link::#-test:: is true, reschedule blocked threads.
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@section{method}
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unhang
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Resume threads.
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@section{EXAMPLES}
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@racketblock[
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(
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c = Condition.new(false);
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Routine {
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1.wait;
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"waited for 1 second".postln;
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1.wait;
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"waited for another second, now waiting for you ... ".postln;
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c.wait;
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"the condition has stopped waiting.".postln;
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1.wait;
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"waited for another second".postln;
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"waiting for you ... ".postln;
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c.test = false;
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c.wait;
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"the condition has stopped waiting.".postln;
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1.wait;
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"the end".postln;
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}.play;
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)
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// continue
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(
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c.test = true;
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c.signal;
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)
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// a typical use is a routine that can pause under certain conditions:
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(
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c = Condition.new;
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fork { loop { 1.wait; "going".postln; c.wait } };
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)
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c.test = true; c.signal;
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c.test = false;
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::
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]
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@racketblock[
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// the same, using hang
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(
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c = Condition.new;
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Routine {
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1.wait;
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"waited for 1 second".postln;
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1.wait;
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"waited for another second, now waiting for you ... ".postln;
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c.hang;
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"the condition has stopped waiting.".postln;
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1.wait;
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"waited for another second".postln;
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"waiting for you ... ".postln;
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c.hang;
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"the condition has stopped waiting.".postln;
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}.play;
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)
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// continue
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c.unhang;
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::
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Waiting for Synths to end (waitForFree) uses a Condition implicitly:
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]
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@racketblock[
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(
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SynthDef(\help, {
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var mod = LFNoise2.kr(ExpRand(0.5, 2)) * 0.5;
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var snd = mod * Blip.ar(Rand(200, 800) * (mod + 1));
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Out.ar(0, snd);
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FreeSelf.kr(mod < 0); // free the synth when amplitude goes below 0.
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}).add;
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)
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(
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fork {
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10.do {
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"started a synth".postln;
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Synth(\help).waitForFree;
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"This one ended. Wait a second, I will start the next one.".postln;
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1.wait;
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};
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"This is it.".postln;
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}
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);
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]
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