CalculateEachElementOnce [1032122]

< > BotCompany Repo | #1032122 // CalculateEachElementOnce

JavaX fragment (include) [tags: use-pretranspiled]

// TODO: it isn't actually multithreaded at all
sclass CalculateEachElementOnce<A, B> {
  Map<A, Flag> calculating = syncMap();
  Map<A, OKOrError<B>> calculated = syncMap();
  
  synchronized B get(A a, IF1<A, B> f) {
    Flag flag = calculating.get(a);
    if (flag != null) {
      flag.waitUntilUp();
      ret unpackOKOrError(calculated.get(a));
    } else {
      flag = new Flag;
      calculating.put(a, flag);
      OKOrError<B> b = okOrError(() -> f.get(a));
      calculated.put(a, b);
      calculating.remove(a);
      flag.raise();
      ret b!;
    }
  }
}

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Snippet ID:

#1032122

Snippet name:

CalculateEachElementOnce

Eternal ID of this version:

#1032122/7

Text MD5:

63af94d1bcb880ad6923f1c1a977bb6c

Transpilation MD5:

1696c8636c54a28d9fb2abc5b957a0d1

Author:

stefan

Category:

javax / gazelles

Type:

JavaX fragment (include)

Public (visible to everyone):

Yes

Archived (hidden from active list):

Created/modified:

2021-08-14 03:10:53

Source code size:

591 bytes / 21 lines

Pitched / IR pitched:

No / No

Views / Downloads:

171 / 314

Version history:

6 change(s)

Referenced in:

[show references]

1	// TODO: it isn't actually multithreaded at all
2	sclass CalculateEachElementOnce<A, B> {
3	Map<A, Flag> calculating = syncMap();
4	Map<A, OKOrError<B>> calculated = syncMap();
5
6	synchronized B get(A a, IF1<A, B> f) {
7	Flag flag = calculating.get(a);
8	if (flag != null) {
9	flag.waitUntilUp();
10	ret unpackOKOrError(calculated.get(a));
11	} else {
12	flag = new Flag;
13	calculating.put(a, flag);
14	OKOrError<B> b = okOrError(() -> f.get(a));
15	calculated.put(a, b);
16	calculating.remove(a);
17	flag.raise();
18	ret b!;
19	}
20	}
21	}