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3668 :: cpuTime not in JS backend?

• sdwfrost (orginal) [2018-03-19T11:21:10+01:00] view original

  Dear All,

  In compiling my Nim code here using the Javascript backend, I got an error message:

  
  nim js -d:release -o:sir_opt.js  sir_opt
  sir_opt.nim(55, 12) Error: undeclared identifier: 'cpuTime'
  Run

  Is cpuTime not defined within the times package (which in the docs, says it is compatible with JS)?

  Best wishes

  Simon

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• GULPF (orginal) [2018-03-19T14:44:46+01:00] view original

  cpuTime is not supported for the JS backend, because there is no way to get the CPU time from the browser. I suppose it would be possible to implement it for Nodejs though. Your best bet for measuring time in the browser is to wrap performance.now, or to use times.epochTime (which is not monotonic). I plan to add a proper monotonic time type to the times module (which will use performance.now for the JS backend) after my nanosecond resolution PR has been merged.

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• Araq (orginal) [2018-03-19T17:36:50+01:00] view original

  In some old version of times.nim cpuTime was mapped to epochTime if the platform would not support cpuTime. I think we can do that again; best effort approximations for the JS target are a fact of life.

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• GULPF (orginal) [2018-03-19T20:38:36+01:00] view original

  In some old version of times.nim cpuTime was mapped to epochTime if the platform would not support cpuTime. I think we can do that again; best effort approximations for the JS target are a fact of life.

  I disagree. The whole point of a monotonic clock is that it's guaranteed to be monotonic. A non-monotonic clock should not be used as a approximation. If cpuTime has to work in the browser (and I don't think it has to if the times module gets a proper monotonic time type) it should use performance.now. If the user decides that a non-monotonic clock is an acceptable fallback for their use case they can use a shim for performance.now.

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• treeform (orginal) [2018-03-20T18:48:57+01:00] view original

  Also DOM package does not include performance.now which requires and {.emit.} to get working.

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