current-jiffy -- r7rs Definition

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Kind

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procedure;

Implemented by

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• current-jiffy (from vonuvoli);

Procedure signature

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Procedure variants:

• (() -> (timestamp-jiffy))
  • inputs: none;
  • output: a value of type timestamp-jiffy;

Exports

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• scheme:time -- (scheme time);

Exports recursive

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• scheme -- (scheme);

Description

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(current-jiffy)

Returns the number of jiffies as an exact integer that have elapsed since an arbitrary, implementation-defined epoch. A jiffy is an implementation-defined fraction of a second which is defined by the return value of the jiffies-per-second procedure. The starting epoch is guaranteed to be constant during a run of the program, but may vary between runs.

Rationale: Jiffies are allowed to be implementation-dependent so that current-jiffy can execute with minimum overhead. It should be very likely that a compactly represented integer will suffice as the returned value. Any particular jiffy size will be inappropriate for some implementations: a microsecond is too long for a very fast machine, while a much smaller unit would force many implementations to return integers which have to be allocated for most calls, rendering current-jiffy less useful for accurate timing measurements.

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The text herein was sourced and adapted as described in the "R7RS attribution of various text snippets" appendix.

Referenced-types

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• timestamp-jiffy;