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rudolph-miller / jonathan

JSON encoder and decoder.
http://rudolph-miller.github.io/jonathan/overview.html
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Performance optimization to parsing of floating point numbers #59

Closed jlahd closed 5 years ago

jlahd commented 5 years ago

Parsing of floating point numbers was very slow, due to calling (expt 10) to scale the decimal part. This change uses a look-up table instead, falling back to calling expt only if there are more than 20 decimal digits in the input.

Test case: (let ((s "{\"foo\":42.17,\"bar\":12.3456789012345}")) (time (dotimes (_ 1000000) (jonathan:parse s :as :alist))))

Before change, on CCL 1.11.5 (LinuxX8664): took 13,166,328 microseconds (13.166328 seconds) to run. After change, on CCL: took 1,488,017 microseconds (1.488017 seconds) to run.

Before change, on SBCL 1.4.15: 1.757 seconds of real time After change, on SBCL: 0.814 seconds of real time.

coveralls commented 5 years ago

Coverage Status

Coverage remained the same at 71.186% when pulling 43a1f6ab8c81412807dfbffc27197d19889657c2 on jlahd:float-reading-optimization into 1f448b4f7ac8265e56e1c02b32ce383e65316300 on Rudolph-Miller:master.