[ruby-core:92916] [Ruby trunk Bug#15807] Range#minmax is slow and never returns for endless ranges

From: mohsen@...
Date: 2019-05-31 19:31:24 UTC
List: ruby-core #92916
Issue #15807 has been updated by mohsen (Mohsen Alizadeh).


i had the same problem with minmax in Range.

I made a MR


https://github.com/ruby/ruby/pull/2216

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Bug #15807: Range#minmax is slow and never returns for endless ranges
https://bugs.ruby-lang.org/issues/15807#change-78292

* Author: janosch-x (Janosch Mler)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: 2.6.3p62
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
current situation:

- `(1..).minmax` runs forever
- `(1..).max` raises "cannot get the maximum of endless range"
- `(1..Float::INFINITY).minmax` runs forever
- `(1..Float::INFINITY).max` returns instantly
- `(1..1_000_000_000).minmax` takes one minute
- `(1..1_000_000_000).max` returns instantly

my suggestion:

- implement `minmax` in range.c, return [`range_min`, `range_max`]
- for endless ranges, this will trigger the same error as `max` does
- delegate to enum (rb_call_super) only if called with a block (?)

i could perhaps provide a PR if you can point me to some information on how to contribute.

cheers!



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