[9fans] env walk optimization

[9fans] env walk optimization

[Peter Schay]

Hello,

Here's more on the performance subject; I hope the
following optimization is useful and not too inelegant.

The algorithm for walking in #e seems to be O(n*n).
I think it's pretty easy to make it O(n).

For example, on my system the following script takes no
time with 42 environment variables takes 4 seconds with
441 vars:

term% time /fd/0 <<.
#!/bin/rc
rfork e
eval X^(`{seq 1})^('=1')
echo nvars `{ls /env | wc -l}