Change interface to qsieve to not use system time command

[jpflori]

On some systems (including but not limited to Cygwin), there is a bash "time" keyword but no time command.

This is problematic in sage/interfaces/qsieve.py (see optional - time) doctests.

See also:

• #14184 comment:16
• #9164 comment:3
• https://groups.google.com/d/topic/sage-devel/WtvaNKHdnts/discussion
• http://comments.gmane.org/gmane.os.cygwin/106331

CC: @kcrisman @dimpase

Component: interfaces: optional

Keywords: time optional sieve

Issue created by migration from https://trac.sagemath.org/ticket/14202

[dimpase]

comment:2

Cygwin has /usr/bin/time, it just needs to be installed. Thus, I propose making the presence of time a Cygwin prereq.

[jdemeyer]

Changed keywords from cygwin time optional to time optional

[jdemeyer]

comment:3

This ticket has absolutely nothing to do with Cygwin.

Regardless, making time a prereq is not needed, it would be easy to fix the qsieve code not to rely on a time command.

[jpflori]

comment:4

Replying to @jdemeyer:

This ticket has absolutely nothing to do with Cygwin.

Regardless, making time a prereq is not needed, it would be easy to fix the qsieve code not to rely on a time command.

I agree with that, and would really not like to add new prereqs on any platform.

[kcrisman]

Changed keywords from time optional to time optional sieve

[kcrisman]

comment:5

I'm changing the summary. This is really a bug, if it's a bug, in the way interface/qsieve.py is written. Could we use whatever does time or timeit in Sage?

[jdemeyer]

comment:6

Replying to @kcrisman:

I'm changing the summary. This is really a bug, if it's a bug, in the way interface/qsieve.py is written. Could we use whatever does time or timeit in Sage?

Try this:

sage: ?walltime
Type:       function
String Form:<function walltime at 0xb9d488>
File:       /usr/local/src/sage-5.7.beta1/local/lib/python2.7/site-packages/sage/misc/misc.py
Definition: walltime(t=0)
Docstring:
   Return the wall time in second, or with optional argument t, return
   the wall time since time t. "Wall time" means the time on a wall
   clock, i.e., the actual time.

   INPUT:

   * "t" - (optional) float, time in CPU seconds

   OUTPUT:

   * "float" - time in seconds

   EXAMPLES:

      sage: w = walltime()
      sage: F = factor(2^199-1)
      sage: walltime(w)   # somewhat random
      0.8823847770690918