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interruptedWhile (useful for monitoring a computation non-interactively)

• To: mathgroup at smc.vnet.net
• Subject: [mg24595] interruptedWhile (useful for monitoring a computation non-interactively)
• From: Daniel Reeves <dreeves at eecs.umich.edu>
• Date: Tue, 25 Jul 2000 00:56:26 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

MathGroupies,
I think the following may be generally useful so I thought I'd share it:

(PS: I've noticed that the AbortProtect slows this down a bit; can anyone
think of a better way of doing this?) 

(* Like a While loop except for the 1st 2 args, which say: every so many
   seconds pause and execute some code, presumably with the purpose of
   announcing some partial results or the status of the computation.
*)
SetAttributes[interruptedWhile, HoldRest];
interruptedWhile[interruptFreq_, interruptBody_, whileTest_, whileBody_] 
:= 
Module[{compLoop, goComp},
  compLoop := While[whileTest, AbortProtect[whileBody]];
  goComp := TimeConstrained[compLoop, interruptFreq, 
              Evaluate[interruptBody]; goComp];
  goComp;
]


Here's an example of using it:

i = 1;
numFound = 0;
interruptedWhile[3,
  Print["Checked 1 thru ", i - 1, " and found ", numFound, 
    " primes (expected ", PrimePi[i - 1], ")..."],
  i <= 1000000,
    If[PrimeQ[i], numFound++];
    i++;
]

Of course, you can manually interrupt and check on a computation from the
front-end, so this is most useful for a really long computation that you
have running in the background.  In those cases, I often like to have the
program send periodic emails.  So while I'm at it, I'll paste in code to
do that (of course this only works on Unix/Linux):

SYSTEMINFO::usage = 
    "A string with things like machine and user name and process IDs.";

ENV::usage = "A string showing all operating system environment
variables.";

mail::usage = "mail[
  to -> {list of addresses},  \n
  from -> \"Some Name <some at email.address>\",  (* or just email address
*) \n
  subject -> \"string\", \n
  body -> \"string\", (* see SYSTEMINFO and BODY *)\n
  headers -> {list of \"Header: stuff\" strings}  (* additional headers
*)].  
Use Options[mail] to see default options.";

SYSTEMINFO := 
    StringJoin @@ 
      ToString /@ {"$MachineName: ", $MachineName, 
          "\n$MachineDomain: ", $MachineDomain, "\n$UserName: ",
$UserName, 
          "\n$ProcessID: ", $ProcessID, 
          "\n$ParentProcessID: ", $ParentProcessID, 
          "\n$CommandLine: ", $CommandLine, "\nARGV: ", Global`ARGV,
"\n"};

ENV = Read["!/usr/bin/env", Record, RecordSeparators -> {}];
Close["!/usr/bin/env"];

(* Default options for mail. *)
Options[mail] := {
      to -> {"dreeves at eecs.umich.edu"},
      from -> "MY-MMA-AGENT <dreeves at maria.physics.lsa.umich.edu>",
      subject -> 
        StringJoin @@ 
          ToString /@ {"OUTPUT from process ", $ProcessID, 
              " on ", $MachineName},
      body -> SYSTEMINFO <> "\nEnvironment:\n\n" <> ENV,
      headers -> {}
      };

(*like perl's join function*)
intersperse[delim_String, l_List] := 
  Module[{pair}, 
    StringJoin @@ Drop[pair[#, delim] & /@ l /. pair -> Sequence, -1]]

mail[opts___] := Module[{opt, allHeaders, stream},
    opt[x_] := x /. {opts} /. Options[mail];
    allHeaders = Join[opt[headers], {
          "Subject: [mg24595] " <> opt[subject],
          "From: " <> opt[from],
To: mathgroup at smc.vnet.net
          "To: " <> intersperse[", ", opt[to]]}];
    stream = OpenWrite["!/usr/lib/sendmail -oi -t"];
    WriteString[stream, intersperse["\n", allHeaders], "\n\n", opt[body]];
    Close[stream];]


--    --    --    --    --    --    --    --    --    --    --    -- 
Daniel Reeves               http://ai.eecs.umich.edu/people/dreeves/

"Jesus is coming, everyone look busy."