Implement jitter function.

Fix tests and checking in cronwrap that --suppress/--jitter are
specified with positive integers.

cronwrap

@@ -7,6 +7,7 @@ use File::Path;
 use Getopt::Long;
 use Pod::Usage;
 use Data::Dumper;
+use Sys::Hostname;
 # Digest::SHA supports SHA-1 and SHA-2, but alas Red Hat Enterprise only comes
 # with Digest::SHA1
 use Digest::SHA1;
@@ -31,6 +32,8 @@ my $result = GetOptions(\%options,
 
 # See below __END__ for usage message in POD format
 pod2usage(1) if $options{help};
+pod2usage(1) if defined $options{suppress} && $options{suppress} <= 0;
+pod2usage(1) if defined $options{jitter} && $options{jitter} <= 0;
 pod2usage(-exitstatus => 0, -verbose => 2) if $options{man};
 
 # Anything leftover in @ARGV is the job command and arguments
@@ -77,6 +80,22 @@ if (! -f $cmdfile)
   close $cmdfh;
 }
 
+#
+# Jitter
+#
+
+if ($options{jitter})
+{
+  # Seed the random number generator with the hostname of this box so that
+  # we get a consistent random number.  We want to run the registration at a
+  # consistent time on each individual box, but randomize the runs across
+  # the environment.
+  srand(hex(substr(Digest::SHA1->sha1_hex(hostname()), -8)));
+
+  # Option is specified in minutes, sleep expects seconds
+  sleep(int(rand($options{jitter} * 60)));
+}
+
 #
 # Overlap protection
 #

t/jitter.t

@@ -21,13 +21,13 @@ $number_of_tests_run++;
 # Ensure that the argument must be a positive integer
 #
 
-system('./cronwrap --jitter bogus > /dev/null 2>&1');
+system('./cronwrap --jitter bogus true > /dev/null 2>&1');
 isnt($?, 0, '--jitter rejects string');
 $number_of_tests_run++;
-system('./cronwrap --jitter 0 > /dev/null 2>&1');
+system('./cronwrap --jitter 0 true > /dev/null 2>&1');
 isnt($?, 0, '--jitter rejects 0');
 $number_of_tests_run++;
-system('./cronwrap --jitter -1 > /dev/null 2>&1');
+system('./cronwrap --jitter -1 true > /dev/null 2>&1');
 isnt($?, 0, '--jitter rejects -1');
 $number_of_tests_run++;
 
@@ -37,13 +37,15 @@ $number_of_tests_run++;
 #
 
 #
-# However, we do expect the jitter to be consistent on any given machine. 
-# That we can test
+# However, we do expect the jitter to be consistent on any given machine. That
+# we can test.  One minute (--jitter 1) is good enough for testing as cronwrap
+# actually sleeps for a random number of seconds, so even with one minute of
+# jitter cronwrap will sleep anywhere from 0-59 seconds.
 #
 
 # Time one run
 my $start = time;
-system('./cronwrap --jitter 5 true');
+system('./cronwrap --jitter 1 true');
 my $end = time;
 
 my $elapsed = $end - $start;
@@ -52,7 +54,7 @@ my $elapsed = $end - $start;
 foreach (1, 2)
 {
   my $start = time;
-  system('./cronwrap --jitter 15 true');
+  system('./cronwrap --jitter 1 true');
   my $end = time;
 
   my $test_elapsed = $end - $start;

t/suppress.t

@@ -23,13 +23,13 @@ $number_of_tests_run++;
 # Ensure that the argument must be a positive integer
 #
 
-system('./cronwrap --suppress bogus > /dev/null 2>&1');
+system('./cronwrap --suppress bogus true > /dev/null 2>&1');
 isnt($?, 0, '--suppress rejects string');
 $number_of_tests_run++;
-system('./cronwrap --suppress 0 > /dev/null 2>&1');
+system('./cronwrap --suppress 0 true > /dev/null 2>&1');
 isnt($?, 0, '--suppress rejects 0');
 $number_of_tests_run++;
-system('./cronwrap --suppress -1 > /dev/null 2>&1');
+system('./cronwrap --suppress -1 true > /dev/null 2>&1');
 isnt($?, 0, '--suppress rejects -1');
 $number_of_tests_run++;