+ # stop iterations if errors or converged
+ my $stop_now = $logger_object->{_warning_count};
+ if ($stop_now) {
+ $convergence_log_message = <<EOM;
+Stopping iterations because of errors.
+EOM
+ }
+ elsif ($do_convergence_test) {
+ my $digest = md5_hex($sink_buffer);
+ if ( !$saw_md5{$digest} ) {
+ $saw_md5{$digest} = $iter;
+ }
+ else {
+
+ # Saw this result before, stop iterating
+ $stop_now = 1;
+ my $iterm = $iter - 1;
+ if ( $saw_md5{$digest} != $iterm ) {
+
+ # Blinking (oscillating) between two stable
+ # end states. This has happened in the past
+ # but at present there are no known instances.
+ $convergence_log_message = <<EOM;
+Blinking. Output for iteration $iter same as for $saw_md5{$digest}.
+EOM
+ $diagnostics_object->write_diagnostics(
+ $convergence_log_message)
+ if $diagnostics_object;
+ }
+ else {
+ $convergence_log_message = <<EOM;
+Converged. Output for iteration $iter same as for iter $iterm.
+EOM
+ $diagnostics_object->write_diagnostics(
+ $convergence_log_message)
+ if $diagnostics_object && $iterm > 2;
+ }
+ }
+ } ## end if ($do_convergence_test)
+
+ if ($stop_now) {
+
+ # we are stopping the iterations early;
+ # copy the output stream to its final destination
+ $sink_object = $sink_object_final;
+ while ( my $line = $source_object->get_line() ) {
+ $sink_object->write_line($line);
+ }
+ $source_object->close_input_file();
+ last;
+ }
+ } ## end if ( $iter < $max_iterations)
+ } # end loop over iterations for one source file
+
+ # restore objects which have been temporarily undefined
+ # for second and higher iterations
+ $debugger_object = $debugger_object_final;
+ $logger_object = $logger_object_final;