Test for jordansissel/eventmachine-tail#23

Makefile

all: writer

clean:
	rm -f writer

writer: writer.c
	gcc -Wall -Wextra -W -o writer writer.c

reader.rb

# craig65535@gmail.com

require 'rubygems'
gem 'eventmachine-tail', '=0.6.5'
require 'eventmachine-tail'

if ARGV.length != 2
  abort("args")
end

file = File.open(ARGV[1], "w")

EM.run do
  EventMachine::file_tail(ARGV[0], nil, 0) do |filetail, line|
    file.write(line + "\n")
  end
end

tester.pl

#!/usr/bin/perl -w

# craig65535@gmail.com

use warnings;
use strict;

my $DELAY = 0.2;
my $TIMES = 50;
my $INFILE = "/tmp/x";
my $INFILE_BAK = "$INFILE.bak";
my $INFILE_FULL = "$INFILE.full";
my $OUTFILE = "/tmp/y";
my $TEXT = "We're no strangers to love. You know the rules and so do I. A full commitment's what I'm thinking of. You wouldn't get this from any other guy.";

sub log_msg($)
{
  my ($msg) = @_;
  #print "[tester] $msg";
}

sub spawn
{
  my $pid = fork;
  die unless defined $pid;
  return $pid unless $pid == 0;
  exec @_;
  die;
}

sub roll()
{
  return unless -e $INFILE_BAK;
  log_msg("concat $INFILE_BAK >> $INFILE_FULL\n");
  system("cat $INFILE_BAK >> $INFILE_FULL");
  log_msg("unlink $INFILE_BAK\n");
  unlink $INFILE_BAK;
}

unlink $INFILE_FULL;
unlink $INFILE_BAK;

my @cmd = ("./writer", $INFILE, $TEXT);
log_msg("Run ".join(" ", map("'$_'", @cmd))."\n");
my $writer_pid = spawn(@cmd);
log_msg("writer_pid = $writer_pid\n");

@cmd = ("ruby", "reader.rb", $INFILE, $OUTFILE);
log_msg("Run ".join(" ", map("'$_'", @cmd))."\n");
my $reader_pid = spawn(@cmd);
log_msg("reader_pid = $reader_pid\n");

my $ok = 0;
if ($writer_pid =~ /^\d+$/ && $reader_pid =~ /^\d+$/) {
  $ok = 1;
}

if ($ok) {
  eval {
    for (my $i = 0; $i < $TIMES; $i++) {
      log_msg("sleep $DELAY\n");
      select(undef, undef, undef, $DELAY);
      roll();
      log_msg("rename $INFILE,$INFILE_BAK\n");
      rename $INFILE,$INFILE_BAK or die "rename ($INFILE,$INFILE_BAK): $!";
      log_msg("USR1 -> $writer_pid\n");
      kill(10, $writer_pid);
    }

    log_msg("sleep $DELAY\n");
    select(undef, undef, undef, $DELAY);
  };
  if ($@) {
    $ok = 0;
    print STDERR $@;
  }
}

if ($writer_pid =~ /^\d+$/) {
  log_msg("TERM writer (pid $writer_pid)\n");
  kill(15, $writer_pid);
}

log_msg("sleep 1 so writer finishes\n");
sleep 1;
roll();
log_msg("rename $INFILE,$INFILE_BAK\n");
rename $INFILE,$INFILE_BAK or die "rename ($INFILE,$INFILE_BAK): $!";
roll();
if ($reader_pid =~ /^\d+$/) {
  log_msg("TERM reader (pid $reader_pid)\n");
  kill(15, $reader_pid);
}

if ($ok) {
  print "open $OUTFILE\n";
  open FILE, '<', $OUTFILE or die "open $OUTFILE: $!";

  print "scanning\n";
  my $last_line = 0;
  my $num = 0;
  while (my $line = <FILE>) {
    $num++;
    if ($line =~ /^\[(\d+)\] [^\[]+$/) {
      my $read_num = $1;
      if ($read_num - $last_line > 1) {
        print "Lines ".($last_line+1)." through ".($read_num-1)." missing\n";
      }
      $last_line = $read_num;
    } else {
      print "Line $num: [$line]\n";
    }
  }

  print "close\n";
  close FILE;
}

writer.c

#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

/* craig65535@gmail.com */

volatile sig_atomic_t reopen = 0;
volatile sig_atomic_t term = 0;

void usr1_handler()
{
  reopen = 1;
}

void term_handler()
{
  term = 1;
}

int main(int argc, char **argv)
{
  FILE *f;
  char *s;
  int len;
  int line = 0;

  if (argc < 3)
    return 1;
  s = argv[2];

  if (signal(SIGUSR1, usr1_handler)) {
    perror("signal");
    return 1;
  }
  if (signal(SIGTERM, term_handler)) {
    perror("signal");
    return 1;
  }

  while (!term) {
    printf("[writer] fopen\n");
    f = fopen(argv[1], "w");
    if (!f) {
      perror("fopen");
      return 1;
    }
    len = (int)strlen(s) + 1;
    while (!term && !reopen) {
      line++;
      int n = fprintf(f, "[%06d] %s\n", line, s);
      if (n < 0) {
        printf ("fprintf returned %d (errno=%s)\n", n, strerror(errno));
      } else if (n != len + 9) {
        printf ("fprintf returned %d\n", n);
      }
      usleep(1000);
    }
    if (reopen) {
      printf("[writer] got signal. last line was %d\n", line);
      reopen = 0;
    }
    printf("[writer] fclose\n");
    if (fclose(f) != 0) {
      perror("fclose");
      return 1;
    }
  }
  return 0;
}