From a08bf4c4fced7fd0b0272c15079332e717f0e9f5 Mon Sep 17 00:00:00 2001
From: Daniel Nichter <daniel@percona.com>
Date: Mon, 27 Aug 2012 15:19:35 -0600
Subject: [PATCH] Add code comments.  Make Pingback.t tests more explicity. 
 Don't '1 while unlink file'.  Remove get_mysql_status() stub.

---
 lib/Pingback.pm     | 41 +++++++++++++++++++++++++----------------
 lib/VersionCheck.pm | 14 ++------------
 t/lib/Pingback.t    | 20 +++++++++++---------
 3 files changed, 38 insertions(+), 37 deletions(-)

diff --git a/lib/Pingback.pm b/lib/Pingback.pm
index a1d90bbc..21b002de 100644
--- a/lib/Pingback.pm
+++ b/lib/Pingback.pm
@@ -33,7 +33,6 @@ use Digest::MD5    qw(md5_hex);
 use Sys::Hostname  qw(hostname);
 use Fcntl          qw(:DEFAULT);
 use File::Basename qw();
-
 use File::Spec;
 
 my $dir              = File::Spec->tmpdir();
@@ -204,41 +203,50 @@ sub time_to_check {
    my ($file, $instance_ids) = @_;
    die "I need a file argument" unless $file;
 
+   # If there's no time limit file, then create it and check everything.
    if ( !-f $file ) {
       PTDEBUG && _d('Creating', $file);
       _touch($file);
       return 1;
    }
 
-   # If we have instances to check, 
-   my $time = int(time());
-   return _time_to_check_by_instances($file, $instance_ids, $time)
-            if @$instance_ids;
-   
+   my $time = int(time());  # current time
+
+   # If we have MySQL instances, check only the ones that haven't been
+   # seen/checked before or were check > 24 hours ago.
+   if ( $instance_ids && @$instance_ids ) {
+      return _time_to_check_by_instances($file, $instance_ids, $time);
+   }
+
+   # No MySQL instances (happens with tools like pt-diskstats), so just
+   # check the file's mtime and check if it was updated > 24 hours ago.
    my $mtime  = (stat $file)[9];
    if ( !defined $mtime ) {
       PTDEBUG && _d('Error getting modified time of', $file);
       return 0;
    }
-
-   # Otherwise, if there's been more than a day since the last check,
-   # update the file and return true.
    PTDEBUG && _d('time=', $time, 'mtime=', $mtime);
    if ( ($time - $mtime) > $check_time_limit ) {
       _touch($file);
       return 1;
    }
 
-   # Otherwise, we're still within the day, so don't do the version check.
+   # File was updated less than a day ago; don't check yet.
    return 0;
 }
 
 sub _time_to_check_by_instances {
    my ($file, $instance_ids, $time) = @_;
-   
+
+   # The time limit file contains "ID,time" lines for each MySQL instance
+   # that the last tool connected to.  The last tool may have seen fewer
+   # or more MySQL instances than the current tool, but we'll read them
+   # all and check only the MySQL instances for the current tool.
    chomp(my $file_contents = Percona::Toolkit::slurp_file($file));
    my %cached_instances = $file_contents =~ /^([^,]+),(.+)$/mg;
-   
+
+   # Check the MySQL instances that have either 1) never been checked
+   # (or seen) before, or 2) were check > 24 hours ago.
    my @instances_to_check = grep {
       my $update;
       if ( my $mtime = $cached_instances{$_} ) {
@@ -253,14 +261,15 @@ sub _time_to_check_by_instances {
       $update
    } @$instance_ids;
 
+   # Overwrite the time limit file with the check times for instances
+   # we're going to check or with the original check time for instances
+   # that we're still waiting on.
    open my $fh, ">", $file
       or die "Cannot open $file for writing: $OS_ERROR";
-
    while ( my ($k,$v) = each %cached_instances ) {
       print { $fh } "$k,$v\n";
    }
-
-   close $fh or die "Cannot close: $OS_ERROR";
+   close $fh or die "Cannot close $file: $OS_ERROR";
 
    return @instances_to_check ? \@instances_to_check : 0;
 }
@@ -281,7 +290,7 @@ sub _generate_identifier {
    my $sql  = q{SELECT MD5(CONCAT(@@hostname, @@port))};
    my ($id) = eval { $dbh->selectrow_array($sql) };
    if ( $EVAL_ERROR ) { # assume that it's MySQL 4.x
-      $id = md5_hex( $dsn->{h}, $dsn->{P} || 3306 );
+      $id = md5_hex( ($dsn->{h} || 'localhost'), ($dsn->{P} || 3306) );
    }
 
    return $id;
diff --git a/lib/VersionCheck.pm b/lib/VersionCheck.pm
index b3b380f2..16cd411d 100644
--- a/lib/VersionCheck.pm
+++ b/lib/VersionCheck.pm
@@ -91,11 +91,11 @@ sub get_versions {
    my %versions;
    foreach my $item ( values %$items ) {
       next unless $self->valid_item($item);
-      
+
       eval {
          my $func    = 'get_' . $item->{type};
          my $version = $self->$func(
-            item => $item,
+            item      => $item,
             instances => $instances,
          );
          if ( $version ) {
@@ -229,16 +229,6 @@ sub get_mysql_variable {
    );
 }
 
-# This isn't implemented yet.  It's easy to do (TYPE=mysql_status),
-# but it may be overkill.
-#sub get_mysql_status {
-#   my $self = shift;
-#   return $self->_get_from_mysql(
-#      show => 'STATUS',
-#      @_,
-#   );
-#}
-
 sub _get_from_mysql {
    my ($self, %args) = @_;
    my $show = $args{show};
diff --git a/t/lib/Pingback.t b/t/lib/Pingback.t
index 73078afc..582d539a 100644
--- a/t/lib/Pingback.t
+++ b/t/lib/Pingback.t
@@ -90,7 +90,7 @@ sub test_pingback {
 
    is(
       $post ? ($post->{content} || '') : '',
-      join("", map { "$general_id;$_\n" } split /\n/, $args{post}),
+      $args{post},
       "$args{name} client response"
    );
 
@@ -114,7 +114,7 @@ test_pingback(
       }
    ],
    # client should POST this
-   post => "Data::Dumper;$dd_ver\nPerl;$perl_ver\n",
+   post => "$general_id;Data::Dumper;$dd_ver\n$general_id;Perl;$perl_ver\n",
    # Server should return these suggetions after the client posts
    sug  => [
       'Data::Printer is nicer.',
@@ -136,7 +136,7 @@ test_pingback(
         content => "",
       }
    ],
-   post => "Data::Dumper;$dd_ver\nPerl;$perl_ver\n",
+   post => "$general_id;Data::Dumper;$dd_ver\n$general_id;Perl;$perl_ver\n",
    sug  => undef,
 );
 
@@ -161,7 +161,7 @@ test_pingback(
         content => "Perl;perl_version;PERL_VERSION\nData::Dumper;perl_module_version\n",
       },
    ],
-   post => "Data::Dumper;$dd_ver\nPerl;$perl_ver\n",
+   post => "$general_id;Data::Dumper;$dd_ver\n$general_id;Perl;$perl_ver\n",
    sug  => undef,
 );
 
@@ -190,7 +190,7 @@ SKIP: {
          }
       ],
       # client should POST this
-      post => "MySQL;$mysql_ver $mysql_distro\n",
+      post => "$general_id;MySQL;$mysql_ver $mysql_distro\n",
       # Server should return these suggetions after the client posts
       sug => ['Percona Server is fast.'],
    );
@@ -203,7 +203,7 @@ SKIP: {
 my $dir   = File::Spec->tmpdir();
 my $file  = File::Spec->catfile($dir, 'percona-toolkit-version-check-test');
 
-unlink $file;
+unlink $file if -f $file;
 
 ok(
    Pingback::time_to_check($file, []),
@@ -260,11 +260,12 @@ SKIP: {
       "_generate_identifier() works with a dbh"
    );
 
-   
+   # The time limit file already exists (see previous tests), but this is
+   # a new MySQL instance, so it should be time to check it.
    is_deeply(
       Pingback::time_to_check($file, [ $id ]),
       [ $id ],
-      "But even in an old file, it'll return true, and an arrayref, if we pass a new id",
+      "Time to check a new MySQL instance ID",
    );
 
    ok(
@@ -297,7 +298,8 @@ SKIP: {
    ) or diag(Dumper($check));
 }
 
-1 while unlink $file;
+unlink $file if -f $file;
+PerconaTest::wait_until( sub { !-f $file } );
 
 # #############################################################################
 # Done.