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2019-02-06 00:49:12 +03:00
commit 8dbb1bb605
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package DBI::Role;
use 5.006;
use strict;
use warnings;
BEGIN {
$DBI::Role::HAVE_HIRES = eval "use Time::HiRes (); 1;";
}
our $VERSION = '1.00';
# $self contains:
#
# DBINFO --- hashref. keys = scalar roles, one of which must be 'master'.
# values contain DSN info, and 'role' => { 'role' => weight, 'role2' => weight }
#
# DEFAULT_DB -- scalar string. default db name if none in DSN hashref in DBINFO
#
# DBREQCACHE -- cleared by clear_req_cache() on each request.
# fdsn -> dbh
#
# DBCACHE -- role -> fdsn, or
# fdsn -> dbh
#
# DBCACHE_UNTIL -- role -> unixtime
#
# DB_USED_AT -- fdsn -> unixtime
#
# DB_DEAD_UNTIL -- fdsn -> unixtime
#
# TIME_CHECK -- if true, time between localhost and db are checked every TIME_CHECK
# seconds
#
# TIME_REPORT -- coderef to pass dsn and dbtime to after a TIME_CHECK occurence
sub new
{
my ($class, $args) = @_;
my $self = {};
$self->{'DBINFO'} = $args->{'sources'};
$self->{'TIMEOUT'} = $args->{'timeout'};
$self->{'DEFAULT_DB'} = $args->{'default_db'};
$self->{'TIME_CHECK'} = $args->{'time_check'};
$self->{'TIME_LASTCHECK'} = {}; # dsn -> last check time
$self->{'TIME_REPORT'} = $args->{'time_report'};
bless $self, ref $class || $class;
return $self;
}
sub set_sources
{
my ($self, $newval) = @_;
$self->{'DBINFO'} = $newval;
$self;
}
sub clear_req_cache
{
my $self = shift;
$self->{'DBREQCACHE'} = {};
}
sub disconnect_all
{
my ($self, $opts) = @_;
my %except;
if ($opts && $opts->{except} &&
ref $opts->{except} eq 'ARRAY') {
$except{$_} = 1 foreach @{$opts->{except}};
}
foreach my $cache (qw(DBREQCACHE DBCACHE)) {
next unless ref $self->{$cache} eq "HASH";
foreach my $key (keys %{$self->{$cache}}) {
next if $except{$key};
my $v = $self->{$cache}->{$key};
next unless ref $v eq "DBI::db";
$v->disconnect;
delete $self->{$cache}->{$key};
}
}
$self->{'DBCACHE'} = {};
$self->{'DBREQCACHE'} = {};
}
sub same_cached_handle
{
my $self = shift;
my ($role_a, $role_b) = @_;
return
defined $self->{'DBCACHE'}->{$role_a} &&
defined $self->{'DBCACHE'}->{$role_b} &&
$self->{'DBCACHE'}->{$role_a} eq $self->{'DBCACHE'}->{$role_b};
}
sub flush_cache
{
my $self = shift;
foreach (keys %{$self->{'DBCACHE'}}) {
my $v = $self->{'DBCACHE'}->{$_};
next unless ref $v;
$v->disconnect;
}
$self->{'DBCACHE'} = {};
$self->{'DBREQCACHE'} = {};
}
# old interface. does nothing now.
sub trigger_weight_reload
{
my $self = shift;
return $self;
}
sub use_diff_db
{
my $self = shift;
my ($role1, $role2) = @_;
return 0 if $role1 eq $role2;
# this is implied: (makes logic below more readable by forcing it)
$self->{'DBINFO'}->{'master'}->{'role'}->{'master'} = 1;
foreach (keys %{$self->{'DBINFO'}}) {
next if /^_/;
next unless ref $self->{'DBINFO'}->{$_} eq "HASH";
if ($self->{'DBINFO'}->{$_}->{'role'}->{$role1} &&
$self->{'DBINFO'}->{$_}->{'role'}->{$role2}) {
return 0;
}
}
return 1;
}
sub get_dbh
{
my $self = shift;
my $opts = ref $_[0] eq "HASH" ? shift : {};
my @roles = @_;
my $role = shift @roles;
return undef unless $role;
my $now = time();
# if 'nocache' flag is passed, clear caches now so we won't return
# a cached database handle later
$self->clear_req_cache if $opts->{'nocache'};
# otherwise, see if we have a role -> full DSN mapping already
my ($fdsn, $dbh);
if ($role eq "master") {
$fdsn = make_dbh_fdsn($self, $self->{'DBINFO'}->{'master'});
} else {
if ($self->{'DBCACHE'}->{$role} && ! $opts->{'unshared'}) {
$fdsn = $self->{'DBCACHE'}->{$role};
if ($now > $self->{'DBCACHE_UNTIL'}->{$role}) {
# this role -> DSN mapping is too old. invalidate,
# and while we're at it, clean up any connections we have
# that are too idle.
undef $fdsn;
foreach (keys %{$self->{'DB_USED_AT'}}) {
next if $self->{'DB_USED_AT'}->{$_} > $now - 60;
delete $self->{'DB_USED_AT'}->{$_};
delete $self->{'DBCACHE'}->{$_};
}
}
}
}
if ($fdsn) {
$dbh = get_dbh_conn($self, $fdsn, $role);
return $dbh if $dbh;
delete $self->{'DBCACHE'}->{$role}; # guess it was bogus
}
return undef if $role eq "master"; # no hope now
# time to randomly weightedly select one.
my @applicable;
my $total_weight;
foreach (keys %{$self->{'DBINFO'}}) {
next if /^_/;
next unless ref $self->{'DBINFO'}->{$_} eq "HASH";
my $weight = $self->{'DBINFO'}->{$_}->{'role'}->{$role};
next unless $weight;
push @applicable, [ $self->{'DBINFO'}->{$_}, $weight ];
$total_weight += $weight;
}
while (@applicable) {
my $rand = rand($total_weight);
my ($i, $t) = (0, 0);
for (; $i<@applicable; $i++) {
$t += $applicable[$i]->[1];
last if $t > $rand;
}
my $fdsn = make_dbh_fdsn($self, $applicable[$i]->[0]);
$dbh = get_dbh_conn($self, $opts, $fdsn);
if ($dbh) {
$self->{'DBCACHE'}->{$role} = $fdsn;
$self->{'DBCACHE_UNTIL'}->{$role} = $now + 5 + int(rand(10));
return $dbh;
}
# otherwise, discard that one.
$total_weight -= $applicable[$i]->[1];
splice(@applicable, $i, 1);
}
# try others
return get_dbh($self, $opts, @roles);
}
sub make_dbh_fdsn
{
my $self = shift;
my $db = shift; # hashref with DSN info
return $db->{'_fdsn'} if $db->{'_fdsn'}; # already made?
my $fdsn = "DBI:mysql"; # join("|",$dsn,$user,$pass) (because no refs as hash keys)
$db->{'dbname'} ||= $self->{'DEFAULT_DB'} if $self->{'DEFAULT_DB'};
$fdsn .= ":$db->{'dbname'}";
$fdsn .= ";host=$db->{'host'}" if $db->{'host'};
$fdsn .= ";port=$db->{'port'}" if $db->{'port'};
$fdsn .= ";mysql_socket=$db->{'sock'}" if $db->{'sock'};
$fdsn .= "|$db->{'user'}|$db->{'pass'}";
$db->{'_fdsn'} = $fdsn;
return $fdsn;
}
sub get_dbh_conn
{
my $self = shift;
my $opts = ref $_[0] eq "HASH" ? shift : {};
my $fdsn = shift;
my $role = shift; # optional.
my $now = time();
my $retdb = sub {
my $db = shift;
$self->{'DBREQCACHE'}->{$fdsn} = $db;
$self->{'DB_USED_AT'}->{$fdsn} = $now;
return $db;
};
# have we already created or verified a handle this request for this DSN?
return $retdb->($self->{'DBREQCACHE'}->{$fdsn})
if $self->{'DBREQCACHE'}->{$fdsn} && ! $opts->{'unshared'};
# check to see if we recently tried to connect to that dead server
return undef if $self->{'DB_DEAD_UNTIL'}->{$fdsn} && $now < $self->{'DB_DEAD_UNTIL'}->{$fdsn};
# if not, we'll try to find one we used sometime in this process lifetime
my $dbh = $self->{'DBCACHE'}->{$fdsn};
# if it exists, verify it's still alive and return it. (but not
# if we're wanting an unshared connection)
if ($dbh && ! $opts->{'unshared'}) {
# return $retdb->($dbh) unless connection_bad($dbh, $opts);
undef $dbh;
undef $self->{'DBCACHE'}->{$fdsn};
}
# time to make one!
my ($dsn, $user, $pass) = split(/\|/, $fdsn);
my $timeout = $self->{'TIMEOUT'} || 2;
$dsn .= ";mysql_connect_timeout=$timeout";
my $loop = 1;
my $tries = $DBI::Role::HAVE_HIRES ? 8 : 2;
while ($loop) {
$loop = 0;
$dbh = DBI->connect($dsn, $user, $pass, {
PrintError => 1,
AutoCommit => 1,
});
# if max connections, try again shortly.
if (! $dbh && $DBI::err == 1040 && $tries) {
$tries--;
$loop = 1;
if ($DBI::Role::HAVE_HIRES) {
Time::HiRes::usleep(250_000);
} else {
sleep 1;
}
}
}
my $DBI_err = $DBI::err || 0;
# check replication/busy processes... see if we should not use
# this one
# undef $dbh if connection_bad($dbh, $opts);
# if this is an unshared connection, we don't want to put it
# in the cache for somebody else to use later. (which happens below)
return $dbh if $opts->{'unshared'};
# mark server as dead if dead. won't try to reconnect again for 5 seconds.
if ($dbh) {
$self->{'DB_USED_AT'}->{$fdsn} = $now;
if ($self->{'TIME_CHECK'} && ref $self->{'TIME_REPORT'} eq "CODE") {
my $now = time();
$self->{'TIME_LASTCHECK'}->{$dsn} ||= 0; # avoid warnings
if ($self->{'TIME_LASTCHECK'}->{$dsn} < $now - $self->{'TIME_CHECK'}) {
$self->{'TIME_LASTCHECK'}->{$dsn} = $now;
my $db_time = $dbh->selectrow_array("SELECT UNIX_TIMESTAMP()");
$self->{'TIME_REPORT'}->($dsn, $db_time, $now);
}
}
} else {
# mark the database as dead for a bit, unless it was just because of max connections
$self->{'DB_DEAD_UNTIL'}->{$fdsn} = $now + 5
unless $DBI_err == 1040;
}
return $self->{'DBREQCACHE'}->{$fdsn} = $self->{'DBCACHE'}->{$fdsn} = $dbh;
}
sub connection_bad {
my ($dbh, $opts) = @_;
return 1 unless $dbh;
my $ss = eval {
$dbh->selectrow_hashref("SHOW SLAVE STATUS");
};
# if there was an error, and it wasn't a permission problem (1227)
# then treat this connection as bogus
if ($dbh->err && $dbh->err != 1227) {
return 1;
}
# connection is good if $ss is undef (not a slave)
return 0 unless $ss;
# otherwise, it's okay if not MySQL 4
return 0 if ! $ss->{'Master_Log_File'} || ! $ss->{'Relay_Master_Log_File'};
# all good if within 100 k
if ($opts->{'max_repl_lag'}) {
return 0 if
$ss->{'Master_Log_File'} eq $ss->{'Relay_Master_Log_File'} &&
($ss->{'Read_Master_Log_Pos'} - $ss->{'Exec_master_log_pos'}) < $opts->{'max_repl_lag'};
# guess we're behind
return 1;
} else {
# default to assuming it's good
return 0;
}
}
1;
__END__
=head1 NAME
DBI::Role - Get DBI cached handles by role, with weighting & failover.
=head1 SYNOPSIS
use DBI::Role;
my $DBIRole = new DBI::Role {
'sources' => \%DBINFO,
'default_db' => "somedbname", # opt.
};
my $dbh = $DBIRole->get_dbh("master");
=head1 DESCRIPTION
To be written.
=head2 EXPORT
None by default.
=head1 AUTHOR
Brad Fitzparick, E<lt>brad@danga.comE<gt>
=head1 SEE ALSO
L<DBI>.

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# Package that handles redirects of the form:
# http://[sitename]/users/name1/[digits].html[anything else] =>
# http://[sitename]/users/name2/[digits].html[anything else]
# if digits < maxid
# Maxid is a prescribed number, name 1 and name 2 are prescribd usernames.
# The same works for http://[sitename]/~name1/...
# name 2 must be an existing users
#
# How it works:
# all processing of *.html passes through Apache::Livejournal::trans
# A hook has been added to that function that calls
# LJ:Rewriteuser::uri_check, then uri_rew
# The list of known redirects is kept in a table "rewriteusers" in
# the livejournal database; this package also provides functions
# to work with this table in a safe way.
#
# Additionally, the part in LJ::alloc_user_counter which gives id to
# new entries has been modified in the following way: instead of
# taking max of all the existing entries, it now checks whether we
# have a redirect in the table, and if "yes", takes max of all
# existing entries and maxid from redirect table
#
# Table structure:
#+----------+------------------+------+-----+---------+-------+
#| Field | Type | Null | Key | Default | Extra |
#+----------+------------------+------+-----+---------+-------+
#| fromuser | char(15) | | PRI | | |
#| touser | char(15) | | | | |
#| maxid | int(10) unsigned | | | 0 | |
#+----------+------------------+------+-----+---------+-------+
package LJ::Rewriteuser;
use strict;
use Carp;
use lib "$ENV{'LJHOME'}/cgi-bin";
use DBI;
use DBI::Role;
use DBIx::StateKeeper;
#use LJ;
my %REWRITE=();
# Check whether uri needs to be rewritten
sub uri_check {
my ($uri)=@_;
# Scan the redirect table to see whether username matches
foreach my $rwuser (keys %REWRITE){
if ($uri =~ m|users/$rwuser/(\d+)|i) {if($1 < $REWRITE{$rwuser}{'maxnum'}){ return 1;}}
if ($uri =~ m|~$rwuser/(\d+).html|i) {if($1 < $REWRITE{$rwuser}{'maxnum'}){ return 1;}}
if ($uri =~ m|community/$rwuser/(\d+).html|i) {if($1 < $REWRITE{$rwuser}{'maxnum'}){ return 1;}}
}
return 0;
}
# Rewrite uri (if it's needed -- if not, return the intact original)
sub uri_rew {
my ($uri)=@_;
if(uri_check($uri)){
foreach my $rwuser (keys %REWRITE){
foreach my $type ("~","users/","community/"){
my $to=$type.$rwuser;
my $from=$type.$REWRITE{$rwuser}{'newname'};
$uri =~ s|$to|$from|i;
}
}
}
return $uri;
}
# Check the database for redirects, and if yes, return maxid (to
# give it to LJ:alloc_user_counter). If not, return 0.
sub get_min_jid {
my ($journalid)= @_;
my $user=LJ::get_username($journalid);
foreach my $rwuser (keys %REWRITE){
if ($rwuser eq $user){
return ($REWRITE{$rwuser}{'maxnum'} / 256)+1;
}
}
return 0;
}
# Check whether there is a redirect from name1, if yes, return
# name2, if not, return 0
sub get_rewrite {
my ($fromuser)= @_;
if($REWRITE{$fromuser}) {return $REWRITE{$fromuser}{'newname'};}
else {return 0;}
}
# The function to init the redirect table in the database during
# httpd restart
sub init {
my $dbh = LJ::get_db_writer();
my $sth = $dbh->prepare("SELECT fromuser, touser, maxid FROM rewriteusers");
$sth->execute;
while (my ($from, $to, $maxid) = $sth->fetchrow_array) {
$REWRITE{$from}{'newname'}=$to;
$REWRITE{$from}{'maxnum'}=$maxid;
}
}
# Remove a redirect from the table
sub delete_rewrite_hash{
my ($fromuser) = @_;
delete($REWRITE{$fromuser});
my $dbh = LJ::get_db_writer();
$dbh->do("DELETE FROM rewriteusers WHERE fromuser = ?", undef, $fromuser);
}
# Add a redirect to the table
sub insert_rewrite_hash{
my ($from, $to, $maxid) =@_;
$REWRITE{$from}{'newname'}=$to;
$REWRITE{$from}{'maxnum'}=$maxid;
my $dbh = LJ::get_db_writer();
$dbh->do("INSERT INTO rewriteusers VALUES (?, ?, ?)", undef, $from, $to, $maxid);
}
init();
1;