=head1 NAME
-DBIx::Class::Storage::DBI::Replicated::Pool; Manage a pool of replicants
+DBIx::Class::Storage::DBI::Replicated::Pool - Manage a pool of replicants
=head1 SYNOPSIS
This class is used internally by L<DBIx::Class::Storage::DBI::Replicated>. You
shouldn't need to create instances of this class.
-
+
=head1 DESCRIPTION
In a replicated storage type, there is at least one replicant to handle the
This class defines the following attributes.
-=head2 replicant_type
+=head2 maximum_lag ($num)
+
+This is a number which defines the maximum allowed lag returned by the
+L<DBIx::Class::Storage::DBI/lag_behind_master> method. The default is 0. In
+general, this should return a larger number when the replicant is lagging
+behind it's master, however the implementation of this is database specific, so
+don't count on this number having a fixed meaning. For example, MySQL will
+return a number of seconds that the replicating database is lagging.
+
+=cut
+
+has 'maximum_lag' => (
+ is=>'rw',
+ isa=>'Num',
+ required=>1,
+ lazy=>1,
+ default=>0,
+);
+
+=head2 last_validated
+
+This is an integer representing a time since the last time the replicants were
+validated. It's nothing fancy, just an integer provided via the perl time
+builtin.
+
+=cut
+
+has 'last_validated' => (
+ is=>'rw',
+ isa=>'Int',
+ reader=>'last_validated',
+ writer=>'_last_validated',
+ lazy=>1,
+ default=>0,
+);
+
+=head2 replicant_type ($classname)
Base class used to instantiate replicants that are in the pool. Unless you
need to subclass L<DBIx::Class::Storage::DBI::Replicated::Replicant> you should
=cut
has 'replicant_type' => (
- is=>'ro',
- isa=>'ClassName',
- required=>1,
- default=>'DBIx::Class::Storage::DBI',
- handles=>{
- 'create_replicant' => 'new',
- },
+ is=>'ro',
+ isa=>'ClassName',
+ required=>1,
+ default=>'DBIx::Class::Storage::DBI',
+ handles=>{
+ 'create_replicant' => 'new',
+ },
);
=head2 replicants
A hashref of replicant, with the key being the dsn and the value returning the
actual replicant storage. For example if the $dsn element is something like:
- "dbi:SQLite:dbname=dbfile"
-
+ "dbi:SQLite:dbname=dbfile"
+
You could access the specific replicant via:
- $schema->storage->replicants->{'dbname=dbfile'}
-
-This attributes also supports the following helper methods
+ $schema->storage->replicants->{'dbname=dbfile'}
+
+This attributes also supports the following helper methods:
=over 4
=cut
has 'replicants' => (
- is=>'rw',
- metaclass => 'Collection::Hash',
- isa=>'HashRef[DBIx::Class::Storage::DBI]',
- default=>sub {{}},
- provides => {
- 'set' => 'set_replicant',
- 'get' => 'get_replicant',
- 'empty' => 'has_replicants',
- 'count' => 'num_replicants',
- 'delete' => 'delete_replicant',
- },
+ is=>'rw',
+ metaclass => 'Collection::Hash',
+ isa=>'HashRef[DBIx::Class::Storage::DBI]',
+ default=>sub {{}},
+ provides => {
+ 'set' => 'set_replicant',
+ 'get' => 'get_replicant',
+ 'empty' => 'has_replicants',
+ 'count' => 'num_replicants',
+ 'delete' => 'delete_replicant',
+ },
);
=head1 METHODS
=cut
-use Data::Dump qw/dump/;
-
sub connect_replicants {
- my $self = shift @_;
- my $schema = shift @_;
-
- my @newly_created = ();
- foreach my $connect_info (@_) {
-
- my $replicant = $self->create_replicant($schema);
- $replicant->connect_info($connect_info);
- $replicant->ensure_connected;
-
- DBIx::Class::Storage::DBI::Replicated::Replicant->meta->apply($replicant);
-
- my ($key) = ($connect_info->[0]=~m/^dbi\:.+\:(.+)$/);
- $self->set_replicant( $key => $replicant);
- push @newly_created, $replicant;
- }
-
- return @newly_created;
+ my $self = shift @_;
+ my $schema = shift @_;
+
+ my @newly_created = ();
+ foreach my $connect_info (@_) {
+ my $replicant = $self->connect_replicant($schema, $connect_info);
+ my ($key) = ($connect_info->[0]=~m/^dbi\:.+\:(.+)$/);
+ $self->set_replicant( $key => $replicant);
+ push @newly_created, $replicant;
+ }
+
+ return @newly_created;
+}
+
+=head2 connect_replicant ($schema, $connect_info)
+
+Given a schema object and a hashref of $connect_info, connect the replicant
+and return it.
+
+=cut
+
+sub connect_replicant {
+ my ($self, $schema, $connect_info) = @_;
+ my $replicant = $self->create_replicant($schema);
+ $replicant->connect_info($connect_info);
+ $self->_safely_ensure_connected($replicant);
+ DBIx::Class::Storage::DBI::Replicated::Replicant->meta->apply($replicant);
+ return $replicant;
+}
+
+=head2 _safely_ensure_connected ($replicant)
+
+The standard ensure_connected method with throw an exception should it fail to
+connect. For the master database this is desirable, but since replicants are
+allowed to fail, this behavior is not desirable. This method wraps the call
+to ensure_connected in an eval in order to catch any generated errors. That
+way a slave to go completely offline (ie, the box itself can die) without
+bringing down your entire pool of databases.
+
+=cut
+
+sub _safely_ensure_connected {
+ my ($self, $replicant, @args) = @_;
+ my $return; eval {
+ $return = $replicant->ensure_connected(@args);
+ };
+ return $return;
}
=head2 connected_replicants
Returns true if there are connected replicants. Actually is overloaded to
return the number of replicants. So you can do stuff like:
- if( my $num_connected = $storage->has_connected_replicants ) {
- print "I have $num_connected connected replicants";
- } else {
- print "Sorry, no replicants.";
- }
+ if( my $num_connected = $storage->has_connected_replicants ) {
+ print "I have $num_connected connected replicants";
+ } else {
+ print "Sorry, no replicants.";
+ }
This method will actually test that each replicant in the L</replicants> hashref
is actually connected, try not to hit this 10 times a second.
=cut
sub connected_replicants {
- my $self = shift @_;
- return sum( map {
- $_->connected ? 1:0
- } $self->all_replicants );
+ my $self = shift @_;
+ return sum( map {
+ $_->connected ? 1:0
+ } $self->all_replicants );
}
=head2 active_replicants
=cut
sub active_replicants {
- my $self = shift @_;
- return ( grep {$_} map {
- $_->active ? $_:0
- } $self->all_replicants );
+ my $self = shift @_;
+ return ( grep {$_} map {
+ $_->active ? $_:0
+ } $self->all_replicants );
}
=head2 all_replicants
=cut
sub all_replicants {
- my $self = shift @_;
- return values %{$self->replicants};
+ my $self = shift @_;
+ return values %{$self->replicants};
+}
+
+=head2 validate_replicants
+
+This does a check to see if 1) each replicate is connected (or reconnectable),
+2) that is ->is_replicating, and 3) that it is not exceeding the lag amount
+defined by L</maximum_lag>. Replicants that fail any of these tests are set to
+inactive, and thus removed from the replication pool.
+
+This tests L<all_replicants>, since a replicant that has been previous marked
+as inactive can be reactived should it start to pass the validation tests again.
+
+See L<DBIx::Class::Storage::DBI> for more about checking if a replicating
+connection is not following a master or is lagging.
+
+Calling this method will generate queries on the replicant databases so it is
+not recommended that you run them very often.
+
+=cut
+
+sub validate_replicants {
+ my $self = shift @_;
+ foreach my $replicant($self->all_replicants) {
+ if(
+ $self->_safely_ensure_connected($replicant) &&
+ $replicant->is_replicating &&
+ $replicant->lag_behind_master <= $self->maximum_lag
+ ) {
+ $replicant->active(1)
+ } else {
+ $replicant->active(0);
+ }
+ }
+ ## Mark that we completed this validation.
+ $self->_last_validated(time);
}
=head1 AUTHOR
=cut
+__PACKAGE__->meta->make_immutable;
+
1;
projects / dbsrgits/DBIx-Class.git / blobdiff