changed the balancer to a role, created a new class to define the default balancer...

[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Storage / DBI / Replicated / Pool.pm

diff --git a/lib/DBIx/Class/Storage/DBI/Replicated/Pool.pm b/lib/DBIx/Class/Storage/DBI/Replicated/Pool.pm
index 5bf61e6..123cc47 100644 (file)
--- a/lib/DBIx/Class/Storage/DBI/Replicated/Pool.pm
+++ b/lib/DBIx/Class/Storage/DBI/Replicated/Pool.pm
@@ -24,7 +24,45 @@ replicants, and gives some methods for querying information about their status.
 
 This class defines the following attributes.
 
-=head2 replicant_type
+=head2 maximum_lag ($num)
+
+This is a number which defines the maximum allowed lag returned by the
+L<DBIx::Class::Storage::DBI/lag_behind_master> method.  The default is 0.  In
+general, this should return a larger number when the replicant is lagging
+behind it's master, however the implementation of this is database specific, so
+don't count on this number having a fixed meaning.  For example, MySQL will
+return a number of seconds that the replicating database is lagging.
+
+=cut
+
+has 'maximum_lag' => (
+    is=>'rw',
+    isa=>'Num',
+    required=>1,
+    lazy=>1,
+    default=>0,
+);
+
+=head2 last_validated
+
+This is an integer representing a time since the last time the replicants were
+validated. It's nothing fancy, just an integer provided via the perl time 
+builtin.
+
+=cut
+
+has 'last_validated' => (
+    is=>'rw',
+    isa=>'Int',
+    reader=>'last_validated',
+    writer=>'_last_validated',
+    lazy=>1,
+    default=>sub {
+        time;
+    },
+);
+
+=head2 replicant_type ($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
@@ -107,8 +145,6 @@ L</replicants> attribute.
 
 =cut
 
-use Data::Dump qw/dump/; 
-
 sub connect_replicants {
        my $self = shift @_;
        my $schema = shift @_;
@@ -119,7 +155,6 @@ sub connect_replicants {
                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\:.+\:(.+)$/);
@@ -176,8 +211,46 @@ array is given, nor should any meaning be derived.
 =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(
+            $replicant->is_replicating &&
+            $replicant->lag_behind_master <= $self->maximum_lag &&
+            $replicant->ensure_connected
+        ) {
+               ## TODO:: Hook debug for this
+            $replicant->active(1)
+        } else {
+               ## TODO:: Hook debug for this
+            $replicant->active(0);
+        }
+    }
+    
+    ## Mark that we completed this validation.
+    $self->_last_validated(time);
 }
 
 =head1 AUTHOR