Some cleanups to the m2m warnings test
[dbsrgits/DBIx-Class.git] / lib / DBIx / Class / Storage / DBI / Replicated / Pool.pm
CommitLineData
26ab719a 1package DBIx::Class::Storage::DBI::Replicated::Pool;
2
3use Moose;
4use MooseX::AttributeHelpers;
5use DBIx::Class::Storage::DBI::Replicated::Replicant;
6use List::Util qw(sum);
7
8=head1 NAME
9
21fc4719 10DBIx::Class::Storage::DBI::Replicated::Pool - Manage a pool of replicants
26ab719a 11
12=head1 SYNOPSIS
13
14This class is used internally by L<DBIx::Class::Storage::DBI::Replicated>. You
15shouldn't need to create instances of this class.
64cdad22 16
26ab719a 17=head1 DESCRIPTION
18
19In a replicated storage type, there is at least one replicant to handle the
20read only traffic. The Pool class manages this replicant, or list of
21replicants, and gives some methods for querying information about their status.
22
23=head1 ATTRIBUTES
24
25This class defines the following attributes.
26
4a607d7a 27=head2 maximum_lag ($num)
28
29This is a number which defines the maximum allowed lag returned by the
30L<DBIx::Class::Storage::DBI/lag_behind_master> method. The default is 0. In
31general, this should return a larger number when the replicant is lagging
32behind it's master, however the implementation of this is database specific, so
33don't count on this number having a fixed meaning. For example, MySQL will
34return a number of seconds that the replicating database is lagging.
35
36=cut
37
38has 'maximum_lag' => (
64cdad22 39 is=>'rw',
40 isa=>'Num',
41 required=>1,
42 lazy=>1,
43 default=>0,
4a607d7a 44);
45
17b05c13 46=head2 last_validated
47
48This is an integer representing a time since the last time the replicants were
49validated. It's nothing fancy, just an integer provided via the perl time
50builtin.
51
52=cut
53
54has 'last_validated' => (
64cdad22 55 is=>'rw',
56 isa=>'Int',
57 reader=>'last_validated',
58 writer=>'_last_validated',
59 lazy=>1,
60 default=>0,
17b05c13 61);
62
4a607d7a 63=head2 replicant_type ($classname)
26ab719a 64
65Base class used to instantiate replicants that are in the pool. Unless you
66need to subclass L<DBIx::Class::Storage::DBI::Replicated::Replicant> you should
67just leave this alone.
68
69=cut
70
71has 'replicant_type' => (
64cdad22 72 is=>'ro',
73 isa=>'ClassName',
74 required=>1,
75 default=>'DBIx::Class::Storage::DBI',
76 handles=>{
77 'create_replicant' => 'new',
78 },
26ab719a 79);
80
26ab719a 81=head2 replicants
82
83A hashref of replicant, with the key being the dsn and the value returning the
84actual replicant storage. For example if the $dsn element is something like:
85
64cdad22 86 "dbi:SQLite:dbname=dbfile"
87
26ab719a 88You could access the specific replicant via:
89
64cdad22 90 $schema->storage->replicants->{'dbname=dbfile'}
91
92This attributes also supports the following helper methods:
26ab719a 93
94=over 4
95
96=item set_replicant($key=>$storage)
97
98Pushes a replicant onto the HashRef under $key
99
100=item get_replicant($key)
101
102Retrieves the named replicant
103
104=item has_replicants
105
106Returns true if the Pool defines replicants.
107
108=item num_replicants
109
110The number of replicants in the pool
111
112=item delete_replicant ($key)
113
114removes the replicant under $key from the pool
115
116=back
117
118=cut
119
120has 'replicants' => (
64cdad22 121 is=>'rw',
122 metaclass => 'Collection::Hash',
123 isa=>'HashRef[DBIx::Class::Storage::DBI]',
124 default=>sub {{}},
125 provides => {
126 'set' => 'set_replicant',
127 'get' => 'get_replicant',
128 'empty' => 'has_replicants',
129 'count' => 'num_replicants',
130 'delete' => 'delete_replicant',
131 },
26ab719a 132);
133
26ab719a 134=head1 METHODS
135
136This class defines the following methods.
137
955a6df6 138=head2 connect_replicants ($schema, Array[$connect_info])
26ab719a 139
140Given an array of $dsn suitable for connected to a database, create an
141L<DBIx::Class::Storage::DBI::Replicated::Replicant> object and store it in the
142L</replicants> attribute.
143
144=cut
145
955a6df6 146sub connect_replicants {
64cdad22 147 my $self = shift @_;
148 my $schema = shift @_;
149
150 my @newly_created = ();
151 foreach my $connect_info (@_) {
bbafcf26 152 my $replicant = $self->connect_replicant($schema, $connect_info);
64cdad22 153 my ($key) = ($connect_info->[0]=~m/^dbi\:.+\:(.+)$/);
154 $self->set_replicant( $key => $replicant);
155 push @newly_created, $replicant;
156 }
157
158 return @newly_created;
26ab719a 159}
160
bbafcf26 161=head2 connect_replicant ($schema, $connect_info)
162
163Given a schema object and a hashref of $connect_info, connect the replicant
164and return it.
165
166=cut
167
168sub connect_replicant {
169 my ($self, $schema, $connect_info) = @_;
170 my $replicant = $self->create_replicant($schema);
f15afa13 171 $replicant->connect_info($connect_info);
172 $self->_safely_ensure_connected($replicant);
173 DBIx::Class::Storage::DBI::Replicated::Replicant->meta->apply($replicant);
bbafcf26 174 return $replicant;
175}
176
f15afa13 177=head2 _safely_ensure_connected ($replicant)
178
179The standard ensure_connected method with throw an exception should it fail to
180connect. For the master database this is desirable, but since replicants are
181allowed to fail, this behavior is not desirable. This method wraps the call
182to ensure_connected in an eval in order to catch any generated errors. That
183way a slave to go completely offline (ie, the box itself can die) without
184bringing down your entire pool of databases.
185
186=cut
187
188sub _safely_ensure_connected {
189 my ($self, $replicant, @args) = @_;
190 my $return; eval {
191 $return = $replicant->ensure_connected(@args);
192 };
193 return $return;
194}
195
26ab719a 196=head2 connected_replicants
197
198Returns true if there are connected replicants. Actually is overloaded to
199return the number of replicants. So you can do stuff like:
200
64cdad22 201 if( my $num_connected = $storage->has_connected_replicants ) {
202 print "I have $num_connected connected replicants";
203 } else {
204 print "Sorry, no replicants.";
205 }
26ab719a 206
207This method will actually test that each replicant in the L</replicants> hashref
208is actually connected, try not to hit this 10 times a second.
209
210=cut
211
212sub connected_replicants {
64cdad22 213 my $self = shift @_;
214 return sum( map {
215 $_->connected ? 1:0
216 } $self->all_replicants );
26ab719a 217}
218
50336325 219=head2 active_replicants
220
221This is an array of replicants that are considered to be active in the pool.
222This does not check to see if they are connected, but if they are not, DBIC
223should automatically reconnect them for us when we hit them with a query.
224
225=cut
226
227sub active_replicants {
64cdad22 228 my $self = shift @_;
229 return ( grep {$_} map {
230 $_->active ? $_:0
231 } $self->all_replicants );
50336325 232}
233
26ab719a 234=head2 all_replicants
235
236Just a simple array of all the replicant storages. No particular order to the
237array is given, nor should any meaning be derived.
238
239=cut
240
241sub all_replicants {
64cdad22 242 my $self = shift @_;
243 return values %{$self->replicants};
26ab719a 244}
245
4a607d7a 246=head2 validate_replicants
247
248This does a check to see if 1) each replicate is connected (or reconnectable),
2492) that is ->is_replicating, and 3) that it is not exceeding the lag amount
250defined by L</maximum_lag>. Replicants that fail any of these tests are set to
251inactive, and thus removed from the replication pool.
252
253This tests L<all_replicants>, since a replicant that has been previous marked
254as inactive can be reactived should it start to pass the validation tests again.
255
256See L<DBIx::Class::Storage::DBI> for more about checking if a replicating
257connection is not following a master or is lagging.
258
259Calling this method will generate queries on the replicant databases so it is
260not recommended that you run them very often.
261
262=cut
263
264sub validate_replicants {
64cdad22 265 my $self = shift @_;
266 foreach my $replicant($self->all_replicants) {
267 if(
f15afa13 268 $self->_safely_ensure_connected($replicant) &&
64cdad22 269 $replicant->is_replicating &&
f15afa13 270 $replicant->lag_behind_master <= $self->maximum_lag
64cdad22 271 ) {
64cdad22 272 $replicant->active(1)
273 } else {
64cdad22 274 $replicant->active(0);
7edf5f1c 275 }
64cdad22 276 }
277 ## Mark that we completed this validation.
278 $self->_last_validated(time);
4a607d7a 279}
280
26ab719a 281=head1 AUTHOR
282
283John Napiorkowski <john.napiorkowski@takkle.com>
284
285=head1 LICENSE
286
287You may distribute this code under the same terms as Perl itself.
288
289=cut
290
c354902c 291__PACKAGE__->meta->make_immutable;
292
cb6ec758 2931;