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1 | package DBIx::Class::Storage::DBI::Replicated::Pool; |
2 | |
3 | use Moose; |
4 | use MooseX::AttributeHelpers; |
5 | use DBIx::Class::Storage::DBI::Replicated::Replicant; |
6 | use List::Util qw(sum); |
7 | |
8 | =head1 NAME |
9 | |
10 | DBIx::Class::Storage::DBI::Replicated::Pool; Manage a pool of replicants |
11 | |
12 | =head1 SYNOPSIS |
13 | |
14 | This class is used internally by L<DBIx::Class::Storage::DBI::Replicated>. You |
15 | shouldn't need to create instances of this class. |
16 | |
17 | =head1 DESCRIPTION |
18 | |
19 | In a replicated storage type, there is at least one replicant to handle the |
20 | read only traffic. The Pool class manages this replicant, or list of |
21 | replicants, and gives some methods for querying information about their status. |
22 | |
23 | =head1 ATTRIBUTES |
24 | |
25 | This class defines the following attributes. |
26 | |
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27 | =head2 maximum_lag ($num) |
28 | |
29 | This is a number which defines the maximum allowed lag returned by the |
30 | L<DBIx::Class::Storage::DBI/lag_behind_master> method. The default is 0. In |
31 | general, this should return a larger number when the replicant is lagging |
32 | behind it's master, however the implementation of this is database specific, so |
33 | don't count on this number having a fixed meaning. For example, MySQL will |
34 | return a number of seconds that the replicating database is lagging. |
35 | |
36 | =cut |
37 | |
38 | has 'maximum_lag' => ( |
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39 | is=>'rw', |
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40 | isa=>'Num', |
41 | required=>1, |
42 | lazy=>1, |
43 | default=>0, |
44 | ); |
45 | |
46 | =head2 replicant_type ($classname) |
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47 | |
48 | Base class used to instantiate replicants that are in the pool. Unless you |
49 | need to subclass L<DBIx::Class::Storage::DBI::Replicated::Replicant> you should |
50 | just leave this alone. |
51 | |
52 | =cut |
53 | |
54 | has 'replicant_type' => ( |
55 | is=>'ro', |
56 | isa=>'ClassName', |
57 | required=>1, |
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58 | default=>'DBIx::Class::Storage::DBI', |
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59 | handles=>{ |
60 | 'create_replicant' => 'new', |
61 | }, |
62 | ); |
63 | |
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64 | =head2 replicants |
65 | |
66 | A hashref of replicant, with the key being the dsn and the value returning the |
67 | actual replicant storage. For example if the $dsn element is something like: |
68 | |
69 | "dbi:SQLite:dbname=dbfile" |
70 | |
71 | You could access the specific replicant via: |
72 | |
73 | $schema->storage->replicants->{'dbname=dbfile'} |
74 | |
75 | This attributes also supports the following helper methods |
76 | |
77 | =over 4 |
78 | |
79 | =item set_replicant($key=>$storage) |
80 | |
81 | Pushes a replicant onto the HashRef under $key |
82 | |
83 | =item get_replicant($key) |
84 | |
85 | Retrieves the named replicant |
86 | |
87 | =item has_replicants |
88 | |
89 | Returns true if the Pool defines replicants. |
90 | |
91 | =item num_replicants |
92 | |
93 | The number of replicants in the pool |
94 | |
95 | =item delete_replicant ($key) |
96 | |
97 | removes the replicant under $key from the pool |
98 | |
99 | =back |
100 | |
101 | =cut |
102 | |
103 | has 'replicants' => ( |
104 | is=>'rw', |
105 | metaclass => 'Collection::Hash', |
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106 | isa=>'HashRef[DBIx::Class::Storage::DBI]', |
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107 | default=>sub {{}}, |
108 | provides => { |
109 | 'set' => 'set_replicant', |
110 | 'get' => 'get_replicant', |
111 | 'empty' => 'has_replicants', |
112 | 'count' => 'num_replicants', |
113 | 'delete' => 'delete_replicant', |
114 | }, |
115 | ); |
116 | |
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117 | =head1 METHODS |
118 | |
119 | This class defines the following methods. |
120 | |
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121 | =head2 connect_replicants ($schema, Array[$connect_info]) |
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122 | |
123 | Given an array of $dsn suitable for connected to a database, create an |
124 | L<DBIx::Class::Storage::DBI::Replicated::Replicant> object and store it in the |
125 | L</replicants> attribute. |
126 | |
127 | =cut |
128 | |
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129 | sub connect_replicants { |
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130 | my $self = shift @_; |
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131 | my $schema = shift @_; |
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132 | |
133 | my @newly_created = (); |
134 | foreach my $connect_info (@_) { |
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135 | |
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136 | my $replicant = $self->create_replicant($schema); |
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137 | $replicant->connect_info($connect_info); |
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138 | $replicant->ensure_connected; |
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139 | DBIx::Class::Storage::DBI::Replicated::Replicant->meta->apply($replicant); |
140 | |
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141 | my ($key) = ($connect_info->[0]=~m/^dbi\:.+\:(.+)$/); |
142 | $self->set_replicant( $key => $replicant); |
143 | push @newly_created, $replicant; |
144 | } |
145 | |
146 | return @newly_created; |
147 | } |
148 | |
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149 | =head2 connected_replicants |
150 | |
151 | Returns true if there are connected replicants. Actually is overloaded to |
152 | return the number of replicants. So you can do stuff like: |
153 | |
154 | if( my $num_connected = $storage->has_connected_replicants ) { |
155 | print "I have $num_connected connected replicants"; |
156 | } else { |
157 | print "Sorry, no replicants."; |
158 | } |
159 | |
160 | This method will actually test that each replicant in the L</replicants> hashref |
161 | is actually connected, try not to hit this 10 times a second. |
162 | |
163 | =cut |
164 | |
165 | sub connected_replicants { |
166 | my $self = shift @_; |
167 | return sum( map { |
168 | $_->connected ? 1:0 |
169 | } $self->all_replicants ); |
170 | } |
171 | |
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172 | =head2 active_replicants |
173 | |
174 | This is an array of replicants that are considered to be active in the pool. |
175 | This does not check to see if they are connected, but if they are not, DBIC |
176 | should automatically reconnect them for us when we hit them with a query. |
177 | |
178 | =cut |
179 | |
180 | sub active_replicants { |
181 | my $self = shift @_; |
182 | return ( grep {$_} map { |
183 | $_->active ? $_:0 |
184 | } $self->all_replicants ); |
185 | } |
186 | |
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187 | =head2 all_replicants |
188 | |
189 | Just a simple array of all the replicant storages. No particular order to the |
190 | array is given, nor should any meaning be derived. |
191 | |
192 | =cut |
193 | |
194 | sub all_replicants { |
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195 | my $self = shift @_; |
196 | return values %{$self->replicants}; |
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197 | } |
198 | |
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199 | =head2 validate_replicants |
200 | |
201 | This does a check to see if 1) each replicate is connected (or reconnectable), |
202 | 2) that is ->is_replicating, and 3) that it is not exceeding the lag amount |
203 | defined by L</maximum_lag>. Replicants that fail any of these tests are set to |
204 | inactive, and thus removed from the replication pool. |
205 | |
206 | This tests L<all_replicants>, since a replicant that has been previous marked |
207 | as inactive can be reactived should it start to pass the validation tests again. |
208 | |
209 | See L<DBIx::Class::Storage::DBI> for more about checking if a replicating |
210 | connection is not following a master or is lagging. |
211 | |
212 | Calling this method will generate queries on the replicant databases so it is |
213 | not recommended that you run them very often. |
214 | |
215 | =cut |
216 | |
217 | sub validate_replicants { |
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218 | my $self = shift @_; |
219 | foreach my $replicant($self->all_replicants) { |
220 | if( |
221 | $replicant->is_replicating && |
222 | $replicant->lag_behind_master <= $self->maximum_lag && |
223 | $replicant->ensure_connected |
224 | ) { |
225 | ## TODO:: Hook debug for this |
226 | $replicant->active(1) |
227 | } else { |
228 | ## TODO:: Hook debug for this |
229 | $replicant->active(0); |
230 | } |
231 | } |
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232 | } |
233 | |
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234 | =head1 AUTHOR |
235 | |
236 | John Napiorkowski <john.napiorkowski@takkle.com> |
237 | |
238 | =head1 LICENSE |
239 | |
240 | You may distribute this code under the same terms as Perl itself. |
241 | |
242 | =cut |
243 | |
cb6ec758 |
244 | 1; |