1DBIx::Class::Storage::DUBsIe:r:RCeoDpnBltIirxci:ab:tuCetldea:ds:sBP:ae:lrSaltnocDreoarcg(ue3m:)e:nDtBaIt:i:oRneplicated::Balancer(3)
2
6 DBIx::Class::Storage::DBI::Replicated::Balancer - A Software Load
7 Balancer
8
10 This role is used internally by DBIx::Class::Storage::DBI::Replicated.
11
13 Given a pool (DBIx::Class::Storage::DBI::Replicated::Pool) of
14 replicated database's
15 (DBIx::Class::Storage::DBI::Replicated::Replicant), defines a method by
16 which query load can be spread out across each replicant in the pool.
17
19 This class defines the following attributes.
20 auto_validate_every ($seconds)
22 If auto_validate has some sort of value, run the validate_replicants
23 every $seconds. Be careful with this, because if you set it to 0 you
24 will end up validating every query.
25 master
27 The DBIx::Class::Storage::DBI object that is the master database all
28 the replicants are trying to follow. The balancer needs to know it
29 since it's the ultimate fallback.
30 pool
32 The DBIx::Class::Storage::DBI::Replicated::Pool object that we are
33 trying to balance.
34 current_replicant
36 Replicant storages (slaves) handle all read only traffic. The
37 assumption is that your database will become readbound well before it
38 becomes write bound and that being able to spread your read only
39 traffic around to multiple databases is going to help you to scale
40 traffic.
41 This attribute returns the next slave to handle a read request. Your
43 "pool" attribute has methods to help you shuffle through all the
44 available replicants via its balancer object.
45
47 This class defines the following methods.
48 _build_current_replicant
50 Lazy builder for the "current_replicant_storage" attribute.
51 next_storage
53 This method should be defined in the class which consumes this role.
54 Given a pool object, return the next replicant that will serve queries.
56 The default behavior is to grab the first replicant it finds but you
57 can write your own subclasses of
58 DBIx::Class::Storage::DBI::Replicated::Balancer to support other
59 balance systems.
60 This returns from the pool of active replicants. If there are no
62 active replicants, then you should have it return the master as an
63 ultimate fallback.
64 around: next_storage
66 Advice on next storage to add the autovalidation. We have this broken
67 out so that it's easier to break out the auto validation into a role.
68 This also returns the master in the case that none of the replicants
70 are active or just just forgot to create them :)
71 increment_storage
73 Rolls the Storage to whatever is next in the queue, as defined by the
74 Balancer.
75 around: select
77 Advice on the select attribute. Each time we use a replicant we need
78 to change it via the storage pool algorithm. That way we are spreading
79 the load evenly (hopefully) across existing capacity.
80 around: select_single
82 Advice on the select_single attribute. Each time we use a replicant we
83 need to change it via the storage pool algorithm. That way we are
84 spreading the load evenly (hopefully) across existing capacity.
85 before: columns_info_for
87 Advice on the current_replicant_storage attribute. Each time we use a
88 replicant we need to change it via the storage pool algorithm. That
89 way we are spreading the load evenly (hopefully) across existing
90 capacity.
91 _get_forced_pool ($name)
93 Given an identifier, find the most correct storage object to handle the
94 query.
95
97 John Napiorkowski <jjnapiork@cpan.org>
98
100 You may distribute this code under the same terms as Perl itself.
101perl v5.12.0 DBIx::2C0l1a0s-s0:5:-S1t2orage::DBI::Replicated::Balancer(3)