Module: Switchman::ActiveRecord::Associations::Preloader::Association

Defined in:
lib/switchman/active_record/associations.rb

Defined Under Namespace

Modules: LoaderRecords

Instance Method Summary collapse

Instance Method Details

#load_records(raw_records = nil) ⇒ Object

significant changes:

* partition_by_shard the records_for call
* re-globalize the fetched owner id before looking up in the map

TODO: the ignored param currently loads records; we should probably not waste effort double-loading them Change introduced here: github.com/rails/rails/commit/c6c0b2e8af64509b699b782aadfecaa430700ece



201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
 
# File 'lib/switchman/active_record/associations.rb', line 201

def load_records(raw_records = nil)
  # owners can be duplicated when a relation has a collection association join
  # #compare_by_identity makes such owners different hash keys
  @records_by_owner = {}.compare_by_identity

  if ::Rails.version >= "7.0"
    raw_records ||= loader_query.records_for([self])
  elsif owner_keys.empty?
    raw_records ||= []
  else
    # determine the shard to search for each owner
    if reflection.macro == :belongs_to
      # for belongs_to, it's the shard of the foreign_key
      partition_proc = lambda do |owner|
        if owner.class.sharded_column?(owner_key_name)
          Shard.shard_for(owner[owner_key_name], owner.shard)
        else
          Shard.current
        end
      end
    elsif !reflection.options[:multishard]
      # for non-multishard associations, it's *just* the owner's shard
      partition_proc = ->(owner) { owner.shard }
    end

    raw_records ||= Shard.partition_by_shard(owners, partition_proc) do |partitioned_owners|
      relative_owner_keys = partitioned_owners.map do |owner|
        key = owner[owner_key_name]
        if key && owner.class.sharded_column?(owner_key_name)
          key = Shard.relative_id_for(key,
                                      owner.shard,
                                      Shard.current(klass.connection_class_for_self))
        end
        convert_key(key)
      end
      relative_owner_keys.compact!
      relative_owner_keys.uniq!
      records_for(relative_owner_keys)
    end
  end

  @preloaded_records = raw_records.select do |record|
    assignments = false

    owner_key = record[association_key_name]
    if owner_key && record.class.sharded_column?(association_key_name)
      owner_key = Shard.global_id_for(owner_key,
                                      record.shard)
    end

    owners_by_key[convert_key(owner_key)]&.each do |owner|
      entries = (@records_by_owner[owner] ||= [])

      if reflection.collection? || entries.empty?
        entries << record
        assignments = true
      end
    end

    assignments
  end
end

#owners_by_key ⇒ Object

significant change: globalize keys on sharded columns



265
266
267
268
269
270
271
272
 
# File 'lib/switchman/active_record/associations.rb', line 265

def owners_by_key
  @owners_by_key ||= owners.each_with_object({}) do |owner, result|
    key = owner[owner_key_name]
    key = Shard.global_id_for(key, owner.shard) if key && owner.class.sharded_column?(owner_key_name)
    key = convert_key(key)
    (result[key] ||= []) << owner if key
  end
end

#records_for(ids) ⇒ Object

Copypasta from Activerecord but with added global_id_for goodness.



163
164
165
166
167
168
169
170
171
172
173
174
 
# File 'lib/switchman/active_record/associations.rb', line 163

def records_for(ids)
  scope.where(association_key_name => ids).load do |record|
    global_key = if model.connection_class_for_self == UnshardedRecord
                   convert_key(record[association_key_name])
                 else
                   Shard.global_id_for(record[association_key_name], record.shard)
                 end
    owner = owners_by_key[convert_key(global_key)].first
    association = owner.association(reflection.name)
    association.set_inverse_instance(record)
  end
end

#scope ⇒ Object

significant change: don’t cache scope (since it could be for different shards)



275
276
277
 
# File 'lib/switchman/active_record/associations.rb', line 275

def scope
  build_scope
end

#set_inverse(record) ⇒ Object

Disabling to keep closer to rails original rubocop:disable Naming/AccessorMethodName, Style/GuardClause significant changes:

* globalize the key to lookup



180
181
182
183
184
185
186
187
188
189
190
191
192
193
 
# File 'lib/switchman/active_record/associations.rb', line 180

def set_inverse(record)
  global_key = if model.connection_class_for_self == UnshardedRecord
                 convert_key(record[association_key_name])
               else
                 Shard.global_id_for(record[association_key_name], record.shard)
               end

  if (owners = owners_by_key[convert_key(global_key)])
    # Processing only the first owner
    # because the record is modified but not an owner
    association = owners.first.association(reflection.name)
    association.set_inverse_instance(record)
  end
end