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

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

Instance Method Summary collapse

Instance Method Details

#associated_records_by_owner(preloader = nil) ⇒ Object 



106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
 
# File 'lib/switchman/active_record/association.rb', line 106

def associated_records_by_owner(preloader = nil)
  return @associated_records_by_owner if defined?(@associated_records_by_owner)
  owners_map = owners_by_key

  if klass.nil? || owners_map.empty?
    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 = ->(owner) do
        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 }
    else
      # for multishard associations, it's the owner object itself
      # (all associated shards)

      # this is the default behavior of partition_by_shard, so just let it be nil
      # to avoid the proc call
      # partition_proc = ->(owner) { owner }
    end

    records = Shard.partition_by_shard(owners, partition_proc) do |partitioned_owners|
      # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
      # Make several smaller queries if necessary or make one query if the adapter supports it
      sliced_owners = partitioned_owners.each_slice(model.connection.in_clause_length || partitioned_owners.size)
      sliced_owners.map do |slice|
        relative_owner_keys = slice.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(owner.class.shard_category))
          end
          key && key.to_s
        end
        relative_owner_keys.compact!
        relative_owner_keys.uniq!
        records_for(relative_owner_keys)
      end
    end
    records.flatten!
  end

  # This ivar may look unused, but remember this is an extension of
  # rails' AR::Associations::Preloader::Association class. It gets used
  # by that class (and its subclasses).
  @preloaded_records = records

  # Each record may have multiple owners, and vice-versa
  @associated_records_by_owner = owners.each_with_object({}) do |owner,h|
    h[owner] = []
  end
  records.each do |record|
    owner_key = record[association_key_name]
    owner_key = Shard.global_id_for(owner_key, record.shard) if owner_key && record.class.sharded_column?(association_key_name)

    owners_map[owner_key.to_s].each do |owner|
      owner.association(reflection.name).set_inverse_instance(record)
      @associated_records_by_owner[owner] << record
    end
  end
  @associated_records_by_owner
end

#owners_by_key ⇒ Object 



176
177
178
179
180
181
182
 
# File 'lib/switchman/active_record/association.rb', line 176

def owners_by_key
  @owners_by_key ||= owners.group_by do |owner|
    key = owner[owner_key_name]
    key = Shard.global_id_for(key, owner.shard) if key && owner.class.sharded_column?(owner_key_name)
    key && key.to_s
  end
end

#records_by_owner ⇒ Object 



101
102
103
 
# File 'lib/switchman/active_record/association.rb', line 101

def records_by_owner
  associated_records_by_owner
end

#records_for(ids) ⇒ Object

Copypasta from Activerecord but with added global_id_for goodness.



88
89
90
91
92
93
94
95
96
97
98
99
 
# File 'lib/switchman/active_record/association.rb', line 88

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

#run(preloader) ⇒ Object 



79
80
81
82
83
 
# File 'lib/switchman/active_record/association.rb', line 79

def run(preloader)
  associated_records_by_owner.each do |owner, records|
    associate_records_to_owner(owner, records)
  end
end

#scope ⇒ Object 



184
185
186
 
# File 'lib/switchman/active_record/association.rb', line 184

def scope
  build_scope
end