Module: IdentityCache::QueryAPI::ClassMethods

Defined in:
lib/identity_cache/query_api.rb

Instance Method Summary collapse

Instance Method Details

#add_cached_associations_to_coder(record, coder) ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 149

def add_cached_associations_to_coder(record, coder)
  if record.class.respond_to?(:all_embedded_associations) && record.class.all_embedded_associations.present?
    coder[:associations] = record.class.all_embedded_associations.each_with_object({}) do |(name, options), hash|
      hash[name] = IdentityCache.map_cached_nil_for(get_embedded_association(record, name, options))
    end
  end
  if record.class.respond_to?(:cached_has_manys) && record.class.cached_has_manys.present?
    coder[:normalized_has_many] = record.class.cached_has_manys.each_with_object({}) do |(name, options), hash|
      hash[name] = record.instance_variable_get(:"@#{options[:ids_variable_name]}") unless options[:embed]
    end
  end
end

#all_cached_associations ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 192

def all_cached_associations
  (cached_has_manys || {}).merge(cached_has_ones || {}).merge(cached_belongs_tos || {})
end

#all_cached_associations_needing_population ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 196

def all_cached_associations_needing_population
  all_cached_associations.select do |cached_association, options|
    options[:population_method_name].present? # non-embedded belongs_to associations don't need population
  end
end

#all_embedded_associations ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 186

def all_embedded_associations
  all_cached_associations.select do |cached_association, options|
    options[:embed].present?
  end
end

#cache_fetch_includes(additions = {}) ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 202

def cache_fetch_includes(additions = {})
  additions = hashify_includes_structure(additions)
  embedded_associations = all_cached_associations.select { |name, options| options[:embed] }

  associations_for_identity_cache = embedded_associations.map do |child_association, options|
    child_class = reflect_on_association(child_association).try(:klass)

    child_includes = additions.delete(child_association)

    if child_class.respond_to?(:cache_fetch_includes)
      child_includes = child_class.cache_fetch_includes(child_includes)
    end

    if child_includes.blank?
      child_association
    else
      { child_association => child_includes }
    end
  end

  associations_for_identity_cache.push(additions) if additions.keys.size > 0
  associations_for_identity_cache.compact
end

#coder_from_record(record) ⇒ Object

:nodoc:



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# File 'lib/identity_cache/query_api.rb', line 140

def coder_from_record(record) #:nodoc:
  unless record.nil?
    coder = {:class => record.class }
    record.encode_with(coder)
    add_cached_associations_to_coder(record, coder)
    coder
  end
end

#exists_with_identity_cache?(id) ⇒ Boolean

Similar to ActiveRecord::Base#exists? will return true if the id can be found in the cache or in the DB.

Returns:

  • (Boolean)

Raises:

  • (NotImplementedError) 


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# File 'lib/identity_cache/query_api.rb', line 23

def exists_with_identity_cache?(id)
  raise NotImplementedError, "exists_with_identity_cache? needs the primary index enabled" unless primary_cache_index_enabled
  !!fetch_by_id(id)
end

#fetch(id) ⇒ Object

Default fetcher added to the model on inclusion, it behaves like ActiveRecord::Base.find, will raise ActiveRecord::RecordNotFound exception if id is not in the cache or the db.



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# File 'lib/identity_cache/query_api.rb', line 51

def fetch(id)
  fetch_by_id(id) or raise(ActiveRecord::RecordNotFound, "Couldn't find #{self.name} with ID=#{id}")
end

#fetch_by_id(id) ⇒ Object

Default fetcher added to the model on inclusion, it behaves like ActiveRecord::Base.where(id: id).first

Raises:

  • (NotImplementedError) 


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# File 'lib/identity_cache/query_api.rb', line 30

def fetch_by_id(id)
  return unless id
  raise NotImplementedError, "fetching needs the primary index enabled" unless primary_cache_index_enabled
  if IdentityCache.should_cache?

    require_if_necessary do
      object = nil
      coder = IdentityCache.fetch(rails_cache_key(id)){ coder_from_record(object = resolve_cache_miss(id)) }
      object ||= record_from_coder(coder)
      IdentityCache.logger.error "[IDC id mismatch] fetch_by_id_requested=#{id} fetch_by_id_got=#{object.id} for #{object.inspect[(0..100)]} " if object && object.id != id.to_i
      object
    end

  else
    self.where(id: id).first
  end
end

#fetch_multi(*ids) ⇒ Object

Default fetcher added to the model on inclusion, if behaves like ActiveRecord::Base.find_all_by_id

Raises:

  • (NotImplementedError) 


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# File 'lib/identity_cache/query_api.rb', line 57

def fetch_multi(*ids)
  raise NotImplementedError, "fetching needs the primary index enabled" unless primary_cache_index_enabled
  options = ids.extract_options!
  if IdentityCache.should_cache?

    require_if_necessary do
      cache_keys = ids.map {|id| rails_cache_key(id) }
      key_to_id_map = Hash[ cache_keys.zip(ids) ]

      coders_by_key = IdentityCache.fetch_multi(*cache_keys) do |unresolved_keys|
        ids = unresolved_keys.map {|key| key_to_id_map[key] }
        records = find_batch(ids, options)
        records.compact.each(&:populate_association_caches)
        records.map {|record| coder_from_record(record) }
      end

      records = cache_keys.map {|key| record_from_coder(coders_by_key[key]) }.compact
      prefetch_associations(options[:includes], records) if options[:includes]

      records
    end

  else
    find_batch(ids, options)
  end
end

#find_batch(ids, options = {}) ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 226

def find_batch(ids, options = {})
  @id_column ||= columns.detect {|c| c.name == "id"}
  ids = ids.map{ |id| @id_column.type_cast(id) }
  records = where('id IN (?)', ids).includes(cache_fetch_includes(options[:includes])).to_a
  records_by_id = records.index_by(&:id)
  records = ids.map{ |id| records_by_id[id] }
  mismatching_ids = records.compact.map(&:id) - ids
  IdentityCache.logger.error "[IDC id mismatch] fetch_batch_requested=#{ids.inspect} fetch_batch_got=#{mismatchig_ids.inspect} mismatching ids "  unless mismatching_ids.empty?
  records
end

#get_embedded_association(record, association, options) ⇒ Object

:nodoc:



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# File 'lib/identity_cache/query_api.rb', line 129

def get_embedded_association(record, association, options) #:nodoc:
  embedded_variable = record.instance_variable_get(:"@#{options[:records_variable_name]}")
  if IdentityCache.unmap_cached_nil_for(embedded_variable).nil?
    nil
  elsif record.class.reflect_on_association(association).collection?
    embedded_variable.map {|e| coder_from_record(e) }
  else
    coder_from_record(embedded_variable)
  end
end

#hashify_includes_structure(structure) ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 304

def hashify_includes_structure(structure)
  case structure
  when nil
    {}
  when Symbol
    {structure => []}
  when Hash
    structure.clone
  when Array
    structure.each_with_object({}) do |member, hash|
      case member
      when Hash
        hash.merge!(member)
      when Symbol
        hash[member] = []
      end
    end
  end
end

#prefetch_associations(associations, records) ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 237

def prefetch_associations(associations, records)
  associations = hashify_includes_structure(associations)

  associations.each do |association, sub_associations|
    case
    when details = cached_has_manys[association]

      if details[:embed]
        child_records = records.map(&details[:cached_accessor_name].to_sym).flatten
      else
        ids_to_parent_record = records.each_with_object({}) do |record, hash|
          child_ids = record.send(details[:cached_ids_name])
          child_ids.each do |child_id|
            hash[child_id] = record
          end
        end

        parent_record_to_child_records = Hash.new { |h, k| h[k] = [] }
        child_records = details[:association_class].fetch_multi(*ids_to_parent_record.keys)
        child_records.each do |child_record|
          parent_record = ids_to_parent_record[child_record.id]
          parent_record_to_child_records[parent_record] << child_record
        end

        parent_record_to_child_records.each do |parent_record, child_records|
          parent_record.send(details[:prepopulate_method_name], child_records)
        end
      end

      next_level_records = child_records

    when details = cached_belongs_tos[association]
      if details[:embed]
        raise ArgumentError.new("Embedded belongs_to associations do not support prefetching yet.")
      else
        ids_to_child_record = records.each_with_object({}) do |child_record, hash|
          parent_id = child_record.send(details[:foreign_key])
          hash[parent_id] = child_record if parent_id.present?
        end
        parent_records = details[:association_class].fetch_multi(*ids_to_child_record.keys)
        parent_records.each do |parent_record|
          child_record = ids_to_child_record[parent_record.id]
          child_record.send(details[:prepopulate_method_name], parent_record)
        end
      end

      next_level_records = parent_records

    when details = cached_has_ones[association]
      if details[:embed]
        parent_records = records.map(&details[:cached_accessor_name].to_sym)
      else
        raise ArgumentError.new("Non-embedded has_one associations do not support prefetching yet.")
      end

      next_level_records = parent_records

    else
      raise ArgumentError.new("Unknown cached association #{association} listed for prefetching")
    end

    if details && details[:association_class].respond_to?(:prefetch_associations)
      details[:association_class].prefetch_associations(sub_associations, next_level_records)
    end
  end
end

#record_from_coder(coder) ⇒ Object

:nodoc:



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# File 'lib/identity_cache/query_api.rb', line 84

def record_from_coder(coder) #:nodoc:
  if coder.present? && coder.has_key?(:class)
    record = coder[:class].allocate
    unless coder[:class].serialized_attributes.empty?
      coder = coder.dup
      coder['attributes'] = coder['attributes'].dup
    end
    if record.class._initialize_callbacks.empty?
      record.instance_eval do
        @attributes = self.class.initialize_attributes(coder['attributes'])
        @relation = nil

        @attributes_cache, @previously_changed, @changed_attributes = {}, {}, {}
        @association_cache = {}
        @aggregation_cache = {}
        @_start_transaction_state = {}
        @readonly = @destroyed = @marked_for_destruction = false
        @new_record = false
        @column_types = self.class.column_types if self.class.respond_to?(:column_types)
      end
    else
      record.init_with(coder)
    end

    coder[:associations].each {|name, value| set_embedded_association(record, name, value) } if coder.has_key?(:associations)
    coder[:normalized_has_many].each {|name, ids| record.instance_variable_set(:"@#{record.class.cached_has_manys[name][:ids_variable_name]}", ids) } if coder.has_key?(:normalized_has_many)
    record
  end
end

#require_if_necessary ⇒ Object

:nodoc:



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# File 'lib/identity_cache/query_api.rb', line 162

def require_if_necessary #:nodoc:
  # mem_cache_store returns raw value if unmarshal fails
  rval = yield
  case rval
  when String
    rval = Marshal.load(rval)
  when Array
    rval.map!{ |v| v.kind_of?(String) ? Marshal.load(v) : v }
  end
  rval
rescue ArgumentError => e
  if e.message =~ /undefined [\w\/]+ (\w+)/
    ok = Kernel.const_get($1) rescue nil
    retry if ok
  end
  raise
end

#resolve_cache_miss(id) ⇒ Object 



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# File 'lib/identity_cache/query_api.rb', line 180

def resolve_cache_miss(id)
  object = self.includes(cache_fetch_includes).where(id: id).try(:first)
  object.try(:populate_association_caches)
  object
end

#set_embedded_association(record, association_name, coder_or_array) ⇒ Object

:nodoc:



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# File 'lib/identity_cache/query_api.rb', line 114

def set_embedded_association(record, association_name, coder_or_array) #:nodoc:
  value = if IdentityCache.unmap_cached_nil_for(coder_or_array).nil?
    nil
  elsif (reflection = record.class.reflect_on_association(association_name)).collection?
    association = reflection.association_class.new(record, reflection)
    association.target = coder_or_array.map {|e| record_from_coder(e) }
    association.target.each {|e| association.set_inverse_instance(e) }
    association
  else
    record_from_coder(coder_or_array)
  end
  variable_name = record.class.all_embedded_associations[association_name][:records_variable_name]
  record.instance_variable_set(:"@#{variable_name}", IdentityCache.map_cached_nil_for(value))
end