Class: Praxis::Mapper::IdentityMap

Inherits:
Object
  • Object
show all
Defined in:
lib/praxis-mapper/identity_map.rb,
lib/praxis-mapper/support/factory_girl.rb

Defined Under Namespace

Classes: UnknownIdentity, UnloadedRecordException, UnsupportedModel

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(scope = {}) ⇒ IdentityMap

TODO: support multiple connections



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# File 'lib/praxis-mapper/identity_map.rb', line 68

def initialize(scope={})
  @connection_manager = ConnectionManager.new
  @scope = scope
  clear!
end

Class Attribute Details

.config ⇒ Object

Returns the value of attribute config.



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# File 'lib/praxis-mapper/identity_map.rb', line 16

def config
  @config
end

Instance Attribute Details

#blueprint_cache ⇒ Object (readonly)

Returns the value of attribute blueprint_cache.



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# File 'lib/praxis-mapper/identity_map.rb', line 12

def blueprint_cache
  @blueprint_cache
end

#queries ⇒ Object (readonly)

Returns the value of attribute queries.



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# File 'lib/praxis-mapper/identity_map.rb', line 12

def queries
  @queries
end

#scope ⇒ Object

Returns the value of attribute scope.



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# File 'lib/praxis-mapper/identity_map.rb', line 13

def scope
  @scope
end

#unloaded ⇒ Object (readonly)

Returns the value of attribute unloaded.



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# File 'lib/praxis-mapper/identity_map.rb', line 12

def unloaded
  @unloaded
end

Class Method Details

.current ⇒ IdentityMap

Returns current identity map from thread-local variable.

Returns:

  • (IdentityMap) —

    current identity map from thread-local variable



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# File 'lib/praxis-mapper/identity_map.rb', line 28

def self.current
  map = Thread.current[:_praxis_mapper_identity_map]
  raise "current IdentityMap not set" unless map
  map
end

.current=(identity_map) ⇒ Object

Stores given identity map in a thread-local variable

Parameters:



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# File 'lib/praxis-mapper/identity_map.rb', line 22

def self.current=(identity_map)
  Thread.current[:_praxis_mapper_identity_map] = identity_map
end

.current? ⇒ Boolean

Returns whether identity map thread-local variable has been set.

Returns:

  • (Boolean) —

    whether identity map thread-local variable has been set



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# File 'lib/praxis-mapper/identity_map.rb', line 36

def self.current?
  Thread.current.key?(:_praxis_mapper_identity_map) && Thread.current[:_praxis_mapper_identity_map].kind_of?(Praxis::Mapper::IdentityMap)
end

.setup!(scope = {}) ⇒ Object

TODO: how come scope can be set from 3 different methods?

Examples:

=> [:account_id, 71], :user => [:user_id, 2]

Parameters:

  • scope (Hash) (defaults to: {}) —

    a set of named filters to apply in query



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# File 'lib/praxis-mapper/identity_map.rb', line 54

def self.setup!(scope={})
  if self.current?
    if !self.current.clear?
      raise "Denied for a pre-existing condition: Identity map has been used."
    else
      self.current.scope = scope
      return self.current
    end
  else
    self.current = self.new(scope)
  end
end

Instance Method Details

#<<(record) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 390

def <<(record)
  model = record.class

  @rows[model] << record
  record.identity_map = self

  model.identities.each do |identity|
    key = record.send(identity)

    get_staged(model, identity).delete(key)
    @row_keys[model][identity][key] = record
  end
end

#add_record(record) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 509

def add_record(record)
  model = record.class
  record.identities.each do |identity, key|
    # FIXME: Should we be overwriting (possibly) a "nil" value from before?
    #        (due to that row not being found by a previous query)
    #        (That'd be odd since that means we tried to load that same identity)

    return false if @row_keys[model][identity].has_key? key

    get_staged(model, identity).delete(key)
    @row_keys[model][identity][key] = record
  end

  record.identity_map = self
  @rows[model] << record
  record
end

#add_records(records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 462

def add_records(records)
  return if records.empty?

  records_added = Array.new

  to_stage = Hash.new do |hash,staged_model|
    hash[staged_model] = Hash.new do |identities, identity_name|
      identities[identity_name] = Set.new
    end
  end

  model = records.first.class

  tracked_associations = if (query = records.first._query)
    query.tracked_associations.each do |tracked_association|
      associated_model = tracked_association[:model]
      to_stage[associated_model][:_queries] << query
    end
  else
    []
  end

  tracked_associations.each do |tracked_association|
    associated_model = tracked_association[:model]
    association_type = tracked_association[:type]

    association_key, row_keys = stage_for!(tracked_association, records)
    row_keys.each do |row_key|
      to_stage[associated_model][association_key].add(row_key)
    end

  end

  records.each do |record|
    if add_record(record)
      records_added << record
    end
  end

  to_stage.each do |model_to_stage, data|
    stage(model_to_stage, data)
  end

  records_added
end

#all(model, conditions = {}) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 325

def all(model,conditions={})
  return rows_for(model) if conditions.empty?

  key, values = conditions.first

  # optimize the common case of a single value
  if values.size == 1
    value = values[0]
    if @row_keys[model].has_key?(key)
      res = row_by_key(model, key, value)
      if res
        [row_by_key(model, key, value)]
      else
        []
      end
    else
      index(model, key, value)
    end
  else
    if @row_keys[model].has_key?(key)
      values.collect do |value|
        row_by_key(model, key, value)
      end
    else
      values.each_with_object(Array.new) do |value, results|
        results.push *index(model, key, value)
      end
    end
  end
end

#clear! ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 74

def clear!
  @rows = Hash.new { |h,k| h[k] = Array.new }

  # for ex:
  #   @staged[Instance][:id] = Set.new
  # yields:
  #  {Instance => {:id => Set.new(1,2,3), :name => Set.new("George Jr.") } }
  @staged = Hash.new do |hash,model|
    hash[model] = Hash.new do |identity_hash, identity_name|
      identity_hash[identity_name] = Set.new
    end
  end

  # for ex:
  #   @row_keys["instances"][:id][1] = Object.new
  # yields:
  #   {"instances"=>{:id=>{1=>Object.new}}
  @row_keys = Hash.new do |row_hash,model|
    row_hash[model] = Hash.new do |primary_keys, key_name|
      primary_keys[key_name] = Hash.new
    end
  end

  @queries = Hash.new { |h,k| h[k] = Set.new }

  # see how it feels to store blueprints here
  # for ex:
  #   @blueprints[User][some_object] = User.new(some_object)
  @blueprint_cache = Hash.new do |cache,blueprint_class|
    cache[blueprint_class] = Hash.new
  end

  # TODO: rework this so it's a hash with default values and simplify #index
  @secondary_indexes =  Hash.new
end

#clear? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/praxis-mapper/identity_map.rb', line 41

def clear?
  @rows.empty? &&
    @staged.empty? &&
    @row_keys.empty? &&
    @queries.empty?
end

#connection(name) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 385

def connection(name)
  @connection_manager.checkout(name)
end

#extract_keys(field, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 405

def extract_keys(field, records)
  row_keys = []
  if field.kind_of?(Array) # composite identities
    records.each do |record|
      row_key = field.collect { |col| record.send(col) }
      row_keys << row_key unless row_key.include?(nil)
    end
  else
    row_keys.push *records.collect(&field).compact
  end
  row_keys
end

#finalize!(*models) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 178

def finalize!(*models)
  if models.empty?
    models = @staged.keys
  end

  did_something = models.any? do |model|
    finalize_model!(model).any?
  end

  finalize! if did_something
end

#finalize_model!(model, query = nil) ⇒ Object

don’t doc. never ever use yourself! FIXME: make private and fix specs that break?



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# File 'lib/praxis-mapper/identity_map.rb', line 193

def finalize_model!(model, query=nil)
  staged_queries = @staged[model].delete(:_queries) || []
  staged_keys = @staged[model].keys
  identities = staged_keys && model.identities
  non_identities = staged_keys - model.identities

  results = Set.new

  return results if @staged[model].all? { |(key,values)| values.empty? }

  if query.nil?
    query_class = @connection_manager.repository(model.repository_name)[:query]
    query = query_class.new(self,model)
  end

  # Apply any relevant blocks passed to track in the original queries
  staged_queries.each do |staged_query|
    staged_query.track.each do |(association_name, block)|
      next unless block

      spec = staged_query.model.associations[association_name]

      if spec[:model] == model
        query.instance_eval(&block)
        if (spec[:type] == :many_to_one || spec[:type] == :array_to_many) && query.where
          file, line = block.source_location
          trace = ["#{file}:#{line}"] | caller
          raise RuntimeError, "Error finalizing model #{model.name} for association #{association_name.inspect} -- using a where clause when tracking associations of type #{spec[:type].inspect} is not supported", trace
        end
      end
    end
  end


  # process non-unique staged keys
  #   select identity (any one should do) for those keys and stage blindly
  #   load and add records.

  if non_identities.any?
    to_stage = Hash.new do |hash,identity|
      hash[identity] = Set.new
    end

    non_identities.each do |key|
      values = @staged[model].delete(key)

      rows = query.multi_get(key, values, select: model.identities)
      rows.each do |row|
        model.identities.each do |identity|
          if identity.kind_of? Array
            to_stage[identity] << row.values_at(*identity)
          else
            to_stage[identity] << row[identity]
          end
        end
      end
    end

    self.stage(model, to_stage)
  end

  model.identities.each do |identity_name|
    values = self.get_staged(model,identity_name)
    next if values.empty?

    query.where = nil # clear out any where clause from non-identity
    records = query.multi_get(identity_name, values).collect do |row|
      m = model.new(row)
      m._query = query
      m
    end

    add_records(records)

    # TODO: refactor this to better-hide queries?
    self.queries[model].add(query)

    results.merge(records)

    # add nil records for records that were not found by the multi_get
    missing_keys = self.get_staged(model,identity_name)
    missing_keys.each do |missing_key|
      @row_keys[model][identity_name][missing_key] = nil
      get_staged(model, identity_name).delete(missing_key)
    end

  end

  query.freeze

  # TODO: check whether really really did get all the records we should have....
  results.to_a
end

#get(model, condition) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 357

def get(model,condition)
  key, value = condition.first

  row_by_key(model, key, value)
end

#get_staged(model, key) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 364

def get_staged(model, key)
  @staged[model][key]
end

#index(model, key, value) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 301

def index(model, key, value)
  @secondary_indexes[model] ||= Hash.new

  unless @secondary_indexes[model].has_key? key
    @secondary_indexes[model][key] ||= Hash.new
    reindex!(model, key)
  end

  @secondary_indexes[model][key][value] ||= Array.new
end

#load(model, &block) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 110

def load(model, &block)
  raise "Can't load unfinalized model #{model}" unless model.finalized?

  query_class = @connection_manager.repository(model.repository_name)[:query]
  query = query_class.new(self, model, &block)

  return finalize_model!(model, query) if query.where == :staged

  records = query.execute
  add_records(records)

  # TODO: refactor this to better-hide queries?
  query.freeze
  self.queries[model].add(query)

  subload(model, query,records)

  records
end

#persist! ⇒ Object 



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# File 'lib/praxis-mapper/support/factory_girl.rb', line 85

def persist!
  @rows.each_with_object(Hash.new) do |(model, records), inserted|
    next unless (table = model.table_name)

    db ||= self.connection(model.repository_name)

    new_records = records.select(&:new_record)
    next if new_records.empty?
    
    db[table.to_sym].multi_insert new_records.collect(&:_data)

    new_records.each { |rec| rec.new_record = false }
    inserted[model] = new_records        
  end
end

#query_statistics ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 527

def query_statistics
  QueryStatistics.new(queries)
end

#reindex!(model, key) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 313

def reindex!(model, key)
  rows_for(model).each do |row|
    val = if key.kind_of? Array
      key.collect { |k| row.send(k) }
    else
      row.send(key)
    end
    index(model, key, val) << row
  end
end

#row_by_key(model, key, value) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 288

def row_by_key(model,key, value)
  @row_keys[model][key].fetch(value) do
    raise UnloadedRecordException, "Did not load #{model} with #{key} = #{value.inspect}."
  end

end

#rows_for(model) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 296

def rows_for(model)
  @rows[model]
end

#stage(model, data) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 369

def stage(model, data)
  data.each do |key, values|
    unless values.kind_of? Enumerable
      values = [values]
    end

    # ignore rows we have already loaded... add sanity checking?
    if model.identities.include?(key)
      values.reject! { |k| @row_keys[model][key].has_key? k }
    end

    get_staged(model,key).merge(values)
  end
end

#stage_array_to_many(tracked_association, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 439

def stage_array_to_many(tracked_association, records)
  key = tracked_association[:key]
  primary_key = tracked_association[:primary_key] || :id

  row_keys = []
  records.collect(&key).each do |keys|
    row_keys.push *keys
  end

  row_keys.reject! do |row_key|
    row_key.nil? || (row_key.kind_of?(Array) && row_key.include?(nil))
  end

  [primary_key, row_keys]
end

#stage_for!(spec, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 130

def stage_for!(spec, records)
  case spec[:type]
  when :many_to_one
    stage_many_to_one(spec, records)
  when :array_to_many
    stage_array_to_many(spec, records)
  when :one_to_many
    stage_one_to_many(spec, records)
  when :many_to_array
    stage_many_to_array(spec, records)
  end
end

#stage_many_to_array(tracked_association, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 457

def stage_many_to_array(tracked_association, records)
  raise "not supported yet"
end

#stage_many_to_one(tracked_association, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 419

def stage_many_to_one(tracked_association, records)
  key = tracked_association[:key]
  primary_key = tracked_association[:primary_key] || :id

  row_keys = extract_keys(key, records)

  [primary_key, row_keys]
end

#stage_one_to_many(tracked_association, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 429

def stage_one_to_many(tracked_association, records)
  key = tracked_association[:key]
  primary_key = tracked_association[:primary_key] || :id

  row_keys = extract_keys(primary_key, records)

  [key, row_keys]
end

#subload(model, query, records) ⇒ Object 



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# File 'lib/praxis-mapper/identity_map.rb', line 143

def subload(model, query, records)
  query.load.each do |(association_name, block)|
    spec = model.associations.fetch(association_name)

    associated_model = spec[:model]

    key, values = stage_for!(spec, records)

    existing_records = []
    values.reject! do |value|
      if @row_keys[associated_model].has_key?(key) &&
          @row_keys[associated_model][key].has_key?(value)
        existing_records << @row_keys[associated_model][key][value]
      else
        false
      end
    end

    new_query_class = @connection_manager.repository(associated_model.repository_name)[:query]
    new_query = new_query_class.new(self,associated_model, &block)

    new_records = new_query.multi_get(key, values).collect do |row|
      m = spec[:model].new(row)
      m._query = new_query
      m
    end

    self.queries[associated_model].add(new_query)

    add_records(new_records)

    subload(associated_model, new_query, new_records + existing_records)
  end
end