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Module: ActiveRecord::ConnectionAdapters::QueryCache

Relationships & Source Files
Namespace Children
Modules:
ConnectionPoolConfiguration
Defined in: activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb

Constant Summary

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Class Method Details

.dirties_query_cache(base, *method_names)

[ GitHub ] 

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 20



def dirties_query_cache(base, *method_names)
  method_names.each do |method_name|
    base.class_eval <<-end_code, __FILE__, __LINE__ + 1
      def #{method_name}(...)
        ActiveRecord::Base.clear_query_caches_for_current_thread
        super
      end
    end_code
  end
end


  








  

    .included(base)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 11



def included(base) # :nodoc:
  dirties_query_cache base, :exec_query, :execute, :create, :insert, :update, :delete, :truncate,
    :truncate_tables, :rollback_to_savepoint, :rollback_db_transaction, :restart_db_transaction,
    :exec_insert_all

  base.set_callback :checkout, :after, :configure_query_cache!
  base.set_callback :checkin, :after, :disable_query_cache!
end


  







Instance Attribute Details



  

    #query_cache   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 53



attr_reader :query_cache, :query_cache_enabled


  








  

    #query_cache_enabled   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 53



attr_reader :query_cache, :query_cache_enabled


  







Instance Method Details



  

    #cache  
  



  

    

Enable the query cache within the block.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 63



def cache
  old, @query_cache_enabled = @query_cache_enabled, true
  yield
ensure
  @query_cache_enabled = old
  clear_query_cache unless @query_cache_enabled
end


  








  

    #cache_notification_info(sql, name, binds)   (private)
  



  

    

Database adapters can override this method to provide custom cache information.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 171



def cache_notification_info(sql, name, binds)
  {
    sql: sql,
    binds: binds,
    type_casted_binds: -> { type_casted_binds(binds) },
    name: name,
    connection: self,
    cached: true
  }
end


  








  

    #cache_sql(sql, name, binds)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 142



def cache_sql(sql, name, binds)
  key = binds.empty? ? sql : [sql, binds]
  result = nil
  hit = false

  @lock.synchronize do
    if (result = @query_cache.delete(key))
      hit = true
      @query_cache[key] = result
    else
      result = @query_cache[key] = yield
      if @query_cache_max_size && @query_cache.size > @query_cache_max_size
        @query_cache.shift
      end
    end
  end

  if hit
    ActiveSupport::Notifications.instrument(
      "sql.active_record",
      cache_notification_info(sql, name, binds)
    )
  end

  result.dup
end


  








  

    #clear_query_cache  
  



  

    

Clears the query cache.



One reason you may wish to call this method explicitly is between queries that ask the database to randomize results. Otherwise the cache would see the same SQL query and repeatedly return the same result each time, silently undermining the randomness you were expecting.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 94



def clear_query_cache
  @lock.synchronize do
    @query_cache.clear
  end
end


  








  

    #configure_query_cache!   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 182



def configure_query_cache!
  case query_cache = pool.db_config.query_cache
  when 0, false
    return
  when Integer
    @query_cache_max_size = query_cache
  when nil
    @query_cache_max_size = DEFAULT_SIZE
  else
    @query_cache_max_size = nil # no limit
  end

  if pool.query_cache_enabled
    enable_query_cache!
  end
end


  








  

    #disable_query_cache!  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 75



def disable_query_cache!
  @query_cache_enabled = false
  clear_query_cache
end


  








  

    #enable_query_cache!  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 71



def enable_query_cache!
  @query_cache_enabled = true
end


  








  

    #initialize  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 55



def initialize(*)
  super
  @query_cache         = {}
  @query_cache_enabled = false
  @query_cache_max_size = nil
end


  








  

    #lookup_sql_cache(sql, name, binds)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 120



def lookup_sql_cache(sql, name, binds)
  key = binds.empty? ? sql : [sql, binds]
  hit = false
  result = nil

  @lock.synchronize do
    if (result = @query_cache.delete(key))
      hit = true
      @query_cache[key] = result
    end
  end

  if hit
    ActiveSupport::Notifications.instrument(
      "sql.active_record",
      cache_notification_info(sql, name, binds)
    )

    result
  end
end


  








  

    #select_all(arel, name = nil, binds = [], preparable: nil, async: false)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 100



def select_all(arel, name = nil, binds = [], preparable: nil, async: false) # :nodoc:
  arel = arel_from_relation(arel)

  # If arel is locked this is a SELECT ... FOR UPDATE or somesuch.
  # Such queries should not be cached.
  if @query_cache_enabled && !(arel.respond_to?(:locked) && arel.locked)
    sql, binds, preparable = to_sql_and_binds(arel, binds, preparable)

    if async
      result = lookup_sql_cache(sql, name, binds) || super(sql, name, binds, preparable: preparable, async: async)
      FutureResult.wrap(result)
    else
      cache_sql(sql, name, binds) { super(sql, name, binds, preparable: preparable, async: async) }
    end
  else
    super
  end
end


  








  

    #uncached  
  



  

    

Disable the query cache within the block.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 81



def uncached
  old, @query_cache_enabled = @query_cache_enabled, false
  yield
ensure
  @query_cache_enabled = old
end