Module: ActiveRecord::ConnectionAdapters::QueryCache

Included in:
AbstractAdapter
Defined in:
activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb

Defined Under Namespace

Modules: ConnectionPoolConfiguration

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#query_cacheObject (readonly)

Returns the value of attribute query_cache.


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 50

def query_cache
  @query_cache
end

#query_cache_enabledObject (readonly)

Returns the value of attribute query_cache_enabled.


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 50

def query_cache_enabled
  @query_cache_enabled
end

Class Method Details

.dirties_query_cache(base, *method_names) ⇒ Object


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 17

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) ⇒ Object

:nodoc:


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 9

def included(base) # :nodoc:
  dirties_query_cache base, :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 Method Details

#cacheObject

Enable the query cache within the block.


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 59

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

#clear_query_cacheObject

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.


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 90

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

#disable_query_cache!Object


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

def disable_query_cache!
  @query_cache_enabled = false
  clear_query_cache
end

#enable_query_cache!Object


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 67

def enable_query_cache!
  @query_cache_enabled = true
end

#initializeObject


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 52

def initialize(*)
  super
  @query_cache         = Hash.new { |h, sql| h[sql] = {} }
  @query_cache_enabled = false
end

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


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 96

def select_all(arel, name = nil, binds = [], preparable: nil, async: false)
  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
      lookup_sql_cache(sql, name, binds) || super(sql, name, binds, preparable: preparable, async: async)
    else
      cache_sql(sql, name, binds) { super(sql, name, binds, preparable: preparable, async: async) }
    end
  else
    super
  end
end

#uncachedObject

Disable the query cache within the block.


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# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 77

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