Module: ActiveRecord::ConnectionAdapters::QueryCache

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#query_cache ⇒ Object (readonly)

Returns the value of attribute query_cache.



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 21

def query_cache
  @query_cache
end

#query_cache_enabled ⇒ Object (readonly)

Returns the value of attribute query_cache_enabled.



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 21

def query_cache_enabled
  @query_cache_enabled
end

Class Method Details

.dirties_query_cache(base, *method_names) ⇒ Object 



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

def dirties_query_cache(base, *method_names)
  method_names.each do |method_name|
    base.class_eval <<-end_code, __FILE__, __LINE__ + 1
      def #{method_name}(*)
        clear_query_cache if @query_cache_enabled
        super
      end
    end_code
  end
end

.included(base) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 5

def included(base) #:nodoc:
  dirties_query_cache base, :insert, :update, :delete, :rollback_to_savepoint, :rollback_db_transaction
end

Instance Method Details

#cache ⇒ Object

Enable the query cache within the block.



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 30

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_cache ⇒ Object

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 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 60

def clear_query_cache
  @query_cache.clear
end

#disable_query_cache! ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 42

def disable_query_cache!
  @query_cache_enabled = false
end

#enable_query_cache! ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 38

def enable_query_cache!
  @query_cache_enabled = true
end

#initialize ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 23

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

#select_all(arel, name = nil, binds = []) ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 64

def select_all(arel, name = nil, binds = [])
  if @query_cache_enabled && !locked?(arel)
    arel, binds = binds_from_relation arel, binds
    sql = to_sql(arel, binds)
    cache_sql(sql, binds) { super(sql, name, binds) }
  else
    super
  end
end

#uncached ⇒ Object

Disable the query cache within the block.



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# File 'lib/active_record/connection_adapters/abstract/query_cache.rb', line 47

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