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_cache ⇒ Object (readonly)

Returns the value of attribute query_cache.


50
51
52
 
# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 50

def query_cache
  @query_cache
end

#query_cache_enabled ⇒ Object (readonly)

Returns the value of attribute query_cache_enabled.


50
51
52
 
# 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 


17
18
19
20
21
22
23
24
25
26
 
# 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:


9
10
11
12
13
14
15
 
# 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

#cache ⇒ Object

Enable the query cache within the block.


59
60
61
62
63
64
65
 
# 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_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.


90
91
92
93
94
 
# 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 


71
72
73
74
 
# 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 


67
68
69
 
# File 'activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb', line 67

def enable_query_cache!
  @query_cache_enabled = true
end

#initialize ⇒ Object 


52
53
54
55
56
 
# 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 


96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
 
# 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

#uncached ⇒ Object

Disable the query cache within the block.


77
78
79
80
81
82
 
# 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