module ActiveRecord::ConnectionAdapters::QueryCache
Attributes
query_cache[R]
query_cache_enabled[R]
Public Class Methods
dirties_query_cache(base, *method_names)
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# File 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
new(*)
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Calls superclass method
# File 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
Public Instance Methods
cache() { || ... }
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Enable the query cache within the block.
# File 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()
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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.
# File 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!()
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# File 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!()
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 67 def enable_query_cache! @query_cache_enabled = true end
select_all(arel, name = nil, binds = [], preparable: nil)
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Calls superclass method
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 96 def select_all(arel, name = nil, binds = [], preparable: nil) if @query_cache_enabled && !locked?(arel) arel = arel_from_relation(arel) sql, binds, preparable = to_sql_and_binds(arel, binds, preparable) cache_sql(sql, name, binds) { super(sql, name, binds, preparable: preparable) } else super end end
uncached() { || ... }
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Disable the query cache within the block.
# File 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
Private Instance Methods
cache_notification_info(sql, name, binds)
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Database adapters can override this method to provide custom cache information.
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 126 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) { || ... }
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 108 def cache_sql(sql, name, binds) @lock.synchronize do result = if @query_cache[sql].key?(binds) ActiveSupport::Notifications.instrument( "sql.active_record", cache_notification_info(sql, name, binds) ) @query_cache[sql][binds] else @query_cache[sql][binds] = yield end result.dup end end
configure_query_cache!()
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 144 def configure_query_cache! enable_query_cache! if pool.query_cache_enabled end
locked?(arel)
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If arel is locked this is a SELECT … FOR UPDATE or somesuch. Such queries should not be cached.
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 139 def locked?(arel) arel = arel.arel if arel.is_a?(Relation) arel.respond_to?(:locked) && arel.locked end