94 lines
2.7 KiB
Ruby
94 lines
2.7 KiB
Ruby
module ActiveRecord
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module ConnectionAdapters # :nodoc:
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module QueryCache
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class << self
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def included(base)
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base.class_eval do
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attr_accessor :query_cache_enabled
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alias_method_chain :columns, :query_cache
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alias_method_chain :select_all, :query_cache
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end
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dirties_query_cache base, :insert, :update, :delete
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end
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def dirties_query_cache(base, *method_names)
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method_names.each do |method_name|
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base.class_eval <<-end_code, __FILE__, __LINE__
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def #{method_name}_with_query_dirty(*args)
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clear_query_cache if @query_cache_enabled
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#{method_name}_without_query_dirty(*args)
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end
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alias_method_chain :#{method_name}, :query_dirty
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end_code
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end
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end
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end
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# Enable the query cache within the block.
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def cache
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old, @query_cache_enabled = @query_cache_enabled, true
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@query_cache ||= {}
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yield
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ensure
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clear_query_cache
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@query_cache_enabled = old
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end
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# Disable the query cache within the block.
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def uncached
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old, @query_cache_enabled = @query_cache_enabled, false
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yield
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ensure
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@query_cache_enabled = old
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end
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# Clears the query cache.
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#
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# One reason you may wish to call this method explicitly is between queries
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# that ask the database to randomize results. Otherwise the cache would see
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# the same SQL query and repeatedly return the same result each time, silently
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# undermining the randomness you were expecting.
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def clear_query_cache
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@query_cache.clear if @query_cache
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end
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def select_all_with_query_cache(*args)
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if @query_cache_enabled
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cache_sql(args.first) { select_all_without_query_cache(*args) }
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else
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select_all_without_query_cache(*args)
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end
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end
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def columns_with_query_cache(*args)
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if @query_cache_enabled
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@query_cache["SHOW FIELDS FROM #{args.first}"] ||= columns_without_query_cache(*args)
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else
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columns_without_query_cache(*args)
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end
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end
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private
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def cache_sql(sql)
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result =
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if @query_cache.has_key?(sql)
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log_info(sql, "CACHE", 0.0)
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@query_cache[sql]
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else
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@query_cache[sql] = yield
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end
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if Array === result
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result.collect { |row| row.dup }
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else
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result.duplicable? ? result.dup : result
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end
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rescue TypeError
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result
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end
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end
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end
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end
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