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module ActiveRecord
class QueryCache #:nodoc:
def initialize(connection)
@connection = connection
@query_cache = {}
end
def clear_query_cache
@query_cache.clear
end
def select_all(sql, name = nil)
cache(sql) { @connection.select_all(sql, name) }
end
def select_one(sql, name = nil)
cache(sql) { @connection.select_one(sql, name) }
end
def select_values(sql, name = nil)
cache(sql) { @connection.select_values(sql, name) }
end
def select_value(sql, name = nil)
cache(sql) { @connection.select_value(sql, name) }
end
def execute(sql, name = nil)
clear_query_cache
@connection.execute(sql, name)
end
def columns(table_name, name = nil)
@query_cache["SHOW FIELDS FROM #{table_name}"] ||= @connection.columns(table_name, name)
end
def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
clear_query_cache
@connection.insert(sql, name, pk, id_value, sequence_name)
end
def update(sql, name = nil)
clear_query_cache
@connection.update(sql, name)
end
def delete(sql, name = nil)
clear_query_cache
@connection.delete(sql, name)
end
private
def cache(sql)
result = if @query_cache.has_key?(sql)
log_info(sql, "CACHE", 0.0)
@query_cache[sql]
else
@query_cache[sql] = yield
end
if result
# perform a deep #dup in case result is an array
result = result.collect { |row| row.dup } if result.is_a?(Array)
result.dup
else
nil
end
end
def method_missing(method, *arguments, &proc)
@connection.send(method, *arguments, &proc)
end
end
class Base
# Set the connection for the class with caching on
class << self
alias_method :connection_without_query_cache, :connection
def query_caches
Thread.current["query_cache_#{connection_without_query_cache.object_id}"] ||= {}
end
def query_cache
if query_caches[self]
query_caches[self]
elsif superclass.respond_to?(:query_cache) and superclass.respond_to?(:connection) and superclass.connection_without_query_cache == connection_without_query_cache
superclass.query_cache
end
end
def query_cache=(cache)
query_caches[self] = cache
end
# Use a query cache within the given block.
def cache
# Don't cache if Active Record is not configured.
if ActiveRecord::Base.configurations.blank?
yield
else
begin
self.query_cache = QueryCache.new(connection_without_query_cache)
yield
ensure
self.query_cache = nil
end
end
end
def connection
query_cache || connection_without_query_cache
end
end
end
end
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