83 lines
3.1 KiB
Ruby
83 lines
3.1 KiB
Ruby
require 'active_support/core_ext/class/attribute'
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module ActiveRecord
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module Explain
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def self.extended(base)
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# If a query takes longer than these many seconds we log its query plan
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# automatically. nil disables this feature.
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base.config_attribute :auto_explain_threshold_in_seconds, :global => true
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end
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# If auto explain is enabled, this method triggers EXPLAIN logging for the
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# queries triggered by the block if it takes more than the threshold as a
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# whole. That is, the threshold is not checked against each individual
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# query, but against the duration of the entire block. This approach is
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# convenient for relations.
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#
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# The available_queries_for_explain thread variable collects the queries
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# to be explained. If the value is nil, it means queries are not being
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# currently collected. A false value indicates collecting is turned
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# off. Otherwise it is an array of queries.
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def logging_query_plan # :nodoc:
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return yield unless logger
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threshold = auto_explain_threshold_in_seconds
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current = Thread.current
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if threshold && current[:available_queries_for_explain].nil?
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begin
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queries = current[:available_queries_for_explain] = []
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start = Time.now
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result = yield
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logger.warn(exec_explain(queries)) if Time.now - start > threshold
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result
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ensure
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current[:available_queries_for_explain] = nil
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end
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else
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yield
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end
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end
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# Relation#explain needs to be able to collect the queries regardless of
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# whether auto explain is enabled. This method serves that purpose.
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def collecting_queries_for_explain # :nodoc:
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current = Thread.current
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original, current[:available_queries_for_explain] = current[:available_queries_for_explain], []
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return yield, current[:available_queries_for_explain]
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ensure
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# Note that the return value above does not depend on this assigment.
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current[:available_queries_for_explain] = original
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end
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# Makes the adapter execute EXPLAIN for the tuples of queries and bindings.
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# Returns a formatted string ready to be logged.
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def exec_explain(queries) # :nodoc:
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queries && queries.map do |sql, bind|
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[].tap do |msg|
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msg << "EXPLAIN for: #{sql}"
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unless bind.empty?
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bind_msg = bind.map {|col, val| [col.name, val]}.inspect
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msg.last << " #{bind_msg}"
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end
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msg << connection.explain(sql, bind)
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end.join("\n")
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end.join("\n")
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end
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# Silences automatic EXPLAIN logging for the duration of the block.
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#
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# This has high priority, no EXPLAINs will be run even if downwards
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# the threshold is set to 0.
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#
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# As the name of the method suggests this only applies to automatic
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# EXPLAINs, manual calls to +ActiveRecord::Relation#explain+ run.
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def silence_auto_explain
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current = Thread.current
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original, current[:available_queries_for_explain] = current[:available_queries_for_explain], false
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yield
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ensure
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current[:available_queries_for_explain] = original
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end
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end
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end
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