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let EXPLAIN use a thread locals registry [John J. Wang & Xavier Noria]

Closes #10198.
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1 parent 0513f6c commit ef7a48df7584b038c6e3e0f1dbca5749310ef9f6 @fxn fxn committed Apr 16, 2013
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15 activerecord/lib/active_record/explain.rb
@@ -1,22 +1,22 @@
require 'active_support/lazy_load_hooks'
+require 'active_record/explain_registry'
module ActiveRecord
module Explain
- # Relation#explain needs to be able to collect the queries.
+ # Executes the block with the collect flag enabled. Queries are collected
+ # asynchronously by the subscriber and returned.
def collecting_queries_for_explain # :nodoc:
- current = Thread.current
- original, current[:available_queries_for_explain] = current[:available_queries_for_explain], []
+ ExplainRegistry.collect = true
yield
- return current[:available_queries_for_explain]
+ ExplainRegistry.queries
ensure
- # Note that the return value above does not depend on this assignment.
- current[:available_queries_for_explain] = original
+ ExplainRegistry.reset
end
# Makes the adapter execute EXPLAIN for the tuples of queries and bindings.
# Returns a formatted string ready to be logged.
def exec_explain(queries) # :nodoc:
- str = queries && queries.map do |sql, bind|
+ str = queries.map do |sql, bind|
[].tap do |msg|
msg << "EXPLAIN for: #{sql}"
unless bind.empty?
@@ -31,6 +31,7 @@ def exec_explain(queries) # :nodoc:
def str.inspect
self
end
+
str
end
end
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30 activerecord/lib/active_record/explain_registry.rb
@@ -0,0 +1,30 @@
+require 'active_support/per_thread_registry'
+
+module ActiveRecord
+ # This is a thread locals registry for EXPLAIN. For example
+ #
+ # ActiveRecord::ExplainRegistry.queries
+ #
+ # returns the collected queries local to the current thread.
+ #
+ # See the documentation of <tt>ActiveSupport::PerThreadRegistry</tt>
+ # for further details.
+ class ExplainRegistry
@frodsan
frodsan added a note Apr 17, 2013

Are there plans to use this outside of Rails?

@fxn
Ruby on Rails member
fxn added a note Apr 17, 2013

Explain support is a feature of Active Record, why?

@rafaelfranca
Ruby on Rails member
rafaelfranca added a note Apr 17, 2013

I think he want to know if we should add # :nodoc:

@fxn
Ruby on Rails member
fxn added a note Apr 17, 2013

Ah, cool, saw the commit adding it :+1:.

@frodsan
frodsan added a note Apr 17, 2013

indeed :smile:

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+ extend ActiveSupport::PerThreadRegistry
+
+ attr_accessor :queries, :collect
+
+ def initialize
+ reset
+ end
+
+ def collect?
+ @collect
+ end
+
+ def reset
+ @collect = false
+ @queries = []
+ end
+ end
+end
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5 activerecord/lib/active_record/explain_subscriber.rb
@@ -1,4 +1,5 @@
require 'active_support/notifications'
+require 'active_record/explain_registry'
module ActiveRecord
class ExplainSubscriber # :nodoc:
@@ -7,8 +8,8 @@ def start(name, id, payload)
end
def finish(name, id, payload)
- if queries = Thread.current[:available_queries_for_explain]
- queries << payload.values_at(:sql, :binds) unless ignore_payload?(payload)
+ if ExplainRegistry.collect? && !ignore_payload?(payload)
+ ExplainRegistry.queries << payload.values_at(:sql, :binds)
end
end
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7 activerecord/test/cases/adapters/postgresql/explain_test.rb
@@ -22,13 +22,6 @@ def test_explain_with_eager_loading
assert_match %(EXPLAIN for: SELECT "audit_logs".* FROM "audit_logs" WHERE "audit_logs"."developer_id" IN (1)), explain
assert_match %(Seq Scan on audit_logs), explain
end
-
- def test_dont_explain_for_set_search_path
- queries = Thread.current[:available_queries_for_explain] = []
- ActiveRecord::Base.connection.schema_search_path = "public"
- assert queries.empty?
- end
-
end
end
end
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59 activerecord/test/cases/explain_subscriber_test.rb
@@ -1,55 +1,54 @@
require 'cases/helper'
+require 'active_record/explain_subscriber'
+require 'active_record/explain_registry'
if ActiveRecord::Base.connection.supports_explain?
class ExplainSubscriberTest < ActiveRecord::TestCase
SUBSCRIBER = ActiveRecord::ExplainSubscriber.new
- def test_collects_nothing_if_available_queries_for_explain_is_nil
- with_queries(nil) do
- SUBSCRIBER.finish(nil, nil, {})
- assert_nil Thread.current[:available_queries_for_explain]
- end
+ def setup
+ ActiveRecord::ExplainRegistry.reset
+ ActiveRecord::ExplainRegistry.collect = true
end
def test_collects_nothing_if_the_payload_has_an_exception
- with_queries([]) do |queries|
- SUBSCRIBER.finish(nil, nil, :exception => Exception.new)
- assert queries.empty?
- end
+ SUBSCRIBER.finish(nil, nil, exception: Exception.new)
+ assert queries.empty?
end
def test_collects_nothing_for_ignored_payloads
- with_queries([]) do |queries|
- ActiveRecord::ExplainSubscriber::IGNORED_PAYLOADS.each do |ip|
- SUBSCRIBER.finish(nil, nil, :name => ip)
- end
- assert queries.empty?
+ ActiveRecord::ExplainSubscriber::IGNORED_PAYLOADS.each do |ip|
+ SUBSCRIBER.finish(nil, nil, name: ip)
end
+ assert queries.empty?
+ end
+
+ def test_collects_nothing_if_collect_is_false
+ ActiveRecord::ExplainRegistry.collect = false
+ SUBSCRIBER.finish(nil, nil, name: 'SQL', sql: 'select 1 from users', binds: [1, 2])
+ assert queries.empty?
end
def test_collects_pairs_of_queries_and_binds
sql = 'select 1 from users'
binds = [1, 2]
- with_queries([]) do |queries|
- SUBSCRIBER.finish(nil, nil, :name => 'SQL', :sql => sql, :binds => binds)
- assert_equal 1, queries.size
- assert_equal sql, queries[0][0]
- assert_equal binds, queries[0][1]
- end
+ SUBSCRIBER.finish(nil, nil, name: 'SQL', sql: sql, binds: binds)
+ assert_equal 1, queries.size
+ assert_equal sql, queries[0][0]
+ assert_equal binds, queries[0][1]
end
- def test_collects_nothing_if_unexplained_sqls
- with_queries([]) do |queries|
- SUBSCRIBER.finish(nil, nil, :name => 'SQL', :sql => 'SHOW max_identifier_length')
- assert queries.empty?
- end
+ def test_collects_nothing_if_the_statement_is_not_whitelisted
+ SUBSCRIBER.finish(nil, nil, name: 'SQL', sql: 'SHOW max_identifier_length')
+ assert queries.empty?
+ end
+
+ def teardown
+ ActiveRecord::ExplainRegistry.reset
end
- def with_queries(queries)
- Thread.current[:available_queries_for_explain] = queries
- yield queries
- ensure
- Thread.current[:available_queries_for_explain] = nil
+ def queries
+ ActiveRecord::ExplainRegistry.queries
end
end
end

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