From e4c197c7698e204d0c74a2ece20adf831c2f9a8d Mon Sep 17 00:00:00 2001 From: Matthew Draper Date: Tue, 11 Apr 2017 08:10:24 +0930 Subject: Add comprehensive locking around DB transactions Transactional-fixture using tests with racing threads and inter-thread synchronisation inside transaction blocks will now deadlock... but without this, they would just crash. In 5.0, the threads didn't share a connection at all, so it would've worked... but with the main thread inside the fixture transaction, they wouldn't've been able to see each other. So: as far as I can tell, the set of operations this "breaks" never had a compelling use case. Meanwhile, it provides an increased level of coherency to the operational feel of transactional fixtures. If this does cause anyone problems, they're probably best off disabling transactional fixtures on the affected tests, and managing transactions themselves. --- .../connection_adapters/abstract/transaction.rb | 88 ++++++++++++---------- .../connection_adapters/abstract_adapter.rb | 2 +- .../connection_adapters/postgresql_adapter.rb | 32 +++++--- 3 files changed, 70 insertions(+), 52 deletions(-) (limited to 'activerecord') diff --git a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb index 6bb072dd73..19b7821494 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb @@ -149,57 +149,67 @@ module ActiveRecord end def begin_transaction(options = {}) - run_commit_callbacks = !current_transaction.joinable? - transaction = - if @stack.empty? - RealTransaction.new(@connection, options, run_commit_callbacks: run_commit_callbacks) - else - SavepointTransaction.new(@connection, "active_record_#{@stack.size}", options, - run_commit_callbacks: run_commit_callbacks) - end + @connection.lock.synchronize do + run_commit_callbacks = !current_transaction.joinable? + transaction = + if @stack.empty? + RealTransaction.new(@connection, options, run_commit_callbacks: run_commit_callbacks) + else + SavepointTransaction.new(@connection, "active_record_#{@stack.size}", options, + run_commit_callbacks: run_commit_callbacks) + end - @stack.push(transaction) - transaction + @stack.push(transaction) + transaction + end end def commit_transaction - transaction = @stack.last + @connection.lock.synchronize do + transaction = @stack.last - begin - transaction.before_commit_records - ensure - @stack.pop - end + begin + transaction.before_commit_records + ensure + @stack.pop + end - transaction.commit - transaction.commit_records + transaction.commit + transaction.commit_records + end end def rollback_transaction(transaction = nil) - transaction ||= @stack.pop - transaction.rollback - transaction.rollback_records + @connection.lock.synchronize do + transaction ||= @stack.pop + transaction.rollback + transaction.rollback_records + end end def within_new_transaction(options = {}) - transaction = begin_transaction options - yield - rescue Exception => error - if transaction - rollback_transaction - after_failure_actions(transaction, error) - end - raise - ensure - unless error - if Thread.current.status == "aborting" - rollback_transaction if transaction - else - begin - commit_transaction - rescue Exception - rollback_transaction(transaction) unless transaction.state.completed? - raise + @connection.lock.synchronize do + begin + transaction = begin_transaction options + yield + rescue Exception => error + if transaction + rollback_transaction + after_failure_actions(transaction, error) + end + raise + ensure + unless error + if Thread.current.status == "aborting" + rollback_transaction if transaction + else + begin + commit_transaction + rescue Exception + rollback_transaction(transaction) unless transaction.state.completed? + raise + end + end end end end diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb index 96083e6519..85d6fbe8b3 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb @@ -74,7 +74,7 @@ module ActiveRecord SIMPLE_INT = /\A\d+\z/ attr_accessor :visitor, :pool - attr_reader :schema_cache, :owner, :logger, :prepared_statements + attr_reader :schema_cache, :owner, :logger, :prepared_statements, :lock alias :in_use? :owner def self.type_cast_config_to_integer(config) diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb index 0ad114165e..7ae9bd9a5f 100644 --- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb @@ -239,7 +239,9 @@ module ActiveRecord # Is this connection alive and ready for queries? def active? - @connection.query "SELECT 1" + @lock.synchronize do + @connection.query "SELECT 1" + end true rescue PG::Error false @@ -247,26 +249,32 @@ module ActiveRecord # Close then reopen the connection. def reconnect! - super - @connection.reset - configure_connection + @lock.synchronize do + super + @connection.reset + configure_connection + end end def reset! - clear_cache! - reset_transaction - unless @connection.transaction_status == ::PG::PQTRANS_IDLE - @connection.query "ROLLBACK" + @lock.synchronize do + clear_cache! + reset_transaction + unless @connection.transaction_status == ::PG::PQTRANS_IDLE + @connection.query "ROLLBACK" + end + @connection.query "DISCARD ALL" + configure_connection end - @connection.query "DISCARD ALL" - configure_connection end # Disconnects from the database if already connected. Otherwise, this # method does nothing. def disconnect! - super - @connection.close rescue nil + @lock.synchronize do + super + @connection.close rescue nil + end end def native_database_types #:nodoc: -- cgit v1.2.3