From e96558f8138d01ea64096f152f32c480af0861e6 Mon Sep 17 00:00:00 2001
From: Jon Leighton <j@jonathanleighton.com>
Date: Fri, 31 Aug 2012 14:54:43 +0100
Subject: Cache the connection pool for a given class
---
.../abstract/connection_pool.rb | 55 ++++++++++++++--------
.../connection_adapters/connection_handler_test.rb | 2 +
2 files changed, 37 insertions(+), 20 deletions(-)
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
index 09a2c28351..7a3d9bfd3e 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -497,15 +497,17 @@ module ActiveRecord
# determine that connection pool that they should use.
class ConnectionHandler
def initialize
+ @owner_to_pool = Hash.new { |h,k| h[k] = {} }
@class_to_pool = Hash.new { |h,k| h[k] = {} }
end
def connection_pools
- class_to_pool.values.compact
+ owner_to_pool.values.compact
end
- def establish_connection(klass, spec)
- class_to_pool[klass] = ConnectionAdapters::ConnectionPool.new(spec)
+ def establish_connection(owner, spec)
+ @class_to_pool.clear
+ owner_to_pool[owner] = ConnectionAdapters::ConnectionPool.new(spec)
end
# Returns true if there are any active connections among the connection
@@ -550,48 +552,61 @@ module ActiveRecord
# connection and the defined connection (if they exist). The result
# can be used as an argument for establish_connection, for easily
# re-establishing the connection.
- def remove_connection(klass)
- if pool = class_to_pool.delete(klass)
+ def remove_connection(owner)
+ if pool = owner_to_pool.delete(owner)
+ @class_to_pool.clear
pool.automatic_reconnect = false
pool.disconnect!
pool.spec.config
end
end
+ # Retrieving the connection pool happens a lot so we cache it in @class_to_pool.
+ # This makes retrieving the connection pool O(1) once the process is warm.
+ # When a connection is established or removed, we invalidate the cache.
+ #
+ # Ideally we would use #fetch here, as class_to_pool[klass] may sometimes be nil.
+ # However, benchmarking (https://gist.github.com/3552829) showed that #fetch is
+ # significantly slower than #[]. So in the nil case, no caching will take place,
+ # but that's ok since the nil case is not the common one that we wish to optimise
+ # for.
def retrieve_connection_pool(klass)
- pool = get_pool_for_class(klass)
+ class_to_pool[klass] ||= begin
+ until pool = pool_for(klass)
+ klass = klass.superclass
+ break unless klass < Model::Tag
+ end
- until pool
- klass = klass.superclass
- break unless klass < Model::Tag
- pool = get_pool_for_class(klass)
+ class_to_pool[klass] = pool || pool_for(ActiveRecord::Model)
end
-
- pool || get_pool_for_class(ActiveRecord::Model)
end
private
+ def owner_to_pool
+ @owner_to_pool[Process.pid]
+ end
+
def class_to_pool
@class_to_pool[Process.pid]
end
- def get_pool_for_class(klass)
- class_to_pool.fetch(klass) {
- if ancestor_pool = get_pool_for_class_from_any_process(klass)
+ def pool_for(owner)
+ owner_to_pool.fetch(owner) {
+ if ancestor_pool = pool_from_any_process_for(owner)
# A connection was established in an ancestor process that must have
# subsequently forked. We can't reuse the connection, but we can copy
# the specification and establish a new connection with it.
- establish_connection klass, ancestor_pool.spec
+ establish_connection owner, ancestor_pool.spec
else
- class_to_pool[klass] = nil
+ owner_to_pool[owner] = nil
end
}
end
- def get_pool_for_class_from_any_process(klass)
- c_to_p = @class_to_pool.values.find { |class_to_pool| class_to_pool[klass] }
- c_to_p && c_to_p[klass]
+ def pool_from_any_process_for(owner)
+ owner_to_pool = @owner_to_pool.values.find { |v| v[owner] }
+ owner_to_pool && owner_to_pool[owner]
end
end
diff --git a/activerecord/test/cases/connection_adapters/connection_handler_test.rb b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
index 2286ef1391..e1579d037f 100644
--- a/activerecord/test/cases/connection_adapters/connection_handler_test.rb
+++ b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
@@ -37,6 +37,8 @@ module ActiveRecord
def test_retrieve_connection_pool_uses_superclass_pool_after_subclass_establish_and_remove
@handler.establish_connection 'north america', Base.connection_pool.spec
+ assert_same @handler.retrieve_connection_pool(@klass),
+ @handler.retrieve_connection_pool(@subklass)
@handler.remove_connection @subklass
assert_same @handler.retrieve_connection_pool(@klass),
--
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