Deprecate allow_concurrency and make it have no effect

4 files changed, 20 insertions, 59 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index b5ffc471bc..bc6d61301f 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -452,13 +452,6 @@ module ActiveRecord #:nodoc:
     cattr_accessor :default_timezone, :instance_writer => false
     @@default_timezone = :local
 
-    # Determines whether to use a connection for each thread, or a single shared connection for all threads.
-    # Defaults to false. If you're writing a threaded application, set to true
-    # and periodically call verify_active_connections! to clear out connections
-    # assigned to stale threads.
-    cattr_accessor :allow_concurrency, :instance_writer => false
-    @@allow_concurrency = false
-
     # Specifies the format to use when dumping the database schema with Rails'
     # Rakefile.  If :sql, the schema is dumped as (potentially database-
     # specific) SQL statements.  If :ruby, the schema is dumped as an
@@ -1943,22 +1936,11 @@ module ActiveRecord #:nodoc:
           end
         end
 
-        def thread_safe_scoped_methods #:nodoc:
+        def scoped_methods #:nodoc:
           scoped_methods = (Thread.current[:scoped_methods] ||= {})
           scoped_methods[self] ||= []
         end
 
-        def single_threaded_scoped_methods #:nodoc:
-          @scoped_methods ||= []
-        end
-
-        # pick up the correct scoped_methods version from @@allow_concurrency
-        if @@allow_concurrency
-          alias_method :scoped_methods, :thread_safe_scoped_methods
-        else
-          alias_method :scoped_methods, :single_threaded_scoped_methods
-        end
-
         def current_scoped_methods #:nodoc:
           scoped_methods.last
         end
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 365c80fe1d..04c8361c64 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -154,7 +154,7 @@ module ActiveRecord
 
       private
       def new_connection
-        config = spec.config.reverse_merge(:allow_concurrency => ActiveRecord::Base.allow_concurrency)
+        config = spec.config.reverse_merge(:allow_concurrency => true)
         ActiveRecord::Base.send(spec.adapter_method, config)
       end
 
@@ -285,9 +285,12 @@ module ActiveRecord
       end
     end
 
-    module ConnectionHandlerMethods
+    class ConnectionHandler
+      attr_reader :connection_pools_lock
+
       def initialize(pools = {})
         @connection_pools = pools
+        @connection_pools_lock = Monitor.new
       end
 
       def connection_pools
@@ -361,24 +364,6 @@ module ActiveRecord
           klass = klass.superclass
         end
       end
-    end
-
-    # This connection handler is not thread-safe, as it does not protect access
-    # to the underlying connection pools.
-    class SingleThreadConnectionHandler
-      include ConnectionHandlerMethods
-    end
-
-    # This connection handler is thread-safe. Each access or modification of a thread
-    # pool is synchronized by an internal monitor.
-    class MultipleThreadConnectionHandler
-      attr_reader :connection_pools_lock
-      include ConnectionHandlerMethods
-
-      def initialize(pools = {})
-        super
-        @connection_pools_lock = Monitor.new
-      end
 
       # Apply monitor to all public methods that access the pool.
       synchronize :establish_connection, :retrieve_connection,
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
index 0910db1951..47fc11a620 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
@@ -14,25 +14,7 @@ module ActiveRecord
 
     # The connection handler
     cattr_accessor :connection_handler, :instance_writer => false
-    @@connection_handler = ConnectionAdapters::SingleThreadConnectionHandler.new
-
-    # Turning on allow_concurrency changes the single threaded connection handler
-    # for a multiple threaded one, so that multi-threaded access of the
-    # connection pools is synchronized.
-    def self.allow_concurrency=(flag)
-      if @@allow_concurrency != flag
-        @@allow_concurrency = flag
-        # When switching connection handlers, preserve the existing pools so that
-        # #establish_connection doesn't need to be called again.
-        if @@allow_concurrency
-          self.connection_handler = ConnectionAdapters::MultipleThreadConnectionHandler.new(
-            self.connection_handler.connection_pools)
-        else
-          self.connection_handler = ConnectionAdapters::SingleThreadConnectionHandler.new(
-            self.connection_handler.connection_pools)
-        end
-      end
-    end
+    @@connection_handler = ConnectionAdapters::ConnectionHandler.new
 
     # Returns the connection currently associated with the class. This can
     # also be used to "borrow" the connection to do database work that isn't
@@ -109,6 +91,16 @@ module ActiveRecord
     end
 
     class << self
+      # Deprecated and no longer has any effect.
+      def allow_concurrency
+        ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency has been deprecated and no longer has any effect. Please remove all references to allow_concurrency.")
+      end
+
+      # Deprecated and no longer has any effect.
+      def allow_concurrency=(flag)
+        ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency= has been deprecated and no longer has any effect. Please remove all references to allow_concurrency=.")
+      end
+
       # Returns the connection currently associated with the class. This can
       # also be used to "borrow" the connection to do database work unrelated
       # to any of the specific Active Records.
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index c37ebf1410..7ef8834547 100755
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -109,7 +109,9 @@ module ActiveRecord
       # ROLLBACK and swallows any exceptions which is probably not enough to
       # ensure the connection is clean.
       def reset!
-        execute "ROLLBACK" rescue nil
+        silence_stderr do # postgres prints on stderr when you do this w/o a txn
+          execute "ROLLBACK" rescue nil
+        end
       end
 
       # Returns true if its safe to reload the connection between requests for development mode.