Switch to Rack based session stores.

2 files changed, 320 insertions, 0 deletions

diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index 1aaf456c0f..c428366a04 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -60,6 +60,7 @@ module ActiveRecord
   autoload :Schema, 'active_record/schema'
   autoload :SchemaDumper, 'active_record/schema_dumper'
   autoload :Serialization, 'active_record/serialization'
+  autoload :SessionStore, 'active_record/session_store'
   autoload :TestCase, 'active_record/test_case'
   autoload :Timestamp, 'active_record/timestamp'
   autoload :Transactions, 'active_record/transactions'
diff --git a/activerecord/lib/active_record/session_store.rb b/activerecord/lib/active_record/session_store.rb
new file mode 100644
index 0000000000..bd198c03b2
--- /dev/null
+++ b/activerecord/lib/active_record/session_store.rb
@@ -0,0 +1,319 @@
+module ActiveRecord
+  # A session store backed by an Active Record class.  A default class is
+  # provided, but any object duck-typing to an Active Record Session class
+  # with text +session_id+ and +data+ attributes is sufficient.
+  #
+  # The default assumes a +sessions+ tables with columns:
+  #   +id+ (numeric primary key),
+  #   +session_id+ (text, or longtext if your session data exceeds 65K), and
+  #   +data+ (text or longtext; careful if your session data exceeds 65KB).
+  # The +session_id+ column should always be indexed for speedy lookups.
+  # Session data is marshaled to the +data+ column in Base64 format.
+  # If the data you write is larger than the column's size limit,
+  # ActionController::SessionOverflowError will be raised.
+  #
+  # You may configure the table name, primary key, and data column.
+  # For example, at the end of <tt>config/environment.rb</tt>:
+  #   ActiveRecord::SessionStore::Session.table_name = 'legacy_session_table'
+  #   ActiveRecord::SessionStore::Session.primary_key = 'session_id'
+  #   ActiveRecord::SessionStore::Session.data_column_name = 'legacy_session_data'
+  # Note that setting the primary key to the +session_id+ frees you from
+  # having a separate +id+ column if you don't want it.  However, you must
+  # set <tt>session.model.id = session.session_id</tt> by hand!  A before filter
+  # on ApplicationController is a good place.
+  #
+  # Since the default class is a simple Active Record, you get timestamps
+  # for free if you add +created_at+ and +updated_at+ datetime columns to
+  # the +sessions+ table, making periodic session expiration a snap.
+  #
+  # You may provide your own session class implementation, whether a
+  # feature-packed Active Record or a bare-metal high-performance SQL
+  # store, by setting
+  #   ActiveRecord::SessionStore.session_class = MySessionClass
+  # You must implement these methods:
+  #   self.find_by_session_id(session_id)
+  #   initialize(hash_of_session_id_and_data)
+  #   attr_reader :session_id
+  #   attr_accessor :data
+  #   save
+  #   destroy
+  #
+  # The example SqlBypass class is a generic SQL session store.  You may
+  # use it as a basis for high-performance database-specific stores.
+  class SessionStore < ActionController::Session::AbstractStore
+    # The default Active Record class.
+    class Session < ActiveRecord::Base
+      ##
+      # :singleton-method:
+      # Customizable data column name.  Defaults to 'data'.
+      cattr_accessor :data_column_name
+      self.data_column_name = 'data'
+
+      before_save :marshal_data!
+      before_save :raise_on_session_data_overflow!
+
+      class << self
+        # Don't try to reload ARStore::Session in dev mode.
+        def reloadable? #:nodoc:
+          false
+        end
+
+        def data_column_size_limit
+          @data_column_size_limit ||= columns_hash[@@data_column_name].limit
+        end
+
+        # Hook to set up sessid compatibility.
+        def find_by_session_id(session_id)
+          setup_sessid_compatibility!
+          find_by_session_id(session_id)
+        end
+
+        def marshal(data)
+          ActiveSupport::Base64.encode64(Marshal.dump(data)) if data
+        end
+
+        def unmarshal(data)
+          Marshal.load(ActiveSupport::Base64.decode64(data)) if data
+        end
+
+        def create_table!
+          connection.execute <<-end_sql
+            CREATE TABLE #{table_name} (
+              id INTEGER PRIMARY KEY,
+              #{connection.quote_column_name('session_id')} TEXT UNIQUE,
+              #{connection.quote_column_name(@@data_column_name)} TEXT(255)
+            )
+          end_sql
+        end
+
+        def drop_table!
+          connection.execute "DROP TABLE #{table_name}"
+        end
+
+        private
+          # Compatibility with tables using sessid instead of session_id.
+          def setup_sessid_compatibility!
+            # Reset column info since it may be stale.
+            reset_column_information
+            if columns_hash['sessid']
+              def self.find_by_session_id(*args)
+                find_by_sessid(*args)
+              end
+
+              define_method(:session_id)  { sessid }
+              define_method(:session_id=) { |session_id| self.sessid = session_id }
+            else
+              def self.find_by_session_id(session_id)
+                find :first, :conditions => ["session_id #{attribute_condition(session_id)}", session_id]
+              end
+            end
+          end
+      end
+
+      # Lazy-unmarshal session state.
+      def data
+        @data ||= self.class.unmarshal(read_attribute(@@data_column_name)) || {}
+      end
+
+      attr_writer :data
+
+      # Has the session been loaded yet?
+      def loaded?
+        !!@data
+      end
+
+      private
+        def marshal_data!
+          return false if !loaded?
+          write_attribute(@@data_column_name, self.class.marshal(self.data))
+        end
+
+        # Ensures that the data about to be stored in the database is not
+        # larger than the data storage column. Raises
+        # ActionController::SessionOverflowError.
+        def raise_on_session_data_overflow!
+          return false if !loaded?
+          limit = self.class.data_column_size_limit
+          if loaded? and limit and read_attribute(@@data_column_name).size > limit
+            raise ActionController::SessionOverflowError
+          end
+        end
+    end
+
+    # A barebones session store which duck-types with the default session
+    # store but bypasses Active Record and issues SQL directly.  This is
+    # an example session model class meant as a basis for your own classes.
+    #
+    # The database connection, table name, and session id and data columns
+    # are configurable class attributes.  Marshaling and unmarshaling
+    # are implemented as class methods that you may override.  By default,
+    # marshaling data is
+    #
+    #   ActiveSupport::Base64.encode64(Marshal.dump(data))
+    #
+    # and unmarshaling data is
+    #
+    #   Marshal.load(ActiveSupport::Base64.decode64(data))
+    #
+    # This marshaling behavior is intended to store the widest range of
+    # binary session data in a +text+ column.  For higher performance,
+    # store in a +blob+ column instead and forgo the Base64 encoding.
+    class SqlBypass
+      ##
+      # :singleton-method:
+      # Use the ActiveRecord::Base.connection by default.
+      cattr_accessor :connection
+
+      ##
+      # :singleton-method:
+      # The table name defaults to 'sessions'.
+      cattr_accessor :table_name
+      @@table_name = 'sessions'
+
+      ##
+      # :singleton-method:
+      # The session id field defaults to 'session_id'.
+      cattr_accessor :session_id_column
+      @@session_id_column = 'session_id'
+
+      ##
+      # :singleton-method:
+      # The data field defaults to 'data'.
+      cattr_accessor :data_column
+      @@data_column = 'data'
+
+      class << self
+        def connection
+          @@connection ||= ActiveRecord::Base.connection
+        end
+
+        # Look up a session by id and unmarshal its data if found.
+        def find_by_session_id(session_id)
+          if record = @@connection.select_one("SELECT * FROM #{@@table_name} WHERE #{@@session_id_column}=#{@@connection.quote(session_id)}")
+            new(:session_id => session_id, :marshaled_data => record['data'])
+          end
+        end
+
+        def marshal(data)
+          ActiveSupport::Base64.encode64(Marshal.dump(data)) if data
+        end
+
+        def unmarshal(data)
+          Marshal.load(ActiveSupport::Base64.decode64(data)) if data
+        end
+
+        def create_table!
+          @@connection.execute <<-end_sql
+            CREATE TABLE #{table_name} (
+              id INTEGER PRIMARY KEY,
+              #{@@connection.quote_column_name(session_id_column)} TEXT UNIQUE,
+              #{@@connection.quote_column_name(data_column)} TEXT
+            )
+          end_sql
+        end
+
+        def drop_table!
+          @@connection.execute "DROP TABLE #{table_name}"
+        end
+      end
+
+      attr_reader :session_id
+      attr_writer :data
+
+      # Look for normal and marshaled data, self.find_by_session_id's way of
+      # telling us to postpone unmarshaling until the data is requested.
+      # We need to handle a normal data attribute in case of a new record.
+      def initialize(attributes)
+        @session_id, @data, @marshaled_data = attributes[:session_id], attributes[:data], attributes[:marshaled_data]
+        @new_record = @marshaled_data.nil?
+      end
+
+      def new_record?
+        @new_record
+      end
+
+      # Lazy-unmarshal session state.
+      def data
+        unless @data
+          if @marshaled_data
+            @data, @marshaled_data = self.class.unmarshal(@marshaled_data) || {}, nil
+          else
+            @data = {}
+          end
+        end
+        @data
+      end
+
+      def loaded?
+        !!@data
+      end
+
+      def save
+        return false if !loaded?
+        marshaled_data = self.class.marshal(data)
+
+        if @new_record
+          @new_record = false
+          @@connection.update <<-end_sql, 'Create session'
+            INSERT INTO #{@@table_name} (
+              #{@@connection.quote_column_name(@@session_id_column)},
+              #{@@connection.quote_column_name(@@data_column)} )
+            VALUES (
+              #{@@connection.quote(session_id)},
+              #{@@connection.quote(marshaled_data)} )
+          end_sql
+        else
+          @@connection.update <<-end_sql, 'Update session'
+            UPDATE #{@@table_name}
+            SET #{@@connection.quote_column_name(@@data_column)}=#{@@connection.quote(marshaled_data)}
+            WHERE #{@@connection.quote_column_name(@@session_id_column)}=#{@@connection.quote(session_id)}
+          end_sql
+        end
+      end
+
+      def destroy
+        unless @new_record
+          @@connection.delete <<-end_sql, 'Destroy session'
+            DELETE FROM #{@@table_name}
+            WHERE #{@@connection.quote_column_name(@@session_id_column)}=#{@@connection.quote(session_id)}
+          end_sql
+        end
+      end
+    end
+
+    # The class used for session storage.  Defaults to
+    # ActiveRecord::SessionStore::Session
+    cattr_accessor :session_class
+    self.session_class = Session
+
+    SESSION_RECORD_KEY = 'rack.session.record'.freeze
+
+    private
+      def get_session(env, sid)
+        Base.silence do
+          sid ||= generate_sid
+          session = @@session_class.find_by_session_id(sid)
+          session ||= @@session_class.new(:session_id => sid, :data => {})
+          env[SESSION_RECORD_KEY] = session
+          [sid, session.data]
+        end
+      end
+
+      def set_session(env, sid, session_data)
+        Base.silence do
+          record = env[SESSION_RECORD_KEY]
+          record.data = session_data
+          return false unless record.save
+
+          session_data = record.data
+          if session_data && session_data.respond_to?(:each_value)
+            session_data.each_value do |obj|
+              obj.clear_association_cache if obj.respond_to?(:clear_association_cache)
+            end
+          end
+        end
+
+        return true
+      end
+  end
+end