Make many parts of Rails lazy. In order to facilitate this,

add lazy_load_hooks.rb, which allows us to declare code that
should be run at some later time. For instance, this allows
us to defer requiring ActiveRecord::Base at boot time purely
to apply configuration. Instead, we register a hook that should
apply configuration once ActiveRecord::Base is loaded.

With these changes, brings down total boot time of a
new app to 300ms in production and 400ms in dev.

TODO: rename base_hook

1 files changed, 165 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/errors.rb b/activerecord/lib/active_record/errors.rb
new file mode 100644
index 0000000000..cf5ddca2ba
--- /dev/null
+++ b/activerecord/lib/active_record/errors.rb
@@ -0,0 +1,165 @@
+module ActiveRecord
+  # Generic Active Record exception class.
+  class ActiveRecordError < StandardError
+  end
+
+  # Raised when the single-table inheritance mechanism fails to locate the subclass
+  # (for example due to improper usage of column that +inheritance_column+ points to).
+  class SubclassNotFound < ActiveRecordError #:nodoc:
+  end
+
+  # Raised when an object assigned to an association has an incorrect type.
+  #
+  #   class Ticket < ActiveRecord::Base
+  #     has_many :patches
+  #   end
+  #
+  #   class Patch < ActiveRecord::Base
+  #     belongs_to :ticket
+  #   end
+  #
+  #   # Comments are not patches, this assignment raises AssociationTypeMismatch.
+  #   @ticket.patches << Comment.new(:content => "Please attach tests to your patch.")
+  class AssociationTypeMismatch < ActiveRecordError
+  end
+
+  # Raised when unserialized object's type mismatches one specified for serializable field.
+  class SerializationTypeMismatch < ActiveRecordError
+  end
+
+  # Raised when adapter not specified on connection (or configuration file <tt>config/database.yml</tt> misses adapter field).
+  class AdapterNotSpecified < ActiveRecordError
+  end
+
+  # Raised when Active Record cannot find database adapter specified in <tt>config/database.yml</tt> or programmatically.
+  class AdapterNotFound < ActiveRecordError
+  end
+
+  # Raised when connection to the database could not been established (for example when <tt>connection=</tt> is given a nil object).
+  class ConnectionNotEstablished < ActiveRecordError
+  end
+
+  # Raised when Active Record cannot find record by given id or set of ids.
+  class RecordNotFound < ActiveRecordError
+  end
+
+  # Raised by ActiveRecord::Base.save! and ActiveRecord::Base.create! methods when record cannot be
+  # saved because record is invalid.
+  class RecordNotSaved < ActiveRecordError
+  end
+
+  # Raised when SQL statement cannot be executed by the database (for example, it's often the case for MySQL when Ruby driver used is too old).
+  class StatementInvalid < ActiveRecordError
+  end
+
+  # Raised when SQL statement is invalid and the application gets a blank result.
+  class ThrowResult < ActiveRecordError
+  end
+
+  # Parent class for all specific exceptions which wrap database driver exceptions
+  # provides access to the original exception also.
+  class WrappedDatabaseException < StatementInvalid
+    attr_reader :original_exception
+
+    def initialize(message, original_exception)
+      super(message)
+      @original_exception = original_exception
+    end
+  end
+
+  # Raised when a record cannot be inserted because it would violate a uniqueness constraint.
+  class RecordNotUnique < WrappedDatabaseException
+  end
+
+  # Raised when a record cannot be inserted or updated because it references a non-existent record.
+  class InvalidForeignKey < WrappedDatabaseException
+  end
+
+  # Raised when number of bind variables in statement given to <tt>:condition</tt> key (for example, when using +find+ method)
+  # does not match number of expected variables.
+  #
+  # For example, in
+  #
+  #   Location.find :all, :conditions => ["lat = ? AND lng = ?", 53.7362]
+  #
+  # two placeholders are given but only one variable to fill them.
+  class PreparedStatementInvalid < ActiveRecordError
+  end
+
+  # Raised on attempt to save stale record. Record is stale when it's being saved in another query after
+  # instantiation, for example, when two users edit the same wiki page and one starts editing and saves
+  # the page before the other.
+  #
+  # Read more about optimistic locking in ActiveRecord::Locking module RDoc.
+  class StaleObjectError < ActiveRecordError
+  end
+
+  # Raised when association is being configured improperly or
+  # user tries to use offset and limit together with has_many or has_and_belongs_to_many associations.
+  class ConfigurationError < ActiveRecordError
+  end
+
+  # Raised on attempt to update record that is instantiated as read only.
+  class ReadOnlyRecord < ActiveRecordError
+  end
+
+  # ActiveRecord::Transactions::ClassMethods.transaction uses this exception
+  # to distinguish a deliberate rollback from other exceptional situations.
+  # Normally, raising an exception will cause the +transaction+ method to rollback
+  # the database transaction *and* pass on the exception. But if you raise an
+  # ActiveRecord::Rollback exception, then the database transaction will be rolled back,
+  # without passing on the exception.
+  #
+  # For example, you could do this in your controller to rollback a transaction:
+  #
+  #   class BooksController < ActionController::Base
+  #     def create
+  #       Book.transaction do
+  #         book = Book.new(params[:book])
+  #         book.save!
+  #         if today_is_friday?
+  #           # The system must fail on Friday so that our support department
+  #           # won't be out of job. We silently rollback this transaction
+  #           # without telling the user.
+  #           raise ActiveRecord::Rollback, "Call tech support!"
+  #         end
+  #       end
+  #       # ActiveRecord::Rollback is the only exception that won't be passed on
+  #       # by ActiveRecord::Base.transaction, so this line will still be reached
+  #       # even on Friday.
+  #       redirect_to root_url
+  #     end
+  #   end
+  class Rollback < ActiveRecordError
+  end
+
+  # Raised when attribute has a name reserved by Active Record (when attribute has name of one of Active Record instance methods).
+  class DangerousAttributeError < ActiveRecordError
+  end
+
+  # Raised when unknown attributes are supplied via mass assignment.
+  class UnknownAttributeError < NoMethodError
+  end
+
+  # Raised when an error occurred while doing a mass assignment to an attribute through the
+  # <tt>attributes=</tt> method. The exception has an +attribute+ property that is the name of the
+  # offending attribute.
+  class AttributeAssignmentError < ActiveRecordError
+    attr_reader :exception, :attribute
+    def initialize(message, exception, attribute)
+      @exception = exception
+      @attribute = attribute
+      @message = message
+    end
+  end
+
+  # Raised when there are multiple errors while doing a mass assignment through the +attributes+
+  # method. The exception has an +errors+ property that contains an array of AttributeAssignmentError
+  # objects, each corresponding to the error while assigning to an attribute.
+  class MultiparameterAssignmentErrors < ActiveRecordError
+    attr_reader :errors
+    def initialize(errors)
+      @errors = errors
+    end
+  end
+end
\ No newline at end of file