11908: Migrate collections.properties to jsonb.
[arvados.git] / services / api / app / models / arvados_model.rb
index 16bafcaf5f4ff1bde48a2acf11a20e909a4bfce1..08d7e9345dbb8178d6891821277e6a01958aeacd 100644 (file)
@@ -1,14 +1,18 @@
+# Copyright (C) The Arvados Authors. All rights reserved.
+#
+# SPDX-License-Identifier: AGPL-3.0
+
 require 'has_uuid'
+require 'record_filters'
+require 'serializers'
 
 class ArvadosModel < ActiveRecord::Base
   self.abstract_class = true
 
   include CurrentApiClient      # current_user, current_api_client, etc.
+  include DbCurrentTime
+  extend RecordFilters
 
-  attr_protected :created_at
-  attr_protected :modified_by_user_uuid
-  attr_protected :modified_by_client_uuid
-  attr_protected :modified_at
   after_initialize :log_start_state
   before_save :ensure_permission_to_save
   before_save :ensure_owner_uuid_is_permitted
@@ -21,14 +25,18 @@ class ArvadosModel < ActiveRecord::Base
   after_update :log_update
   after_destroy :log_destroy
   after_find :convert_serialized_symbols_to_strings
-  validate :ensure_serialized_attribute_type
-  validate :normalize_collection_uuids
+  before_validation :normalize_collection_uuids
+  before_validation :set_default_owner
   validate :ensure_valid_uuids
 
   # Note: This only returns permission links. It does not account for
   # permissions obtained via user.is_admin or
   # user.uuid==object.owner_uuid.
-  has_many :permissions, :foreign_key => :head_uuid, :class_name => 'Link', :primary_key => :uuid, :conditions => "link_class = 'permission'"
+  has_many(:permissions,
+           ->{where(link_class: 'permission')},
+           foreign_key: :head_uuid,
+           class_name: 'Link',
+           primary_key: :uuid)
 
   class PermissionDeniedError < StandardError
     def http_status
@@ -36,12 +44,36 @@ class ArvadosModel < ActiveRecord::Base
     end
   end
 
+  class AlreadyLockedError < StandardError
+    def http_status
+      422
+    end
+  end
+
+  class LockFailedError < StandardError
+    def http_status
+      422
+    end
+  end
+
+  class InvalidStateTransitionError < StandardError
+    def http_status
+      422
+    end
+  end
+
   class UnauthorizedError < StandardError
     def http_status
       401
     end
   end
 
+  class UnresolvableContainerError < StandardError
+    def http_status
+      422
+    end
+  end
+
   def self.kind_class(kind)
     kind.match(/^arvados\#(.+)$/)[1].classify.safe_constantize rescue nil
   end
@@ -50,6 +82,52 @@ class ArvadosModel < ActiveRecord::Base
     "#{current_api_base}/#{self.class.to_s.pluralize.underscore}/#{self.uuid}"
   end
 
+  def self.permit_attribute_params raw_params
+    # strong_parameters does not provide security: permissions are
+    # implemented with before_save hooks.
+    #
+    # The following permit! is necessary even with
+    # "ActionController::Parameters.permit_all_parameters = true",
+    # because permit_all does not permit nested attributes.
+    if raw_params
+      serialized_attributes.each do |colname, coder|
+        param = raw_params[colname.to_sym]
+        if param.nil?
+          # ok
+        elsif !param.is_a?(coder.object_class)
+          raise ArgumentError.new("#{colname} parameter must be #{coder.object_class}, not #{param.class}")
+        elsif has_nonstring_keys?(param)
+          raise ArgumentError.new("#{colname} parameter cannot have non-string hash keys")
+        end
+      end
+    end
+    ActionController::Parameters.new(raw_params).permit!
+  end
+
+  def initialize raw_params={}, *args
+    super(self.class.permit_attribute_params(raw_params), *args)
+  end
+
+  # Reload "old attributes" for logging, too.
+  def reload(*args)
+    super
+    log_start_state
+  end
+
+  def self.create raw_params={}, *args
+    super(permit_attribute_params(raw_params), *args)
+  end
+
+  def update_attributes raw_params={}, *args
+    super(self.class.permit_attribute_params(raw_params), *args)
+  end
+
+  def self.selectable_attributes(template=:user)
+    # Return an array of attribute name strings that can be selected
+    # in the given template.
+    api_accessible_attributes(template).map { |attr_spec| attr_spec.first.to_s }
+  end
+
   def self.searchable_columns operator
     textonly_operator = !operator.match(/[<=>]/)
     self.columns.select do |col|
@@ -90,16 +168,67 @@ class ArvadosModel < ActiveRecord::Base
     api_column_map
   end
 
-  # Return nil if current user is not allowed to see the list of
-  # writers. Otherwise, return a list of user_ and group_uuids with
-  # write permission. (If not returning nil, current_user is always in
-  # the list because can_manage permission is needed to see the list
-  # of writers.)
+  def self.ignored_select_attributes
+    ["href", "kind", "etag"]
+  end
+
+  def self.columns_for_attributes(select_attributes)
+    if select_attributes.empty?
+      raise ArgumentError.new("Attribute selection list cannot be empty")
+    end
+    api_column_map = attributes_required_columns
+    invalid_attrs = []
+    select_attributes.each do |s|
+      next if ignored_select_attributes.include? s
+      if not s.is_a? String or not api_column_map.include? s
+        invalid_attrs << s
+      end
+    end
+    if not invalid_attrs.empty?
+      raise ArgumentError.new("Invalid attribute(s): #{invalid_attrs.inspect}")
+    end
+    # Given an array of attribute names to select, return an array of column
+    # names that must be fetched from the database to satisfy the request.
+    select_attributes.flat_map { |attr| api_column_map[attr] }.uniq
+  end
+
+  def self.default_orders
+    ["#{table_name}.modified_at desc", "#{table_name}.uuid"]
+  end
+
+  def self.unique_columns
+    ["id", "uuid"]
+  end
+
+  def self.limit_index_columns_read
+    # This method returns a list of column names.
+    # If an index request reads that column from the database,
+    # APIs that return lists will only fetch objects until reaching
+    # max_index_database_read bytes of data from those columns.
+    []
+  end
+
+  # If current user can manage the object, return an array of uuids of
+  # users and groups that have permission to write the object. The
+  # first two elements are always [self.owner_uuid, current user's
+  # uuid].
+  #
+  # If current user can write but not manage the object, return
+  # [self.owner_uuid, current user's uuid].
+  #
+  # If current user cannot write this object, just return
+  # [self.owner_uuid].
   def writable_by
+    return [owner_uuid] if not current_user
     unless (owner_uuid == current_user.uuid or
             current_user.is_admin or
-            current_user.groups_i_can(:manage).index(owner_uuid))
-      return nil
+            (current_user.groups_i_can(:manage) & [uuid, owner_uuid]).any?)
+      if ((current_user.groups_i_can(:write) + [current_user.uuid]) &
+          [uuid, owner_uuid]).any?
+        return [owner_uuid, current_user.uuid]
+      else
+        return [owner_uuid]
+      end
     end
     [owner_uuid, current_user.uuid] + permissions.collect do |p|
       if ['can_write', 'can_manage'].index p.name
@@ -123,92 +252,151 @@ class ArvadosModel < ActiveRecord::Base
       kwargs = {}
     end
 
-    # Check if any of the users are admin.  If so, we're done.
-    if users_list.select { |u| u.is_admin }.any?
-      return self
-    end
+    # Collect the UUIDs of the authorized users.
+    sql_table = kwargs.fetch(:table_name, table_name)
+    include_trash = kwargs.fetch(:include_trash, false)
+    query_on = kwargs.fetch(:query_on, self)
 
-    # Collect the uuids for each user and any groups readable by each user.
-    user_uuids = users_list.map { |u| u.uuid }
-    uuid_list = user_uuids + users_list.flat_map { |u| u.groups_i_can(:read) }
     sql_conds = []
-    sql_params = []
-    sql_table = kwargs.fetch(:table_name, table_name)
-    or_object_uuid = ''
+    user_uuids = users_list.map { |u| u.uuid }
 
-    # This row is owned by a member of users_list, or owned by a group
-    # readable by a member of users_list
-    # or
-    # This row uuid is the uuid of a member of users_list
-    # or
-    # A permission link exists ('write' and 'manage' implicitly include
-    # 'read') from a member of users_list, or a group readable by users_list,
-    # to this row, or to the owner of this row (see join() below).
-    sql_conds += ["#{sql_table}.uuid in (?)"]
-    sql_params += [user_uuids]
+    if users_list.select { |u| u.is_admin }.any?
+      if !include_trash
+        # exclude rows that are explicitly trashed.
+        if sql_table != "api_client_authorizations"
+          sql_conds.push "NOT EXISTS(SELECT 1
+                  FROM #{PERMISSION_VIEW}
+                  WHERE trashed = 1 AND
+                  (#{sql_table}.uuid = target_uuid OR #{sql_table}.owner_uuid = target_uuid))"
+        end
+      end
+    else
+      if include_trash
+        trashed_check = ""
+      else
+        trashed_check = "AND trashed = 0"
+      end
 
-    if uuid_list.any?
-      sql_conds += ["#{sql_table}.owner_uuid in (?)"]
-      sql_params += [uuid_list]
+      if sql_table != "api_client_authorizations" and sql_table != "groups"
+        owner_check = "OR (target_uuid = #{sql_table}.owner_uuid AND target_owner_uuid IS NOT NULL)"
+      else
+        owner_check = ""
+      end
 
-      sanitized_uuid_list = uuid_list.
-        collect { |uuid| sanitize(uuid) }.join(', ')
-      permitted_uuids = "(SELECT head_uuid FROM links WHERE link_class='permission' AND tail_uuid IN (#{sanitized_uuid_list}))"
-      sql_conds += ["#{sql_table}.uuid IN #{permitted_uuids}"]
-    end
+      sql_conds.push "EXISTS(SELECT 1 FROM #{PERMISSION_VIEW} "+
+                     "WHERE user_uuid IN (:user_uuids) AND perm_level >= 1 #{trashed_check} AND (target_uuid = #{sql_table}.uuid #{owner_check}))"
 
-    if sql_table == "links" and users_list.any?
-      # This row is a 'permission' or 'resources' link class
-      # The uuid for a member of users_list is referenced in either the head
-      # or tail of the link
-      sql_conds += ["(#{sql_table}.link_class in (#{sanitize 'permission'}, #{sanitize 'resources'}) AND (#{sql_table}.head_uuid IN (?) OR #{sql_table}.tail_uuid IN (?)))"]
-      sql_params += [user_uuids, user_uuids]
+      if sql_table == "links"
+        # Match any permission link that gives one of the authorized
+        # users some permission _or_ gives anyone else permission to
+        # view one of the authorized users.
+        sql_conds.push "(#{sql_table}.link_class IN (:permission_link_classes) AND "+
+                       "(#{sql_table}.head_uuid IN (:user_uuids) OR #{sql_table}.tail_uuid IN (:user_uuids)))"
+      end
     end
 
-    if sql_table == "logs" and users_list.any?
-      # Link head points to the object described by this row
-      sql_conds += ["#{sql_table}.object_uuid IN #{permitted_uuids}"]
+    query_on.where(sql_conds.join(' OR '),
+                    user_uuids: user_uuids,
+                    permission_link_classes: ['permission', 'resources'])
+  end
+
+  def save_with_unique_name!
+    uuid_was = uuid
+    name_was = name
+    max_retries = 2
+    transaction do
+      conn = ActiveRecord::Base.connection
+      conn.exec_query 'SAVEPOINT save_with_unique_name'
+      begin
+        save!
+      rescue ActiveRecord::RecordNotUnique => rn
+        raise if max_retries == 0
+        max_retries -= 1
+
+        conn.exec_query 'ROLLBACK TO SAVEPOINT save_with_unique_name'
+
+        # Dig into the error to determine if it is specifically calling out a
+        # (owner_uuid, name) uniqueness violation.  In this specific case, and
+        # the client requested a unique name with ensure_unique_name==true,
+        # update the name field and try to save again.  Loop as necessary to
+        # discover a unique name.  It is necessary to handle name choosing at
+        # this level (as opposed to the client) to ensure that record creation
+        # never fails due to a race condition.
+        err = rn.original_exception
+        raise unless err.is_a?(PG::UniqueViolation)
+
+        # Unfortunately ActiveRecord doesn't abstract out any of the
+        # necessary information to figure out if this the error is actually
+        # the specific case where we want to apply the ensure_unique_name
+        # behavior, so the following code is specialized to Postgres.
+        detail = err.result.error_field(PG::Result::PG_DIAG_MESSAGE_DETAIL)
+        raise unless /^Key \(owner_uuid, name\)=\([a-z0-9]{5}-[a-z0-9]{5}-[a-z0-9]{15}, .*?\) already exists\./.match detail
+
+        new_name = "#{name_was} (#{db_current_time.utc.iso8601(3)})"
+        if new_name == name
+          # If the database is fast enough to do two attempts in the
+          # same millisecond, we need to wait to ensure we try a
+          # different timestamp on each attempt.
+          sleep 0.002
+          new_name = "#{name_was} (#{db_current_time.utc.iso8601(3)})"
+        end
 
-      # This object described by this row is owned by this user, or owned by a group readable by this user
-      sql_conds += ["#{sql_table}.object_owner_uuid in (?)"]
-      sql_params += [uuid_list]
+        self[:name] = new_name
+        self[:uuid] = nil if uuid_was.nil? && !uuid.nil?
+        conn.exec_query 'SAVEPOINT save_with_unique_name'
+        retry
+      ensure
+        conn.exec_query 'RELEASE SAVEPOINT save_with_unique_name'
+      end
     end
+  end
 
-    if sql_table == "collections" and users_list.any?
-      # There is a 'name' link going from a readable group to the collection.
-      name_links = "(SELECT head_uuid FROM links WHERE link_class='name' AND tail_uuid IN (#{sanitized_uuid_list}))"
-      sql_conds += ["#{sql_table}.uuid IN #{name_links}"]
-    end
+  def logged_attributes
+    attributes.except(*Rails.configuration.unlogged_attributes)
+  end
 
-    # Link head points to this row, or to the owner of this row (the
-    # thing to be read)
-    #
-    # Link tail originates from this user, or a group that is readable
-    # by this user (the identity with authorization to read)
-    #
-    # Link class is 'permission' ('write' and 'manage' implicitly
-    # include 'read')
-    where(sql_conds.join(' OR '), *sql_params)
+  def self.full_text_searchable_columns
+    self.columns.select do |col|
+      [:string, :text, :jsonb].include?(col.type)
+    end.map(&:name)
   end
 
-  def logged_attributes
-    attributes
+  def self.full_text_tsvector
+    parts = full_text_searchable_columns.collect do |column|
+      cast = serialized_attributes[column] ? '::text' : ''
+      "coalesce(#{column}#{cast},'')"
+    end
+    "to_tsvector('english', #{parts.join(" || ' ' || ")})"
   end
 
-  def has_permission? perm_type, target_uuid
-    Link.where(link_class: "permission",
-               name: perm_type,
-               tail_uuid: uuid,
-               head_uuid: target_uuid).any?
+  def self.apply_filters query, filters
+    ft = record_filters filters, self
+    if not ft[:cond_out].any?
+      return query
+    end
+    query.where('(' + ft[:cond_out].join(') AND (') + ')',
+                          *ft[:param_out])
   end
 
   protected
 
+  def self.deep_sort_hash(x)
+    if x.is_a? Hash
+      x.sort.collect do |k, v|
+        [k, deep_sort_hash(v)]
+      end.to_h
+    elsif x.is_a? Array
+      x.collect { |v| deep_sort_hash(v) }
+    else
+      x
+    end
+  end
+
   def ensure_ownership_path_leads_to_user
     if new_record? or owner_uuid_changed?
       uuid_in_path = {owner_uuid => true, uuid => true}
       x = owner_uuid
-      while (owner_class = self.class.resource_class_for_uuid(x)) != User
+      while (owner_class = ArvadosModel::resource_class_for_uuid(x)) != User
         begin
           if x == uuid
             # Test for cycles with the new version, not the DB contents
@@ -236,29 +424,54 @@ class ArvadosModel < ActiveRecord::Base
     true
   end
 
-  def ensure_owner_uuid_is_permitted
-    raise PermissionDeniedError if !current_user
-    if new_record? and respond_to? :owner_uuid=
+  def set_default_owner
+    if new_record? and current_user and respond_to? :owner_uuid=
       self.owner_uuid ||= current_user.uuid
     end
-    # Verify permission to write to old owner (unless owner_uuid was
-    # nil -- or hasn't changed, in which case the following
-    # "permission to write to new owner" block will take care of us)
-    unless !owner_uuid_changed? or
-        owner_uuid_was.nil? or
-        current_user.uuid == self.owner_uuid_was or
-        current_user.uuid == self.uuid or
-        current_user.can? write: self.owner_uuid_was
-      logger.warn "User #{current_user.uuid} tried to modify #{self.class.to_s} #{uuid} but does not have permission to write old owner_uuid #{owner_uuid_was}"
-      errors.add :owner_uuid, "cannot be changed without write permission on old owner"
+  end
+
+  def ensure_owner_uuid_is_permitted
+    raise PermissionDeniedError if !current_user
+
+    if self.owner_uuid.nil?
+      errors.add :owner_uuid, "cannot be nil"
       raise PermissionDeniedError
     end
-    # Verify permission to write to new owner
-    unless current_user == self or current_user.can? write: owner_uuid
-      logger.warn "User #{current_user.uuid} tried to modify #{self.class.to_s} #{uuid} but does not have permission to write new owner_uuid #{owner_uuid}"
-      errors.add :owner_uuid, "cannot be changed without write permission on new owner"
+
+    rsc_class = ArvadosModel::resource_class_for_uuid owner_uuid
+    unless rsc_class == User or rsc_class == Group
+      errors.add :owner_uuid, "must be set to User or Group"
       raise PermissionDeniedError
     end
+
+    if new_record? || owner_uuid_changed?
+      # Permission on owner_uuid_was is needed to move an existing
+      # object away from its previous owner (which implies permission
+      # to modify this object itself, so we don't need to check that
+      # separately). Permission on the new owner_uuid is also needed.
+      [['old', owner_uuid_was],
+       ['new', owner_uuid]
+      ].each do |which, check_uuid|
+        if check_uuid.nil?
+          # old_owner_uuid is nil? New record, no need to check.
+        elsif !current_user.can?(write: check_uuid)
+          logger.warn "User #{current_user.uuid} tried to set ownership of #{self.class.to_s} #{self.uuid} but does not have permission to write #{which} owner_uuid #{check_uuid}"
+          errors.add :owner_uuid, "cannot be set or changed without write permission on #{which} owner"
+          raise PermissionDeniedError
+        end
+      end
+    else
+      # If the object already existed and we're not changing
+      # owner_uuid, we only need write permission on the object
+      # itself.
+      if !current_user.can?(write: self.uuid)
+        logger.warn "User #{current_user.uuid} tried to modify #{self.class.to_s} #{self.uuid} without write permission"
+        errors.add :uuid, "is not writable"
+        raise PermissionDeniedError
+      end
+    end
+
+    true
   end
 
   def ensure_permission_to_save
@@ -302,28 +515,44 @@ class ArvadosModel < ActiveRecord::Base
   end
 
   def update_modified_by_fields
-    self.updated_at = Time.now
+    current_time = db_current_time
+    self.created_at = created_at_was || current_time
+    self.updated_at = current_time
     self.owner_uuid ||= current_default_owner if self.respond_to? :owner_uuid=
-    self.modified_at = Time.now
+    self.modified_at = current_time
     self.modified_by_user_uuid = current_user ? current_user.uuid : nil
     self.modified_by_client_uuid = current_api_client ? current_api_client.uuid : nil
     true
   end
 
+  def self.has_nonstring_keys? x
+    if x.is_a? Hash
+      x.each do |k,v|
+        return true if !(k.is_a?(String) || k.is_a?(Symbol)) || has_nonstring_keys?(v)
+      end
+    elsif x.is_a? Array
+      x.each do |v|
+        return true if has_nonstring_keys?(v)
+      end
+    end
+    false
+  end
+
   def self.has_symbols? x
     if x.is_a? Hash
       x.each do |k,v|
         return true if has_symbols?(k) or has_symbols?(v)
       end
-      false
     elsif x.is_a? Array
       x.each do |k|
         return true if has_symbols?(k)
       end
-      false
-    else
-      (x.class == Symbol)
+    elsif x.is_a? Symbol
+      return true
+    elsif x.is_a? String
+      return true if x.start_with?(':') && !x.start_with?('::')
     end
+    false
   end
 
   def self.recursive_stringify x
@@ -337,27 +566,43 @@ class ArvadosModel < ActiveRecord::Base
       end
     elsif x.is_a? Symbol
       x.to_s
+    elsif x.is_a? String and x.start_with?(':') and !x.start_with?('::')
+      x[1..-1]
     else
       x
     end
   end
 
-  def ensure_serialized_attribute_type
-    # Specifying a type in the "serialize" declaration causes rails to
-    # raise an exception if a different data type is retrieved from
-    # the database during load().  The validation preventing such
-    # crash-inducing records from being inserted in the database in
-    # the first place seems to have been left as an exercise to the
-    # developer.
-    self.class.serialized_attributes.each do |colname, attr|
-      if attr.object_class
-        if self.attributes[colname].class != attr.object_class
-          self.errors.add colname.to_sym, "must be a #{attr.object_class.to_s}, not a #{self.attributes[colname].class.to_s}"
-        elsif self.class.has_symbols? attributes[colname]
-          self.errors.add colname.to_sym, "must not contain symbols: #{attributes[colname].inspect}"
-        end
-      end
+  def self.where_serialized(colname, value)
+    if value.empty?
+      # rails4 stores as null, rails3 stored as serialized [] or {}
+      sql = "#{colname.to_s} is null or #{colname.to_s} IN (?)"
+      sorted = value
+    else
+      sql = "#{colname.to_s} IN (?)"
+      sorted = deep_sort_hash(value)
     end
+    where(sql, [sorted.to_yaml, SafeJSON.dump(sorted)])
+  end
+
+  Serializer = {
+    Hash => HashSerializer,
+    Array => ArraySerializer,
+  }
+
+  def self.serialize(colname, type)
+    coder = Serializer[type]
+    @serialized_attributes ||= {}
+    @serialized_attributes[colname.to_s] = coder
+    super(colname, coder)
+  end
+
+  def self.serialized_attributes
+    @serialized_attributes ||= {}
+  end
+
+  def serialized_attributes
+    self.class.serialized_attributes
   end
 
   def convert_serialized_symbols_to_strings
@@ -370,14 +615,14 @@ class ArvadosModel < ActiveRecord::Base
     self.class.serialized_attributes.each do |colname, attr|
       if self.class.has_symbols? attributes[colname]
         attributes[colname] = self.class.recursive_stringify attributes[colname]
-        self.send(colname + '=',
-                  self.class.recursive_stringify(attributes[colname]))
+        send(colname + '=',
+             self.class.recursive_stringify(attributes[colname]))
       end
     end
   end
 
   def foreign_key_attributes
-    attributes.keys.select { |a| a.match /_uuid$/ }
+    attributes.keys.select { |a| a.match(/_uuid$/) }
   end
 
   def skip_uuid_read_permission_check
@@ -392,7 +637,7 @@ class ArvadosModel < ActiveRecord::Base
     foreign_key_attributes.each do |attr|
       attr_value = send attr
       if attr_value.is_a? String and
-          attr_value.match /^[0-9a-f]{32,}(\+[@\w]+)*$/
+          attr_value.match(/^[0-9a-f]{32,}(\+[@\w]+)*$/)
         begin
           send "#{attr}=", Collection.normalize_uuid(attr_value)
         rescue
@@ -402,12 +647,11 @@ class ArvadosModel < ActiveRecord::Base
     end
   end
 
-  @@UUID_REGEX = /^[0-9a-z]{5}-([0-9a-z]{5})-[0-9a-z]{15}$/
-
   @@prefixes_hash = nil
   def self.uuid_prefixes
     unless @@prefixes_hash
       @@prefixes_hash = {}
+      Rails.application.eager_load!
       ActiveRecord::Base.descendants.reject(&:abstract_class?).each do |k|
         if k.respond_to?(:uuid_prefix)
           @@prefixes_hash[k.uuid_prefix] = k
@@ -418,11 +662,15 @@ class ArvadosModel < ActiveRecord::Base
   end
 
   def self.uuid_like_pattern
-    "_____-#{uuid_prefix}-_______________"
+    "#{Rails.configuration.uuid_prefix}-#{uuid_prefix}-_______________"
+  end
+
+  def self.uuid_regex
+    %r/[a-z0-9]{5}-#{uuid_prefix}-[a-z0-9]{15}/
   end
 
   def ensure_valid_uuids
-    specials = [system_user_uuid, 'd41d8cd98f00b204e9800998ecf8427e+0']
+    specials = [system_user_uuid]
 
     foreign_key_attributes.each do |attr|
       if new_record? or send (attr + "_changed?")
@@ -468,17 +716,12 @@ class ArvadosModel < ActiveRecord::Base
     unless uuid.is_a? String
       return nil
     end
-    if uuid.match /^[0-9a-f]{32}(\+[^,]+)*(,[0-9a-f]{32}(\+[^,]+)*)*$/
-      return Collection
-    end
-    resource_class = nil
 
-    Rails.application.eager_load!
-    uuid.match @@UUID_REGEX do |re|
+    uuid.match HasUuid::UUID_REGEX do |re|
       return uuid_prefixes[re[1]] if uuid_prefixes[re[1]]
     end
 
-    if uuid.match /.+@.+/
+    if uuid.match(/.+@.+/)
       return Email
     end
 
@@ -491,22 +734,21 @@ class ArvadosModel < ActiveRecord::Base
     if self == ArvadosModel
       # If called directly as ArvadosModel.find_by_uuid rather than via subclass,
       # delegate to the appropriate subclass based on the given uuid.
-      self.resource_class_for_uuid(uuid).find_by_uuid(uuid)
+      self.resource_class_for_uuid(uuid).unscoped.find_by_uuid(uuid)
     else
       super
     end
   end
 
   def log_start_state
-    @old_etag = etag
-    @old_attributes = logged_attributes
+    @old_attributes = Marshal.load(Marshal.dump(attributes))
+    @old_logged_attributes = Marshal.load(Marshal.dump(logged_attributes))
   end
 
   def log_change(event_type)
     log = Log.new(event_type: event_type).fill_object(self)
     yield log
     log.save!
-    connection.execute "NOTIFY logs, '#{log.id}'"
     log_start_state
   end
 
@@ -519,14 +761,14 @@ class ArvadosModel < ActiveRecord::Base
 
   def log_update
     log_change('update') do |log|
-      log.fill_properties('old', @old_etag, @old_attributes)
+      log.fill_properties('old', etag(@old_attributes), @old_logged_attributes)
       log.update_to self
     end
   end
 
   def log_destroy
-    log_change('destroy') do |log|
-      log.fill_properties('old', @old_etag, @old_attributes)
+    log_change('delete') do |log|
+      log.fill_properties('old', etag(@old_attributes), @old_logged_attributes)
       log.update_to nil
     end
   end